The Science Behind SQUALENE
The Human Antioxidant
Dr. BIKUL DAS
Foreword By
Dr. Sylvain Baruchel
This Book discusses the function of Squalene in the human body and has been written for the reader interested in the changing perspective of research on bioactive nutrients, including Squalene. To substantiate the explanations in this book we have included research findings concerning the role of Squalene in the prevention of cancer and heart disease and in the enhancement of the immune function. This book does not suggest that people take Squalene as a dietary supplement, nor that they should not. It is the author’s sincere advice that before considering Squalene dietary supplementation, readers consult their physicians as this book is not meant as a substitute for competent medical care.
Despite rapid progress in medical research, fundamental biological mechanisms governing our body are still incompletely understood. However, a discussion of these
mechanisms is needed to link diverse research findings on nutrients. We encourage readers to take a science- oriented approach on nutrition rather than one based on
passive belief. Bear in mind that this book discusses biological hypotheses that should not be taken as established fact.
The author has checked the scientific literature referred to throughout this book in an effort to provide credible information on Squalene. However the possibility of human error cannot be discounted and the author, publisher and editor cannot and do not warrant the accuracy of the information contained herein.
The author hopes that this book will help to generate a further awareness of the need for environmental protection. Without a clean environment, even the best drug or dietary supplement is fighting a tough battle against both existent and newly-emerging diseases.
The author, editor and publisher expressly disclaim responsibility from the use or application of information described in this book.
I dedicate this book to my mother Mahindri and my wife Britta whose support is unending and who have graciously accepted my repeated absence from them in my
pursuit of knowledge.
Foreword 6
Preface 8
Editor’s note 10
Introduction 11
PART 1 – What is Squalene? 14
1 – The Primordial balance 14
The first antioxidants 15
Free Radicals 16
Types of antioxidants 16
Oxidant-antioxidant balance 17
Oxidative damage 17
Oxidative stress and antioxidant metabolism 19
Antioxidant metabolism and Squalene 19
Conclusion 20
2 – A History of Squalene 21
Squalene’s importance in the origins of life 21
Early Squalene research 22
The Isoprenoid synthesis pathway 22
Squalene’s importance recognized 23
Clinical applications of Squalene 24
Two forms of Squalene 24
Conclusion 26
3 – Squalene the antioxidant 27
Isoprene 27
Biomembrane structure 29
Vitamin E and Squalene compared 29
Squalene in the skin 31
Squalene’s role in the immune system 31
Squalene metabolism and cell growth 31
Squalene and aging 32
Conclusion 33
4 – Balance and stress in bodily systems 34
Immune imbalance 34
Effective immune balance 35
Oxidative Stress and immune imbalance 36
Apoptosis 37
Metabolic stress 39
An example of metabolic stress 39
Metabolic stress and immune suppression 39
Conclusion 40
Carcinogenesis 41
The evolution of Cancer 41
Cancer’s secret to success 42
The ras oncogene 42
Squalene’s inhibition of cancer proliferation 43
Carcinogenic agents 44
Squalene’s preventive/therapeutic potential 44
A growing body of research 45
Potential clinical applications 46
Cytoprotection – an undervalued modality 46
Criteria for a cytoprotective agent 47
Squalene’s cytoprotective roles 47
A multi-target approach to cancer therapy 49
Conclusion 49
6 – Cholesterol and heart disease 50
Coronary heart disease 50
Atherosclerosis 50
Good Cholesterol 51
Bad Cholesterol 51
Cholesterol transport 51
The worst cholesterol of all 53
Cholesterol lowering effects of Squalene 53
Conclusion 55
Part 11 – Squalene and Disease – Squalene and Disease Contents 5 – Squalene’s role in cancer & cancer therapy 41
Part 111
Squalene and environmental pollution 56
7 – Human skin: first casualty of ozone depletion
The epithelium – a protective coat 56
Ultraviolet radiation 57
The skin 58
Absorption of UV rays by skin 58
The skin’s natural antioxidant 59
Evolutionary Adaptation to Loss of Hair 59
Ozone depletion 60
Skin Cancer 60
Immune depression 60
Protecting against UV radiation 61
Are we safe? 62
Conclusion 62
8 – Background radiation 63
Sources of radiation 63
Ionizing radiation 63
Medical sources 63
Internal sources 63
Depleted uranium 63
Geological radiation 64
Cosmic radiation 64
Non-ionizing radiation 64
Consequences of background radiation 64
The radio protective role of Squalene 65
Squalene depletion due to radiation 65
Depleted uranium 63
Geological radiation 64
Cosmic radiation 64
Non-ionizing radiation 64
Consequences of background radiation 64
The radio protective role of Squalene 65
Squalene depletion due to radiation 65
Conclusion 66
9 – Air pollution, allergies and lung disease 67
Lipid peroxidation and allergies 67
Squalene synthesis – a potential adaptive mechanism
Conclusion 68
10 – The fat cell – A Storehouse of Toxins 69
Adipose Tissue – Depot or Organ? 69
Toxin Accumulation 70
Detoxification by the Liver 71
Detoxification by Adipose Tissue 71
The Xenobiotic Squalene Link 72
Conclusion 72
11 – Metabolic stress and chaos 73
Metabolic response to stress 73
Squalene metabolism 74
Squalene in the skin 74
Squalene in the fat tissue 74
Cyclic and Acyclic Squalene 75
Two metabolic pools 75
State of disequilibrium 76
The mechanism of metabolic stress 76
Chaos 77
Metabolic stress & chaos 77
Conclusion 78
Epilogue 79
Glossary 80
References
Index
Foreword
We talk daily about dietary nutrients, yet give little thought to how they work at the cellular level. Many people are amazed to learn that individual cells actually
synthesize some of the nutrients they need to maintain inner health. We pay even less attention to how research is progressing and which directions will reveal therapeutic solutions based on dietary nutrients. It is customary in our society to leave such questions in the hands of doctors and researchers. Few people are interested, perhaps in part because eating a salad is much more enjoyable than pondering its nutritional value. However, nutritional research is providing us with information crucial to our long-term health. Soon, more people will want to understand how nutrients work at a cellular level so they can adjust their diets to life style, specific disease risk and perhaps even according to genetic makeup.
The emerging awareness of cell signaling in nutrient research suggests that such an era of nutritional self-awareness is approaching. Our under-standing of cell signaling is revolutionizing nutrient research, but lay people remain largely unaware of the fact. Cell signaling describes how cells communicate with each other right into their interior. This information exchange employs molecules like a telephone network, one molecule relaying information to another in a domino sequence that eventually carries it to specific genes. Several such pathways are active in specific cells, just as one home may have several telephones. Cells rely on signaling pathways for growth, proliferation and various functional activities. Hormones and other biomolecules influence cells by acting on these signaling pathways.
In the last fifteen years, great progress has been made in unlocking the code of these signaling pathways, suggesting that many diseases are either caused or exacerbated by faulty cell signaling. This list includes cancer, diabetes, immune disorders and disorders of the nervous system. Signaling research shows that certain nutrients influence the signaling pathways and prevent or inhibit the growth of cancer. This research provides hope for the effective prevention and even the adjuvant treatment of some cancers.
The most promising approach seems to be the use of a nutrient combination to influence several signaling pathways at once in the hope that this will be more
effective than using a single nutrient. In this multi-target strategy “cocktails” of various nutrients would be given to people either at risk of a certain cancer or already suffering from it. Such nutrient cocktails may also sensitize tumor cells to chemotherapeutic agents, making conventional anti-cancer therapy both more effective and less toxic.
Only vigorous research can determine which signaling pathways to target and how. This explains why research into various bioactive nutrient groups is becoming
increasingly important. Isoprenoids are one such group of nutrients and are particularly significant to cellular growth and proliferation. There are hundreds, and
some are found to influence various signaling pathways. Squalene and its cyclic derivatives are non toxic Isoprenoids with great promise. The molecular activities of
Squalene and its related Isoprenoids – ursolic acid, oleanolic acid , geranyl and geraniol – can play a role in the anticancer cocktail and may contribute to other nutrient cocktails formulated to prevent such other disease states as elevated cholesterol.
This book’s appearance is very timely and reveals a new approach to nutrient
research. It discusses Squalene and its metabolism in the light of the latest understanding of molecular biology, giving an overview of Squalene metabolism and
how it seems to be much more than a mere cholesterol metabolite. Squalene is a powerful antioxidant with a potentially crucial role in the cellular antioxidant defense
system. However, Doctor Bikul Das points out that this research is still at an early stage and he discusses hypotheses about areas of fundamental biology that are not yet fully understood. This book is also an example of how ideas develop and scientific knowledge grows. Readers should therefore maintain caution and apply a critical eye in their interpretation of this book.
Dr. Das also hopes to provoke new directions in the study of pollution-induced disease. The idea of metabolic stress and its relation to oxidative stress outlined in this book, though not yet completely understood, shines a new light on the biology of such pollution-related health problems as UV radiation induced immune suppression.
We appreciate innovative thinking and hard work of the author and encourage him to continue his research on nutrients and their metabolism.
Dr. Sylvain Baruchel. M.D.
Associate Professor of Pediatrics, University of Toronto.
Staff Oncologist, Division of Hematology & Oncology.
Senior Scientist & Director of New Agent and Innovative Therapy Program
The Hospital for Sick Children, Toronto.
PREFACE
This book calls attention to Squalene – a remarkable nutrient produced in our body and also found in nature. Just a few decades ago, nutrients were thought to have
minimal research value. Today, nutrient research is a hot topic among medical circles, the research community and the general public. Several factors account for this
changing trend.
Firstly, there are today many calls for nontoxic, natural therapies to prevent or treat various disease processes. The hope is that understanding the cellular mechanism
of healing nutrients may lead to combination therapies in which several nutrients each target different mechanisms of a disease to achieve a common goal. Rapid advances in cell signaling research provide hope for such natural combinations, which may become more effective than artificial drugs. Squalene and its various cyclic derivatives such as ursolic acid are showing great promise in preventive therapy, particularly in the chemoprevention of cancer.
Secondly, there is also a great interest in the innate healing processes of the body. By understanding them we will learn to help and enhance our natural defenses.
Individual cells have sophisticated abilities to heal themselves. The cellular DNA repair process is an impressive example. During cell division, DNA divides into two identical strands of daughter DNA. When- as happens on occasion- this process leads to damage, a repairing process corrects it. Another example of cellular healing is when the cell systematically checks the cell membrane for defects or damage and employs several molecules to fix it. There are other examples of self-healing, for example the healing of skin lesions and broken bones. In these processes body tissues synthesize and distribute additional nutrients to facilitate repair and regeneration. For example, the concentration of glutathione – a cellular antioxidant – increases around a wound and facilitates the healing process.
Vitamins and other nutrients are already known to contribute to the healing processes of the body and there are probably many others, either synthesized by our
body or obtained from diet. An understanding of their function will shed new insight into innate healing processes. Dietary Squalene has been found to enhance the
elimination of toxins and minimize the toxic effect of UV radiation. With this in mind, the presence of very high levels of Squalene in human skin and adipose tissue is
attracting significant interest among researchers who are exploring the cellular mechanism of Squalene.
The third reason for renewed interest in nutrient research is an appreciation and understanding of the evolutionary dynamics of health and sickness. Evolution
focuses on the survival of a species. It helps organisms adapt to changing environments. During our species” turbulent evolution, we have learned to protect our
health. There is every reason to believe that the tissue distribution of certain nutrients has an evolutionary history. The presence of Squalene in our skin could be an example of such an evolutionary protective mechanism. I have taken Theodosius Dobzhansky’s famous quotation, “Nothing in biology makes sense except tin the light of evolution,” as encouragement to examine the evolutionary aspect of Squalene’s presence in our skin.
The growing interest in nutrient research has three general themes: medical practitioners are interested in using nutrients in preventative therapy, other individuals are interested in strengthening the innate healing processes through the use of scientifically proven nutrients, and medical researchers and biologists want to understand the evolutionary aspect of health and sickness.
ling processes through the use of scientifically proven nutrients, and medical researchers and biologists want to understand the evolutionary aspect of health and sickness.
The evolutionary aspect of nutrient research particularly interests me and I believe it may provide clues as to how pollution is affecting us. Health, evolution, and
pollution are very much related to each other. Research into such nutrients as Squalene may help clarify this relationship. In this industrial era, pollution is affecting all
biological systems. The question is, how can we best understand the long term impact of pollution: This new theme is discussed in part three.
Beyond this emerging frontier of nutrient research in the skin, Squalene’s rich history is primitive life, the ancient legends surrounding its healing power and the
modern insights into its unique presence in our skin is a fascinating human story that can bridge ancient legends and modern medical research.
The cover of the book illustrates a human cell against a background of the Earth. This image came to me as I was writing chapter 1, and thinking of human
vulnerability and our interdependence with the entire biosphere. The more we understand about our cells and organs and about nutrients like Squalene, the better we
will appreciate the need to maintain our own health and that out our environment. It is my sincere hope that this book will bring a fresh perspective to nutrient research.
Dr. Bikul Das
Research Fellow
Hospital For Sick Children
Toronto, Canada,
August 2000
Editor’s Note
Squalene is an Isoprenoid – an ancient biochemical that made it possible for archaic bacteria to flourish when our planet was an inhospitable, unrecognizable place.
Life began here on surfaces hot enough to boil water, with a virtual absence of atmospheric oxygen and no ozone layer to filter out the fierce ultraviolet radiation of
the sun. In fact, Earth’s surface looked more like Mars than the green orb we now cling to so precariously.
Under the protection of this lowly molecule, ancient bacteria proliferated, transforming the atmosphere so that green plants could emerge and harness the sun’s energy. They too depended on Isoprenoids to avoid being burned into a crisp in the process. Plant life in turn transformed the atmosphere into an oxygen-rich soup that made oxygen respiration possible – yet another reaction in which Squalene protects living tissue from oxyradicals. Then something extraordinary happened – and has been happening ever since – the linear Squalene curled up and provided the basis for the sterol nucleus of cholesterol, without which the modern animal cell would be unthinkable. This biochemical reaction, still not fully explained, remains “the most complex single step reaction in the biological world”. Among other things, it enabled
our forefathers to shed their furry outer coat and expose their naked skin to the sun’s rays without being destroyed by UV radiation.
Today, Squalene protects the biomembrane of cells and the myriad organelles within from oxidative stress. It helps the cholesterol metabolism maintain order and
keep levels of harmful LDL –cholesterol to a minimum. It contributes to the cell-renewal cycle and keeps cancer at bay.
But now this ubiquitous life-enabling Isoprenoid is under stress. Our environment is undergoing unprecedented oxidative and metabolic attack at the hands of p9ollutants, carcinogens and increased ultraviolet radiation. Has the molecule that has protected life for billions of years finally met its match? Or does this simple
substance, for so long considered virtually insignificant hole the clues to our evolutionary survival?
I share the author’s hope that this book will help to generate further awareness of the need to protect ourselves and our fragile planet. We must acknowledge that there is no guarantee of ultimate victory unless we act together to ensure that our environment remains amenable to life.
Stephen Schettini
Montreal May 2000
Stephen Schettini is a writer, illustrator and designer of medical books for professionals
and the general public. He has developed extensive training guides and learning
programs on the cardiovascular system, arthritis, hormone replacement therapy,
allergies & antihistamines, dermatology and prostate cancer. He has also coauthored
Glutathione [GSH]: Your Body’s Most Powerful Healing Agent [with Dr. Jimmy
Gutman] and the Osteoporosis Remedy [with Dr. I. William Lane]
Introduction
It has been clear for some years that Mediterranean peoples tend to suffer considerably less than others from heart disease and certain cancers. Scientists have
linked this to relatively high levels of olive oil consumption, but they aren’t first to make this connection. Many ancient Mediterranean cultures believed that olive oil
increases strength and longevity, and indeed the olive tree is a rich source of Squalene!
The olive tree has always been more than just another food source. Since the earliest days of Mediterranean civilization it has been surrounded by a wealth of cultural
symbolism. Ancient kings ruled with scepters of olive wood, priests still anoint the worthy with olive oil, and the olive branch is a recognized symbol of peace in many
cultures. Early Mediterranean peoples considered it a gift from the gods, worthy of be adored and defended. Old Greek and Roman writers referred to it as the Eternal Tree of Peach and the Jewish bible includes dozens of references to the tree. Ancient Indian physicians were well aware of the great healing power of the olive tree and its oil. The Koran too describes it as a “Precious Condiment.”
The city of Athens was mythically named after Pallas Athena, goddess of peace and wisdom. She was said to have created a tree able to light up the night [olive
oil lamps produce a warm, gentle light], to soothe wounds and to produce a food rich in flavor and energy. According to Roman legend, Hercules strode along the shores of the Mediterranean, his olive staff sending out roots every time it struck the ground and sprouting new trees. The Phoenicians helped spread the tree westward from Asia Minor and around the shores of the Mediterranean.
Olive trees live for centuries, even millennia. When a main trunk dies, new shoots sprout from its base and grow. Add to this the many uses which it is put and the distinctive cuisine that has emerged from it, it is not surprising that it has become so rich in myth. And now we discover there may be some factual basis to its reputation for health and healing.
Another rich source of herbal Squalene is the amaranth plant, an extremely robust type of grain that can survive both scorching heat and extremely dry soil. It
produces six-foot stalks with brilliant feathery red or magenta plumes. The Greek word “amarantus” means “never withering.” In India the amaranth herb has been
widely used for thousands of years. It is as rich in Squalene and as common in that region as the olive tree in the Mediterranean basin. In the great epics of the ancient Indian cultures the herb is believed to be empowered with immortal strength and fertility. The Sanskrit word for the plant “amaranth” [not “amaranth”] means “King of Immortality.”
Once a North American staple and the preferred grain of Aztec royalty, the broad leafed grain was believed to have sacred healing power. Aztec soldiers are a very
thick soup of this herb before going to war, and the amaranth plant was outlawed by Spanish missionaries who were disturbed by its association with human sacrifice. In fact, they believed the key to suppression of the Aztec culture was the annihilation of the plant.
The Swedish Order of the Amaranth dates back to the 1653 reign of Queen Christina, who brought European culture to her country and negotiated the landmark
Peace Treaty of Westphalia in 1648. The amaranth has frequently represented distinction and honour, and was formed into the “Amaranthine Wreath” symbol of the
Swedish Order and of the Bond of Fraternal Friendship representing the strength and power of the plant.
In Japan, a rich source of Squalene is shark liver oil [sharks belong to the species squali]. In ancient times, this rich oil was thought to increase strength and longevity. This miraculous healing power of shark liver oil is even mentioned in some old Japanese folk stories. The shark was considered a legendary creature living in the ocean depths. Many Japanese people believed the liver of the shark to contain powerful healing agents. Like the Aztecs who drank a soup of amaranth, ancient warriors of Japan and China – and even the Maoris of New Zealand- were known to drink shark liver oil before leaving for war.
We can therefore trace cultural recognition of Squalene-rich products with unique survival qualities to the Mediterranean region, Scandinavian, the Indian subcontinent, the Far East and Central America. The claims made by the ancient peoples of these lands may not be based on science, but they lend color and warmth to our research and prompt us to place the full glare of the scientific spotlight on this intriguing substance.
Chinese healers were the first to conduct pre-scientific research into a rich natural source of Squalene. In 1596 Lee Ji Chin, a Chinese healer of the Ming Dynasty
[1369 – 1644] composed a 52 volume compendium of some two thousand herbs, including the liver oil of the deep sea shark. Chinese traders subsequently brought the
book to Japan, where it was known as Honzokomoku. Samurai warriors used this oil to increase their strength.
Villagers of Suruga Bay on the Izu Peninsula of Japan were accustomed to drinking the same oil. The local name of this special extract was Samedawa or “cureall.:
In 1906, Dr. Mitsumaru Tsujimoto, a Japanese industrial engineer, discovered that Samedawa contains extremely large quantities of an unsaturated hydrocarbon. He
named the hydrocarbon Squalene, from the Latin root squalus [shark]. Dr. Tsujimoto was presented the Imperial Award of the Japan Academy in honor of his achievement.
Squalene was first found in the human body in the 1950’s, when the cholesterol metabolism was first identified. This is a complex pathway by which glucose is converted to the all-important cholesterol molecule. The pathway entails dozens of transformations of one biochemical to another. Squalene is just one of those
intermediate steps. At the time the significance of the transitional biochemicals was lost in the excitement of the greater picture. They were considered just a means to an end, and not significant in their own right. However, three of the biochemicals in that pathway – molecules that perform vital functions including the regulation of cell growth and proliferation through a process named after them – isoprenylation. Without this process, cell membranes could not anchor proteins vital to cell growth.
Some Isoprenoids –notably Squalene- are also strong antioxidants. They have lately been discovered to play protective roles not only in the antioxidant system but also in the immune function. Isoprenoids also play a part in the regulation of apoptosis [programmed cell death].
The history of Isoprenoids goes back billions of years. There are thousands of varieties, some of which played a crucial role in the protection of early life on this planet. This Isoprenoid nature of vitamin A, vitamin E, beta-carotene and other well known nutrients is discussed in chapters 2 and 3.
Indeed there has been a flurry of experimental activity around Isoprenoids, and things are now known about these humble molecules that were never imagined by the researchers who first identified Squalene. This book is a synopsis of that research and weaves the threads of these various experimental findings into a overall picture.
and things are now known about these humble molecules that were never imagined by the researchers who first identified Squalene. This book is a synopsis of that research and weaves the threads of these various experimental findings into a overall picture.
In fact this bigger picture is still growing. Squalene has been found abundantly in the skin, the membranous lining of the gastrointestinal and respiratory tracts and in adipose tissue [fat]. There is serves independent functions of great importance to hour health.
This skin of primates has virtually no Squalene but the sebum secreted by human skin contains about 12% -a huge proportion. This appears to be an evolutionary requirement of our unique nakedness, protecting us from our unparalleled exposure to the sun’s ultraviolet radiation. As environmental pollution leading to ozone depletion exposes us to rising levels of these harmful rays, the burden on Squalene in our inner and outer protective coatings may exceed its ability to cope. This could stress Squalene metabolism and contribute to immune suppression.
This book examines our body’s natural use of Squalene as well as research suggesting its potential dietary usefulness. Emphasis has been placed on the impact of pollution upon antioxidant balance, using Squalene metabolism as a model. It has three parts:
PART ONE – WHAT IS SQUALENE?
Squalene is a strong antioxidant Isoprenoid. It helps our cells avoid oxidative
stress and prevents lipid peroxidation. It also contributes to a balanced immune
response. Part One describes Squalene’s role:
• As an antioxidant
• As a regulator of the Isoprenoid metabolism
• In an effective immune response.
PART TWO – SQUALENE AND DISEASE
Squalene’s influence on the vital pathway that transforms glucose into
cholesterol may be pivotal. It regulates or controls the rate of synthesis of the enzyme
HMG Co-A reductase, and may contribute to effective treatments for cancer and heart
disease. Several research studies have already demonstrated Squalene’s anticancer and
cholesterol lowering activities. Part Two describes the potential use of Squalene in
disease management, especially against;
• Cancer, and
• Heart disease.
PART THREE – SQUALENE AND ENVIRONMENTAL POLLUTION
Squalene is present in high concentrations in human skin and in fat cells. This
may be an evolutionary requirement. Most likely the pressure of evolution in the
human protective coat and the requirements of its macrophage system have led to the
storage of large amounts of Squalene in the cellular protective system of the skin and
underlying fat tissue. Rapid changes in the environment may be placing oxidative
pressure on the protective coat of our body with potentially disastrous effects. Part
Three describes:
• Environmental pollution, and
• Pollution-induced oxidative stress leading to stress in Squalene metabolism
Part 1 - What is Squalene?
This part of the book describes Squalene and how it works in the healthy
individual, suggesting the possibility that stress in Squalene metabolism contributes to
immune suppression. It also raises questions about the possible therapeutic and
preventive role of Squalene modulation.
1 - The Primordial Balance
During most of the twentieth century medical researchers were preoccupied
with identifying various disease states and treating them as they arose. Extensive
studies of the immune system contributed to the development of effective
pharmaceutical drubs that today successfully deal with a wide variety of bacterial and
viral illnesses. However, many diseases remain only partly understood and relatively
intractable, including Alzheimer’s disease, Parkinson’s disease, diabetes, mellitus,
rheumatoid diseases and most common and most feared of all, heart disease and
cancer. New research and technology is at last enabling doctors and scientists to better
explain the mechanisms of these and many other diseases.
Some of the most striking advances in recent years are emerging from
research into free radical biology. It is now clear that specific disease agents are not the
only source of ill-health. Cells and tissue can also be destroyed by a breakdown of the
very molecules of which they are composed. Polluting free radicals such as oxyradicals
– noxious by-products of the energy production process in each cell – constantly
threaten the inner environment of our body. Free radical molecules are unbalanced by
having too few or too many electrons. They are dangerous because in their attempt to
regain balance they upset the stability of surrounding molecules, Sometimes initiating
chain reactions that can spiral out of control.
Still, free radicals are necessary for our survival as well. The are used in
intracellular communication, and immune cells produce huge amounts of free radicals
to attack bacteria and other harmful agents. Sometimes they produce to many, yet the
free radicals do not harm the cell. Each cell possesses its own defense mechanism –
the antioxidant defense system – that maintains a dynamic internal balance between
free radicals and antioxidant nutrients. Without this balance the cell would not survive,
tissue would degenerate and we would be unable to maintain our health. This oxidant-
antioxidant balance is presumably a primordial equilibrium without which life would
never have been possible.
Increased generation of free radicals can lead to oxidative stress, producing
imbalance and resulting in oxidative damage, cell death, tissue damage and disease.
Fortunately, cells and tissues implement a compensatory mechanism, tending to
minimize oxidative stress by synthesizing more antioxidants as they need them. This
dependence on endogenous rather than dietary antioxidants suggests that a study of the
metabolism of endogenous antioxidants will enlighten our understanding of the
relationship between oxidant- antioxidant balance and oxidative stress.
The purpose of this chapter is to discuss the role of endogenous anti-oxidants
in oxidant-antioxidant balance. Since Squalene is an endogenous antioxidant that is
where we will begin.
The First Antioxidants.
Primitive living cells first emerged on this planet about four billion years ago.
They survived by converting light energy into chemical food, just as plants harvest the
sun’s energy. Plants initiate photosynthesis with chlorophyll, which is activated by
sunlight and helps carbon dioxide interact with water to produce glucose and release
oxygen. This activation is sometimes transferred to oxygen molecules in the form of
extra electrons, and they become oxyradicals. In addition, the early biosphere lacked
any protective ozone layer and was subject to fierce ultraviolet radiation. This too
generated free radicals. For years, biologists have wondered how these primitive
organisms protected themselves from such strong radiation and so many free radicals.
It was presumed that the “skin” enclosing their single-celled bodies must have
contained a protective agent.
Recent breakthroughs by NASA scientists may provide a piece of the puzzle.
They have speculated that the powerful antioxidant quinine was deposited on Earth by
incoming meteorites. It seems that quinone was the first Isoprenoid. Quinone is
especially able to neutralize the free radicals generated by ultraviolet rays and may have
enabled a few lucky cells to become evolutionary survivors. Without quinone and
other antioxidant molecules primordial organisms would not have survived the hazards
of unshielded ultraviolet radiation. Today, quinone is one among many Isoprenoid
antioxidants found abundantly in the plant and animal kingdoms.
Light harvesting complexes [LHCs] are another type of Isoprenoid that
protects plants. These are a group of carotenoids antioxidants that surround the
chlorophyll molecules and use an electron transfer reaction to protect them from
ultraviolet radiation damage, principally by preventing the oxidation of molecular
oxygen. They also help absorb extra electrons before they can damage other
molecules. The outer coating of many seeds and fruits also contains Isoprenoids. For
example, tomatoes contain the antioxidant Isoprenoid lycopene.
Unlike plant cells, animal cells absorb oxygen and derive energy from its
reaction with glucose. In this process, protons flow through special molecules in the
mitochondria [energy producers] of each cell.
Electrical energy is produced and moves through the mitochondria as
electrons are shunted from one molecule to another in a process known as the
reduction-oxidation [redox] reaction. Molecules in the mitochondria are alternatively
reduced [receive electrons] and oxidized [donate electrons]. This generates electricity,
which is converted into chemical energy. During redox reactions electrons sometimes
escape, damaging either the redox molecule itself or the cell. However, redox
molecules such as ubiquinone have an Isoprenoid tail capable of neutralizing numerous
free radicals and keeping the mother molecule extremely stable.
Once again, Isoprenoids helps protect the organism. The Isoprenoid
ubiquinone [also known as coenzyme Q10] – is synthesized inside the cell and is
involved in the energy releasing process of the mitochondria. Many antioxidants are
either isoprenoids or have an Isoprenoid tail. Vitamin E, vitamin A and flavonoid are
all isoprenoids.
Free Radicals
The damage caused by free radicals occurs at a subatomic level. In any stable
atom, electrons orbit the nucleus in pairs and any breakup of this pairing makes the
atom unstable. It or the molecule of which it is part is said to be in a state of
imbalance and is called a free radical.
One of the most common sources of free radicals is the process burns
glucose with oxygen to produce energy through oxidation reduction [redox] reactions
in the mitochondria. The type of free radical it releases – an oxyradicals – is a routine
by-product. As you might expect, the production of oxyradicals increases when our
energy requirements increase – for example when exercising, fighting sickness or
eating.
Not all free radicals are manufactured within the cells of our body. They are
everywhere. Ultraviolet radiation can create them in the skin and even turn ground
level oxygen molecules into free radicals. We are surrounded by pollutants, some of
which are themselves free radicals and some of which interact with metabolic
processes, causing further subatomic damage.
Types of Antioxidants
Antioxidants are antidotes to free radicals, including oxyradicals. Many
substances act as antioxidants, but they all have one thing in common – the capacity to
stabilize the imbalance of unpaired electrons and neutralize the harmful potential of
free radicals without themselves becoming unstable. If it is true that the first
isoprenoids arrived from outer space, we living organisms can literally thank the stars
for our evolutionary survival. However, even though we still benefit from
environmental antioxidants – chiefly from food sources – most forms of life have
learned to produce antioxidants endogenously [within the cells where they are needed].
In the human body they include glutathione sulfhydride [GSH], superoxide dismutase
[SOD] catalase, Squalene and coenzyme Q10 [ubiquinone]. These last two are both
isoprenoids. The protective coat of many organisms – from the biomembranes of
cellular organelles to human skin – are protected from free radical damage by
antioxidant isoprenoids.
Other antioxidant isoprenoids are obtained from nutrients and are said to be
exogenous. The include substances like vitamins E and A, lycopene and beta-carotene.
These are usually found in various foods but they are also frequently taken as
concentrates in pills, food supplements or nutriceuticals. They are used by health-
conscious individuals in many ways, usually in the hope that they will maintain good
health, prevent all sorts of disease and hopefully slow the aging process. Their
usefulness is not in question, but there is wide disagreement over what constitutes an
appropriate dosage. It is well known, for example, that taking too much Vitamin A or
E can have harmful toxic consequences. There is also growing evidence that having
too many antioxidants is just as harmful as not having enough. In fact our body as a
whole must maintain a proper balance between oxidants antioxidants.
Oxidant-Antioxidant Balanc-Antioxidant Balance
The idea of oxidant-antioxidant balance emerged from research showing that
for any given level of free radicals, tissue damage is prevented most effectively by just
the right concentration of antioxidants. We have long known that during periods of
oxidative stress the antioxidant defense system increases the synthesis of antioxidants.
Now we are learning that at other times our body actually decreases production
because too many antioxidants can harm the body as well. Such adjustments suggest
the existence of any antioxidant defense system – an overseeing mechanism used by the
body to monitor and maintain an appropriate balance, just as the immune defense
system controls the synthesis and activity of immune cells.
However, in the same way that the immune defense system can lose its
balance, this system too can be disrupted. Our focus should not be to take as many
antioxidants as possible but to help the system maintain its oxidant-antioxidant balance.
It alone knows its precise needs, and therefore endogenous antioxidants-those
synthesized in the cell – will play a greater role in oxidant-antioxidant balance than
exogenous [dietary] ones. To do this of course, the body must have the necessary raw
materials [precursors] at hand. Aging makes it increasingly difficult for us to maintain
this balance, because synthesis of Squalene, GHS and coenzyme Q10 all decline as we
get older.
The direct result of a disrupted oxidant-antioxidant balance is cellular damage,
and one of the worst types of damage caused by free radicals is to the cell wall
[biomembrane].
Oxidative Damage
Cell and tissue damage caused by oxidant-antioxidant imbalance is referred to
as oxidative damage. The first step of this damage process is the lipid peroxidation
chain reaction, which breaks down cell membranes.
Every living cell is enclosed by a membrane – a double layer of lipids [fats]. A
cell also has organelles [functional parts] that help it grow, replicate and do its work.
These organelles include the nucleus, mitochondria and ribosomes. Like the cell itself,
each organelle has its own membranous wall, known as the biomembrane. The
biomembrane’s surface is a sort of complex electric fence, with biological devices such
as receptors [entry points for specific molecules] and electrical channels through which
energy is exchanged. All these devices generate free radicals. In fact, free radicals are
produced constantly within and outside the cell, some as by-products of energy-
releasing oxidation in the mitochondria, others quite usefully, as in the case of immune
cells that use them as weapons against invading pathogens. The biomembranes
themselves are highly vulnerable to free radical damage, especially in the hydrophobic
[waterless] band between the two lipid layers.
The fatty acids that constitute the two layers of the cell membrane are lipid
molecules and like gasoline, are flammable hydrocarbons. They are packed very close
to each other and are oxidized [catch fire] quickly. When one molecule is ignited it
quickly triggers the same reaction in its neighbors – a chain reaction called lipid
peroxidation. Lipid peroxidation [the burning of liquids] quickly damages the entire
biomembrane and threatens adjoining cells.
Lipid peroxidation is the most common and pernicious source of damage to
biomembranes. It impairs the cells function and leads to its eventual death. Diseased
cells spill their contents into surrounding tissue and cause inflammation. As more cells
are damaged or destroyed tissue damage follows and disease sets in. The effects of
lipid peroxidation are initially microscopic and not immediately apparent, but they
accumulate over time and are important factors in the progression of chronic diseases
such as atherosclerosis and the rheumatoid group of disorders. In fact such diseases
are turning out to be more numerous than was ever imagined.
A large portion of the biological molecules that form the basic building blocks
of life are glucose, fatty acids and amino acids and the constituent atoms of these
molecules can be destabilized by many types of biochemical reactions leaving them
with unpaired electrons. Free radicals spontaneously seek to correct their imbalance by
stealing electrons from any available molecule. Hopefully they encounter antioxidant
molecules, which render them harmless. Not infrequently however they encounter
defenseless neighboring molecules that in turn lose electrons and become free radicals
themselves. This can promote an ever-widening chain reaction leading to a disruption
and destruction of living tissue leading to oxidative damage.
Even when these chain reactions are eventually stopped by our body’s
antioxidant defenses, the damage already caused to cells, tissues and organs
accumulates over time and provides a foothold for incoming pathogens [disease
causing substances]. The damage also contributes to the progression of such diseases
as cancer, heart disease, arthritis and AIDS. An unconventional but significant
segment of the scientific community even considers aging itself to be largely
preventable disease, caused mostly by free radical damage. Nowadays there is
enormous scientific and public interest in reinforcing the antioxidant defense system as
a way to break the cycle of free radical damage, slow the aging process, extend life-span
and improve overall health.
Diseases associated with oxidative damage
1. Cancer
2. Diabetes Mellitus [peripheral neuropathy of this disease is due to free radical damage to the nerve heath
3. Heart failure and ischemia-reperfusion injury
4. Autoimmune disorders e.g. the rheumatoid group
5. Kidney disorders e.g. glomerulo-nephritis, tubulointerstitial diseases
6. Infective disorders e.g. AIDS and AIDS related dementia, pulmonary fibrosis due to tuberculosis, secondary anemia due to malaria
7. Neurodegenerative disorders such as Alzheimer’s disease
8. Dermatological disorders such as photosensitivity disorder, psoriasis, pemphigus vulgaris
9. Atherosclerosis
Free radicals are thought to cause many pathological conditions including the transformation of a normal cell into a cancer cell. Also, redox molecules which are
normally immune to free radicals can sometimes be overcome by them, with disastrous consequences. At the root of these many specific occurrences of oxidative damage lies the bigger and even more disturbing picture of oxidative stress. the bigger and even more disturbing picture of oxidative stress.
Oxidative Stress & Antioxidant
Metabolism
Oxidative stress results when antioxidant balance fails. Although oxidative
damage is implicated in the progression of many diseases, it develops only when
oxidative stress rises above a certain threshold. As soon as cells and tissues experience
oxidative stress, the compensatory mechanism of the oxidant-antioxidant balance
immediately tries to preempt oxidative damage by synthesizing antioxidants. Only if
and when the stress crosses a certain threshold does the mechanism fail and oxidative
damage occur. The mechanism of oxidative damage is not unlike that of heart failure.
In response to failure, the heart accommodates the increased load by increasing in size,
but beyond a certain limit its pumping ability declines sharply and eventually fails.
Similarly, although the antioxidant defense system can increase its synthesis of
antioxidants, oxidative stress may cross the threshold at which the compensatory
mechanism fails. Endogenous antioxidants [those synthesized in the cell] probably play
a greater role in this compensatory mechanism because their rate of production is
within the control of the body. Exogenous antioxidants like Vitamin E may help
reduce oxidative stress but cannot directly affect the compensatory mechanism. This is
supported by the evidence that as age-related tissue levels of endogenous antioxidants
decrease, the body is more prone to oxidative stress. Therefore oxidative stress results
from the failure of endogenous antioxidants.
Such a reciprocal relationship between oxidative stress and endogenous
antioxidants suggests that endogenous antioxidants and their metabolisms require
further study. If we can understand when and why the compensatory mechanism fails,
we may find ways to prevent its failure. We hypothesize that metabolic stress
determines the failure of the compensatory mechanism. Examining this hypothesis will
provide valuable insight into the relationship between oxidant- antioxidant balance and
oxidative stress.
Antioxidant Metabolism and Squalene
The above discussion suggests the great importance of clearly defining
metabolic stress, why it occurs and how it leads to oxidative stress. These questions
may lead to new insights into balance and stress in the immune system. They may also
provide more insight into oxidant-antioxidant balance, which we can justifiably
consider primordial balance. Since Squalene is synthesized in our cells, it is an
endogenous antioxidant. It may therefore serve as an appropriate model for the study
of antioxidant metabolic stress its influence on oxidative stress. We examine this
possibility in chapters 4 & 11.
We must also consider Squalene’s history as a antioxidant. The cell
membranes of archae and bacteria that lived about 3.5 billion years ago were rich in
Squalene. Along with coenzyme Q, lycopene and some other isoprenoids, Squalene
was among the first antioxidant group to take part in the primordial balance of life.
Indeed, research reveals that Squalene’s antioxidant properties resemble those of
vitamin E and other Isoprenoid antioxidants. The natural presence of this strong
antioxidant in human cells and its particularly high concentration in human skin do not
seem coincidental. Our job is to identify the exact antioxidant role it plays in the body.
Conclusion
All life forms must deal with the everyday threat of free radicals. While early
life first benefited by exogenous [environmental] antioxidants, those organisms that
were able to manufacture endogenous antioxidants in their own metabolism gained the
evolutionary upper hand. The new science of free radical biology suggests that
oxidative damage is responsible for some of the most intractable diseases of the
twentieth century and that maintaining an oxidant-antioxidant balance is a crucial first
step to overcoming some of them. Since levels of endogenous antioxidants decline
with the aging process, it becomes increasingly difficult to maintain this balance and the
question naturally arises of whether the process of disease and aging can be slowed by
therapies that might arrest or reverse this antioxidant decline.
A History of Squalene
Squalene’s Importance in the Origin of Life
Squalene has served as an antioxidant for terrestrial life for over three billion
years, a fact due in great part to its nature as a pure Isoprenoid. Without isoprenoids,
the history of life on Earth would be unrecognizable, if indeed there were any life at all.
About 3.5 billion years ago during the Precambrian era, the surface of Earth was very
hot and the atmosphere was filled with methane, ammonia and other toxic gases.
Nevertheless, huge colonies of archae and cyanobacteria [organisms resembling
bacteria seem to have thrived. They left a vivid fossil record. Archae – which date
from that time – survived in temperatures of 100 deg Celsius and on very little oxygen.
The membrane of their cells was rich acyclic isoprenoids – mainly Squalene. These
Isoprenoid-rich life forms dominated the Earth right up to the Cambrian era – a period
of more than three billion years. Fungi, plants and animal life forms appeared only
about 500 million years ago and primitive humans barely two million. The fossils of
these three billion year old isoprenoids are found well preserved in the deep sediments
under the ocean floor. Marine biologists routinely use Squalene, lycopene and other
isoprenoids as biological markers of these sediments.
Isoprenoids may also one day help astrobiologists trace the evidence of life
beyond this planet. Just as several billion year old isopreniods fossils are found in all
sorts of terrestrial rock, they hope that similar fossils on meteorites will indicate the
existence of life in outer space.
A 1999 scientific paper published in the journal Science traces the probably
origin of quinone an early Isoprenoid molecule – right back to the cosmos. Author
Max P. Bernstein writes that isoprenoid molecules were probably carried to Earth by
meteorites and that their presence enabled primitive cells and organisms to protect
themselves from the harsh living conditions of early life, especially exposure to extreme
ultraviolet radiation. At that time, the ozone layer of Earth was not fully formed and
the surface of the planet was relatively unshielded from the full effects of the sun’s rays.
The earliest evidence of life on Earth is a several billion year old isoprenoid fossil –
pentamethyleicosane [PME], the molecular structure of which is similar to Squalene.
PME is an acyclic isoprenoid, the product of primitive methane-producing bacteria.
This is why the PME fossil is so significant, especially given its striking molecular
resemblance to Squalene. A present day study of Squalene will help us understand the
probable function of PME and other acyclic isopreniods in ancient life forms.
Early Squalene Research
In 1936, Nobel laureate Paul Karrer described the biochemical structure of
Squalene for the first time. This medical researcher was already famous for his account
of the chemical structures of Vitamins E and A. He was surprised to find that
Squalene had a similar structure to these two antioxidant vitamins. This may have
hinted at Squalene’s antioxidant characteristics, but far more interesting things were yet
to be discovered.
In the 1950’s Squalene was found to occur naturally in the human body,
although it was not considered particularly significant at the time. Researchers were
trying to describe how cholesterol is synthesized in the cell when it was discovered that
Squalene happens to be one of the steps in the transformation of glucose into this vital
substance.
High cholesterol levels are so feared these days that many people are unaware
that normal levels are absolutely essential to health. Cholesterol is manufactured in
individual cells in a complex series of biochemical steps known as the mevalonate
pathway [see below]. Glucose is first converted into mevalonic acid, and this in turn
produces isoprenoids – geranyl, farnesyl and squalene. Some two dozen steps later, the
cell has a supply of cholesterol, essential for the manufacture of hormones and bile salts.
The Greater mevalonate pathway
Glucose
Mevalonic acid
Geranyl
Farnesyl
Co-enzyme Q10 Squalene Dolichol
Cyclic squalene
About 20 steps
Cholesterol
The Isoprenoid Synthesis Pathway
Within the greater mevalonate pathway, the four steps from mevalonate to
squalene are known as the isoprenoid synthesis pathway. We now know that they are
of critical importance in a range of functions including cell growth and proliferation as
well as cholesterol synthesis. Many of the discussions in this book are concerned with
this pathway as well as the step immediately preceding it – the synthesis of HMG
Coenzyme-A reductase [HMG Co-A]. It turns out that these are mot merely
intermediates, but also rate-controlling steps – reactions that slow down or speed up
according to the body’s requirements. They have profound implications for the
function, growth, replication and life span of individual cells. The presence of squalene
in cells affects the rate of synthesis of HMG Co-A reductase, which in turn affects the
entire synthesis of cellular isoprenoids and cholesterol, offering tantalizing possibilities
for the prevention and treatment of high blood levels of bad cholesterol – one of the
most important risk factors for heart disease. But we are getting ahead of the scientific
detective story. When its natural occurrence was discovered in the body in the 1950’s
Squalene’s antioxidant function was still unknown.
function, growth, replication and life span of individual cells. The presence of squalene
in cells affects the rate of synthesis of HMG Co-A reductase, which in turn affects the
entire synthesis of cellular isoprenoids and cholesterol, offering tantalizing possibilities
for the prevention and treatment of high blood levels of bad cholesterol – one of the
most important risk factors for heart disease. But we are getting ahead of the scientific
detective story. When its natural occurrence was discovered in the body in the 1950’s
Squalene’s antioxidant function was still unknown.
Squalene’s Importance Recognized
There was in face a delay of over a decade before the spotlight was finally
placed upon this antioxidant agent found in olives, amaranth and shark liver oil. The
abundant folk tales and anecdotal stories created a negative bias in the scientific
community – squalene was considered a “mere” folk cure and its potential was ignored.
In any case, limited research funding and the relative immaturity of biochemical
technology hindered further understanding.
Research avenues reopened in 1963, when an article in the scientific journal
Nature demonstrated that squalene stimulates macrophages – the principal immune
cells in the inner and outer protective coat of our body. This empirical observation was
exciting news, but an explanation of how and why it was so remained elusive.
In 1950, researchers led by McKenna found that human skin secretes very
high levels of squalene. Subsequently, C.K. George and others at Rockefeller
University, New York demonstrated the widespread occurrence of squalene in
subcutaneous and submucosal human tissue. This finding of significant squalene levels
in the protective coat of the body raised the immediate question of whether it plays a
protective role. This second research group also found a separate source [pool] of
human squalene in the body, quite independent of the cellular cholesterol metabolism.
Its biological function there remained unknown but its existence could not be ignored.
There was no longer any doubt – squalene was much more than a simple by product of
cholesterol metabolism.
In 1982, R. Tilvis and his group found another pool of squalene synthesis –
this time in fat cells. And in 189 C. De Luca and colleagues compared the squalene
content of human skin to that of other primates and found it to be much greater. The
sebum of gorillas, for example, contains about 0.1% squalene, whereas human sebum
contains about 12% - 120 times more! This led to an entirely new notion – that the
presence of squalene in human skin may be an evolutionary requirement.
In an earlier study conducted in 1977, M. Gloor and A. Karenfield had found
that the body’s consumption of squalene increases when skin is exposed to ultraviolet
[UV] radiation. Then in 1993, O. Salamoto and his research group conducted more
specific tests and demonstrated that the first molecule targeted by UV rays as they enter
the human skin is squalene. Since ultraviolet radiation is known to harm unprotected
tissue, the implication is that they protect the skin from UV damage – at least until they
are depleted Several research groups got to work on this question and finally in 1995 a
Japanese team clearly demonstrated that squalene can prevent UV induced oxidation of
lipids in skin – a key finding that finally placed squalene in the scientific spotlight.
23
In 1982 squalene’s detoxifying function was demonstrated in several research
experiments and in 1993 its radioprotective effects were revealed. These discoveries
set the stage for the medicinal use of squalene.
Clinical Applications of Squalene
During the early part of the twentieth century, it was believed in Japan that
squalene could reduce the risk of cancer, and combat tuberculosis and other microbial
diseases. Dr. Keijiro Kogami, a medical research from the Tokyo Imperial University,
conducted extensive research and developed a squalene treatment for tuberculosis. His
work apparently showed significant success but the hospital where he worked and his
records were destroyed in 1945 by World War two bombings and his work was taken
up later by the Yokota Research Institute in Tokyo.
Two prominent Japanese physicians and researchers – Dr. Ryosuke Yokota
and his son Dr. Takashi Yokota – pioneered research on clinical applications. They
established the Yokota Health Institute and worked together from 1968 to 1989.
There they undertook the longest running clinical research trials on the health benefits
of highly purified and carefully preserved squalene obtained from the deep sea shark.
Several laboratory research studies showed that dietary squalene can strengthen the
immune response, especially against radioactive poisoning.
In 1996 a human clinical trial of squalene was performed to examine its
effectiveness in lowering blood cholesterol. As a result of these and consequent
research studies, dietary squalene has been found to:
1. Lower blood cholesterol
2. Enhance the anti-tumor action of chemotherapeutic agents
3. Inhibit cancer growth
4. Increase the efficiency of the immune system
In order to understand these developments, we will examine the isoprenoid
synthesis pathway in which squalene’s role has been expanded from that of a mere
precursor to an important metabolic player in its own right. This is discussed in
chapter 3. First we must describe the squalene molecule.
Two Forms of Squalene
There are two molecular forms of squalene - linear and cyclic. Both have the
same constituents but each one has its own distinct molecular shape and biological
properties. Linear squalene is a long wavy strand – an extremely stable and powerful
antioxidant that protects the biomembrane [envelope] of living cells from lipid
peroxidation [the most dangerous form of free radical damage]. Under certain
conditions acyclic squalene loses this stability, curls in on itself and becomes cyclic,
losing much of its antioxidant potential but becoming the sterol nucleus.
The transformation of acyclic to cyclic squalene has defied synthesis in the
laboratory. It is still a mystery how the molecules form is reconfigured without any
change in its composition. All we know is that the acyclic molecule enters the deep
pocket of a cone shaped protein complex where it is broken down into its six
component isoprene’s and then reassembled in a new configuration. Only then can the
molecule become the nucleus of cholesterol and many other sterols. It has been said
that this cyclization reaction is the most complex single step reaction in the biological
world.
molecule become the nucleus of cholesterol and many other sterols. It has been said
that this cyclization reaction is the most complex single step reaction in the biological
world.
This transformation first took place several billion years ago, during the
Precambrian period, opening up whole new possibilities for life on this planet. The
wavy shape of linear squalene provoked considerable interest when scientist noticed
that it resembled the molecular structures found abundantly in very primitive cells. It
turns out that the cell membranes of archaea – one of the oldest forms of life – are
composed of acyclic isoprenoids like lycopene and squalene. In addition, marine
geologists discovered large amounts of the isoprenoids squalene and lycopene in deep
sea sediments dating back to primordial geological ages [the Precambrian era].
Squalene is a principal constituent of the cell membrane of the archaea that live in such
inhospitable environments as sulfur springs and deep sea volcanic vents. It is believed
that these archaea survived these environments because of the protective acyclic
squalene and other antioxidants in the biomembrane.
As we move up the evolutionary ladder we find that the eubacteria and
cyanobacteria are liberally composed of hopanoids – cyclic squalene molecules that
undergo further modifications to form triterpene compounds. This transformation of
acyclic to cyclic squalene was an evolutionary step of enormous significance.
Cyanobacteria are a product of a relatively temperate oxygen environment and do not
need to maintain such robust protective mechanisms as archaea. Instead, they
developed genes able to provoke the enzymatic transformation of acyclic squalene into
hopanoids, resulting in a stronger cell membrane able to engage in more sophisticated
evolutionary activity. In modern mammal’s cyclic squalene forms the vital sterol
nucleus – the building block of such essential substances as steroids, other hormones,
vitamin D and of course cellular cholesterol.
Although the emergence of cyclic squalene is considered an evolutionary
development, living organisms continued to depend on linear squalene. A very
significant portion of this protective isoprenoid does not become cyclic and the
organism benefits from its antioxidant properties. Today acyclic isoprenoids like
squalene and lycopene are found throughout the plant world. In the animal kingdom,
acyclic isoprenoids remain an invaluable constituent of cellular membranes.
Linear squalene is found abundantly in human skin, where it is also reduced to
squalane, a reverse step that cannot be taken by cyclic squalene. [Squalane is formed
when hydrogen ions saturate squalene’s double bond neutralizing its antioxidant
abilities. Squalane is nevertheless an effective moisturizer used in cosmetic
preparations]. Humans are the only primates with such concentrations of Squalene in
their skin, apparently because of our susceptibility to ultraviolet B radiation. Medical
research has shown that squalene is the first target molecule of UV radiation – it
apparently takes the brunt of UV’s damaging ionizing potential. This radiation may
nevertheless induce stress in squalene metabolism an idea explored in chapters 4 & 11.
Conclusion
The first hints of squalene’s importance in our body were uncovered when it
was found to be an integral part of the cholesterol synthesis pathway in individual cells.
Later discoveries that it stimulates the activity of macro-phage immune cells and also
protects the skin from UV radiation damage have left no doubt as to the body’s day to
day dependence upon squalene.
Following centuries of traditional use in Japan, researchers using natural
squalene in therapeutic applications were rewarded with success, but their findings were
not clearly understood. Recent understanding of squalene’s isoprenoid origins and its
metabolism began to unravel the puzzle, but the big breakthrough was the realization
that it performs a regulatory role in the cholesterol synthesis pathway. There is good
reason to believe that continued research into this regulatory role may help explain and
refine the successes of the applications developed in Japan. The presence of very high
levels of squalene in human skin may have to do with its ability to protect against UV
radiation and other sources of free radicals.
Squalene the Antioxidant
Squalene is an isoprenoid antioxidant – a type of organic molecule vital for
the very existence of life on Earth. Hundreds of thousands of isoprenoids are found in
nature, of which squalene and some others are potent antioxidants – notably Vitamin
E, beta-carotene, lycopene, phytol and coenzyme Q10. They all contain isoprene units.
This chapter outlines the antioxidant mechanism of squalene and its significance in
cellular protection.
Isoprenes
Isoprene units are very small molecules containing five carbon atoms and are
found in all isoprenoids. There are many isoprenoids on Earth – perhaps several
hundred thousand. Each contains isoprenes attached in different configurations or to
different molecules. Molecules containing only isoprene’s – like Squalene – are said to
be pure isoprenoids. Those with one or more isoprene units attached to the mother
molecule – like Coenzyme Q10 and Vitamin E – are mixed isoprenoids. The isoprene
unit contributes to the antioxidant properties of the whole molecule but does not by
itself account for them. Dolichol, for example is a pure isoprenoid of twelve isoprene
units with no significant antioxidant abilities, whereas coenzyme Q10, a mixed
isoprenoid with ten units, is a good antioxidant. Squalene’s six units give the molecule
an effective and stable antioxidant configuration. All these isoprenoids, it should be
noted, are intermediate metabolites of the mevalonate pathway.
The usefulness of an antioxidant is largely determined by its ability to stop a
lipid peroxidation chain reaction. Lipids [fatty acids] in the biomembrane [outer
envelope] of a cell are arranged like long chains of molecules, aligning themselves in
parallel. When a free radical approaches one of these fatty acid chains, it liberates a
lipid peroxide radical – a fatty acid chain with an oxyradicals at the end. This radical
then goes on to attack another fatty acid chain, liberating a new peroxide radical.
However, when it encounters an antioxidant molecule, it is quenched and the chain
reaction is stopped.
Antioxidant isoprenoids are ideal for stopping lipid peroxidation chain
reactions in the biomembrane. They are water insoluble and can be easily incorporated
into the lipid bilayer. Squalene and coenzyme Q10 – two endogenous antioxidant
isoprenoids – are indeed found there and laboratory research has shown them to be
effective.
Not every isoprenoid has antioxidant properties, and even an antioxidant can
be overwhelmed by free radicals. Its effectiveness all depends upon the stability of the
molecule. Like any other molecule encountering a free radical, antioxidants are obliged
to either donate or receive an electron. Unlike other molecules, the loss of the electron
does not destabilize them. Squalene is an excellent antioxidant because of its great
capacity to receive or donate electrons without suffering molecular disruption. There
are two ways in which it can neutralize [or quench] a free radical, either physically or
chemically. Physical quenching involves the donation of an electron by squalene,
stabilizing the radical without itself becoming unstable. In a chemical quenching
reaction the radical is chemically incorporated with the squalene molecule, producing
squalene hydroperoxide – a new molecule. Squalene hydroperoxide is not an
antioxidant but is an excellent emollient that in the skin serves as a natural sunscreen.
In the case of physical quenching, the squalene molecule contributes an
electron without changing its own nature. This is a necessary prerequisite for any
antioxidant, but squalene does so in a particularly effective way. The key to its stability
is the configuration of atoms in its constituent quaternary carbon and methyl group,
known as its pi electron system. It is a quaternary carbon group because the central
carbon atom is directly connected only to other carbon atoms, making it particularly
stable. In additions, the pi electron systems of six isoprene units enable each unit to
interconnect forty-four hydrogen atoms, providing it with extraordinary stability.
Because of all this, squalene is said to have a low ionization threshold – its
atoms are held in place by a strong natural bond that is maintained with little
expenditure of energy. Therefore, even when it donates electrons its energy field
remains stable. Squalene’s very low ionization threshold accounts for its very large
capacity to donate electrons, like vitamin E. This unique stability is the key to
squalene’s ability to terminate a lipid peroxidation chain reaction.
Once a lipid peroxidation chain reaction is underway it will damage one lipid
molecule after another unless it is stopped by the intervention of a terminator – an
appropriate antioxidant molecule standing in its path. Most terminator molecules
contain isoprene units. Isoprenes have excellent shock absorbing capabilities and are
the right molecule to terminate the chain reaction. This is why antioxidant isoprenoids
are vital to such a vast range of living tissue.
The antioxidant property of squalene has been known for a long time, and
laboratory research has shown that squalene specifically terminates lipid peroxidation
chain reactions in the skin’s surface. Y. Kohno and his colleagues have shown that
squalene is stable [i.e. cannot be easily oxidized] and is capable of terminating chain
reactions. It is reasonable to assume that it performs a similar function wherever it is
found, for example within individual cells and in the biomembrane.
M.K. Rao first wrote of squalene’s antioxidant properties in 1968 in an article
published in the Journal of the American Oil Chemical Society. However the origin of
these properties was still unknown. Only recently – in the light of free radical biology –
have scientists realized that they derive from squalene’s isoprenoid nature.
In both plant and animal life isoprene’s play a significant role in protecting the
cell or redox molecule from free radical induced damage. In the cytoplasm [ the whole
cell except the nucleus] where most of the cell’s work takes place, electrons are
produced by many of its metabolic reactions. Especially, large numbers are released as
by-products of the energy generating activity of the mitochondria. Electrons reacting
with water inside a cell will generate hydroxyl ions {OH} and hydrogen ions [H] – both
free radicals and highly toxic to lipid and protein molecules within the cell. Leaked
electrons may also collide with molecular oxygen inside the cell, producing superoxide
ions [O]. Most importantly, free radicals may convert molecular oxygen in the
cytoplasm into free radicals.
Plant chloroplasts contain LHC [light harvesting complex] isoprenoid
molecules to prevent molecular oxygen from being rendered into oxyradicals.
However, we still do not know whether similar defense mechanisms exist in the
mammalian cell. Does cytoplasm contain isoprenoid molecules to recognize and
neutralize these free radicals? It is highly possible that squalene may act in animal cells
Biomembrane Structure
The part of the body where the biological properties of isoprenes are in
greatest demand is the biomembrane. This two layered lipid skin envelops each cell
and each of the various organelles within. In particular, the biomembranes of the
mitochondria – the site of energy releasing electrical activity – are particularly prone to
a lipid peroxidation chain reaction. There, nutrients are oxidized, constantly releasing
free radicals in the midst of this intense concentration of lipids.
Each of the biomembrane’s two layers is a collection of longitudinally
arranged lipid molecule chains, including cholesterol, vitamin E and fatty acids. The
molecule chains have one hydrophobic [water avoiding] end and one hydrophilic [water
seeking] end. Like a magnet, they are said to be polarized, and naturally arrange
themselves in a n orderly pattern. By avoiding the watery environments both outside
and inside the cell, the hydrophobic ends enclose a waterless band between the two
layers. Acyclic squalene is entirely hydrophobic and is not anchored in the
biomembrane. It is therefore attracted to this waterless band and accumulates there
where it performs its crucial antioxidant function. Squalene’s ability to protect the
biomembrane from free radical damage is discussed below.
Vitamin E & Squalene Compared
Of all isoprenoids that can act as antioxidants, we so far know most about
vitamin E. Its structure of three isoprenoid side chains and two phenol rings makes it a
very effective antioxidant. It is commonly believed that Vitamin E is the principal
antioxidant of lipid peroxidation chain reactions in the biomembrane, but this may not
be the case after all.
An ideal antioxidant should fulfill three criteria. It must:
1. stop the chain reaction
2. be synthesized and regulated on demand [so the body does not need to depend upon an outside supply]:
3. incorporate itself into the biomembrane without altering or damaging the membrane
We can compare vitamin E and squalene in the light of these requirements.
Vitamin E’s ability to completely protect the biomembrane is limited by its uneven
distribution throughout the biomembrane. Because it is an exogenous antioxidant and
must be obtained from dietary sources, the body has no control over where and when
it is available. Squalene on the other hand, is synthesized within the cell from glucose –
a readily available nutrient under normal circumstances.
Also, the large benzene structure in vitamin E limits its integration into the
biomembrane, which can incorporate no more than two molecules per 2,000 lipid
molecules. Too many vitamin E molecules disturb the biomembrane’s physiological
properties. It has been shown that large quantities of squalene do not alter the
physiological property of the biomembrane.
Squalene has additional advantages over vitamin E. It does not require
recycling, whereas Vitamin E must be continuously recycled by endogenous
29
antioxidants such as glutathione and squalene. And, during periods of oxidative stress,
the availability of antioxidants decreases, limiting the potential of recycling Vitamin E.
For all these reasons, the usefulness of vitamin E as the primary antioxidant in
the biomembrane may be exaggerated and the role played by squalene may be more
significant. Also, squalene is not fixed in the biomembrane and scavenges free radicals
in the hydrophobic intermembrane band. It is also highly resistant to free radical
attacks on itself.
Squalene has an additional advantage – it can recycle Vitamin E. Antioxidant
molecules such as Vitamin E neutralize free radicals by donating electrons but then
become radical themselves. However they are recycled by the intracellular antioxidants
glutathione and squalene and sent back to work. This recycling is a reduction process
involving a biochemical “ENE” reaction which stabilizes a free radical by donating a
hydrogen atom.
Comparisons of vitamin E and squalene
Vitamin E.
•
A mixed isoprenoid of three isoprene units and very good antioxidant
capacity
•
Exogenous [dependent upon dietary sources] and not necessarily available
when needed
•
Cannot be synthesized in the body – available only in certain foods
•
Limited integration into the biomembrane, where it becomes embedded in the
lipid bilayers
•
Is fixed in the lipid layer and cannot move freely
•
Too many vitamin E molecules alter the biomembrane’s physiological
properties and structural configuration
•
Vitamin E requires recycling by endogenous antioxidants such as glutathione
and squalene
•
Is itself susceptible to free radical attacks
The usefulness of vitamin E as the sole terminator in the biomembrane is limited
Squalene:
•
A pure isoprenoid of six isoprene units and very good antioxidant capacity
•
Endogenous [manufactured on demand] readily available under normal
circumstances
•
Manufactured within the cell from readily available glucose
•
Strongly attracted to the hydrophobic band between the two lipid layers of the
biomembrane, where risk of lipid peroxidation is greatest
•
Can move freely thoroughly the biomembrane
•
Large quantities do not alter the physiological properties of the biomembrane
•
Does not require recycling
•
Relatively resistant to free radical attacks on itself
The role played by squalene as a terminator in the biomembrane is significant
Usually a molecule’s methyl group supplies the hydrogen atom for the ENE
reaction. Squalene has six methyl groups capable of participating in the ENE reaction.
This may explain squalene’s ability to recycle oxidized vitamin E back in to recycled
vitamin E.
30
Squalene in the Skin
The human cell synthesizes two isoprenoid antioxidants: ubiquinone
[coenzyme Q10] and squalene. The former is mostly distributed within the
mitochondria [energy production centres] of our cells. Squalene is found mainly in the
biomembrane, but also in the fatty layer just beneath the skin. In addition, the outer
surface of our skin is covered by a coating of squalene rich fat. Laboratory research
has shown that squalene is capable of protecting the skin surface from free radical
induced lipid peroxidation confirming its antioxidant properties.
Squalene’s Role in the Immune System
Squalene’s antioxidant properties also contribute to protective functions in the
immune system. As primitive organisms learned to survive the threat of free radicals
and proliferate in number and variety, they needed increasingly to protect themselves
from viruses and bacteria, which were also proliferating. Only those able to do so
avoided extinction. The first step was the emergence of the macrophage – an immune
cell that kills, eats and digests bacteria and viruses. Today the macrophage remains the
principal immune defense of fish and many invertebrates. Humans have developed a
more sophisticated army of immune mechanisms, including lymphocytes that can
attack different antigens in specific ways and can even recognize particular invaders and
know how to overcome them. But we still depend largely on the macrophage for
protection. In fact it remains the frontline defense in the present day human body
especially in the protective coat – those parts of the body in direct contact with the
outside environment.
Laboratory tests have shown that squalene enhances the function of
macrophages. It seems that the concentration and distribution of squalene in skin and
adipose tissue is an evolutionary requirement to strengthen the defense function of the
protective coat of our body.
Squalene Metabolism & Cell Growth
Researchers developed ways to arrest the mevalonate pathway by blocking it
at the squalene stage, preventing the progress of glucose into cholesterol. But there
was an unexpected consequence – cell growth came to a halt, obviously because
something crucial was missing. However, adding cholesterol to the cell culture medium
afterwards did not correct the problem. The researchers deduced that one or more
intermediaries of the pathway were essential for cell functions. These intermediate
metabolites obviously play a more significant role than was previously thought.
The squalene synthesis segment of the mevalonate pathway produces some
isoprenoids essential for cell growth and proliferation. Of these four products, the two
isopreniods geranyl and farnesyl are derived from mevalonic acid and are direct
precursors of squalene.
In order to perform its work – and particularly when it undergoes division –
the cell depends upon certain proteins and growth factors. The isoprenoids geranyl
31
and farnesyl help the cell by providing an anchorage in the biomembrane for these
proteins. This is called protein isoprenylation.
Deficient squalene precursors at this stage can prevent protein isoprenylation
and inhibit cell growth. For cells to function efficiently, squalene and its precursors are
essential.
These precursors also function as signaling molecules for cell growth and
proliferation. Close to the beginning of the mevalonate pathway the synthesis of HMG
–Co-A immediately precedes the four steps of the squalene synthesis segment –
mevalonic acid to geranyl to farnesyl to squalene [see below]. This step is of particular
interest because it determines the mevalonate pathway’s rate of production as a whole
and is the key to many cellular functions. The production of HMG Co-A is dependent
upon the availability of HMG Co-A reductase, which determines several important
cellular functions including:
•
Control of the rate of production of cellular cholesterol
•
The entire mevalonate pathway in the cell, including production of geranyl
and farnesyl – two isoprenoids crucial to cellular growth and proliferation
•
Squalene has been found to regulate HMG Co-A activity
The regulatory role of squalene on HMG Co-A reductase and the roles of
squalene’s molecular cousins and precursors geranyl and farnesyl are the key to
understanding squalene’s full metabolic role in the cell.
The Squalene synthesis segment of the mevalonate pathway controls the isoprenoid metabolism by
regulating enzyme HMG Co-A reductase levels
Glucose
HMG Co-A Reductase
Mevalonic acid
Squalene synthesis segment Geranyl
Farnesyl
SQUALENE
Cyclic Squalene
About 20 steps
CHOLESTEROL
HMG Co-A reductase is the rate-limiting enzyme of the mevalonate pathway and therefore the
controller of the mevalonate production factory
Squalene & Aging
For unknown reasons the distribution and concentration of squalene and
other isoprenoids including coenzyme Q10 changes as a person ages. The activity of
HMG Co-A reductase too is age specific. Generally speaking isoprenoid
concentrations decrease with aging, particularly in the brain. It is not clearly known
why such changes occur but this undoubtedly affects our health adversely. More
research is required to uncover the implication of the age specific change in the
isoprenoid metabolism and to investigate the possibilities of modulating it.
32
Conclusion
Squalene is an ancient and potent isoprenoid antioxidant. Its isoprene
constituents and its special molecular structure provide its antioxidant properties. It is
stable enough to resist oxidation itself when quenching free radicals and also recycles
vitamin E.
The biochemical structure of squalene not only makes it a stable antioxidant
but also a regulator of cellular growth. It has recently been discovered that squalene
plays a key role in the regulation of the cholesterol synthesis pathway through its
influence on the enzyme HMG Co-A reductase – an enzyme crucial for growth and
cellular proliferation. There is no doubt that squalene’s protective role in the body is
profound and the question arises of whether squalene levels in the body can be
modulated to provide antioxidant protection in ways similar to dietary vitamin E. This
is especially significant in elderly people whose isoprenoid concentrations are
particularly depleted.
33
4 - Balance & Stress In Bodily Systems
Our body is an extraordinary network of interconnected operating systems.
In good health, the balanced interaction of these systems keeps our cells healthy and
happy. However – as we know from the second law of thermodynamics – entropy [the
tendency to fall into disorder] universally increases in all systems. For example, the
homeostatic conditions of water flow – when the flow rises or falls beyond a certain
threshold, entropy disrupts the phenomenon and it disappears.
Systems in our bodies are no exception – when balance is disturbed, disease
results. However, biological systems are sophisticated masters of entropy that work
hard to maintain a state of balance [low entropy] and some biologists consider life to be
the antithesis of entropy. Life has its own control mechanisms that maintain constant,
dynamic balance. Scientists call this “homeostasis” a sort of inherent wisdom of the
biological system. It is also called “health”.
Invading viruses or bacteria interfere with our health by targeting bodily
control systems and creating imbalance. More complex disease processes such as
diabetes and rheumatoid arthritis also break down control systems. Those most
commonly targeted are the immune control system, the oxidant-antioxidant control
system and the metabolic control system. Each has evolutionary niches that can be
targeted by pathogens, resulting in increased entropy for all. A good example is the
way the human immuno-deficiency virus [HIV] targets the immune system and leads to
AIDS. There are some experimental evidence to suggest that it upsets key processes of
the oxidant-antioxidant control system by creating a deficiency of glutathione. This
results in oxidative stress and immune imbalance that undermine the oxidant-
antioxidant control system eventually contributing to its collapse.
This finding suggests that a proper balance in the antioxidant metabolism is a
prerequisite for an effective immune system and indeed, squalene’s immune enhancing
properties have been long known, Since squalene metabolism is an antioxidant
metabolism, a study of its role in the immune balance may provide more insight into
the crucial relation between antioxidant metabolism and immune function. Such
insight will contribute to the development of useful therapies to reinforce the immune
system.
This chapter describes the fundamentals of immune balance and the role of
squalene and its metabolism in effective immune response.
Immune Imbalance
The balanced immune response defines the meaning of immunodeficiency.
The function of the immune system is to keep the internal environment of our body
free of pathogens and xenobiotics. To do this it relies on a network of special cells and
molecules, principally macrophages, lymphocytes and cytokines. It was long thought
that a large number of immune cells resulted in a stronger and more balanced internal
environment. In parallel to the concept of oxidant-antioxidant balance however, it has
become increasingly apparent that too active or too many immune cells can lead to
immune deficiency s readily as too few. Our body’s ability to resist disease does not
depend on the brute strength or numbers of immune cells but on their state of balance.
34
Consider the case history of a thirty-eight year old woman suffering from
chronic pharyngitis [sore throat] for two years. When she eventually developed lesions
in her mouth, her doctor diagnosed bacterial pharyngitis. His examination led him to
suspect her immune status. A battery of tests revealed large numbers of lymphocytes
[immune cells] and high levels of immunoglobulin [antibodies] in the blood and yet
infectious bacteria were found in a throat swab. The doctor wondered “If she has so
many antibodies and immune cells, why aren’t they killing the viruses and bacteria?”
He was forced to conclude that something was wrong with the woman’s immune
response.
-eight year old woman suffering from
chronic pharyngitis [sore throat] for two years. When she eventually developed lesions
in her mouth, her doctor diagnosed bacterial pharyngitis. His examination led him to
suspect her immune status. A battery of tests revealed large numbers of lymphocytes
[immune cells] and high levels of immunoglobulin [antibodies] in the blood and yet
infectious bacteria were found in a throat swab. The doctor wondered “If she has so
many antibodies and immune cells, why aren’t they killing the viruses and bacteria?”
He was forced to conclude that something was wrong with the woman’s immune
response.
The imbalance in this woman’s immune system is probably due to some
underlying disorder that prevents it from effectively responding to outside attacks.
Such diseases are characterized by an excessive immune response to a real or imagined
threat, resulting in damage to the host. Thus immunodeficiency does not always imply
a reduced number of immune cells or fewer antibodies. Rather, it refers to the lack of a
balanced immune response in which the internal functioning of immune cells plays the
main role.
Effective Immune Balance
Individual immune cells are the functional units of effective immune
response. Among them, macrophages are the frontline protective cells. They are large
white blood cells that simply engulf invaders and metabolic debris – old red blood cells,
dead tissue and even cells that have become malignant. Once it is safely contained
within the macrophage, the material is “digested” and conveyed safely out of our body.
Other immune cells such as lymphocytes use extremely sophisticated means
to fight off equally sophisticated viruses, but macrophages operate by brute force.
They create within themselves vesicles [sacs] filled with the free radical hydrogen
peroxide, which are transported to the outer cell membrane and squirted into the path
of oncoming enemies. Once released, the enormous quantities of these free radicals
are as potentially dangerous to the immune cell’s own membrane as to the invaders. In
a battle situation, immune cells are often called upon to grow and proliferate rapidly.
Their ability to do so depends upon effective biomembrane protection which is a
function of the antioxidant defense system. Antioxidants such as glutathione and
vitamin E prevent and stop lipid peroxidation chain reactions. Squalene has been
found to optimize the macrophage’s function.
Evidence suggests that the immune cells biomembrane s protected by
squalene during phagocytosis, and the synthesis and consumption of squalene probably
increases at this time, as do other antioxidants such as glutathione.
Quite apart from the oxidant-antioxidant balance within individual immune
cells, the immune response as a whole must maintain its own balance. Many types of
immune cells must work together as a team. This is maintained by a system of
communication that not only distinguishes friendly from enemy cells, but also identifies
the type of threat and encourages the growth and activity of the appropriate immune
response. Like a ball game in which players cooperate for the sake of the whole, each
one recognizes different needs in different parts of the field and communicates with
the others through words and signals.
35
The communication mechanism that ensures a balanced response and lets
immune cells know what to expect from each other is called negative feedback and is a
universal law of bodily control systems. According to our body’s needs, over excited
cells receive signals to slow down and follow an overall strategy, while sluggish cells are
encouraged to become more active. In short, macrophages, lymphocytes and other
immune cells work as a team, exciting or inhibiting each other with chemical signals to
maintain over balance.
The messengers of the immune system are cytokines – chemicals released by
immune cells that travel quickly through the blood, lymph and other body fluids to and
from the battle site. They carry excitatory or inhibitory messages, encouraging or
restraining other immune cells. Simply put, cytokines regulate the immune response.
Keeping the immune system working as a unit requires a balanced expression
of cytokines. Each immune cell synthesizes both excitatory and inhibitory cytokines
and releases them on demand. This cytokine balance depends upon a balanced internal
environment in the immune cell and here the squalene metabolic process plays an
important role.
Two precursors of squalene – geranyl and farnesyl – have been found to
influence cytokine synthesis and secretion. Experimental research shows that
deficiency of these two precursors inhibits the macrophage’s ability to synthesize
cytokines causing the cytokine system to lose its balanced expression.
Individual cells use squalene to protect their biomembrane, and two squalene
precursors are used for cytokine synthesis and secretion. In addition, research on
oxidative stress induced immune imbalance shows that endogenous antioxidant
metabolisms are factors in an effective immune balance. It therefore appears that
squalene and its metabolism may contribute to effective immune balance. This is
hardly surprising when we consider that squalene is an endogenous antioxidant. The
metabolism of glutathione – another endogenous antioxidant – also contributes to
effective immune balance.
Oxidative Stress & Immune Imbalance
A system falls into stress when it is overburdened by the demands placed on
it. Disease agents such as HIV encourage the release of large numbers of free radicals.
These destructive agents either burn up the cell or trigger its suicide [apoptosis]. These
combined assaults on the cells of our body are referred to as cellular oxidative stress.
Oxidative stress occurs when our body cannot access enough antioxidants
and free radicals gain the upper hand. Once balance is lost, the deficiency of
antioxidants becomes increasingly acute and the cytokine expression becomes overexcited.
Our body’s defense systems spiral out of control. Instead of slowing down,
they frantically secrete excitatory cytokines, worsening the situation. The immune
system becomes more and more aggressive, desperately trying to maintain our health
but in fact pushing the body into greater and greater levels of imbalance. This is like a
ball game in which the players see themselves facing defeat, become desperate, lose
their emotional balance and enter into uncoordinated attack leaving themselves
increasingly vulnerable. Excessive levels of excitatory cytokines cause untold damage
to healthy tissue.
36
Over excitation of cytokines can initiate positive feedback, further increasing
oxidative stress. This soon depletes endogenous antioxidants such as glutathione and
squalene leaving the cell membrane open to lipid peroxidation. Each state of
imbalance causes further imbalances, amplifying the damage in an ever-widening spiral
of destruction. The greater part of acute damage leading to disease occurs through this
vicious circle of amplification. Positive feedback poses two dangers in particular the
appearance of autoantibodies and further unrestrained amplification of cytokines
induced tissue damage.
oxidative stress. This soon depletes endogenous antioxidants such as glutathione and
squalene leaving the cell membrane open to lipid peroxidation. Each state of
imbalance causes further imbalances, amplifying the damage in an ever-widening spiral
of destruction. The greater part of acute damage leading to disease occurs through this
vicious circle of amplification. Positive feedback poses two dangers in particular the
appearance of autoantibodies and further unrestrained amplification of cytokines
induced tissue damage.
1.
While antibodies are normally produced by the immune response to
pathogens, autoantibodies turn on our body’s own proteins. Normally they
are controlled when negative feedback causes antibodies to inhibit their
production. When oxidative stress disrupts negative feedback however,
positive feedback takes over and autoantibodies can cause considerable
damage. The appearance of autoantibodies in AIDS is an example of positive
feedback initiated by stress.
2.
The other danger of positive feedback is an unbalanced cytokine expression
leading to lipid peroxidation and subsequent tissue damage. The damage
caused by too many excitatory cytokines leads to progressive and wide-
ranging destruction of all sorts of tissue, as demonstrated by the activity of the
human immunodeficiency virus {HIV] in the human brain. Although HIV
cannot replicate in the brain as it does in other parts of the body, AIDS
patients frequently develop marked symptoms of dementia, such as memory
loss and shortened attention span. The damage is triggered by the few HI
viruses that do pass into the brain. Although they cannot themselves act,
their presence stimulates immune cells in the brain to secrete an aggressive
cytokine {TNF-alpha]. This cytokine in turn amplifies cytokine secretion by
activating more immune cells, resulting in oxidative stress that further
increases the secretion of excitatory cytokines. The production of TNF-alpha
is caught in the vicious circle of positive feedback. By disrupting the balance
expression of cytokines, this tiny population of HI viruses – unable even to
replicate – can initiate a snowball leading to extensive brain tissue damage.
Such effects are seen in many ailments, including allergies, tuberculosis and
kidney failure. Increasing oxidative stress in brain leads to extensive damage
at the hands of apoptosis. In other words, oxidative stress pushes normal
cells towards programmed cell death [apoptosis]. And apoptosis is a major
contributing factor to oxidative stress induced immune suppression.
Apoptosis
Every second 25 million cells die [and 25 million are born] inside our body,
and the body needs to maintain order. This order is maintained by apoptosis – a
natural process of cell death which is normally harmless. Healthy cells have several
inherited genetic mechanisms that, when triggered, force them to commit
“suicide”. If apoptosis were not a controlled mechanism and cell deaths were
random, toxic debris would be strewn about surrounding tissue. Many cells
contain free radicals and other toxic substances. For example, pancreatic cells
37
have powerful digestive enzymes. Macrophages and neutrophils contain hydrogen
peroxide and digestive enzymes within special sacs in their cells. If the cell
membranes break – for example due to a lipid peroxidation chain reaction – the
release of these substances into surrounding tissue causes extensive inflammation.
Apoptosis is a way for our body to contain these toxins. Dead cells are engulfed
by the trash-collecting macrophages before their membranes break open.
Apoptosis is an essential part of overall health and development of the body.
It is for example, responsible for the resorption of a tadpole’s tail, the removal of
webbing between the fingers and toes of a human fetus, the formation of adequate
gaps, [synapses] between neurons in the brain and the sloughing off of the inner
lining of the uterus [the endometrium] at the start of menstruation. Apoptosis is
not the random death of worn-out cells but highly organized behavior, which is
why it is defined as programmed cell death. Without apoptosis, these processes
would not proceed in a systematic fashion and would result in severe
inflammation. Some body cells only undergo apoptosis at the end of their useful
life, when they begin to malfunction. But other cells are discarded as part of a
particular bodily function – for example, endometrial cells die not according to
their age or condition but according to the rhythms of the menstrual cycle.
The complex cellular mechanisms that decide a cell’s fate are known as
apoptosis regulators. An example is the tumor suppressor gene [a killer gene] that
identifies cells about to become cancerous and forces them to undergo apoptosis.
A link between apoptosis and the squalene synthesis pathway has been established
experimentally, although the precise mechanism has not yet been explained. In
these research experiments, cells underwent apoptosis when their squalene
synthesis pathway was inhibited. It has been found that apoptosis can also be
induced by free radicals. During periods of oxidative stress, for example, the
incidence of apoptotic cell death increases. This has been blamed for the
development of Alzheimer’s disease, Parkinson’s disease, diabetes mellitus and
other illnesses. In cases of myocardial infarction too, many cardiac cells die of
apoptosis. In AIDS a large number of healthy immune cells die due to forced
apoptosis triggered by oxidative stress.
Disease agents and disease processes generate additional free radicals,
resulting in increased production of excitatory cytokines. This in turn promotes
uncontrollable excitement in the immune response, increasing the generation of
free radicals and thus oxidative stress levels. The response of the endogenous
antioxidant metabolism is to increase production of antioxidants, in order to meet
increased demand. For reasons which are still unclear however, the metabolism
fails, resulting in diminished antioxidant synthesis. The cause of this failure must
be clarified. In chapter one, we hypothesized that stress in the antioxidant
metabolism may cause such failure. What is this metabolic stress and why does it
occur?
38
Metabolic Stress
The cell must produce various biochemicals on demand and its ability to
respond depends on the competence of metabolic pathways. These pathways are
sequences of events that in the healthy body lead to the manufacture of the right
molecule in the right place at the right time. When our body is in a state of
metabolic stress, the competence of these metabolic pathways is easily disturbed.
Once consequence of this disturbance is metabolic stress.
We have already explained that a system falls into stress when it is
overwhelmed by the demands placed upon it. Just as oxidative stress can lead to
an oxidant-antioxidant imbalance; this imbalance in turn can lead to the greater
problem of metabolic stress.
An Example of Metabolic Stress
A well known cause of metabolic stress is hypoxia reperfusion injury – a
common consequence of blocked coronary arteries. The blockage cuts off the
blood supply to the heart tissues, resulting in hypoxia – inadequate levels of
oxygen. If the tissue is reperfused – replenished with oxygenated blood – it
consumes the incoming oxygen as desperately as we gasp for air after being under
water for too long. The first part of the problem is that much of the tissue’s
antioxidant supply has been exhausted during the period of hypoxia and it is
unable to cope with even normal levels of oxyradicals, resulting in oxidative stress.
The second part is that the production of cellular antioxidants suddenly increases
to counteract their increased consumption. However, this production depends
upon the metabolic process of antioxidant synthesis, which is overwhelmed by the
demands placed on it, leading to metabolic stress. Tissue levels of antioxidants
then plummet, leading to hypoxia-reperfusion injury.
Thus, oxidative stress increases demand for a particular nutrient, leading to
stress in its metabolism and in turn compounding oxidative stress.
Metabolic Stress & Immune
Suppression
This idea that metabolic stress may lead to an ineffective immune response or
even immune collapse is central to this chapter. This immune system is normally
able to operate effectively even in the midst of free radicals because the
endogenous antioxidant metabolisms synthesize enough antioxidants to counter
the oxidative threat. However, this stress reaches a certain threshold when the
body’s ability to synthesize endogenous antioxidants has reached its limit, at which
point the antioxidant metabolism falls into a state of stress. Cytokine synthesis,
membrane protection and other normal cellular functions are then impaired,
leading to immune imbalance.
Since metabolic stress therefore limits the ability of the immune system to
operate in normally acceptable situations of oxidative stress, prevention of
metabolic stress should help to maintain the immune function in spite of oxidative
stress.
Conclusion
Immune suppression is a result of an imbalance in the immune system rather
than a simple lack of immune cells. Oxidative stress may increase the
consumption of antioxidants, create stress in the antioxidant metabolism and lead
to immune suppression.
Experimental studies have shown that squalene-supplemented diets lead to
increased performance of the immune system. This can be explained by squalene’s
essential roles in the protection of the biomembrane of immune cells against
oxidative stress.
Most importantly, the squalene metabolic process is an antioxidant
metabolism. It is there for vulnerable to oxidative stress induced metabolic stress.
Such stress may contribute to free radical induced immune suppression particularly
in the skin. This is discussed in detail in the last chapter of the book: Metabolic
Stress and Chaos.
39 40
Part 11
Squalene & Disease
This part of the book describes how squalene has the potential to be used as a
cytoprotective agent against cancer and as a cholesterol lowering agent.
5 -Squalene’s Role in Cancer &
Cancer Therapy: Carcinogenesis
Cancer’s biological mechanism has been so mysterious for so long, that of all
diseases in the modern world it is one of the most difficult to treat. During the
last decade however, many of its secrets have been revealed, including its genetic
evolution.
It is commonly believed that healthy cells suddenly and inexplicably become
cancerous and develop quickly into tumors. Nothing could be further from the
truth. Cancer develops in a single cell through a process of evolution, and in most
cases – excepting acute childhood cancers – cancer cells must struggle for years to
divide and proliferate into a tiny mass of one-thousand cells. The initial
development of cancer is extremely slow but once a certain limit is reached tumors
progress rapidly and aggressively.
This chapter describes how a healthy cell becomes cancerous and how it
develops into a large mass. It also discusses the role of squalene metabolism in the
evolution of cancer cells and how dietary squalene shows significant potential for
cancer chemoprevention and Cytoprotection.
The Evolution of Cancer
Cancer is like a sleepy settlement that hardly changes for centuries, and then
in a few decades suddenly grows into a town, a city and finally a metropolis that
consumes the surrounding countryside in concrete, smoke, dust and noise.
Cancer begins when a cell suddenly breaks away from the control systems
governing surrounding tissue and looks after itself, irrespective of the needs of the
body. It grows into a multicellular mass and develops its own autonomous
biomechanisms that can survive attacks by the immune system and by even the
most brutal radiation and chemical therapy. This development is known as the
clonal evolution of cancer.
As it divides and evolves, a cancer cell transfers its hereditary blueprint to the
child cell. This child cell acquires all the strengths of its parent cell, most notably
its ability to grow independently and to survive attacks from immune cells. This
child cell itself acquires new techniques to grow more rapidly and aggressively.
When it multiplies, its own child cells inherit and benefit from the parent’s hard
earned techniques. Thus, with each cell division, the cancer becomes stronger and
more resilient. Like any other living thing, only those cells that can acquire strong
survival properties will make it. Even cancer obeys the Darwinian law of natural
selection. Through evolutionary processes the cancer becomes autonomous,
resistant to immune attack and increasingly dangerous.
The cloned child cells eventually grow into a small colony. At some point they
differentiate [take on different roles] and acquire new properties. Some become
invaders, some metastasize [mobilize and seek new sites to colonize] and some
become specialists in the art of survival. Their environment [the body] is
extremely hostile. After all, the immune system recognizes the threat, uses every
weapon at its disposal and is often victorious. Cancers that survive this hostility are
inherently tenacious.
All but a few types of cancer develop very slowly. Breast cancer cells divide
every 100 days and a one centimeter growth in diameter [about a billion cells] takes
an average of nine year to evolve. Lung cancer growths reach this size in ten to
twelve years. However the next step is considerably more rapid. Both breast and
lung cancers progress from a one gram mass to a one kilogram mass within three
years.
Cancer’s Secret to Success
Every cell in the body has the potential to become cancerous. Most of those
that tend to do so inadvertently activate a gene called p53, which generally triggers
their self destruction through a process called apoptosis. Alternatively, the
immune system routinely detects cells with cancerous tendencies and sends
macrophages to engulf and destroy them. Only an extremely small number of
cells that attempt to become cancerous actually succeed in gaining a foothold.
Still, even one is enough to eventually kill the whole organism.
Cancer’s secret to success lies in the early, clonal stage of its growth. During
this time it learns to survive as an independent mass by controlling its genetic
expression and gaining “immortality” – in the sense that it is no longer subject to
apoptosis. Cancer cells bypass the body’s defenses by activating oncogenes
[cancer genes]. Oncogenes are usually inactive in normal cells, but are relocated
and mutated in cancer cells so that they are “switched” on.
The Ras Oncogene
Ras was the first and most common family of oncogenes to be discovered – it
is found in some 30% of cancers. Although many others have since been
identified, ras remains the most dangerous and most triumphant because in
combination with other oncogenes an evolved ras oncogene can transform a
normal cell into a cancerous one in a single step. It also plays a somewhat central
role in the activation of other oncogenes. In normal cells ras acts as a switch to
trigger cell growth when conditions are right. In many human cancers, ras is
hyperactivated - permanently switched on – enabling the cancerous cell to grow
autonomously. Oncogenes are a potent factor in cancer evolution – in fact they are
the backbone of cancer evolution. Without them few cancers if any would survive
41 42
the coordinated opposition of the immune system and the apoptosis control
system. Cancer’s perverse ability to invade and consume increasingly large areas of
healthy tissue distinguishes it as a powerful evolutionary force in the biological
system.
system. Cancer’s perverse ability to invade and consume increasingly large areas of
healthy tissue distinguishes it as a powerful evolutionary force in the biological
system.
Cancer cells activate the ras gene, which in turn synthesizes ras proteins and
performs ras functions. The activation of these proteins depends upon the
isoprenoid metabolism in the cancer cells. Through protein isoprenylation,
farnesyl anchors the ras protein to the cell membrane. Without this vital step, the
ras oncogene cannot get to work. This is extremely interesting because of
farnesyl’s place in the isoprenoid synthesis pathway and it’s dependence upon
HMG Co-A reductase, which is regulated by squalene.
A dietary supply of exogenous squalene can inhibit isoprenoid production in
cancer cells and hamper their growth and development. It has been suggested that
this may explain olive oil’s anticancer property. Several experiments have
demonstrated that the anticancer property of dietary squalene. Before we recount
them we will see how chemical carcinogens induce oncogene activity and the role
of squalene in the detoxification of such carcinogens.
Squalene’s Inhibition of Cancer
Proliferation
When dividing and multiplying, cells go through four phases. Cancer cells are
no exception. These phases are G1 [pre DNA synthetic phase], S [DNA synthesis
phase], G2 [Post DNA synthesis phase], and M [Mitosis or cell division phase]. A
G1 phase cell moving towards the S phase requires two products of the
mevalonate pathway for protein isoprenylation – geranyl pyrophosphate and
farnesyl pyrophosphate. Protein isoprenylation attaches some important proteins
to the cell membrane or nuclear envelope. However, the presence of exogenous
squalene sets up negative feedback inhibition by down-regulating the enzyme
HMG Co-A reductase, decreasing farnesyl synthesis, disrupting the mevalonate
synthesis pathway and inhibiting protein isoprenylation. Protein isoprenylation is
even more important in tumor cells than in normal cells, especially when the ras
oncogene is hyperactivated [permanently turned on] so its disruption is calamitous
to the cancer cell. By locking the cell in the G1 phase, squalene prevents cancer
cell growth and proliferation.
Both caution and further research are necessary. The degree of squalene’s
inhibitory effects varies from one cancer to another. Also, squalene has other
mechanisms that may prevent cancer, apart from its role in cell growth.
Carcinogenic Agents
43
Certain carcinogens [cancer causing chemicals] can activate oncogenes or
cause mutations, making a normal cell cancerous and initiating the ominous
evolution of clonal proliferation.
Many carcinogens – such as 4-[methylnitrosamino]-1 – [pyridyl] – 1 –
butanone [NNK] found in tobacco smoke – target the ras oncogene. With
increasing frequency, environmental pollutants and some types of radiation
promote the transformation of normal cells into cancerous ones. Increased
amounts and varieties of industrial carcinogens are blamed for the growing rate of
cancer throughout the world. We are only just beginning to identify these
substances and learning to avoid them.
Squalene’s Preventive/Therapeutic
Potential
Squalene’s potential detoxification properties may be useful against chemical
carcinogens. T.J. Smith and his colleagues demonstrated that dietary squalene can
prevent lung carcinogenesis induced by NNK 4-methylnitrosamino-1-3-pyridyl-1butanone]
and also proved squalene able to detoxify NNK in laboratory mice.
Squalene has been also found to inhibit the carcinogenesis induced by TPA [12tetradecanoyl
phorbol-13-acetate] a [7-12-dimethylbenz[a]anthracene]. C.V. Rao’s
team successfully used squalene to neutralize the potent carcinogen AOM
[azoxymethane].
Two properties of squalene may contribute to its anti-carcinogenic activity –
its separate abilities to prevent ras activation and to detoxify harmful chemicals.
Any way to inhibit oncogene activation is an extremely interesting and
potentially powerful weapon in the anticancer arsenal. Because it combats cancer
at the earliest stages, squalene’s preventive and therapeutic possibilities are
extremely promising. Several research findings show that squalene and other
closely related isoprenoids may play a very important role and deserve in depth
investigation. Squalene has been shown to:
1. prevent the occurrence of certain cancers
2. prevent carcinogenic agents from inducing cancer
3. act directly against tumor activity
4. optimize the activity of chemotherapeutic agents.
It has been found that several plant-derived isoprenoids share squalene’s
cancer inhibiting mechanism, and apparently exogenous isoprenoids are the most
effective ras inhibitors. Although the precise mechanism has yet to be clarified, the
cancer preventing action of squalene is supported by many epidemiological and
laboratory findings.
44
A Growing Body of Research
Several laboratory experiments have shown squalene to be anticarcinogenic. A
particularly interesting article appeared in the April 1998 issue of Carcinogenesis, a peer
review journal for physicians specializing in Cancer. It describes an experiment in
which three separate groups of female mice were fed a diet containing 5% corn
[control group] 19.6% olive oil [second group] and 2% squalene [third group], starting
3 weeks before being given a single dose of the potent carcinogen NNK. Sixteen
weeks after the NNK had been given all the mice in the control group had multiple
lung tumors averaging 16 tumors per mouse. The mice in the olive oil and squalene
groups exhibited significantly decreased lung tumor multiplicity – 46% & 58%
respectively. The squalene diet also decreased lung hyperplasia by 70%. Hyperplasia is
the abnormal proliferation of normal cells – a first step towards cancer.
A research paper published two months earlier in the same journal reported
research carried out by the Nutritional Carcinogenesis division of the American Health
Foundation, Valhalla, New York. Male mice on a diet enriched with one-percent
squalene were exposed to AOM –azoxymethane – a chemical which can cause colonic
aberrant crypt foci, a pre-cancerous condition of colon cancer. These mice did not
develop colonic aberrant crypt foci, while the control group on a normal diet did so.
These results are considered a highly significant indication of squalene’s cancer
preventing properties.
Olive oil contains a certain percentage of squalene and several studies have
been conducted in Mediterranean countries to examine the oil’s possible cancer
prophylactic properties. Mediterranean people consume relatively large amounts of
olive oil and high consumption levels have been associated with lessened risk of breast
and prostate cancers among others.
For many years researchers have been trying to understand why. It was first
thought that oleic acid – a monounsaturated fatty acid – might account for the cancer
protective effects of olive oil. However research by major research institutions around
the world has found that oleic acid may not possess such properties. Now there is an
increasing tendency to link the cancer preventive role of olive oil to its high
concentration of squalene.
Several laboratory experiments have found that squalene is beneficial even as
an adjunct to conventional cancer treatments. Usually, cancerous cells develop a
mechanism that will pump out any anti-tumor drugs. Squalene somehow promotes
their accumulation in the cancer cell, making the drug much more effective. More
research is underway.
There are many similar research experiments. However one report deserves
particular attention. Published in the October 1985 issue of the Japan Journal for
Cancer Research, it describes an experiment showing squalene’s ability to enhance the
action of anticancer drugs. This research finding strongly suggests several major
therapeutic advantages to using squalene as an adjunct to anticancer chemotherapy and
radiotherapy. By inhibiting the development of drug resistance, tumors can be
overcome with a decreased dose of anticancer agents. This has the two fold advantage
of attacking the cancer more aggressively while causing considerably less damage to
healthy tissue – a common undesirable and often dangerous side effect of conventional
chemotherapy and radiotherapy. Similar research findings from several such
45
experiments are encouraging more and more physicians to include squalene in the
anticancer arsenal.
Potential Clinical Applications
Squalene’s powerful antioxidant and cytoprotective effects are very significant.
Chemotherapeutic agents such as cyclophosphamide and cisplatin induce bone marrow
and kidney damage by generating free radicals or enhancing the oxidative metabolism.
Since it is a strong antioxidant, squalene may be able to minimize such tissue damage.
Also, squalene has been found to potentiate the cancer killing abilities of some
chemotherapeutic agents. In addition squalene’s ability to protect cells from the effects
of radiation makes it a suitable protector of healthy cells against cancer radiotherapy.
Cytoprotective therapy promises to play a much greater role in future cancer
treatments. Squalene in combination with some cytoprotective agents such as
amifostine may bring considerable relief to cancer patients. Further clinical and
laboratory research is necessary to explore such possibilities. We outline these
possibilities below.
Cytoprotection – an Undervalued
Modality
The last decades have seen the development of many anticancer drugs, some
of which have shown great promise. However, most of them have the short coming of
producing severe side effects – including the free radical destruction of bone marrow
and kidney failure. Another problem is that cancer cells are ferociously adaptable and
soon learn to tolerate or resist these drugs. To achieve effective results, it is often
necessary to increase the dose – and the corresponding side effects. This includes
cellular DNA damage and mutation leading to further cancers.
One emerging avenue of research focuses on substances that help our bodies
tolerate anticancer drugs and radiation and/or make cancer cells more susceptible to
these treatments. To be truly useful, these substances must have a differentiating
action and must maximize the benefits of the anticancer agent at a minimum dose.
This is called cytoprotective therapy. A good cytoprotective agent must:
1. discriminate a normal cell from a cancer cell
2. protect the former but not the latter
So far a mere handful of cytoprotective agents has been developed and of
these only one is considered in any way satisfactory – amifostine. It has broad range of
cytoprotective action against several anticancer drugs, but is not without its drawbacks
– it promotes hypotension and allergic reaction. It is also very poorly tolerated by
children. It must be given intravenously and since it rapidly loses its effectiveness, it
cannot protect against the long term accumulation of drugs in the bodily tissue.
The development of a powerful and effective cytoprotective agent would be a
significant advance in anticancer therapy. However the list of necessary requirements is
46
long and every potential candidate must undergo extensive laboratory and clinical
testing. This chapter examines these requirements and considers squalene’s
qualifications as a cytoprotective agent.
clinical
testing. This chapter examines these requirements and considers squalene’s
qualifications as a cytoprotective agent.
Criteria for a Cytoprotective Agent
Although it primary function is not to actually attack the cancer, an ideal
cytoprotective agent will promote some sort of direct anticancer action – however
slight – as a reassurance that it does not protect cancer cells in any way. This is asking
a great deal. Most early candidates for this sophist aced job turn out to either have no
anticancer activity or to indiscriminately protect both cancerous and normal cells.
Another factor that must be countered is the direct activity of cancer cells against
pharmaceutical threats – an efflux mechanism enables them to pump anticancer drugs
out of the cell, while healthy cells have no such protection. An ideal cytoprotective
agent should do precisely the opposite – protect healthy cells from the toxicity of
anticancer drugs while disarming the cancer cells self protecting mechanism.
A cytoprotective agent should therefore provide selective protection of
normal tissue against chemotherapeutic agents in two ways:
1.
by entering more readily into normal tissue than cancerous tissue – a higher
accumulation in normal tissue and lesser in cancer cells is the key to selective
protection
2.
by decreasing the cancer cells efflux [ability to pump out anticancer drugs] the
unique efflux mechanism of cancer cells may differentiate them from normal
cells and enhance selective action
After successful laboratory experiments a potential agent should be evaluated
in human clinical trials. Experimental therapy in cancer patients may reveal a reduction
of side effects to the anticancer therapy, but this is not enough. Researchers should not
lose sight of the most important criterion of all – without measurable tumor shrinkage;
no candidate can be considered a true cytoprotective agent.
Squalene’s Cytoprotective Roles
Six properties of dietary squalene lead us to suggest its great potential as a
cytoprotective agent:
1.
ANTI CANCER ACTION: Squalene’s ability to inhibit protein
isoprenylation prevents the unrestrained growth characteristic of cancer cells.
Like many molecules with isoprenoid side chains squalene may also act as a
differentiating agent, making cancer cells less dangerous by prompting them
to divide normally.
2.
ANTI EFFLUX ACTION: Squalene has already been found to increase the
accumulation of chemotherapeutic drugs like adriamycin and bleomycin in
cancer cells by decreasing the cells ability to pump them out. This
biochemical resistance is effective against a variety of drugs. The pump is
built from the p-glycoprotein complex and usually expels large amounts of
47
hydrophobic compounds. Squalene is a hydrophobic compound and could
potentially monopolize the cell’s pumping functions, enabling the anti-cancer
drugs to destroy the cell before they are expelled. In this way, Nakagawa and
colleagues found that dietary squalene supplementation caused cisplatin,
adriamycin and bleomycin to accumulate in cancer cells. This is an important
property of squalene. Research is needed to further explore these
mechanisms and to determine the effective doses that produce such a result.
3.
ANTIOXIDANT ACTIVITY: Many anti cancer drugs damage body tissues
by generating highly toxic free radicals. Adriamycin – a widely used drug –
generates a superoxide anion that damages heart tissues. Cyclophosphamide,
another very potent and important anti-cancer drug is metabolized in the
kidney into a highly toxic free radical, chloroacetaldehyde, which may generate
oxidative stress leading to kidney damage. Anti cancer drugs that employ
platinum cause bone marrow damage by generating free radicals. Squalene
protects against oxidative stress and free radical damage. Squalene’s proven
antioxidant properties may neutralize these free radicals and protect normal
tissue.
4.
EFFECTIVE TISSUE DISTRIBUTION: The tissue distribution of dietary
squalene has been studied in laboratory animals. Dr. H. M. Storm and his
colleagues at the Kansas Medical Center fed mice a squalene rich diet. After
two weeks the squalene concentration in their intestinal mucosa increased
fifteen fold. There is every reason to expect a similar distribution in humans.
This finding is extremely significant since both anti cancer drugs and
radiotherapy can damage the intestinal mucosa and disrupt the cytokine
network, threatening the integrity of the epithelium. The researchers
concluded that squalene protects intestinal cells from high doses of radiation
by increasing the cellular metabolism and thus minimizing tissue damage.
5.
SAFETY PROFILE: Complementary health practitioners usually promote a
dietary supplement of one to four grams of squalene per day as an anti cancer
therapy. So far, no serious side effects have been reported. Generally
speaking, squalene can be consumed safely as a dietary supplement in food or
capsules [but it should not be drunk since this may result in accidental
inhalation, leading to lipoid pneumonia]. This does not , however, mean that
all squalene dietary supplements on the market are safe. Some have been
found to contain PCB’s and other carcinogens. In other words, squalene is
safe as long as it is carefully extracted and a purity of 99.9% is maintained at
every stage of production.
6.
IMMUNE RESPONSE BOOSTER: Cancer induces a nonspecific immune
response, increasing opportunistic infections and diminishing quality of life.
Squalene’s ability to protect and enhance the immune response is therefore
one more advantage.
48
A Multi-Target Approach To Cancer
Therapy
-Target Approach To Cancer
Therapy
The progress of potential anti cancer treatments was for some time frustrated
by our poor understanding of the generation and progression of cancer cells. Recent
advances in cancer biology are helping us see cancer cells in a whole new light. Step by
step cancer biologists are learning the survival secrets of cancer. Much effort is made
to understand how cancer cells feed on the same glucose and amino acid nutrients as
normal cells, and yet achieve such enormously successful proliferation and growth.
So far we know that the hallmark of cancer’s success is its ability to survive
even in the midst of genetic and metabolic instability. Although our knowledge of
what goes on within these cells is still incomplete, we do know that they explore many
avenues of survival. A new approach to cancer treatment is to target as many of these
avenues as possible by natural agents such as flavonoids and isoprenoids. This multi
target strategy aims to challenge cancer from as many directions as possible by targeting
its metabolism, its cell signaling, its angiogenesis, etc. Cancer researchers no longer
seriously expect to find a single miracle drug to defeat cancer as definitively as penicillin
was able to defeat bacterial infections. Squalene contributes to at least two of these
approaches. Most promising is squalene’s cytoprotective activity and research is
ongoing in Canada to discover its full potential. Also, it can control the isoprenoid
metabolism by inhibiting HMG Co-A reductase and activating the differential pathway
that pushes cancer cells to slow down and grow like normal cells.
Conclusion
Various epidemiological and laboratory data suggest that squalene may help
prevent cancer at its outset and can also fight established tumors. These findings are
consistent with the known role of squalene in the regulation of the isoprenoid
metabolism.
The isoprenoid metabolism in the cancer cell is highly active, and protein
isoprenylation is an essential first step in the activities of oncogenes such as ras.
However, exogenous isoprenoids rapidly enter cancer cells, which are very susceptible
to their action. Their production of isoprenoids is inhibited as the enzyme HMG Co-A
reductase is down regulated and their growth is curbed as they become more
susceptible to the body’s natural defense system. Squalene may also exert its anti cancer
effect through other mechanisms, notably by detoxifying carcinogens and augmenting
the natural defense systems of the body. Extensive research into the link between
carcinogenesis and the anti-cancer properties of squalene is imperative.
Squalene may have a valuable role to play as a cytoprotective agent in cancer
chemotherapy. At present, ongoing laboratory and clinical research is exploring the
cytoprotective role of squalene in cancer chemotherapy
49
6 – Cholesterol & Heart Disease.
Coronary Heart Disease
Coronary heart disease [CHD] is a widespread disease often blamed on
modern lifestyle. In the United States, the number of victims is 1.5 million per year, of
whom about one quarter do not survive. An additional 150,000 people die within one
year of the attack. In 1995, 40% of all deaths in the USA were due to CHD. In Britain
300,000 people suffer from a heart attach each year, of whom more than half – approx
170,000 – die.
CHD is the leading cause of death, disease and health care spending in the
modern world. In India, Brazil, China and other developing nations the death rate due
to CHD is rising alarmingly and the cost of hospitalization for survivors is extremely
high. The World Health Organization [WHO] warns that unless this trend is reversed
the increasing costs of treating heart diseases and the rapid growth of a sedentary
middle class in developing nations will rapidly erode their advances in healthcare.
Governments have generously funded scientific research and scientists have made
enormous efforts to identify the risk factors of CHD.
Four major risk factors are known to increase the chances of coronary heart
disease:
1. high blood pressure
2. cigarette smoking
3. lack of physical exercise
4. high levels of bad cholesterol in the blood
During the last two decades of the twentieth century, the world of healthcare
has had some success in controlling blood pressure levels. Social groups are always
hard at work trying to lower smoking rates and more people than ever before – though
still only a fraction – are excising regularly. The fight against cholesterol however
remains an uphill battle.
More than nine out of ten heart attacks are precipitated by the narrowing of
the inner passage of coronary arteries as they are blocked by plaque that includes
cholesterol deposits. Any artery can be damaged by atherosclerosis. The most
common sites of damage are the blood vessels of the heart, abdomen, lower extremities
and brain.
Atherosclerosis
The heart is a muscular pump that forces oxygenated nutrient rich blood
through the arteries to all the cells of the body. These nutrients include sugar, amino
acids and fats. Like any other part of the body, the heart itself requires fresh blood,
which is delivered through the coronary arteries. If these arteries become blocked and
worse still, the tissue may die due to lack of oxygen and the patient suffers cardiac
arrest.
There are two major coronary arteries, right and left. Each divides and
spreads over the surface of the heart rather as the roots of a tree spread over a rock.
50
Hundreds of branches form small arteries, creating a network over the surface of the
heart. Each artery is a conduit. Cholesterol is sometimes deposited in the lumen
[interior] of these arteries just as silt accumulates on a river bed. The deposits of
cholesterol harden, constricting the artery and reducing its flexibility. These are the
mechanics of atherosclerosis. Its exact cause has still not been clearly explained,
although many risk factors have been identified. Cholesterol deposition on blood vessel
walls is a principal one.
heart. Each artery is a conduit. Cholesterol is sometimes deposited in the lumen
[interior] of these arteries just as silt accumulates on a river bed. The deposits of
cholesterol harden, constricting the artery and reducing its flexibility. These are the
mechanics of atherosclerosis. Its exact cause has still not been clearly explained,
although many risk factors have been identified. Cholesterol deposition on blood vessel
walls is a principal one.
Artery walls have two layers – inner [intima] and outer [media].
Atherosclerosis begins when the smooth muscle cells of the media migrate to the
intima. If bad cholesterol levels rise in the blood, build up of cholesterol plaque in the
intima gradually hardens and narrows the arteries.
Good Cholesterol
Cholesterol is widely believed by the general public to be an unmitigated evil.
It is in fact vital to life – an important lipid in the cell membrane structure and in nerve
fiber sheaths. It is also the basic molecule for the production of certain important
hormones, including corticosteroids and sex hormones. It is only harmful when –
having built up high concentrations in the arteries – it becomes a major constituent of
atherosclerotic plaque.
Bad Cholesterol
Medical researcher Dr. Joseph L. Goldstein – awarded the 1985 Nobel Prize
for Medicine following his research into the cholesterol regulatory mechanism of the
liver – once remarked that cholesterol is “…. A Dr. Jekyll & Mr. Hyde thing,” because
it is both necessary and a harmful agent. Dr. Goldstein discovered how the liver filters
excess cholesterol from blood. He and his colleague M.S. Brown published a research
article in the Journal Science, prompting the major pharmaceutical companies to
develop drugs to increase the liver’s cholesterol filtering function.
For good or bad, the liver is the body’s main manufacturer of cholesterol –
which is manufactured along the mevalonate pathway as in any other cell. Quite apart
from this, cholesterol also enters the body from dietary source. The blood circulation
transports it to the liver where it is normally filtered. However some of it leaves the
liver and circulates in the blood supply. This is the cholesterol that contributes to
plaque build up in the arteries and is known as “bad cholesterol”. It is not chemically
different from “good” cholesterol but is associated with fats that transport it through
the body differently.
Cholesterol Transport
Cholesterol cannot swim. Or to put it more scientifically, it cannot travel
alone through the body because it is not water soluble. It is carried through the
bloodstream on a “boat” of fat and protein called a lipoprotein. There are three types
51
of lipoprotein – high density [heavyweight], low density and very low density
[lightweight].
1.
High density lipoproteins [HDLs] transport cholesterol into the liver without
harming the body – this is known as good cholesterol.
2.
Low density lipoproteins [LDLs] and very low density lipoproteins [VLDLs]
transport cholesterol out of the liver and around the body, where it is often
deposited in arteries. This is known as bad cholesterol.
One of the liver’s functions is to filter excess cholesterol from the blood.
LDL receptors constitute the filtering system of the liver. These receptors [attractive
doorways] protrude from liver cells and snag the LDLs, which are either put to
metabolic use or – if not required by the body – are consumed by the macrophages that
populate the liver. However if the liver’s macrophages can’t keep up with the flow of
incoming LDLs they end up back in the blood stream where they contribute to the
buildup of atherosclerotic plaque.
The filtering mechanism depends greatly on the feedback inhibition of HMG
Co-A reductase. Researchers have found that if this enzyme is inhibited the production
of LDL receptors is stepped up, thus increasing the liver’s filtering capacity. As a result
of these findings, pharmaceutical drugs were developed to inhibit HMG Co-reductase
notably a group of drugs called statins. During the nineteen nineties, three large long
term epidemiological studies comparing different population groups examined the
efficacy of these drugs with encouraging results.
Harvard School of Medicine researchers described the positive results of the
Cholesterol and Recurrent Events [CARE] study, which employed pravastatin. The
other two studies – the West Scotland Coronary Prevention Study {WOSCOPS] and
the Scandinavian Simvastatin Survival Study [4S] showed that either pravastatin or
Simvastatin can significantly reduce heart attack deaths. The success of these trials
provides empirical support for the theory of cholesterol and LDL receptor synthesis.
These large scale research results have encouraged doctors to prescribe these
cholesterol lowering drugs in order to reduce the chances of heart attacks and to
prolong the lives of heart attack survivors. However, they are expensive and their side
effects are very much at issue since their effectiveness depends on long term use.
A report from the United Kingdom National Health Service Center for
Reviews and Dissemination criticized the routine use of cholesterol lowering drugs
such as pravastatin, commenting that “… the intervention represents poor value for
money.” The report estimated that the cost of one year of life gained from taking
Simvastatin is 7,240 pounds [about U.S. $11,656]. The report reflects the wider
concerns of hearth service economists around the world. A huge number of people are
at high risk for CHD and the costs of pharmacological prevention of coronary heart
disease are simply becoming unmanageable.
Patients must take statins for at least four years to derive positive results.
Since the drug can damage the liver its use must be monitored during this period along
with certain blood parameters. Prolonged use can cause myopathy [muscle damage
leading to inflammation], especially if dosage is raised. Newer variations like
pravastatin can also damage the liver, pancreas, muscles and skin. Accounts of such
negative effects have been published in various clinical journals.
Statins interrupt the cholesterol synthesis pathway before the synthesis of
squalene and ubiquinone [coenzyme Q10]. Perhaps at the same time that they preempt
52
the buildup of harmful cholesterol levels in endothelial cells, they also deprive them of
these two vitally important endogenous antioxidants and give rise to some of the long
term side effects of the drug. Indeed, it has recently been suggested that statins may
actually help turn bad cholesterol into the worst cholesterol.
these two vitally important endogenous antioxidants and give rise to some of the long
term side effects of the drug. Indeed, it has recently been suggested that statins may
actually help turn bad cholesterol into the worst cholesterol.
The Worst Cholesterol of All
It appears that an imbalance in the cholesterol metabolism underlies CHD
and atherosclerosis. However, bad cholesterol alone is not the only culprit in CHD.
When bad cholesterol is attacked by free radicals it becomes an even more harmful
substance – oxidized cholesterol [oxLDL] – increasingly known as the worst
cholesterol. This may be the greatest risk factor in atherosclerosis. And oxidized LDL
may increase the proliferation of vascular smooth muscle cells [SMC] a crucial event in
atherosclerosis.
Lipid peroxidation of LDL leads to the MDA-modification [malondialdehyde]
of oxidized LDL, which has been found in atherosclerotic lesions. The body responds
by producing MDA specific antibodies in these sites and the presence of these
antibodies is used to predict the progression of carotid atherosclerosis and CHD.
Oxidized LDL cholesterol accumulates as plaque on the inner walls of the
blood vessels in the heart and sets up oxidative stress in the affected areas. This
irritates the smooth muscle cells just beneath the intima and they migrate inwards
towards the lumen where they are subjected to oxidative stress by oxLDL free radicals.
The result is lipid peroxidation and inflammation. In an attempt to correct the
situation, macrophages accumulate, engulf the cholesterol and soon become fatty
themselves [foam cells]. Instead of clearing up the mess, they become part of it. The
result is a thick plaque and significantly narrowed blood vessels.
Cholesterol-Lowering Effects of
Squalene
Dietary squalene has been found to lower cholesterol levels in blood,
apparently increasing the liver’s filtering capacity. This mechanism seemingly derives
from Squalene’s ability to down regulate the HMG Co-A reductase, which in turn
enhances the liver’s capacity to filter bad cholesterol. These laboratory findings are
supported by epidemiological correlations of squalene rich olive oil consumption with a
low incidence of CHD.
The laboratory evidence of the cholesterol lowering ability of squalene has
prompted pharmacologists to combine statin drugs with squalene. This may lead to
reduced statin doses, thus reducing its side effects. At the same time, squalene may
prevent the lipid peroxidation of bad cholesterol and prevent the formation of “worst”
cholesterol. A large clinical trial conducted in Taiwan and published in the Journal of
Clinical Pharmacology documented the effectiveness and safety of squalene in
combination with pravastatin – the statin drug used in the Harvard CARE study.
53
A double blind, placebo controlled, 20 week trial was conducted on a
randomized selection of 102 elderly people, all suffering from high cholesterol levels.
They received 10 mg pravastatin and /or 860 mg squalene daily, either separately or in
combination. The results showed that both pravastatin and squalene effectively
reduced levels of total cholesterol and LDL cholesterol, while increasing levels of HDL
cholesterol.
Interestingly, combination therapy reduced all bad cholesterol parameters and
increased HDL cholesterol to a greater extent than either agent alone. The research
paper concluded, “Co-administration of pravastatin and squalene combines the specific
effects of the two drugs on lipoprotein in elderly patients with hypercholesterolemia,
who might have a higher incidence of side effects when using larger doses of
pravastatin alone.”
The protective role of a diet rich in squalene [such as olive oil] suggested by
some epidemiological studies may be due not only to the squalene0induced reduction
in LDL cholesterol levels, but also to its role in preventing oxidation of LDL.
Squalene’s powerful antioxidant properties are well known but further research is
expected to clarify its ability to prevent conversion of bad cholesterol to the worst type.
Historical research into squalene’s cholesterol-diminishing potential
In 1953 D. Kritchevsky and his fellow researchers explored squalene’s HDL
cholesterol diminishing role in a laboratory study on four groups of rabbits on various
diets for seven weeks. Their aortae were subsequently examined for signs of
atherosclerotic plaques and it was concluded that, unlike cholesterol, dietary squalene
did not induce atherosclerosis.
In 1974, another experiment conducted by I. Prance and his colleagues found
that squalene protects laboratory mice against gallstone formation. They hypothesized
that squalene reduced cholesterol synthesis in the liver.
In 1985, T.A. Miettinen presented findings to the seventh International
Atherosclerosis Symposium in Melbourne, Australia suggesting that a squalene rich
olive oil diet could effectively reduce serum cholesterol levels.
In 1989, T.E. Strandberg and his fellow researchers reported that rats given
1% dietary squalene for 5 days experienced strongly suppressed [-80%] HMG Co-A
reductase activity in the liver cells.
In 1990, Miettinen and his colleagues published the results of another study in
the Journal of Lipid Research. They fed human subjects 900mg of squalene per day for
seven to ten days and produced a seventeen fold increase in serum squalene, with no
significant increase in serum cholesterol level.
In 1994, Miettinen and his colleagues proposed that the cholesterol reducing
mechanism of dietary squalene may result from the down regulation of HMG Co-A
reductase activity, leading to decreased cholesterol synthesis in the liver.
The relationship between cholesterol synthesis and LDL receptor synthesis in
liver cells was first proposed by Dr. Joseph L. Goldstein [1985 Nobel Laureate] who
proposed that increased cholesterol levels in the liver decreased LDL receptor
synthesis.
54
Conclusion
The liver’s filtering mechanism removes bad cholesterol from blood. Central
to this mechanism is the liver’s LDL receptor. Synthesis of this receptor is linked to
the activity of the enzyme HMG Co-A reductase, which is involved in cholesterol
manufacture in the liver. By inhibiting this enzyme’s activity, squalene increased the
bad cholesterol filtering capacity of liver cells. Squalene may also play an important
role in preventing the oxidation of bad cholesterol into worst cholesterol. Further
research is required to explore this potential therapeutic application in combination
with existing cholesterol lowering drugs. Such use may reduce the cost and toxicity of
the statin groups of drugs while simultaneously enhancing their effectiveness.
55
Part 111
Squalene & Environmental Pollution
In this part of the book, we seek a model to explain the impact of pollution upon the
evolutionary mechanism of our body. Readers may be surprised to encounter the term
“evolution” in this book, but without it we cannot properly explore the impact of
pollution, which in evolutionary terms has come upon us suddenly and with great
force.
Theodosius Dobzhansky, one of the greatest biologists of the twentieth century
remarked that “Nothing in biology makes sense except in the light of evolution”.
We ourselves are biological systems and in order to understand the impact of pollution
in our bodies we must understand the full implications of this new evolutionary
pressure.
The arguments in Part Three depend upon an understanding of the martial presented
in Part One.
Human Skin: First Casualty of Ozone
Depletion
In this chapter, we try to identify the body’s natural protective system against
UV radiation and to examine how it is affected by ozone depletion.
We have already discussed oxidative stress in the immune system and its
impact on squalene metabolism. Now we will apply this knowledge to the effects of
oxidative stress in the protective coat of our body, comprising the skin [external
surfaces]. Ultraviolet-B rays from the sun generate free radicals in exposed skin. They
also convert ground-level oxygen to ozone, a powerful oxidant that attacks the internal
protective coat. As the ozone layer is depleted, more UV rays reach the Earth’s
surface, increasing these threats. Both the external and internal surfaces of the
protective coat therefore suffer oxidative attack due to the diminishing ozone layer and
increasing levels of UV radiation.
The Epithelium – A Protective Coat
The epithelium coat is a fine layer covering the skin and the lining of the
mouth, throat, lungs and digestive tract and constitutes a protective coat with a surface
area greater than a tennis court. These surfaces of the body are all in direct contact
with environmental substances – air, food and drink, plus of course, bacteria, viruses
and toxins. The layer covering the outermost surface of the skin is also in direct
contact with sunlight and is covered by a combination of lipids called sebum of which
almost one part in eight is squalene. The inner parts of the protective coat are covered
by a mucosal layer. The adipose [fat] layers beneath both skin and mucosal cells also
contain a large proportion of squalene.
56
Skin contains a large number of macrophages that defend the body against
outside invaders. They may be part of the original immune system developed in
mammals. We have already seen that their main function is to destroy and consume
incoming bacteria and viruses. They also bring a part of the dead intruder to the
internal immune system – a process called antigen presentation. This enables the body
to recognize the antigen in the future so that it can respond more efficiently.
t
outside invaders. They may be part of the original immune system developed in
mammals. We have already seen that their main function is to destroy and consume
incoming bacteria and viruses. They also bring a part of the dead intruder to the
internal immune system – a process called antigen presentation. This enables the body
to recognize the antigen in the future so that it can respond more efficiently.
Unlike the internal mucosae, the skin is subjected to direct sunlight, which
includes UV-B radiation, a source of free radicals and potential skin damage. This may
help explain why sebum contains such a high proportion [12%] of squalene. If the
performance of macrophages is increased by squalene, it is reasonable to assume that
the substantial presence of squalene in the skin is helpful to their role, providing a
protection unique in the animal world. This high concentration may be an evolutionary
requirement for the defense of the protective coat against UV radiation and other
outside threats.
Because the skin and mucosae are constantly exposed to the outside
environment, the chances of oxidative stress here are high. We know that the threat of
UV-B rays is very serious, and that many environmental toxins can also initiate
oxidative stress in the skin. Therefore we must ask:
•
Does skin have a normal defense against oxidative stress and if so,
•
Could ongoing ozone depletion overwhelm this defense?
It is known that intense UV-B radiation can suppress the immune function in
the skin, perhaps because of increased oxidative stress and subsequent stress in
squalene metabolism.
Ultraviolet Radiation
Sunlight includes a wide spectrum of radiation; of which visible light is just
one tiny slice. All energy from the sun moves at the speed of light and comes in waves
of varying frequency. Waves of shorter length are more energetic [vibrate more
frequently] than those with a longer wavelength. The wavelengths of visible light rays
range from 400 to 700 nm [nanometers] and produce the different colors we see.
Ultraviolet light has a shorter wavelength than visible light, ranging from
400nm to 10nm in length. It is generally divided into categories, UV-A [from 400nm
to 32nm], UV-B [from 32nm to 290nm] and UV-C [from 290nm to 10nm].
UV-B and UV-C are harmful to the body. The upper atmosphere’s ozone
layer usually absorbs all rays shorter than 310nm, blocking them from the Earth’s
surface. Normally, only UV-A and a small portion of UV-B rays reach us. A paradox
of nature is that although UV-B rays can profoundly damage skin DNA and lead to
skin cancer, small portions are actually used in the skin to synthesize vitamin D, a
nutrient of great importance to normal bone maintenance.
Even slight exposure of the skin’s surface to UV-B rays can turn molecular
oxygen into singlet oxygen, which attacks skin lipids, creates lipid radicals and starts a
chain reaction. Skin lipids are particularly vulnerable to such oxygen derived free
radicals and these chain reactions can lead to inflammation and oxidative stress in the
skin.
57
It is believed that increased UV-B radiation is responsible for worldwide
increase in skin cancer. Other possible consequences may include immune
suppression, allergies, memory loss, blood cancer and cataracts.
On the one hand UV-B in direct sunlight damages our skin directly. On the
other hand it converts normal oxygen molecules into ground level ozone – free radicals
that threaten our protective coat around the clock. Ozone [O3] may accumulate near
the ground in polluted cities. Ozone’s volatile union of the three oxygen atoms make it
a powerful free radical. Ozone is an irritant to the skin and can be a major source of
oxidative damage to the protective coat. It may also be responsible for the rising
incidence of asthma and other respiratory diseases within urban populations.
The Skin
The skin is the largest organ in the body and among other functions serves as
a protective covering. It has an outer [epithelial] and an inner layer. The cells of the
outer layer produce three important substances:
1.
sebum – a mainly lipid secretion of the sebaceous glands
2.
keratin – a fibrous protein that acts as a waterproof barrier [letting us swim in
fresh water without swelling, or in salt water without shrinking]
3.
melanin – secreted by melanocytes, acts as an ultraviolet filter, controlling the
passage of ultraviolet rays into the skin.
Our discussion focuses on sebum since it coats the outermost skin surface.
The total surface area of the skin is between 16 and 20 square feet. The outer layer is
only 1 millimeter thick and its surface layer of fatty sebum measures about one quarter
of a millimeter. Sebum keeps the skin’s surface smooth and moist and also serves an
antibacterial and antifungal function.
Absorption of UV Rays by Skin
Ultraviolet rays penetrate the skin and product vitamin D without harming
surrounding tissue – at least for a while. However, UV-B radiation also reacts with
atmospheric oxygen to produce singlet oxygen [oxygen with an extra electron] and can
set up severe oxidative stress throughout the entire skin surface, Sebum is the first
victim of this stress and lipid peroxidation would normally set in immediately.
Our ancestors spent most of their waking hours out under the sun. Without
some sort of protection, even very low doses of UV-B rays would produce harmful
consequences, and they must have developed a skin defense against UV-B rays.
Human skin should have sufficient antioxidants to neutralize these free radicals while
still allowing UV-B radiation to penetrate for the purpose of vitamin D synthesis.
Therefore we can expect to find some natural protection in the skin against UV-B
radiation.
58
The Skin’s Natural Antioxidant
The skin’s natural antioxidant would have to fulfill four roles to protect the
skin from UV radiation and its consequent oxidative stress:
1.
It should be able to prevent or limit UV radiation induced lipid peroxidation.
2.
It should not become toxic or harmful after absorbing UV rays.
3.
It should not transform into a pro-oxidant [an agent that at first behaves like
an antioxidant, then becomes a free radical]
4.
The skin should be able to synthesize and accumulate it without any harmful
effects
Three isoprenoids in the skin fulfill the first criteria – vitamin E, vitamin A
and squalene. The two vitamins are relatively scarce in the skin, which cannot
synthesize them. Squalene on the other hand is abundant [ 12 % of the sebum] and is
also synthesized in the skin. In fact, squalene is one of the skin’s major surface lipids
and is also present in underlying fat [subcutaneous tissue].
Given that it is an excellent antioxidant, this makes squalene a likely candidate
to be the skin’s best natural protector and has led researchers to test its antioxidant
properties in the skin. In a unique research project sebum was tested for its ability to
prevent lipid peroxidation or to neutralize singlet oxygen. Y. Kohno and colleagues
compared the antioxidant capacity of squalene with that of sixteen other fats found in
skin. They showed that squalene more than any other could protect the skin’s surface
from lipid peroxidation. They also discovered that squalene’s stable molecular
structure resists outside attack by peroxide radicals – meaning that it does not act as a
pro-oxidant. Finally, they found that squalene more efficiently recycles oxidized
vitamin E than such strong antioxidant skin fats as methol oleate. Other research
reports substantiate squalene’s role in protecting skin from UV radiation.
Unlike vitamin E, squalene is readily available and is synthesized locally. So
under normal circumstances squalene is instrumental in protecting the lipid content of
sebum from UV induced lipid peroxidation. In fact, the action of squalene in skin and
subcutaneous fat resembles that of the light harvesting complex [LHC] in plant leaves.
Both seem to prevent molecular oxygen from undergoing oxidation.
Evolutionary Adaptation to Loss of
Hair
Compared to human beings, apes and other primates have insignificant
amounts of squalene in their skin. C. Luca and his colleagues studies the skin surface
lipids of nine different species of monkeys and found only trace amounts. The sebum
of gorillas for example is only 0.1% squalene [one thousandth] compared to a human’s
12% [almost one eighth]. Indeed, human skin secretes 125-420 mg of squalene daily.
What accounts for such a discrepancy: The obvious answer is that in the process of
losing our fur, squalene protected our increasingly naked skin from oxidative stress.
Apart from its fur covering, the skin of nonhuman primates is much thicker, adding to
its protection against UV-B radiation. Evolution may have covered human skin with
squalene for good reason.
59
However, the world we live in is changing more quickly than our evolutionary
ability to adapt. Squalene and its synthetic pathway are likely suffering from increasing
stress. This danger is exacerbated by the fact that the squalene synthesis pathway in
skin is not only involved in vitamin D synthesis but also in effective immune response.
Ozone Depletion
The ozone layer in the uppermost layer of the Earth’s atmosphere is
continuously formed by the interaction of very strong, short-wavelength ultraviolet rays
[ below 100nm] with oxygen and acts as a shield to prevent strong UV rays [below
290nm] from entering the earth’s atmosphere. Chlorofluorocarbons [CFCs] deplete
the ozone layer, thinning our protective shield and making pollution a constantly
growing threat.
Industrial societies have long been releasing two atmospheric pollutants –
CFCs and methyl bromide – into the upper atmosphere. These have already thinned
the ozone layer to the extent that holes are appearing in it, so more UV-B radiation is
getting through to our skin. The planet’s surface at the end of the twentieth century
was getting four times as much ultraviolet radiation as it had done a half century earlier.
Scientists have found that UV rays can now penetrate non turbulent ocean water to an
unprecedented depth of nine feet. This has very tangible health implication.
Skin Cancer
Industrialization has changed the world, and this change is mirrored in our protective
coat – skin and respiratory and intestinal mucosae. During the last two decades of the
twentieth century the incidence of skin cancer has risen significantly around the world.
Medical research has confirmed that strong UV-B rays break the molecular bonds of
skin DNA, leading to mutation and significantly increasing the risk of skin cancer.
The United Nations Environmental Program estimates that each 1% decrease
in upper atmospheric ozone will result in a 2% increase in UV-B radiation and a 6%
increase in squamous cell carcinoma – one of the most common forms of skin cancer.
The incidence of melanoma – another common and lethal skin cancer – has doubled in
the United States in 20 years. This is the result of both direct ultraviolet radiation on
the skin and indirect oxidative stress caused by UV induced free radicals in the air.
Immune Depression
Doctors worldwide are also seeing an increased incidence of allergy related
disorders. Not only are viral infections more common, they are appearing on a global
scale and their behavior is changing – even the common cold now takes much longer
to overcome than it used to. HIV and its attack on the immune system [AIDS]
continues to create havoc, despite the developments of potent drugs. All of these
threats have a common theme – a weakened immune system. One factor known to
contribute to weakened immunity is excessive UV-B radiation, which alters the
60
function of skin macrophages and promotes the secretion of inhibitory cytokines,
leading to depression of the entire immune system.
secretion of inhibitory cytokines,
leading to depression of the entire immune system.
Another source is ground level ozone, which takes up where UV radiation
leaves off. Cities with highly polluted air are partially shielded from the sun’s rays by
dust and smog, but are breeding grounds for ozone. This toxin can damage the
protective coat, particularly in the bronchi and bronchioles [air passages of the lungs],
causing chronic coughs, lung infections, asthma, and even lung cancer. It is also
capable of generating oxidative stress which in turn leads to immune suppression.
Protecting Against UV Radiation
There is no realistic hope that ozone depletion will cease in the foreseeable
future. The most optimistic outlook is a possible stabilization or slight reduction in
atmospheric pollution within one or two generations. The burden therefore falls on
medical science to protect us from its harmful effects.
The first way to avoid UV triggered disorders is to minimize our exposure to
sunlight – something easier said than done. Almost everybody enjoys the sensation of
sun on skin from time to time, and it is claimed that a sunscreen with a Sun Protection
Factor of at least 15 blocks harmful UV radiation. However the effectiveness of such
products is more theoretical than real. Even under ideal conditions it must be
reapplied every two hours. Sweat and water – not to mention towels – easily displace
even so called waterproof sunscreens, and exposed patches quickly appear.
Researchers have therefore been searching for other protective agents. Their
first thought was that topical antioxidants would help, but any product layered on the
surface of the skin suffers the same disadvantages as sunscreen. In any case, UV rays
rapidly consume these antioxidants and they must be reapplied even more frequently
then sun blocking lotions.
Nevertheless, the idea of an enhanced antioxidant defense has not been
abandoned. Vitamin A and its related compounds – carotenoids – are known to
protect skin against oxidative damage and lipid peroxidation. OF all carotenoids,
lycopene provides the best UV protection but also causes abnormal skin pigmentation
and may lead to a growth known as lycoma
Researchers have also turned to vitamin E – a natural antioxidant in the skin.
However it has recently been discovered that upon exposure to UV rays, vitamin E acts
as a pro-oxidant – it turns into a free radical itself.
So far no truly effective method exists to protect the skin from UV-B
radiation. The only effective escape is to stay indoors during periods of bright sunlight
and to cover the skin when outside. Similarly the best way to escape ground level
ozone is to stay away from polluted cities or to wear a protective mask. However for
most people these solutions are both inconvenient and socially extreme, and
widespread adherence is unlikely. The development of an ointment with a
combination of such natural antioxidants as squalene, vitamin E and glutathione might
prove very effective but cannot guarantee protection from ozone depletion. The only
sure solution is a reduction in ozone depleting pollutants.
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Are We Safe?
The slightest exposure of any part of the protective coat to UV rays or
polluted air may promote oxidative stress. The protective coat is highly vulnerable –
after all, its total surface area exceeds that of a tennis court. How significant might
oxidative stress be over this huge surface? It depends on the extent to which oxidative
stress exacerbates metabolic stress.
Oxidative stress generated by even a brief period of exposure to UV radiation
or polluted air might induce stress in squalene metabolism. O. Sakamoto and
colleagues found that the first target of UV-B radiation in skin is squalene and that
exposure of skin to UV-B radiation increases its synthesis and consumption.
Considering what we know of the relation between oxidative stress and
squalene metabolism in the immune system, a larger picture emerges. A UV-B induced
increase of squalene synthesis and consumption in the skin may not remain localized
and could spread into the general squalene metabolism throughout the body and this
effect may remain even after the initiating pollutant or UV-B radiation is removed.
Indeed, metabolic stress may be a nonlinear phenomenon in which biological events
can product effects out of proportion toi their stimuli. Such a possibility is the subject
of chapter 11.
Therefore although we tend to focus on the localized effects of UB-B
radiation – such as DNA damage or cytokine synthesis by immune cells – the internal
environment of our body may be undergoing very slow, systemic, long term damage.
Such gradual changes could make us a victim of Darwinian natural selection.
Conclusion
The presence of high concentrations of squalene in the skin presumably
results from an evolutionary survival mechanism. Ozone depletion and the consequent
exposure of the body to significantly stronger UV-B radiation is increasing this
requirement beyond the body’s ability to cope, placing squalene metabolism in stress,
with unknown consequences. New, more effective types of skin protection from
ultraviolet radiation may evolve from the use of internal rather than topical substances,
and their impact may go beyond mere protection of skin and help diminish the impact
of general metabolic stress, which is discussed in chapter 11. The only sure solution
however, is a reduction in the use of ozone depleting pollutants.
62
8 - Background Radiation - Background Radiation
The Universe and the environment in which we live have always been permeated with
radiation. It rises out of the ground and pours down from the cosmos. Light itself is a
form of radiation. The sun and every star in the cosmos emit incalculable amounts of
energy in the form of radiation. It is found in rocks and air. Even our bodies generate
radiation, though negligible amounts.
Some types of radiation pose much more of a threat than others and there are
many each with its own wavelength and frequency.
Sources of Radiation
Our bodies long ago developed mechanisms to protect ourselves from the
normal threat of background radiation. However our exposure to it has increased
considerably in the last century – since the discovery of radioactivity and mankind’s use
of uranium and other radioactive materials. Dozens of nuclear bombs have been
exploded in the atmospheres and underground, and their radioactive residue though
highly diluted, takes centuries or millennia to lose its toxicity. We are exposed
repeatedly to X-rays and other forms of medical radiation. Nuclear power reactors
occasionally leak small amounts of radiation. Some nuclear weapons lie disintegrating
on the sea floor along with the reactors of sunken and irretrievable nuclear submarines.
The storage or transport of growing piles of nuclear waste sometimes leads to leakage
too. In general background radiation threatens and destroys fewer lives than the toxic
by-products of burned fossil fuels, but it is one more form of pollution and it is not
insignificant. Overall background radiation can only be detected with the help of
sensitive equipment but it is on the rise and is harmful to living cells.
Pressure placed by background radiation on the internal environment of the
body may consume squalene in new ways, adding to our overall need for this protective
substance. The consequences of such new requirements and stress in squalene
metabolism are discussed in chapter 11.
Background radiation is either non-ionizing [longer wavelengths, to the left]
or ionizing [shorter wavelengths, to the right].
IONIZING RADIATION
Various frequencies of ionizing radiation are so called because they ionize
body tissue – tear electrons away from their constituent atoms and molecules. There
are several natural and man made sources of ionizing radiation.
MEDICAL SOURCES
Diagnostic X-ray equipment and other machines such as those used in nuclear
medicine, including radiation therapy, all emit ionizing radiation. Exposure to these
sources has doubled in the past 20 years.
INTERNAL SOURCES
Our bodies are composed of radioactive potassium and carbon, accounting
for about 8% of total background radiation absorbed per year.
DEPLETED URANIUM
Mankind’s use of refined radioactive materials has made increased exposure to
radiation a problem of our times. There are many sources, some quite unexpected.
63
For the 1991 Gulf War, for example, a new, exceptionally hard, armor casing was
manufactured from depleted uranium [DU] alloy. DU is a form of nuclear waste –
mainly from uranium-238. The casing itself carries minimal radioactivity, but upon
impact it contaminates the atmosphere with a highly radioactive and easy to inhale
uranium oxide dust in particles as fine as 0.5 microns. These highly toxic armaments,
designed and financed by the Pentagon, are exported around the world. The subject of
depleted uranium and its radioactive nature was initially understated or hidden for
obvious reasons. Since it has become public knowledge, however, it has become the
subject of an emotionally charged political debate that has unfortunately made
objective information very hard to come by.
GEOLOGICAL RADIATION
Geological radiation results from the radioactive decay of thorium and
uranium radio nuclides in the Earth’s crust. Billions of years ago, gravitation caused the
Earth to collapse into its present size, forming elements like uranium-238. Its various
stages of radioactive decay have led to the present day emission of alpha, beta and
gamma rays – much stronger than UV radiation and able to promote cancer and
immune suppression.
Electrically charged subatomic particles emitted by such radiation can
penetrate several centimeters into the body. Colorless, odorless radon [also known as
uranium gas] originates from both uranium deposits and nuclear waste and is believed
to account for about 55% of our background radiation.
COSMIC RADIATION
Cosmic radiation is composed of protons, electrons, neutrons and heavy
nuclei from galactic sources, contributing about 9% of the total background radiation.
The amount doubles with every 1500m increase in altitude.
NON_IONIZING RADIATION
Longer wavelength rays from UV radiation, radio waves, microwaves and
infrared sources do not penetrate out body – that is to say, they do not product free
radicals inside the body. For example, ultraviolet [UV] rays are classified an nonionizing
because they do not penetrate the body deeply like X-rays or gamma rays.
However, they can ionize molecules in the skin, leading to lipid peroxidation. Infrared
waves, microwaves and radio waves on the other hand, do not ionize even the
outermost layers of skin.
Very low frequency radio and other electromagnetic waves have been found
to modulate ion flow and interfere with cellular RNA transcription and DNA synthesis,
but their overall effect in humans remains unknown.
Consequences of Background
Radiation
Our increased exposure to background radiation has both immediate and long
term consequences. In the short-term we can expect an increase in all kinds of cancers,
and a generally weakened immune response. The long range prognosis includes
accelerated aging and changes in psychological behavior. Some scientists have warned
of decreased fertility – human sperm count may be declining because of increased
overall radiation exposure.
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Those exposed to chronic radiation injury commonly experience fatigue, non
restorative sleep, joint pain, weight gain, low self esteem, memory loss, rashes,
headaches, allergic tendencies, asthma, urticaria, sore throats and fever.
igue, non
restorative sleep, joint pain, weight gain, low self esteem, memory loss, rashes,
headaches, allergic tendencies, asthma, urticaria, sore throats and fever.
The high energy of background radiation generates free radicals in our bodies
and initiates oxidative stress. It can increase synthesis and secretion of excitatory
cytokines, unbalancing the immune response. Exposure to very strong ionizing
radiation, such as whole body irradiation with X-rays beyond levels of normal medical
use, leads to a massive release of excitatory cytokines, resulting in severe inflammation,
cell death and the ultimate death of the organism.
The Radioprotective Role of Squalene
Ionizing radiation can inflict either acute or chronic oxidative stress on the
body, depending on its source. The antioxidant defense system, including glutathione,
vitamin E and SOD [superoxide dismutase] can reduce this oxidative stress.
Laboratory experiments show that squalene can protect the body against acute ionizing
radiation, although its exact mechanism remains unknown. Squalene’s antioxidant
nature, its immune stimulant action and its ability to protect cellular structures and
improve cellular repair response may all play a role.
A laboratory study conducted by the Walter Reed Army Institute of Research
entitled “The Ability of Squalene to Protect Against Radiation Injury” was submitted to
the Cosmetics, Fragrance and Toiletry Association [CFTA] in February 1960. In the
experiment, 20 mice were fed 2000 mg/kg of undiluted squalene 15 minutes prior to
receiving 575 roentgens of X-rays. Sixty percent of the animals survived for 30 days.
In a control group [mice not given squalene] only 25% survived.
More recent research at the University of Kansas Medical Center, USA,
confirmed the radioprotective action of squalene. Dr. H. M. Storm and his colleagues
at the Kansas Medical Center published their report in the June 1993 issue of the
medical research journal Lipids. Healthy mice were fed a diet rich in pure squalene and
14 days later exposed to gamma rays. Seven days later total while cell counts and total
lymphocyte counts revealed that the squalene-fed group’s blood count was consistently
18-19% higher than a control group’s. The survival of the squalene fed mice was much
higher than control fed mice [P=0.0054]. So it seems that squalene provides a type of
cellular and systemic radioprotection.
Squalene Depletion Due to Radiation
Radiation induced oxidative stress may affect squalene metabolism with
adverse results. In the human body, squalene is distributed in the fatty tissues of
various organs including lungs, kidneys, spleen and brain. Strong ionizing radiation
may consume the squalene content of these sites when the body suffers chronic
radiation injury. In fact, during each of the experiments described above, the animals’
squalene levels were high before irradiation and low afterwards, confirming that
squalene was consumed. People suffering from chronic radiation injury usually
experience fatigue and loss of energy, perhaps due to impaired energy distribution and
65
consumption in our body. Given the link between squalene synthesis and coenzyme
Q10 synthesis – which is intricately linked to the energy metabolism – there may
reasonably be a connection between increased squalene consumption and fatigue.
Radiation exposure also leads to immune suppression which may have to do with
increased consumption of squalene and other antioxidants.
Thus, the increased background radiation may place new pressure on squalene
metabolism, the consequences of which are discussed in chapter 11.
Conclusion
The health hazards of chronic exposure to ionizing radiation are many.
However the ways in which chronic low doze ionizing radiation are a health hazard are
still not clearly known. It is likely that squalene is rapidly consumed when exposed to
high levels of ionizing radiation, leading to the increased synthesis and subsequent
redistribution of squalene and its immediate isoprenoids in the vital organs of the body.
Moreover, squalene metabolism coincides with the metabolism of coenzyme Q10. The
latter is part of the energy production process inside the cell. Therefore, by affecting
squalene metabolism, chronic radiation may affect the energy metabolism in the body.
There is every reason to believe that research into squalene replenishment during or
following radiation exposure would be justified.
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9 - Air Pollution, Allergies & Lung
Disease
- Air Pollution, Allergies & Lung
Disease
Each breath we take of the polluted air in today’s towns and cities fills our
lungs with two nasty toxins – carbon monoxide and the total suspended particulate
matter [TSP]. Carbon monoxide combines rapidly with blood, reducing its capacity to
transport oxygen. TSP from vehicle exhaust reduces lung function over a period of
time.
The All-India Institute of Medical Sciences in New Delhi – a city particularly
afflicted by vehicle emission and other pollutants – recently conducted a two year large
scale study of over 100,00 people that showed a clear correlation between air pollution
and emergency room admissions for asthma, bronchitis and heart complaints. The
study found a 41% increase in asthma cases, 39% in chronic bronchitis, and 30% in
heart attack cases over a ten year period.
Many such studies have been conducted in recent decades and the link
between air pollutants and allergies – especially asthma – is no longer in doubt.
Lipid Peroxidation & Allergies
Carbon monoxide vehicle emissions and ground level ozone are a deadly
combination. They each act as powerful free radicals, causing lipid peroxidation in the
mucosae of mouth, throat, nose and lungs. When combined this attack can lead to
increased oxidative stress and an imbalance in the cytokine expression of the mucosae’s
macrophage cells.
Without balanced immune protection, the mucosal cells then become prone
to amplified allergic processes. An example of this amplification is seen when a simple
– normally tolerable – cold requires hospital admission. The hospital admissions for
asthma and other pollution exacerbated conditions have grown at an alarming rate in
cities where pollution levels are particularly high.
Squalene Synthesis – A Potential
Adaptive Mechanism
Squalene concentrations in the mouth and respiratory mucosae are minimal
compared with skin levels, possibly because frequent exposure to toxic air is a relatively
recent evolutionary pressure on the body. In earlier centuries, there was no need for
such extensive protection of the inner mucosae because air was much cleaner. The
increase in air pollution may be exerting pressure on squalene metabolism in the lungs
to increase the synthesis and consumption of squalene in the lung. But such changes
take time. The adaptability of a biological system to acute and massive environmental
pressure is quite unknown. What we do know of evolutionary change in various species
has been the product of millions of years of gradual environmental change.
67
It is important to know whether squalene consumption increases in the lung
mucosae after exposure to air pollutants. The long term effect of a consistent increase
in Squalene consumption in the respiratory coat may be deleterious, leading to stress in
squalene metabolism. In particular, it is important to understand the sensitivity of the
mast and other immune cells of the respiratory mucosae to squalene metabolic stress.
Conclusion
The allergic response of the body’s immune system is increasing in urban
environments due to the overwhelming effects of air pollutants on the lung mucosa.
This may increase the consumption of and demand for squalene, leading to metabolic
stress with adverse consequences. Further research is needed to explore the link
between pollution induced lipid peroxidation and amplified allergic conditions such as
asthma and allergic rhinitis, as well as the connection between the isoprenoid
metabolism and the immune response to allergens in the lung. Research is also needed
to find ways to augment the immune response throughout the internal protective coat
in which squalene clearly plays such a profound role.
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10 -The Fat Cell: A Storehouse of
Toxins
-The Fat Cell: A Storehouse of
Toxins
Fat. The word quickly brings to mind oil and grease, or the ring around your
middle which just won’t go away! In the medical world fat is called adipose tissue.
Surgeons slice through it happily because it is soft, hardly bleeds and has no apparent
function other than storage.
However, medical attitudes towards adipose tissue are changing considerably.
New findings suggest that fat could be regarded as an important organ. Adipose tissue
has a highly organized communication network with an connection to the brain. It also
synthesizes large amounts of squalene and stores it in droplet form. Notably, adipose
tissue is found in the protective coat of the body and is engaged in energy metabolism.
Considering what we have learned so far about squalene it seems unlikely that such rich
stores of this valuable substance are there by accident. We need to understand the
significance of squalene stores in adipose tissue.
It is known that many organic solvents including dioxins are deposited in fat
cells. These man made chemicals are called xenobiotics and several researchers have
discovered that squalene enhances the elimination of xenobiotics. Squalene may play a
role in this detoxification. To find out, we much investigate the potential impact of
accumulated toxins on squalene synthesis in fat cells.
Adipose Tissue: Depot or Organ?
A ‘depot’ is merely a place for storage and distribution. An ‘organ’ is a
coherent element of the body with an organized structure and a specific function. The
heart is an organ and so is the skin. Adipose tissue has long been considered a lowly
depot, but scientists are beginning to reconsider this simplistic view. It is true that
adipose tissue stores and later distributes fat according to energy requirements [it also
acts as a heat insulator] but it is slowly gaining recognition as a full fledged organ – for
some people, the largest in the body. Fat cells can grow very large, increasing their
diameter by as much as twenty times and their volume by a thousand. The average
person ‘s 10 – 20 kg of fat stores some 90,000 to 180,000 calories.
Fat cells store triglycerides – long chain hydrocarbons bound to a glycerol
molecule – in liquid form. Triglycerides can be broken down into fatty acids by the
enzyme lipase and are released when the body requires extra energy – during physical
exertion for example, or to compensate for starvation. Indeed, fat is by far the richest
food source of energy.
The new attitudes towards adipose tissue follow remarkable discoveries about
the activity of the fat storage cell – the adipocyte. This humble cell was thought to be
no more than a storage manager until the hormone leptin [a secretion of the adipocyte]
was discovered in the blood. In 1995 a research article appeared in the journal Cell.
Author J.S. Flier, a researcher at the Beth Israel Research Institute, Bethesda, Maryland,
described the hormone leptin in an article entitled, The Adipocyte: Storage Depot or
Node on the Energy Information Superhighway. Flier was the first to recognize the
high activity levels of adipose tissue and to describe it as an organ.
69
Fat cells synthesize leptin and secrete it into the blood. This hormone is just
one component of a highly organized control system that regulates the long term
balance of energy intake and expenditure. Obesity is generally believed to result from
overeating but this is not quite true. Rather it is is a result of this lost balance when
intake chronically exceeds expenditure. Some obese people believe that their bodies
are more energy efficient, meaning that their internal metabolism uses less energy. This
too is not quite true. Obese people in fact burn more energy than the non-obese.
Adipose tissue and the brain regulate leptin secretion via an as yet unidentified
control system. However, a hypothetical model suggests that leptin is an afferent loop
[a loop that sends information from the periphery to the central regulatory body] of a
brain controlled energy regulatory system.
The discovery of leptin and the suggestion that adipose tissue is an organ
triggered a multi-million dollar race as the pharmaceutical industry searched for ways to
control obesity with drugs. Unfortunately, they soon discovered that obese people are
leptin resistant. Although their leptin blood levels may be high, their brains become
insensitive to it. Nevertheless, the discovery of leptin reinvigorated fat cell research
and after the commercial euphoria died down several other surprising molecules were
discovered in adipose tissue. TNF-alpha, a cytokine secreted by fat cells, can cause
fatigue and increase insulin resistance in diabetic patients. This may help explain why
obese people are particularly prone to diabetes.
Some diabetics – particularly obese ones – need more insulin than others.
When their requirements exceed 200 units per day, they are said to be insulin resistant.
This was previously thought to result from some genetic predisposition or a decrease in
insulin receptors. Now it is thought that more fat leads to increased secretion of TNF-
alpha, and therefore greater insulin resistance.
Large amounts of adipose tissue are also thought to contribute to high blood
pressure. Sufferers are often prescribed angiotensin converting enzyme [ACE]
inhibitors that effectively reduce blood pressure by limiting production of angiotensin
11 – a peptide synthesized in the lungs from angiotensionogen and secreted by the
kidneys. It is now known that fat cells too secrete angiotensionogen. Previously the
kidneys were believed the only source.
Since increased adipose tissue has been associated with an increased
circulating level of leptin and angiotensionogen, the links connecting obesity, diabetes
and hypertension are becoming clearer.
Fat cells also maintain large stores of squalene. The average person’s 10 – 20
kilograms of fat contain 5 – 10 grams of squalene, 90% of which is stored unchanged
by the fat cell – only 10% being converted to cholesterol. Of the stored portion, four-
fifths are maintained as liquid droplets within the cell and the remainder is bound to
the cell membrane. However the function of this stored squalene remains unknown.
Toxin Accumulation
Many man made toxins enter the body and accumulate in adipose tissue
without ever being eliminated. The discovery of leptin may have made the fat cell an
object of renewed respect among obesity researchers, but environmental scientists still
70
view it as a reservoir of dioxins, PCB’s and other xenobiotics, including natural
compounds, drugs, environmental agents, carcinogens and insecticides.
luding natural
compounds, drugs, environmental agents, carcinogens and insecticides.
Some xenobiotics act as pro-carcinogens. Some mimic estrogen receptors.
Some are not inherently harmful but become toxic following biotransformation within
the body. For example, the liver enzyme system cytochrome P450 turns some
xenobiotics into dangerous carcinogens.
Increased deposits in adipose tissue of dioxins, dibenzofurans,
polychlorinated biphenyls [PCPs] DDT, DDE, hexachlorbenzene, alkylphenols, and
several organochlorine pesticides have recently been associated with testicular cancer,
lymphoma, leukemia, prostate cancer, malignant melanoma and endometrial cancer.
The many ways in which xenobiotics can harm our bodies have been only partially
uncovered.
Most man-made chemical compounds are lipophilic – they are irresistibly
drawn to fat. The liver breaks down xenobiotics substances into smaller molecules in
an attempt to eliminate the, but some end up more toxic, not less.
Detoxification By the Liver
The detoxification processes of the liver have two phases.
In phase 1, the toxic molecules are modified by oxidation, reduction,
hydroxylation, methylation and other biochemical processes. The reactions are carried
out with cytochrome P450, glutathione S-acyltransferase, and other molecules
synthesized by the liver cells. In these reactions, drugs such as diazepam are
inactivated. However, the same chemical reactions may activate some other drugs such
as prednisone, which is activated to prednisolone. The phase 1 detoxification process
can render some molecules of relatively low toxicity even more dangerous. For
example, the tuberculosis drug isoniazid may cause hepatic failure. Inactive
carcinogens are sometimes converted to active carcinogens by the same process.
The phase 11 reaction attempts to render fat- soluble molecules water-soluble
so they can be more easily excreted – through bile or urine. Unfortunately, the liver is
unable to eliminate all toxins. Xenobiotics that do not submit to this process are
carried by the blood to the adipose tissue and stored in fat cells. There they
accumulate, reach toxic doses and overflow into surrounding tissue where they may act
as carcinogens. It has even been suggested that the increased incidence of breast cancer
may result from the accumulation of xenobiotics in breast tissue.
Detoxification By Adipose Tissue
An organism’s ability to detoxify itself is a crucial step in its evolution. Given
the significance of adipose tissue – where xenobiotics accumulate – the question arises,
does adipose tissue have its own detoxification system?
There is good reason to believe that squalene stored in fat cells may act as a
detoxifying agent. Four independent researchers have tested the detoxifying abilities of
squalene by measuring the extent to which squalene helps cleanse the bodies of
laboratory animals of xenobiotics. Results have been encouraging. Squalene-rich diets
71
leading to increased squalene blood levels do seem to improve the elimination of
organochlorine xenobiotics such as hexachloro-benzene [HCB] and hexachlorobiphenyl
[6-CB].
Other experimental studies also suggest that squalene may be a useful antidote
to drug overdosing. Oral squalene seems to enhance the elimination of theophylline,
Phenobarbital and strychnine in rats. Although its detoxifying mechanism is still not
clearly known, it is thought that squalene may possibly increase the mobilization of
lipid soluble xenobiotics enabling elimination through the intestine.
T.J. Smith and colleagues suggested that squalene may exert its detoxifying
effects by stimulating the body’s central detoxification system in the liver [cytochrome
P450]. Fat cells also contain cytochrome P450 so the question naturally arises of
whether the squalene stored in fat cells also has a detoxifying function.
There is more to squalene’s detoxifying activity. When xenobiotics accumulate
in fat cells, stored squalene may be released into the general circulation, stimulating bile
flow and enhancing xenobiotics elimination. Scientific testing of this hypothesis could
lead to the development of effective new means of detoxification.
The Xenobiotic-Squalene Link
Xenobiotics stored in fat cells may alter the fat cell metabolism. One way to
explore this possibility would be laboratory studies on the sensitivity of squalene
metabolism to various xenobiotics. Since squalene metabolism is found to play an
important role in the cytokine secretion of immune cells, it may also take part in the
cytokine secretion of fat cells. Indeed, the accumulation of xenobiotics may incline the
isoprenoid pathway to either increase or decrease squalene synthesis. This could alter
the way fat cells secrete cytokines such as tumor necrosis factor [TNF]-alpha – an
excitatory cytokine. TNF-alpha is known to sometimes cause fatigue, lethargy, fever,
and increased insulin resistance in diabetics.
Two disorders –chronic fatigue syndrome [CFS] and fibromyalgia – are
commonly found in populations living a modern lifestyle. CFS is characterized by
increased secretion of TNF-alpha, perhaps from fat cells. Studying the relationship
between squalene metabolism and various xenobiotics may help clarify the link
between environmental pollutants and modern illnesses.
Most importantly the accumulated xenobiotics stored in fat cells place
additional stress on squalene metabolism and are yet one more factor contributing to
overall metabolic stress.
Conclusion
When considered as an organ, adipose tissue is responsible for maintaining
the body’s energy balance by producing and secreting leptin – an important hormone in
the highly organized energy control system. It is probably that fat cells must remain
toxin free for optimal functioning and the considerable squalene store of the fat cells
may help keep them so.
72
11 -Metabolic Stress & Chao-Metabolic Stress & Chaos
What is the fate of dietary squalene? Where does it go? Is it converted into
cholesterol? And why does skin contain such high levels of squalene? Why is it not
converted into cholesterol? As they attempt to answer these questions, scientists are
slowly discovering another side of squalene research – its metabolic response to
pollution. The increased synthesis and consumption of squalene in skin following UV
exposure is one illustration of this.
However metabolic response may eventually fall into a state of stress. When
does metabolic stress occur and how does it affect the immune response? [These
questions came up in our chapter 4 discussion of the negative influence of oxidative
stress on effective immune response]. The existence of a state of disequilibrium makes
squalene metabolism an ideal place to seek answers to these questions. We will first
elaborate on the concept of metabolic response to stress, then briefly discuss the
physiology of squalene metabolism, and finally discuss the mechanism of stress in
squalene metabolism.
Metabolic Response to Stress
We believed that an understanding of stress in antioxidant metabolism is best
approached by examining the metabolic response to stress. In many cases, such as a
response follows oxidative stress. It is well known, for example, that surgery causes
oxidative stress. Recovering patients tend to lose weight for a week or so afterwards,
even when fed above normal levels of good food. The body responds to surgical stress
by burning more protein and fat in an attempt to accelerate healing. This normal
metabolic response to stress is perfectly understandable and is generally helpful to the
patient.
However, this response may cross a threshold at which point the metabolic
response to stress becomes itself a source of stress. Positive feedback causes the
metabolic response to continue in an uncontrolled way damaging the body. This is
metabolic stress.
The consequences of metabolic stress have been well studied in the context of
protein energy malnutrition and prolonged fasting. In both cases, doctors observe
accelerated tissue damage, wasting and even immune suppression actually induced by
the over responsive protein energy metabolism.
Hypoxia reperfusion injury is one example of metabolic response to oxidative
stress. Increased squalene synthesis during UV exposure to skin is another. Thus, the
metabolic response to stress is an event of the early adaptive mechanism. It is not itself
a state of stress. Only when the response reaches a certain threshold does the adaptive
mechanism fail and give way to stress. Once that threshold is passed, antioxidant levels
decline in spite of increased antioxidant synthesis. We will try to understand the
threshold concept in antioxidant metabolism by examining the physiology of squalene
metabolism.
Squalene Metabolism
To identify stress in squalene metabolism, we must consider how squalene
metabolism is related to the cholesterol metabolism. As a precursor of cholesterol,
squalene was commonly believed by scientists to be entirely converted to cholesterol.
The suggestion of an independent squalene metabolism is new, and based on research
findings that only a very smell portion of dietary squalene is actually converted. The
rest remains either unchanged or converted into some metabolite other than
cholesterol.
Various human tissues maintain separate squalene concentrations, as follows:
100mcg/dl in plasma, 500mg/kg in adipose tissue, 1g/kg [dry weight] in skin and
50mg/kg in liver. Increased dietary intake of squalene can increase these tissue
concentrations by several times their normal values. The question remains, how does
tissue maintain its own squalene concentration and why is this squalene not converted
into cholesterol?
By discussing squalene metabolism in skin and fat we present evidence that
squalene metabolism is independent of the cholesterol metabolism and explain why
different tissues maintain independent squalene levels.
Squalene in the Skin
Squalene is found abundantly in skin, where it acts to protect against free
radicals. When stimulated, synthesis of squalene in the skin increases independently of
cholesterol synthesis, suggesting that an independent squalene metabolism exists in the
skin.
Both cyclic and acyclic forms of squalene are present in skin. Acyclic squalene
serves as a potent antioxidant and cyclic squalene is used in the synthesis of vitamin D,
cholesterol and other sterols.
Squalene in Fat Tissue
Fat cells have an entirely independent squalene metabolism. The acyclic squalene
remains linear at all times and only 10% is transformed into its cyclic form. This raises
the question of whether there is an acyclic squalene metabolism separate from the
cholesterol metabolism and is supported by the phylogenetic [evolutionary] evidence
that the linear squalene metabolism in fat cells is an unchanged descendant of this
archaic squalene metabolism. Perhaps the skin too retained that metabolism even after
is acquired a cholesterol [cyclic squalene] metabolism.
Experimental evidence suggests that squalene bound in the biomembrane of
the microsome [a cellular organelle] is metabolically active and that approximately 90%
of the newly formed squalene is stored in a lipid droplet and only 10% is used in
cholesterol synthesis. This suggests that 90% of membrane-bound squalene may
remain in its active, linear form.
74
Cyclic & Acyclic Squalene
Acyclic squalene’s history in metabolic processes began with archaea, the
ancient life form that lives on in deep sea volcanoes under extreme pressures [200
atmospheres] and temperatures [85deg celcius]. Archae’s biomembrane is a teeming
soup of biomolecules that includes isoprenoids and acyclic squalene molecules. We
have seen that although vitamin E has been considered one of the most powerful
terminators of lipid peroxidation chain reactions, its large size limits its ability to fit into
the biomembrane. Acyclic squalene’s excellent antioxidant properties make it as
effective as vitamin E, but because of its small size and mobility it encounters far more
lipid molecules and probably neutralizes more oxyradicals than Vitamin E. This is
probably why archae’s biomembrane contains squalene and not vitamin E. As we have
noted earlier, both skin and adipose tissue contain acyclic squalene. Is this acyclic
squalene ever rendered into cholesterol? Perhaps the body somehow determines which
portion fo squalene becomes cyclic and which does not. These are very big questions
to which the answer at the moment is a resounding “Don’t know”. However, the
presence of two distinct forms of squalene in our body tissues strongly suggests that
squalene metabolism takes place in two metabolic pools – one cyclic and one acyclic.
Two Metabolic Pools
Our hypothesis that squalene metabolism is independent of the cholesterol
metabolism is first supported by evidence turned up at Rockefeller University where in
1974 K. Liu and his colleagues investigated the squalene content of the body.
The squalene content of the body was measured back in the days when it is
only known role was as a cholesterol precursor. However, the Rockefeller University
team found that barely one-tenth of plasma squalene is actually converted into
cholesterol. They referred to it a active squalene in contrast to the approximately
2.6grams of so called inactive squalene that mysteriously does not. To identify these
two squalene stores in the body we refer to them as separate pools. The smaller
squalene pool is metabolically transient because it proceeds on its way down the
cholesterol pathway. The other is metabolically stable because it does not.
It is tempting to think that the transient pool is cyclic squalene and the stable
pool is acyclic. The transient pool can also be considered inactive, as it is rapidly
converted into cholesterol. The stable [acyclic] pool can be considered active since it
provides the antioxidant function. Most dietary squalene is probably acyclic and
therefore active.
We have shown that both skin and fat contain very high levels of active
[stable] squalene that is not converted into cholesterol. The active squalene
concentration in skin is about 1g/kg dry weight of skin. However, skin also contains a
very small amount of inactive [transient] squalene which is rapidly converted into
cholesterol. We have also shown that there are two squalene pools in fat tissue. This
distinction between active and inactive pools suggests the significant possibility of
squalene metabolic stress.
75
State of Disequilibrium
So far we have found that active squalene pools [ASPs] exist in the skin and in
fatty tissue for specific functions, such as protection of skin from UV damage. We
hypothesize that ASP’s also exist in immune and other cells. The discussion in the first
part of the book reveals squalene’s independent role in biomembrane protection. It
seems natural that an independent squalene metabolism exists in the cell to control the
cellular distribution of squalene and requires an ASP. It is thus likely that ASP’s exists
even at the cellular level. ASPs may also exist in the liver as hepatic cholesterol
synthesis is affected by dietary squalene.
Of the four active squalene pools, each one has its own level of active
squalene. The skin pools contain about 1g/kg, adipose tissue contains about 500
mg/kg, the body as a whole holds about 20mg/kg in individual cells and the liver
contains about 50mg/kg. The body contains a total of about three grams of active
squalene. Its inactive squalene pool [destined for conversion into cholesterol] adds up
to about 300mg. There is thus a state of disequilibrium between the active and inactive
squalene pools [3gm to 300mg]. The force maintaining this disequilibrium is crucial to
the existence of the active squalene pool. Without it, all active squalene would be
converted into cholesterol. K. Liu and colleagues were surprised to discover such a
state of disequilibrium. It may be visualized as a force that keeps a liquid in the two
arms of a U-tube at different levels.
The Mechanism of Metabolic Stress
A state of disequilibrium similar to that among the squalene metabolic pools
may be common to all endogenous antioxidant metabolisms. It is well known that
oxidant and antioxidants are never in a state of equilibrium. An example is the ratio of
reduced to oxidized glutathione [GSSH: GSSG] in cells and tissue. The value never
settles down to 1:1
This state of disequilibrium suggests the possibility of stress in the antioxidant
metabolism. If sufficient liquid is added to one column of the “tube”, the state of
disequilibrium diminishes and difference in levels will fall. Similarly, when antioxidant
synthesis reaches a certain threshold, the disequilibrium will be disturbed, leading to
rapid consumption of antioxidants. Thus, the very existence of a state of
disequilibrium makes the antioxidant metabolism vulnerable to stress. In the U-tube
example, the magnitude of the force of disequilibrium determines how much liquid
must be added to column A to upset the disequilibrium. Similarly, the performance of
the adaptive mechanism determines the threshold at which stress is provoked in the
antioxidant metabolism. In the squalene metabolic pool, metabolic stress would occur
when the compensatory or adaptive mechanism fails to maintain the state of
disequilibrium. What is this compensatory or adaptive mechanism? How does it
operate on the squalene metabolic pool? When and why will it fail to maintain the state
of disequilibrium? To seek an answer to above questions, we turn to the chaos theory.
76
Chaos
Biological systems are organized differently from mechanical systems. They
are chaotic, but not disorganized. Chaotic organization can fluctuate, enabling
biological systems to adapt to new situations quickly.
Chaos theory grew out of a need to explain phenomena that could not be
explained by linear dynamics, in which an effect is proportional to its cause. Many
bodily processes – such as the normal variations of a heartbeat – can only be well
described by nonlinear dynamics [NLD]. Nonlinear dynamics begins by setting aside
the concept of proportionality. The causal components of an nonlinear system form a
network with multiple interactions, so a small change in a system can have large,
sometimes unanticipated consequences.
The complex fluctuations in the heart rate of a healthy individual are a typical
example. Contrary to the expectations of linear thinking, the beat of a diseased heart –
one for example suffering congestive cardiac failure – is less chaotic than a healthy
heartbeat. It seems that disease states render the biological system more predictable.
Metabolic Stress & Chaos
It seems most likely that the squalene metabolic pools are organized in a nonlinear
fashion. As an example of chaotic organizations, even the small metabolic pool
of an individual immune cell mirrors that of a large one. All metabolic pools, no matter
how large or small, maintain a state of organized disequilibrium. This organization is
not dissimilar to the computer generated leaf, in which even the smallest details always
resemble the largest. This non-linear organization of all squalene metabolic pools
enables the adaptive mechanism to effectively maintain the state of disequilibrium so
that under normal conditions metabolic stress is preempted. However, the generation
of free radicals – for example by the action of UV radiation on skin – stimulates
squalene synthesis. When this synthesis passes its threshold value, the compensatory
mechanism fails and leads to metabolic stress. Chaos theory provides a different
perspective from the mechanistic explanation of metabolic stress, suggesting it to be a
non-linear phenomenon determined by the body’s adaptive mechanism. Metabolic
stress occurs only when the adaptive mechanism fails.
Chaos theory also predicts that disease states will render biological systems
both more predictable and less adaptable. Adaptive mechanisms fail when our systems
fall sick. During normal immune response, the antioxidant metabolism of the adaptive
mechanism maintains the state of disequilibrium until it reaches it s threshold, thereby
minimizing the chances of metabolic stress. But when an existing condition or
repeated oxidative stress pushes the immune system over the antioxidant threshold, the
normal state of disequilibrium fails and metabolic stress follows. This nonlinear
account of metabolic stress satisfactorily explains oxidative stress induced immune
suppression described in chapter 4.
Now we must ask, can pollution induced generation of free radicals cause
squalene metabolic stress in the body’s protective coat. The discussions in chapters 7 –
10 strongly suggest that rising levels of oxidative stress in our environment – due to
ozone depletion, increased background radiation and accumulation of xenobiotics –
77
put tremendous pressure on the squalene metabolism in the protective coat. An
incident of metabolic stress on the protective coat may be transient, but it may also be
sudden and intense, - especially considering the huge surface area of the coat [more
than 400sq.m].
We introduced part three of this book as a search for a model with which to
study the impact of pollution in the evolutionary mechanism of the body. Bearing in
mind that evolution is no more than an extension over many generations of the greater
adaptive mechanism of the body, we have proposed that metabolic stress puts pressure
on the adaptive mechanism implying that squalene metabolic stress would also put
pressure on our evolutionary mechanisms.
Thus, the evolutionary presence of squalene in skin makes squalene
metabolism in suitable model to study the long term impact of pollution in the body.
Conclusion
The existence of two squalene pools in the body is a special characteristic of
squalene metabolism. They are maintained by some force of disequilibrium.
Environmental pollution may create metabolic stress in squalene metabolism,
disrupting the disequilibrium and resulting in chaotic fluctuation of squalene and other
isoprenoids. Such fluctuation may produce gradual but significant changes in our body,
mainly in the protective coat defense system. We have already suggested that the high
concentration of squalene in skin and fat cells is probably due to the accumulated
evolutionary requirements of thousands or millions of years. In contrast, the present
change in our environment is both sudden and enormous, with potentially disastrous
results. Squalene metabolism in skin may serve as a useful model to study the impact
of pollution in the evolutionary dynamics of health and disease.
78
Epilogue
Geological and evolutionary evidence shows that life on this planet has developed a
profound dependence upon antioxidant isoprenoids such as squalene for protection
against the rigors of the environment. Homo sapiens – the most sophisticated product
of evolution – has not outgrown that dependence. The thick coating of squalene on
our skin is an example. It appears that without squalene we could not have shed the
furry outer coat still worn by our fellow primates.
This simple biochemical has played a crucial role in the protection of living
systems for billions of years. Now however, we have inadvertently changed the
environment in ways that are taxing our protective systems, perhaps pushing them to
their very limit. Our voracious industrial societies have produced and propagated
countless carcinogens and other pollutants, diminished atmospheric protection against
ultraviolet radiation, spread new sources of terrestrial radiation and exposed our bodies
to previously unknown chemicals that increase the chances of oxidative stress in the
body.
The greatest threat to terrestrial life is the speed at which these changes are
taking place. The marvelous ability of biological systems to adapt is now profoundly
challenged. We cannot reverse the damage we have done. Nor can we realistically
enumerate the various threats and devise a pharmaceutical remedy for each one –
although sometimes it seems that is exactly what we are attempting. What we can do is
to study our inner protective mechanisms and find ways to help them resist the
oxidative pressure of this sudden and potentially catastrophic environmental change.
Squalene and its metabolism in the skin may serve as a model for such studies.
79
Glossary
Acetone [Ch3Coch3]
Compound with solvent properties and characteristic odor; obtained by fermentation
or synthetically
Acetyl Co-A
A compound from which many other vital substances are derived; derived from sugar
in our cells
Acyltransferase
Enzyme involved in the antioxidant activity of glutathione
Adaptive Mechanism
Control mechanism of the body that adapts to new situations, environmental changes
or generalized threats.
Adipocyte [Fat cell]
Chief constituent cell of adipose [fat] tissue
Adipose tissue
Body’s fat deposits where triglycerides are stored until needed to provide energy; also
provides heat insulation for the body.
Afferent
Signal pathway from the periphery to the center of the body; for example touch
provokes an afferent signal
Aids [Acquired immune deficiency syndrome]
A deficiency in the immune system due to infection by the human immunodeficiency
virus [HIV]
Alkylphenol
Toxic industrial detergent that promotes endocrine disrupting effects
Allergen
Agent that may trigger an allergic reaction in the body;’ for example, dust particles,
pollen, etc
Allergy
Altered response of immune system to an allergen
Alpha Particle
Elemental particle composed of two protons and two neurons; alpha particles have
very strong ionizing power but cannot penetrate the body easily
Alpha-Tocopherol
Chemical name of vitamin E
Amaranth
Plant found in North and South America and in Asia; rich in squalene
Amifostine
Agent used in cancer treatment to protect normal tissue from the damaging effect of
chemotherapeutic agents.
Amyloidosis
A common complication of several diseases [leprosy, tuberculosis], often associated
with immune disorder
Anaplasia
Process of transformation of less cancerous cells to highly cancerous cells; degree of
malignancy
80
Angiotensin converting enzyme [ACE inhibitor]
Potent antihypertensive drug used to treat high blood pressure by converting
angiotensin to angiotensin 11
Angiotensin 11
Potent blood pressure increasing agent, used by the body when kidney blood flow
decreases; patients experiencing high blood pressure often suffer increased levels of
level of angiotensin and angiotensin 11 in the blood
Ankylosing spondylitis
A polyarthritis involving the spine, characterized by progressive, painful stiffening of
the joints and ligaments that almost exclusively affects young men
Antibody
Protein molecule produced by specialized cells when encountering an antigen;
antibodies remember and act specifically against the antigen which originally provoked
their synthesis
Anti-carcinogen
One of three types of cancer fighting agents; those that prevent chemical precursors
forming carcinogens, those that prevent carcinogens from reaching or acting on target
sites and those that suppress the expression of neoplasia in cells already exposed to
carcinogens
Antigen presentation’
Process by which lymphocytes are made aware of a particular antigen
Antioxidant
Molecules able to counteract the damaging effects of free radical induced oxidation by
donating an electron to neutralize free radicals
Antioxidant metabolism
Cellular and tissue synthesis, maintenance and recycling of antioxidants
AOM [Azoxymethane]
Chemical that can cause colonic aberrant crypt foci – a precancerous condition of
colon cancer
Apoptosis control system
Hypothetical control system that regulates programmed cell death
Archae
An ancient form of life, formerly considered a type of bacteria but now considered a
separate and distinct evolutionary branch, found in deep sea hot springs and other
unusual habitats; along with bacteria and eukarya, one of the three domains of life –
while archae resemble bacteria in morphology and genetic organization, they resemble
eukarya in their method of genetic replication.
Asthma
Lung disorder characterized by airway obstruction and recurrent shortness of breath
due to spasmodic contraction of the lung’s airways.
Atherosclerosis
Thickening and hardening of blood vessels resulting in narrowed lumen and
obstruction of blood flow
Atom
Smallest particle of an element; a positively charged nucleus orbited by negatively
charged electrons
81
Atopic dermatitis
An allergic, inflammatory skin disorder resulting in an itchy rash
Auto-antibody
Antibody formed in response to and reacting against a constituent of an individuals
own tissues
Beta Carotene
Group of antioxidant carotenoids found in plants
Biomembrane
Membranous envelope of a living organism such as that enclosing a cell or organelle
Biotransformation
Chemical alteration of a substance by or in a biological system
Bronchi
The larger air passages of the lungs starting at the point where the trachea branches
into two
Bronchiole
Smaller airway of the lungs connecting bronchi to air-sacs [alveoli]
Cachexia
Profound and marked general ill health and malnutrition
Cancer
Malignant cellular tumor
Carbohydrate
Compound of carbon, hydrogen and oxygen, e.g. cellulose, sugar, starch
Carbon Dioxide [CO2]
Odorless, colorless gas produced by oxidation [burning] of carbon; naturally formed in
animal tissue and eliminated by the lungs, or produced by the burning of fossil fuels
Carbon Monoxide [CO]
Odorless, colorless gas produced by burning carbon or organic fuels in a low oxygen
environment, when inhaled, prevents blood from absorbing oxygen and quickly leads
to death
Carcinogen
Substance able to transform normal cell into cancer cell
Carotenoids
Plant derived substances belonging to the isoprenoid antioxidant family, such as
vitamin A
Catalase
Enzyme that catalyzes decomposition of hydrogen peroxide: found in most cells
Cataract
Partial or complete opacity of the lens of the eye, impairing vision or causing blindness
Cell Cycle Proliferation
Proliferation of cells by division into two identical new cells
Cell
Fundamental structural and functional unit of living organisms, consisting of a nucleus
and cytoplasm enclosed in a plasma membrane
Cellular Defense System
System that protects cells from environmental toxins, free radicals, drugs and various
other noxious agents
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Cellular Homeostasis
Dynamic balance of the internal environment of the cell Dynamic balance of the internal environment of the cell
Cellular Oxidative Distress
Inability of cellular microenvironment to maintain oxidant-antioxidant balance due to
intense generation of free radicals inside the cell
Cellular Redox System
System enabling cells to carry out oxidation-reduction reactions and consisting of
special redox molecules to keep the oxidant-antioxidant ratio in balance
Cellular
Pertaining to structure or system of a cell
CFC [Chlorofluorocarbon]
Type of hydrocarbon containing both chlorine and fluorine, used as refrigerants,
blowing agents, cleaning fluids, solvents and for fire extinguishing CFCs – are known
to cause ozone depletion
Chaos Theory [Non-linear Dynamics]
Study of systems that respond in a nonlinear way to initial conditions or perturbing
stimuli; fractal [non-linear] representations of chaotic systems often reveal similar but
nonidentical patterns across varying scales of time and space
Chemical Quenching
Reaction in which a free radical is chemically incorporated with a neutralizing
antioxidant by the sharing, rather than the exchange of an electron
Chlorophyll
Green pigment in plants that harnesses light energy making water and carbon dioxide
react to produce oxygen and glucose
Chloroplast
Chlorophyll-bearing bodies of plant cells
Cholesterol Regulatory Mechanism
Mechanism that controls the synthesis and distribution of cholesterol in the body
Cholesterol
Waxy substance used in construction of cell membranes and synthesis of steroid
hormones; also a precursor of bile acids; mostly manufactured in the liver but also
partially absorbed from diet
Chromanol Ring
Aromatic ring structure; main backbone of vitamin E
Chronic Fatigue Syndrome [CFS]
Long term [six months or more] affliction characterized by persistent or recurrent
fatigue, diffuse musculoskeletal pain, sleep disturbances and subjective cognitive
impairment
Chronic Radiation Injury
Harmful effects of long term exposure to ionizing or non-ionizing radiation
Cirrhosis of the Liver
Damage, scarring and subsequent hardening of the liver
Clonal Evolution
Development of genetically identical cells descended from a single ancestral cell by
division and multiplication, during which daughter cells acquire new properties through
natural selection; used especially regarding development of cancer mass
83
Co-Enzyme Q
Ubiquinone, a quinone with isoprenoid side chains found in mitochondria and
involved in energy production
Colon Cancer
Tumors or cancer of the large intestine
Colonic Aberrant Crypt Foci
Change in normal structure of the epithelial coat of the large intestine; a precancerous
sign
Control Group
A group of subjects used in a test but not undergoing test conditions; used to produce
normal data for comparative purposes
Control System
Operating system that navigates and commands internal body processes
Coronary Artery
Either of two arteries that carries oxygenated blood to the muscular tissue of the heart
Coronary Heart Disease
Disease resulting from a blocked coronary artery, usually due to atherosclerotic plaque
Corticosteroid
Group of hormones that regulate various functions of the body including the energy
metabolism, healing and stress response; corticosteroids are involved in growth,
development and bodily vitality
Cosmic Radiation
High energy radiation of particles originating from extraterrestrial space
Crohn’s Disease
A chronic inflammation in the digestive tract; similar to but more severe than ulcerative
colitis
Cysteine
A sulfur-containing amino acid; scarcest of the three constituents of glutathione
Cytochrome P450
Type of enzyme used in biotransformation of many foreign compounds
Cytokine system
Component of the immune system that regulates messaging among immune cells
Cytokine
Protein mostly secreted by immune cells to regulate immune function by inducing
inhibitory and excitatory activity of other immune cells
Cytoplasm
Substances other than nucleus, mitochondria and chloroplasts that make up the cell
body
Cytoprotection
Process by which chemical compounds protect cells from harmful agents
Cytoprotective Therapy
Use of substances that protect normal tissue from harmful effects of disease processes
or aggressive therapies used to combat them, such as anticancer radiation or
chemotherapy
Cytotoxin
Substance toxic or harmful to cell and its function
DDE An organochlorine pesticide ethylene metabolite of DDT
84
DDT
A polychlorinated pesticide resistant to destruction by light and oxidation and believed
to be carcinogenic
Dementia
An acquired organic mental disorder with significant loss of intellectual abilities
Depleted Uranium
Radioactive by-product of nuclear weapon manufacturing and reactor use
Dibenzofuran
Group of ether compounds related to dioxin and PCBs, used by petrochemical,
pulp/paper and many other industries
Differentiating Action
Drug action pushing a cancer cell towards its normal behavior and function; eg.
Vitamin A can push nerve cancer cell to become a normal nerve cell
Dioxin
Man made chemical found to act as a persistent carcinogen
Disease progression
Progressive damage to the body tissue by a disease process
DNA Synthesis
Cellular production of DNA
Dolichol
Derivative of the mevalonate pathway used for carbohydrate synthesis
Down-Regulation
Process on cell surfaces that decreases interaction with incoming biochemicals by
reducing the number of available receptors
Drug Resistance
Inherent or acquired ability of a disease process to resist effectiveness of a therapeutic
chemical or drug
Efflux
Pumping mechanism of cancer cells by which they expel anticancer drugs; movement
of drug from interior to the exterior of the cell
Electrical Channel
Special doors in a cell wall guarded by proteins and charged with a specific voltage; only
specific ions are allowed to enter through such channels, hence sodium channel,
calcium channel etc
Electron Imbalance
The lack of an electron in an atom’s outer electron ring, such that it seeks a
replacement; usually the result of free radical damage
Electron Transfer Reaction
Chemical reaction within a special molecule involving the transfer of electrons from
one molecule to another
Electron
Negatively-charged particle orbiting the nucleus of an atom; the number or orbits and
the number of electrons in the outer orbit determine all the atom’s physical and
chemical properties except mass and radioactivity
Emit
To liberate, to give off
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Endogenous Anti-Oxidant
Antioxidant synthesized within the body, including glutathione [GSH], coenzyme Q10
catalase, superoxide dismutase [SOD] and squalene
Endogenous
Produced within or caused by factors within an organism
Endogenous Antioxidant Metabolism
Metabolism of antioxidants synthesized within the body e.g. glutathione and squalene
Endometrial Cancer
Tumors or cancer of the inner lining of the uterus
Endometrium
Mucous membrane lining of the uterus
ENE Reaction
Hydrogen atom donation and reception in a biochemical reaction
Entropy
Tendency of all physical systems to fall into disorder
Environmental Pollutant
Substance present in high enough concentrations to produce adverse effects on the
environment
Enzymatic Transformation
Change of one substance to another by enzyme induced chemical reaction; e.g.
transformation of acyclic squalene to cyclic squalene by the enzyme squalene cyclase
Enzyme
Protein produced in a cell and able to accelerate a chemical reaction without being
altered by the reaction
Epidemiology
Branch of medical science dealing with the incidence, distribution and control of
disease in a population; the sum of factors controlling the presence or absence of a
disease or pathogen
Epidermal Fat
Fat present in the epidermis, including cholesterol, triglycerides and various methyl
sterols; a very significant portion – about 12% of epidermal fat in human beings is
squalene
Epidermis
Outermost layer of skin, varying in thickness from 0.07mm to 1.4mm in human beings
Epioxide
Substance formed after oxidation; e.g. squalene epioxide formed by reaction of oxygen
with squalene under the influence of the enzyme squalene epioxidase
Epithelial
Of or relating to the epithelium
Epithelium
Cellular covering of the outer and inner body surfaces, including the lining of vessels
and small cavities
Estrogen Receptor
Protein combination on the surface of a cell that attracts and ‘hooks’ estrogen for use
in cellular activity
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Eukarya
Cells of more complex living organisms, containing a true nucleus enveloped by a
nuclear membrane
Evolution
Developmental process by which an organ or organism becomes more and more
complex through differentiation of its parts
Evolutionary Mechanism
Mechanism of a species that adapts to a changing environment
Evolutionary Pressure
Pressure exerted by the threat of extinction on an organism or a species
Excitatory Cytokine
Cytokine causing increased proliferation of immune cells
Excitatory – Stimulatory
Exfoliative Dermatitis
A scaly dermatitis often associated with the loss of hair and nails, thickening of skin in
the palms and soles and intense itching
Exogenous Antioxidant
Antioxidant not synthesized within the body, usually derived from dietary sources
Exogenous
Originating outside or caused by factors outside the organism
Farnesyl
Small isoprenoid derived from mevalonate and a precursor of squalene and coenzyme
Q10
Fat Transport
The circulation of non-water soluble fats through the water based blood circulation in
combination with proteins, called lipoproteins
Fatty Acid
An acid containing only carbon, hydrogen and oxygen which combine with glycerin to
form fat
Feed Back Control System
Systems used by the body to maintain balance in various metabolic and other processes
Fibromyalgia
Common rheumatic syndrome not affecting the joints and characterized by muscle
tenderness and pain
Force of Disequilibrium
Force by which various parts of a normally balanced system are maintained at different
levels
Free Radical
Molecule or atom containing an unpaired electron in its outer orbit
Free Radical Biology
Branch of medicine that studies and explains disease processes resulting from or
contributed to b y free radicals in the biological system
Frequency
[Of light and other electromagnetic radiation] the number of waves per second; higher
frequency waves have more energy
87
Gene
Functional unit of hereditary material determining characteristics such as blood type,
eye color, etc
Genetic Control System
Biological control system dealing with functioning of genes
Genetic Evolution
Evolution of energetic trends and character
Geranyl
Small isoprenoid of the mevalonate pathway; a precursor to farnesyl ad involved in
protein isoprenylation
Glomerulonephritis
An inflammatory kidney condition; a suspected autoimmune disorder
Glutathione S-Acyltransferase
Enzyme involved in glutathione metabolism
Glutathione
Intracellular antioxidant found in almost all organism; the major component of the
cellular redox system that helps maintain thiol homeostasis within a cell
Glycerol
Type of sugar alcohol
Good Cholesterol [HDL] High Density Lipoprotein
Protein fat complex [lipoprotein] that transports cholesterol from tissue to liver for
excretion in the bile
Granulomatous Disorder
A genetic defect in which phagocytes ingest but fail to digest bacteria, resulting in
recurring bacterial infections
Hepatic [liver] failure
Severe inability of the liver to function normally
Hepatitis
Inflammation of the liver
Hereditary Blueprint
Biological description [genetic information] of an organism passed from parent to child
in genes carried in its cellular nucleus
Hexachlorobenzene
Agricultural fungicide and seed treatment agent
Hexachloro – Biphenyl
Biphenyl group of xenobiotics related to PCBs [PolyChlorinated Biphenyls]
High Density Lipoproteins [HDL; Good Cholesterol]
Protein fat complex [lipoprotein] that transports cholesterol from tissue to liver for
excretion in the bile
HIV [HI virus; Human Immunodeficiency Virus]
Virus believed to cause AIDA [acquired immune deficiency syndrome]
Histamine
A neurotransmitter that plays an important role in the regulation of several
physiological processes, including dilation of capillaries, contraction of most smooth
muscle tissue, induction of increased gastric secretion [ it most important use], and
acceleration of heart rate
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HMG Co-A Reductase -A Reductase
Enzyme that helps conversion of acetyl coenzyme A into mevalonate; the rate limiting
enzyme of the mevalonate pathway controlling the entire isoprenoid metabolism
Homeostasis
Maintenance of normal stability in physio-logical states of an organism, enabling us to
adapt to changing environmental conditions; maintained by the internal control systems
of the body such as genetic control system, immune control system, etc; these systems
operate through negative feedback and positive feedback
Hopanoid
Class of organic compounds derived from cyclic squalene
Hydrogen Peroxide [H2O2]
Strong oxidizing agent
Hydrophobic
Averse to water
Hydroxyl [OH,OH+]
Ion consisting of one atom of hydrogen and one of oxygen, either neutral or positively
charged
Hydroxylation
Introduction of hydroxyl into ion or radical usually by replacement of hydrogen
Hyper activation
Over stimulation
Hypercholesterolemia
Abnormally high levels of cholesterol in the blood
Hyperplasia
Abnormal, non cancerous increase in number of cells in a tissue or organ
Hypoxia
Decreased cellular oxygen content
Hypoxia reperfusion Injury
Cellular damage caused by sudden flow of oxygen to oxygen deprived tissue
Immune Cell
Cells of the immune system principally macrophages, T cells and B cells but including
many others
Immune Defense System
The coordinated system that protects the body from microorganisms and other foreign
agents
Immune Response
Coordinated response of the body to invasion, such as bacterial or viral infection
Immune Suppression [Immunosuppression]
Prevention or diminution of the host’s immune response
Immunodeficiency
Imbalance of immune response due to too much or too little immune activity
Inactivate
Transformation of molecule from functioning to nonfunctioning state
Inactive Squalene [Stable Squalene]
Obsolete term describing the portion of linear squalene that is not metabolized in the
mevalonate pathway and which maintains its antioxidant properties
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Industrial Carcinogen
Industrial cancer causing chemical substance
Infarction
Sudden pathological fall in blood supply to an area resulting in cell death and loss of
function of that particular area
Inflammation
Protective response of tissue to injury and potential destruction; attempt to destroy,
dilute or block the injurious agent and the injured tissues; classical signs of
inflammation pain include warmth, redness, swelling and loss of function
Inflammatory Bowel Disease
Types of chronic intestinal inflammation, including ulcerative colitis and Crohn’s
disease
Inhibitor
Agent that slows or prevents a biological process
Inhibitory Cytokine
Cytokine causing decreased proliferation of immune cells
Insulin Resistance
Diminished response of blood sugar levels to insulin
Internal Metabolic Process
Operating system of a metabolic process such as enzymatic control of a metabolic
pathway, feedback inhibition and hormonal influence
Intima
Innermost coat of an organ
Intracellular Anti-oxidant
Antioxidant present inside the cell
Ion
Atom or molecule with one electron more or less than normal, resulting in an acquired
positive or negative charge
Ionization Threshold
Amount of stimulation required for an electron within a molecular system to break free
Ionization
Break up of a substance into ions
Ionizing Radiation
Radiation that can split atoms and molecules in the body
Iron
Chemical element and essential constituent of hemoglobin, cytochrome, and other
components of the respiratory enzyme system
Irradiate
To expose to radiation
Isoniazid
Therapy of choice for tuberculosis
Isoprene [Isoprene unit]
Building block of isoprenoids; an isoprene unit contains five carbon atoms and a
double bond
Isoprenoid Metabolism
Chemical process that synthesizes three secondary isoprenoids in the mevalonate
pathway; geranyl, farnesyl and squalene
90
Isoprenoid Synthesis Pathway
See – Squalene synthesis pathway
Isoprenoid
Group of molecules with isoprene units
Isoprenylation [ Protein isoprenylation]
Modification of proteins on the surface of a cell by the attachment of one of two
isoprenoids; farnesyl diphosphate or geranyl diphosphate
Keratin
Principal protein constituent of epidermis, hair and nails
LDL [Low Density Lipoprotein; Bad Cholesterol]
Protein fat complex [lipoprotein] that transports cholesterol from the liver through
blood into other tissues, where it leads to plaque buildup
LDL Receptor
Protein complex on the surface of a cell that attracts and ‘hooks’ LDL; prevalent in the
cell membrane of liver cells
Leptin
Hormone secreted by fat cells
Leukemia
Progressive, malignant disease of blood forming organs
Light Harvesting Complex
[LHC] Group of carotenoids antioxidant isoprenoids present in a plant’s chloroplasts
that gather light and make photosynthesis efficient
Light Harvesting Compound
Same as LHC
Linear Dynamics
Conventional branch of physics, in which an effect is proportional to its cause [ in
contrast to chaos theory or nonlinear dynamics]; a branch of mathematics dealing with
systems that obey laws of proportion.
Lipase
An enzyme that is produced by tongue glands and the pancreas, initiating digestion of
dietary fats
Lipid
Fat or fat like substance including fatty acids, neutral fats, waxes, isoprenoids and
steroids, insoluble in water
Lipid Bilayer
Double layer of fats [lipids] forming a biomembrane
Lipid Peroxidation Chain Reaction
Domino effect in which free radical damage to a lipid [fat] molecule renders it radical
itself and similarly affects neighboring molecules; analogous to a multi-vehicle highway
pile up in a rapid sequence of single steps
Lipid Peroxidation
Chemical reaction in which a lipid molecule consisting of mainly unsaturated fat is
oxidized injury that triggers inflammation
Lipophilic
Having an affinity for fat
Lipoprotein
Combination of fats within a protein coat by which lipids are transported in the blood
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Liquid Chromatography
Method of separating mixtures into their constituent substances
Long Chain Hydrocarbon
Carbon compound with a long chain of interlinked carbon atoms, e.g. petroleum
Lumen
Cavity of a tubular organ
Lycoma
Tumor Metabolic Stress
resulting from excessive application of lycopene in the skin
Lycopane
Reduced form of lycopene
Lycopene
Red carotenoids pigment of tomatoes and various berries and fruits
Lymph Gland
Bodily tissue containing lymphocytes and other immune cells that filter micro
organisms and toxins from the body
Lymphocyte
White blood cells formed in the body’s lymphoid tissue
Lymphoma
General term for various cancerous diseases of the lymphoid tissue
Macrophage
Immune cell that envelops and digests incoming pathogens by the process of
phagocytosis; the major cellular constituent of the mucosal defense system;
macrophages also interact with lymphocytes to facilitate antibody production
Mass
In relating to cancer; autonomous accumulation of cancer cells
Mast Cell
Type of white blood cell involved in allergic reaction
MCG/GM
Measure of concentration of one substance within another; microgram [one millionth
of a gram] per gram
Media
Outside wall of an artery
Melanin
Pigments in skin and hair
Melanoma
Type of skin cancer; malignant cell growth originating from cells normally forming
melanin and spreading widely to lymph nodes, liver, lungs, and brain
Metabolic Pathway
Process in which a substance is produced in a series of chemical transformations from
another substance
Metabolic Pool
Portion of a substance that, in contrast to another portion of the same substance, is
destined for different biological activity
Inability of the metabolism to respond to a situation in which demand for a substance
exceeds its production
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Metabolism
Sum of all chemical and physical processes by which living organisms produce organic
substances; also, the transformation by which energy is made available for the uses of
the organism [catabolism]
Metabolite
Any biochemical product of metabolism
Methyl Bromide
Chloroform like volatile and toxic chemical used as fumigant, powerfully destructive of
ozone layer
Methyl Group [CH3]
An organic chemical group
Methylation
Introduction of the methyl group into a chemical compound
Mevalonate Pathway
Metabolic sequence of biochemical reactions leading from glucose to cholesterol;
Mevalonate
Mother molecule of all isoprenoids in the biological system; derived from glucose by
several complex enzymatic process
Mevalonic Acid [C6H12O4]
Precursor of squalene in the biosynthetic pathway forming cholesterol
MG/KG
Measure of concentration of one substance within another; microgram [one millionth
of a gram] per kilogram
Migrate
The departure of a group of cell or tissue from its natural location to another
Mitochondria
Energy production factories within a cell that burn nutrients to produce electrons and
generate electricity which is converted into chemical energy and stored in the cell for
future use
Mitosis
Formation of two new nuclei from a single parent nucleus, each having the same
number of chromosomes as the parent
Mixed isoprenoid
Substance composed of isoprene units attached to some other organic group, in
contrast to pure isoprenoid; e.g. vitamin E, which contains a chomarol group attached
to three isoprenoid side chains
Modulate
To adjust; to influence the fate of a chemical or physical function
Molecular Oxygen [O2]
Oxygen in the form of two combined atoms present in air and surface water; ultraviolet
radiation can break molecular oxygen into separate oxygen atoms [oxygen radicals]
which in turn can combine with molecular oxygen to form ozone
Molecule
Smallest amount of a substance which can exist alone; an aggression of atoms forming
a specific chemical substance
Mucosa
Mucous membrane coating the lumen of intestines, lung, nose mouth etc
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Mucosal Defense System
Immune system of skin and mucosae
Myocardial infarction
Sudden death of part of the heart muscle due to interrupted blood supply, a heart
attack
Myopathy
Disorder of muscle tissue or muscles
Nanometer
Billionth of a meter
Natural Defense System
Term used in this book to denote the immune system and the antioxidant defense
system [ cellular protective system]
Negative Feedback
Modulating process of biological control systems; too much or too little activity of a
particular sort may initiate negative feedback and return the activity to normal levels; a
source of homeostasis
Nerve Fiber Sheath [Myelin]
Electrical insulator covering nerve fibers enabling faster, more efficient transmission of
impulses
Neuron
Principal cells of nervous tissue able to transmit and receive nervous impulses
Neutrophil
Immune cell involved in phagocytosis
NNK [4 Methlynitro-samino -1-3-Pyridyl-1-Butanone]
A potent carcinogen used in laboratory experiments
Non-Ionizing Radiation
Radiation unable to penetrate and ionize deep tissue
Non-Linear Behavior
Behavior that does not follow simple, predictable patterns; biological behavior that
does not obey proportionality; see chaos theory
Non-Linear Dynamics [Chaos Theory]
Study of systems which respond disproportionately [nonlinearly] to initial conditions or
perturbing stimuli; nonlinear systems may exhibit ‘chaos’ classically characterized as
sensitive dependence on initial conditions; chaotic systems are neither ordered in a
mechanistic way nor random; their behavior over time is displayed in ‘phase space’ in
which constraints are described as ‘strange attractors;’ these representations usually
reveal fractal patterns – self-similarity across time scales; biological systems often
display nonlinear dynamics and chaos
Non Specific
An immune response to a pathogen that is not tailored to its specific propertied and or
weaknesses
Normal Chaotic Fluctuation
Fluctuation normally considered abrupt [in linear dynamics] but within normal range of
nonlinear [chaotic] dynamics; e.g. daily fluctuations of heart rate
Nucleus
The ‘heart’ of a cell, containing genes
94
Oleic Acid
An unsaturated fatty acid; the most widely distributed and abundant fatty acid in nature
Oncogene
Cancer promoting gene; gene that transmits the cancer character as cancerous cells
multiply
Oncologist
Specialist in the study of tumors
Organ
Somewhat independent body part with a specialized function
Organelle
Specialized functional structure within a cell
Organochlorine
A pesticide
Oxidant-antioxidant Balance
Appropriate ratio of free radicals to antioxidants under which cells, and tissue can
operate optimally
Oxidation
Removal of electrons
Oxidation- Reduction
Chemical reaction in which electrons are removed [oxidized] from a substance and
transferred to those being reduced [ reduction]
Oxidative Injury
Free radical induced damage to a cell
Oxidative Phosphorylation
Complex electrochemical process by which mitochondria derive energy from nutrients
and oxygen
Oxidative Stress
Overproduction of free radicals causing tissue damage
Oxidized Cholesterol [oxLDL]
Bad Cholesterol subjected to lipid peroxidation; the worst type of cholesterol
Oxygen
Chemical element constituting about 20% of atmospheric air; essential for respiration
in plants and animals
Oxyradical
Oxygen derived free radical
Ozone [O3]
Bluish explosive gas or blue liquid; an antiseptic and a disinfectant; an irritant, toxic to
the respiratory system
Ozone Layer
Outermost layer of the planet’s atmosphere, composed principally of ozone, that filters
a portion of the sun’s harmful ultraviolet radiation
P53 Gene
Natural anticancer defence; tumor suppressor gene located on the short arm of human
chromosome 17 and coding for the phosphoprotein P53
Pathogen
Any specific agent causing or threatening the body with disease
95
Pathology
Structural and functional manifestations of disease
PCBs
See polychlorinated biphenyls
Peer Review Journal
Medical research journal in which research articles are subjected to the approval of a
select committee of established scientists
Pemphigus Vulgaris
A chronic, relapsing sometimes fatal skin disease characterized among other symptoms
by serum autoantibodies directed against antigens in the intracellular zones of the
epidermis
Pentamethyleicosane [PME]
Ancient, acyclic isoprenoid present in primitive bacteria
Phagocyte
Bacteria-eating immune cell
Phagocytosis
Process of engulfing microorganisms and other foreign particles by immune cells
Phenobarbital
A nonselective central nervous system depressant; a barbituric acid derivative
Phenol [C6H5OH]
An antiseptic and disinfectant
Photooxidation
Oxidation of organic molecules by light energy
Photosynthesis
Light induced formation of carbohydrates from carbon dioxide and water in the
chlorophyll tissue of plants
Physical Quenching
Neutralization of free radicals by antioxidant’s donation of an electron without
chemical reaction
PI Electron System
Special arrangement of electrons I a carbon-carbon double bond that activates nearby
hydrogen atoms; each isoprene unit has one double bond and therefore one pi electron;
all pi electrons in an isoprenoid molecule combine to make one pi electron system,
each one stabilizing the molecule’s hydrogen atoms
Plasma
Fluid part especially of blood, lymph, or milk, apart from suspended material
Polarized
To be separated into polar opposites such as off and on; positive and negative,
hydrophilic and hydrophobic
Polychlorinated Biphenyls [PCBs]
Highly lipophilic industrial products and compounds that accumulate in fat stores,
many of which are potential environmental pollutants
Positive Feedback
Process into which many biological control systems fall as they lose homeostatic
control; leads to instability, disease and death; positive feedback is occasionally a
normal process, for example in sexual intercourse
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Pravastatin
Drug acting as a competitive inhibitor of HMG Co-A reductase
Precambrian Era
Geological time that spanned from 3.8 billion to 570 million years ago. The great
Precambrian era is divided into two parts; during the archean period from 3.8 to 2.5
billion years ago archae and cyanobacteria dominated life. The proterozoic era – from
2.5 billion
To 570 million years ago – includes over 85% of living history
Prednisolone [C21H28O5]
Glucocorticoid used in systemic corticosteroid therapy of inflammatory diseases
Prednisone
A synthetic anti-inflammatory glucorticoid derived from cortisone; biologically inert
and converted to prednisolone in the liver
Premature Apoptosis
Apoptosis forced upon a young and active cell; an offensive strategy for example of
HIV
Pro-Carcinogen
Normally noncancerous chemical transformed into a carcinogen within the body
Proliferation
Increase in number, as in cell proliferation [[multiplication]
Pro-oxidant
Antioxidant molecule that has lost its stability and becomes a free radical
Prostate Cancer
Tumors or cancer of the prostate – a male gland surrounding the neck of bladder and
the urethra
Protective Coat
Term used in this book to encompass those bio-surfaces of the body exposed to the
outside environment – skin, mouth, intestine, nose, throat and lung
Proton
Stable elementary particles possessing the smallest known positive charge and found in
the nuclei of all elements
Pure Isoprenoid
Isoprenoid composed exclusively of isoprene units
Pyrophosphate
Inorganic salt of phosphoric acid containing phosphate groups
Quaternary Carbon Group
Carbon atom within an organic compound in which each of its four bonds are
connected directly to another carbon atom
Quench
To neutralize a free radical
Quinone
Benzene derivative in which two hydrogen atoms are replaced by two oxygen atoms;
ubiquinone [Coenzyme Q10] is quinone with an isoprenoid tail
Ras Oncogene
Family of most commonly found oncogenes in human cancerous tumors
97
Reactive Arthritis
Also known as Reiter’s syndrome. An aberrant reaction of the immune system to the
presence of bacterial infections in the genital, urinary, or gastrointestinal systems and
leading to inflammation in the joints and eyes
Receptor
Protein molecule within or on the surface of a cell that recognizes and binds with
specific molecules, producing a specific effect in the cell
Redox Molecule
Type of organic molecule able to participate in reduction oxidation reaction
Redox Reaction
See oxidation – reduction
Reduction
Addition of electron
Reduction – oxidation
Electron transfer from one molecule to another; gain [ reduction] and loss [oxidation]
of electrons
Reperfuse
Restoration of blood flow to oxygen deprived tissue or organ
Respiratory Tract Disease
Disease in airway tubes; e.g. asthma
Rheumatic Fever
Probable autoimmune disease following streptococcal infection and involving
inflammation of joints and damage to heart valves
Rheumatic Heart Disease
The most important manifestation of and sequel to rheumatic fever
Rheumatoid Arthritis
Chronic inflammatory destruction of joints considered by some to be an autoimmune
disorder
Rhinitis
Inflammation of the mucous membrane of the nose
Ribosome
Organelle [ functional unit within a cell] rich in RNA and proteins; site of protein
synthesis
Risk Factor
Contributing cause or circumstance of disease or potential disease
RNA Transcription
Synthesis of RNA from its complementary DNA strand
Roentgen
German term for X-ray – inventor of x-rays
Sarcoidosis
Disease of unknown etiology involving chronic inflammatory Granulomatous lesions
in the lymph nodes and other organs
Scleroderma
Hardening of the skin
Sebum
Fatty, lubricating secretion of skin’s sebaceous glands
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Serum Sickness
A hypersensitivity response to the injection of large amounts of antigen
Sex Hormone
Steroid substances that differentiate male and female beings; testosterone for males and
estrogen for females
Simvastatin
Drug derivative of lovastatin and potent competitive inhibitor of HMG Co-A reductase
– the rate limiting enzyme in cholesterol biosynthesis
Singlet Oxygen
Molecular oxygen with one missing electron
Spleen
Large gland like organ situated in the upper left part of the abdominal cavity
Splenomegaly
Enlargement of the spleen
Squalane
Natural emollient found in skin; squalene with an added hydrogen atom
Squalene
Isoprenoid hydrocarbon consisting of six isoprene units; in linear form an excellent
antioxidant; in cyclic form a principal constituent of the sterol nucleus of cholesterol
Squalene Metabolism
Metabolic process involving production and storage of squalene in the body
Squalene synthase
Enzyme that converts farnesyl to squalene
Squalene synthesis pathway
Metabolic pathway that synthesizes squalene from mevalonate via production of
geranyl and farnesyl; part of the isoprenoid metabolism
Squamous Cell Carcinoma
A type of skin cancer on the increase due to ozone depletion
Statins
Group of drugs that lower production of cholesterol in the body by inhibiting the
enzyme HMG Co-A reductase
Sterol
Solid steroid alcohol widely distributed in animal and plant lipids; fundamental building
block of cholesterol
Strychnine
Alkaloid found in the seeds of nux vomica; a convulsant and poison
Subcutaneous
Beneath the skin
Submucosal
Beneath the mucosa
Superoxide Dismutase [SOD]
Intracellular antioxidant present mostly in a cell’s mitochondria
Superoxide
Highly reactive compound produced when oxygen is reduced by a single electron
Synapse
Specialized junctions from which neurons communicate with target cells
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Synthesis
Creation of compound by the union of elements; manufacture
Systemic Lupus Erythematosus
A probably autoimmune disease characterized by antinuclear and other antibodies in
plasma
Terminator
Antioxidant that can stop [terminate] a lipid peroxidation chain reaction
Terrestrial Radiation
Earthbound radiation from radioactive materials in rocks and sediments
Testicular Cancer
Cancer of the Testicle
Theophylline
Drug that stimulates the heart and central nervous system, dilates bronchi and blood
vessels and causes diuresis
Threshold
[In metabolism] Limit at which biochemical processes undergo drastic change
Tissue
Aggregation of similar cells which together perform certain special functions
TNF-Alpha
Tumor necrosing factor; an excitatory cytokine; increased release of this cytokine can
cause insulin resistance
Topical
Designed for or involving local application to a bodily part
Total Suspended Particulate Matter [TSP]
Solid or liquid atmospheric particles [diameter 10 micrometers] from sources including
diesel exhaust, wood- stoves and power plants; may be formed in the atmosphere from
reaction of So2, NOx and other gaseous pollutants
Toxic Shock Syndrome
A staphylococcal infection of blood
Transient
Temporary
Triglyceride
Compound consisting of three molecules of fatty acid and the usual storage form of
lipids in animals; a neutral fat
Triterpene
Group of isoprenoid compounds having thirty carbon atoms, such as squalene
Tuberculosis
A lung infection caused by a species of mycobacterium
Tumor necrosis Factor [TNF-Alpha]
Type of stimulatory cytokine secreted by immune and fat cells; increased release can
cause insulin resistance
Tumor Neoplasm
New abnormal growth of tissue
Tumor Suppressor Gene
Gene causing suicide of a cell to prevent malignant transformation
Ulcerative Colitis
Chronic inflammatory disease of the mucous membranes of the colon leading to ulcers
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Uranium – 238 – 238
Radioactive uranium of atomic mass 238
Urticaria
Vascular reaction of the skin to allergy, characterized by redness, heat and pain in the
affected area
UV Radiation
Portion of the electromagnetic spectrum immediately below the visible range and
extending into the x-ray frequencies
UV-A Radiation
Ultraviolet spectrum from 320 to 400 nm wavelength; contributes to aging of the skin
UV-B Radiation
Ultraviolet spectrum from 280 to 320 nm wavelength; contributes to sunburn, aging of
the skin and development of skin cancer
Vasculitis
Inflammation of any vessel
Vesicle
Membranous, usually fluid filled pouch
Vitamin
Group of chemically unrelated organic substances occurring in many foods in small
amounts and necessary in trace amounts for the normal metabolic functioning of the
body
Wavelength
Length of a wave from trough to trough or crest to crest; the wave length of light is
measured in nanometers
White Blood Cells
Cells in plasma without red cells; all immune cells are white cells
Xenobiotic
Chemical substances foreign to the biological system