oxidative stress - the leader in online training in ... · copper, manganese, selenium, zinc and...

Functional Medicine University’s Functional Diagnostic Medicine

Training Program

Mod 4 * FDMT 531B

Oxidative Stress

By Wayne L. Sodano, D.C., D.A.B.C.I., & Ron Grisanti, D.C., D.A.B.C.O., M.S. http://www.FunctionalMedicineUniversity.com

Limits of Liability & Disclaimer of Warranty

We have designed this book to provide information in regard to the subject matter covered. It is made available with the understanding that the authors are not liable for the misconceptions or misuse of information provided. The purpose of this book is to educate. It is not meant to be a comprehensive source for the topic covered, and is not intended as a substitute for medical diagnosis or treatment, or intended as a substitute for medical counseling. Information contained in this book should not be construed as a claim or representation that any treatment, process or interpretation mentioned constitutes a cure, palliative, or ameliorative. The information covered is intended to supplement the practitioner’s knowledge of their patient. It should be considered as adjunctive and support to other diagnostic medical procedures. This material contains elements protected under International and Federal Copyright laws and treaties. Any unauthorized reprint or use of this material is prohibited.

Functional Medicine University; Functional Diagnostic Medicine Training Program/Insider’s Guide

Module 3: FDMT 531B: Oxidative Stress Copyright © 2010 Functional Medicine University, All Rights Reserved

http://www.functionalmedicineuniversity.com/

Functional Medicine University’s

Functional Diagnostic Medicine Training Program

Module 3:FDMT 531B: Oxidative Stress

By Wayne L. Sodano, D.C., D.A.B.C.I., & Ron Grisanti, D.C., D.A.B.C.O., M.S.

http://www.FunctionalMedicineUniversity.com

1

Contents

Oxidative Stress 2

Free Radicals and Reactive Oxygen Species 4

The Biological Effects of Reactive Oxygen Species 6

Antioxidants 7

Antioxidant Activity of Metabolic Products 8

Scenarios of Radical Formation and Removal 10

Antioxidants: Redefining Their Roles (“Redox Molecules”) 11

References 12

Required reading: Antioxidants: Redefining Their Roles; Integrative Medicine, Volume 5, No.6, Dec 2006.

This article can be found on the FMU website with this lesson and in the on-line library.






2

Oxidative Stress

Oxidative stress can be defined as the state in which the level of reactive oxygen species is greater than the level

of antioxidants. Oxidative stress is caused by the damaging action of free radicals. Oxidative stress has been

implicated in a large number of diseases, which include: cancer (damage to DNA), atherosclerosis (damage to

the endothelial lining of the blood vessels), neurodegenerative disease (damage to the nerve cells), and diabetes,

to name a few.

http://altered-states.net/barry/update227/freeradicals.jpg

Ref: Reactive Oxygen Species and Antioxidant Vitamins; Balz Frei, PhD.,Linus Pauling Institute






3

A free radical is an atom or group of atoms that have one or more unpaired electrons. Free radicals are partially

reduced metabolites of oxygen or, in some cases nitrogen. Free radicals are formed as intermediates of normal

biochemical (physiological) reactions that occur in the body, especially the mitochondria, intermediates of

enzyme reactions and deliberately in active phagocytes. (The normal mechanism of invading microbe

destruction by macrophages requires an oxidative burst where intense reactive oxygen species formation

occurs.) Free radicals are highly chemically reactive and, therefore, can cause significant tissue damage when

they are produced in excess or with excess exogenous exposure. Free radicals can react with most molecules in

the nearby vicinity including proteins, lipids, carbohydrates and DNA. Any free radical involving oxygen is

referred to as reactive oxygen species (ROS).

Exogenous sources of free radicals include:

Drugs – some antibiotics, antineoplastic agents (e.g. methotrexate) and others including sulphasalazine

which is used to treat inflammatory bowel disease.

Tobacco smoke – there are multiple oxidants in tobacco smoke

Radiation – Electromagnetic (X-ray, UV and gamma) Some examples of gamma radiation exposure

are: naturally occurring radionuclides such as potassium-40, which is found in soil and water, as well as

meats and high potassium foods such as bananas; radium; and nuclear medicine (bone, thyroid and lung

scans)

Endogenous sources of free radicals include:

Oxidation – many molecules of the body undergo auto-oxidation. These molecules cause the reduction

of oxygen forming ROS.

Enzyme oxidation – enzyme systems of the body can generate large amounts of free radicals

Mitochondria and other organelles – The mitochondria are the primary source of production of ROS.

Iron and copper – These are transition metal ions and play a role in the production of ROS. These ions

facilitate lipid peroxidation.

Tissue ischemia – It is counterintuitive to think that low levels of oxygen causes free radical production,

and therefore oxidative stress, however, tissue ischemia causes the loss of antioxidants, in particular,

superoxide dismutase and glutathione peroxidase.

Note: The mitochondrial respiratory chain is the major source of ROS in most tissues. Adequate levels of

antioxidants and repair enzymes maintain non-toxic levels of these oxidants.






4

Free Radicals and Reactive Oxygen Species

As stated earlier, free radicals derived from oxygen are called reactive oxygen species (ROS). Recall that

oxygen has two unpaired electrons in its outer shell which make it susceptible to radical formation.

Oxygen Element: Structure and Properties

The Behavior of Oxygen

The element oxygen can either capture two electrons or share two electrons. This is the process for obtaining

the structure of water, H2O

The other way oxygen can obtain a full outer shell is by capturing two electrons from the environment around it.

This occurs when an oxygen atom, or a molecule of oxygen gas, encounters a metal; as in rust.

The sequential reduction of molecular oxygen leads to the formation of ROS, such as superoxide radical,

hydrogen peroxide, and hydroxyl radical. Singlet oxygen radical is an excited form of oxygen in which one

electron jumps to a high higher orbit following the absorption of energy.






5

Reprinted with permission: Laboratory Evaluations for Integrative and Functional Medicine, 2nd ed., Richard S. Lord & J. Alexander Bralley







6

The Biological Effects of Reactive Oxygen Species

In terms of the biological effects of ROS, it’s all about balance between the level ROS and the level

antioxidants. ROS play a role in killing invading organism, as well as, having the potential for intercellular and

intracellular signaling. ROS are thought to induce programmed cell death, induce or suppress the expression of

many genes, and activate cell signaling cascades, such as those involving mutagen-activated protein kinases.

Mutagen-activated protein kinases are involved with cellular activities, such as gene expression, mitosis,

differentiation, proliferation and apoptosis. An example of intracellular signaling by ROS is illustrated below.

H2O2 →NFKB →Gene Expression

Hydrogen peroxide activates nuclear transcription factor kappa B, which then causes gene expression. In this

case the expressed genes are pro-inflammatory.

Even though there are beneficial effects of ROS, they are, none the less, toxic to the cells. The resulting toxicity

leads to damage to all macromolecules, including nucleic acids (DNA), proteins and lipids. One of the most

susceptible molecules to free radical attack is lipids. As you know, lipids are an integral part of the cell

membranes, including the cells and the organelles. Damage to the membranes results in increased rigidity,

decreased activity of membrane bound enzymes, altered cell receptor activity and altered permeability. (Recall

the insulin cell receptor discussed in a previous lesson)

Hydroxyl Radical Attack on a Polyunsaturated Fatty Acid

The multiple double bonds of PUFA molecules in cell

membranes afford abundant, easily removed electrons. A

hydroxyl radical is shown extracting a single electron and

capturing the proton to form water. The fatty acid radical then

associates with an oxygen molecule, forming the peroxyl radical.

The peroxyl radical can then react with other fatty acids, proteins

and DNA causing molecular and tissue damage. This process is

called peroxidation.






7

Antioxidants Antioxidants are compounds that prevent oxidative damage in biological systems. The primary function of

antioxidants is free radical scavenging. The methods of action of antioxidants are: chain breaking reaction,

reducing the concentration of ROS, and chelating the transition metal catalysts. An example of a chelating

transition metal catalyst is ferritin, which keeps iron sequestered.

Antioxidants are categorized as either enzymatic or non-enzymatic. Non-enzymatic consist of vitamins,

metabolic products and non-vitamin redox molecules. (Minerals that serve as cofactors for antioxidants are also

considered antioxidants.)

Enzymatic Antioxidants

Catalase

Superoxide dismutase

Glutathione peroxidase

Note: Superoxide dismutase is produced by the cells. This enzyme catalyzes the conversion of two

superoxides into hydrogen peroxide and oxygen. Catalase, found in peroxisomes, degrades hydrogen

peroxide to water and oxygen. Glutathione peroxidase degrades hydrogen peroxide to water and oxygen.

Non-enzymatic Vitamin Antioxidants

Vitamin A

Vitamin C

Vitamin E

Coenzyme Q10 (vitamin-like substance)

Non-enzymatic Non-Vitamin Antioxidants

Alpha lipoic acid

B-Carotene

Caffeic acid

Curcumin

Epigallocatechin gallate (EGCG)

Genistein

Kaempferol

Melatonin

N-Acetylcysteine (NAC)

Quercetin

Resveratrol

Silymarin






8

Copper, manganese, selenium, zinc and riboflavin are also considered antioxidant nutrients because they play

specific roles as cofactors for the enzymes that catalyze reactions that remove ROS. Some examples are as

follows:

Selenium is a cofactor for glutathione peroxidase.

Manganese, copper and zinc are cofactors for superoxide dismutase.

Antioxidant Activity of Metabolic Products

Uric acid

Uric acid is the most abundant aqueous antioxidant in the body. Uric acid has antioxidant effects on

hydroxyl, superoxide and peroxynitrite and may play a role in preventing lipid peroxidation. Uric

acid is produced by the enzyme xanthine oxidase from xanthine and hypoxanthine, which are

products of purine metabolism. The mineral molybdenum is a cofactor for xanthine oxidase as well

as sulfite oxidase and aldehyde oxidase. From a functional medicine perspective high levels of uric

acid are associated with gout, cardiovascular disease, oxidative stress, and diabetes. Low levels of

uric acid are associated with a deficiency in molybdenum and multiple sclerosis. It’s important to

keep in mind the optimal serum level of uric acid, since low and high levels are associated with

disease states.

Serum Albumin

About ten percent of the total ROS scavenging activity in the plasma is due to the presence of serum

albumin. A large fraction of the antioxidant property of albumin is due to the numerous cysteine

thiol groups that it carries on its outer surface.

Glutathione

Glutathione has been called the most important intracellular defense against damage by ROS.

Glutathione is made from the amino acids cysteine, glycine and glutamine. The cysteine provides an

exposed sulphydryl group that is able to bind with free radicals. Reaction with free radicals oxidizes

glutathione; however, the reduced form is regenerated by glutathione reductase and the electron

acceptor NADPH.






9







10


Scenarios of Radical Formation and Removal

Reactive oxygen species, such as O2·and OH·, can damage tissues unless they are removed by electron transfer

to vitamins A, C, and E, or by enzymatic conversions of superoxide, first to hydrogen peroxide and then to

harmless water. The enzymatic conversions are dependent on adequate supply of amino acids, vitamins and

essential minerals.






11

Scenario I shows the removal of hydrogen peroxide by either direct conversion to water or by oxidation of

glutathione. The pentose phosphate pathway assures the supply of NADPH-reducing equivalents.

In scenario II, an electron transfer from a membrane fatty acid is processed through antioxidants of decreasing

electron acceptor potential, but of increasing cellular concentrations and regenerative capacity.

Scenario III shows the potential involvement of lipoic acid for regeneration of oxidized forms of glutathione

and thioredoxin, two critical components of cellular response to oxidative stress.

As previously stated, an important concept to understand is that there must be a balance between ROS and

antioxidant levels since they are both involved in normal physiological processes. ROS are normal components

of the mitochondrial membrane and only pose a problem when they are formed in an uncontrollable manner. If

antioxidants are consumed in disproportionate amounts, they too can pose a problem. The best way to ensure

an appropriate balance is through functional medicine testing.

Antioxidants: Redefining Their Roles (“Redox Molecules”)

The traditional understanding of antioxidants is that they are electron donors that scavenge free radicals and

thereby provide a protective role. A new concept with regard to antioxidants is that they modulate cellular redox

potential and cellular physiology by directly altering cell signaling and transcription. In other words, certain

antioxidants can inhibit pro-inflammatory substances.

Required reading: Antioxidants: Redefining Their Roles; Integrative Medicine, Volume 5, No.6, Dec 2006.

This article can be found on the FMU website with this lesson and in the on-line library.






12

References

1. QJ Med 2002; 95:691-693; Commentary; Uric Acid: An Important Antioxidant in Acute Ischemic

Stroke, W.S. Waring, Clinical Pharmacology Unit and Research Centre, The University of Edinburgh,

Western General Hospital, Edinburgh, UK

2. J. Physiol (2003), 552.2, pp, 335-344; Topical Review; Mitochondrial Formation of Reactive Oxygen

Species, Julio F. Turrens, Department of Biomedical Sciences, University of South Alabama, Mobile, Al

36688

3. Linus Pauling Institute at Oregon State University;

http://orgeonstate.edu/infocenter/minerals/molybdenum

4. U.S. National Library of Medicine; National Institutes of Health; PubMed;

http://www.ncbi.nlm.nih.gov/pubmed/16202511; Clin Neurol Neurosurg; 2006 Sept; 108(6):527-31.

Epub 2005 Oct 3; Serum Uric Acid and Multiple Sclerosis; Rentozos M, Nikolaou C; Department of

Neurology, Aeginition Hospital-Athens Medical School, 72-74 Vas.Sophias Av, Greece

5. Role of Reactive Oxygen Species in Cell Signalling Pathways, J.T. Hancock, R. Deskikan, S. Neill; Free

Radical Research Group, Faculty of Applied Sciences, University of West of England, Bristol,

Coldharbour Lane, Bristol BS16 1OY, U.K.

6. http://www.epa.gov/rpdweb00/understand/gamma.html; Radiation Protections; Gamma Rays

7. http://mayoresearch.mayo.edu/isayalab/mitochondrial.cfm

8. Laboratory Evaluations for Integrative and Functional Medicine, 2nd

ed., Richard S. Lord, J. Alexander

Bralley

http://orgeonstate.edu/infocenter/minerals/molybdenum

http://www.ncbi.nlm.nih.gov/pubmed/16202511

http://www.epa.gov/rpdweb00/understand/gamma.html

oxidative stress - the leader in online training in ... · copper, manganese, selenium, zinc and...

Documents