Antioxidants.pptx antioxidants in humans

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1. Antioxidants Dr.Sowmya M

2. Definitions Oxidation = Losing electrons Reduction= Gaining electrons

3. All living organisms utilize oxygen to metabolize and use the dietary nutrients in order to produce energy for survival. Oxygen thus is a vital component for living . Oxygen meditates chemical reactions that metabolize fats, proteins, and carbohydrates to produce energy . While oxygen is one of the most essential components for living, it is also a double edged sword. Oxygen is a highly reactive atom that is capable of becoming part of potentially damaging molecules commonly called “free radicals.”

4. Oxygen → required for life but it is highly reactive During metabolism or infection --- reactive oxygen species (ROS) are formed → Free radicals (FR) H₂O ₂ = Hydrogen peroxide HOCl = Hypochloric acid OH⁻ = Hydroxyl radical O₂⁻ = Superoxide anion Free radicals = unstable and highly reactive molecules (due to unpaired electron ) The body can initiate the creation of free radicals to defend itself against viruses or bacteria.

5. These free radicals are capable of attacking the healthy cells of the body. This may lead to damage, disease and severe disorders. Cell damage caused by free radicals appears to be a major contributor to aging and diseases like: cancer heart disease decline in brain function decline in immune system etc. Free radicals FR can be formed by exposure to UV light, cigarette smoke, radiation, pollution etc. Other Free radicals formed during inflammation and disease: Reactive Nitrogen Species (RNS)

6. Since free radicals contain an unpaired electron they are unstable and reach out and capture electrons from other substances in order to neutralize themselves. This initially stabilizes the free radical but generates another in the process. Soon a chain reaction begins and thousands of free radical reactions can occur within a few seconds on the primary reaction.

7. Free radicals attack stable molecules and steal an electron - creating a new radical → chain reaction .

8. ROS is a term which encompasses all highly reactive, oxygen-containing molecules, including free radicals. Types of ROS include the hydroxyl radical, hydrogen peroxide, the superoxide anion radical, nitric oxide radical, singlet oxygen, hypochlorite radical, and various lipid peroxides. These can react with membrane lipids, nucleic acids, proteins and enzymes, and other small molecules. Reactive oxygen species (ROS)

9. Oxidative stress means is an imbalance between free radicals & antioxidants in body - This results in excessive oxidative metabolism. This stress can be due to several environmental factors such as exposure to pollutants, alcohol, medications, infections, poor diet, toxins, radiation etc. Oxidative damage to DNA, proteins, and other macromolecules may lead to a wide range of human diseases most notably heart disease and cancer. Oxidative stress

10. Antioxidants ( AOx ) are part of the defense system of the body protecting against free radical damage. Most AOx donate an electron to FR without becoming FR themselves → chain reaction stopped. AOx do not remove FR completely → keep them at an optimum level. Dietary AOx not produced in the body→ Food Consumption of AOx is thought to provide protection against oxidative stress → positive impact on health

11. Cancer, atherosclerosis, CVD, cataracts, immune dysfunction, Alzheimer´s disease, age-related macular degeneration, rheumatoid arthritis, aging, etc. Chronic Injury Oxidative Stress

12. Normally free radical formation is controlled naturally by various beneficial compounds known as antioxidants. When there is deficiency of these antioxidants damage due to free radicals can become cumulative and debilitating. Antioxidants are capable of stabilizing, or deactivating, free radicals before they attack cells. Control of free radicals

13. Antioxidant:

14. An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, leading to chain reactions that may damage cells. Types of antioxidants These are 3 types Enzymatic & non enzymatic antioxidants : They are present in both Extracellular & Intracellular environment. Natural & dietary Based on defense mechanism Antioxidant:

15. Types – According to the types- Enzymtic & Non- enymatic Mode of action- Preventive & Scavenging Location- Intracellular, Extracellular & Membrane associated Solubility- water soluble & Fat Soluble Structures they protect – DNA, Protein & Lipid Origin – Exogenous & Endogenous

16. S.No Antioxidant Location Function 1. Glutathione peroxidase Mitochondria & Cytosol Removal of H 2 O 2 & Organic hydro peroxide 2. Catalase Mitochondria & Cytosol Removal of H 2 O 2 Enzymatic antioxidants Antioxidants Enzymatic Non-Enzymatic Nutrient Non- Nutrient Glutathione & catalase Vit -E, Vit -C, Vit -A & selenium Ceruloplasmin , transferin , uric acid 1. According to the types

17. Non Enzymatic Antioxidants S.No Antioxidant Location Function 1. Carotenoids Lipid soluble antioxidants in membrane tissue Removal of ROS 2. Bilirubin Product of heme metabolism in blood Extracellular antioxidants 3. Glutathione Non- protein thiol in cell Cellular oxidant defense 4. Α - Lipoic acid Endogenous thiol Serves ass substitute for glutathione 5. Vitamin C Aqueous phase of Cell Free scavenger, recycle Vit -E 6. Vitamin E Cell Chain breaking Antioxidant 7. Uric acid Product of purine metabolism Scavenging of OH radical

18. 2. Mode of Action Preventive Scavenging 1. Enzymes: Superoxide dismutase, Catalase , glutathione. 2. Metal ion sequestrators : Carotenoids , Superoxide dismutase, catalase , glutathione, Uric acid, flavenoids Vit -C, Carotenoids , uricacid , α - tocopherol , flavenoids , thiols

19. 3. Location Intra cellular Extra cellular Membrane associated Catalase , glutathione peroxidase , DNA repair enzyme Vit –C, carotenoids , uric acid α - Tocopherol

20. 4. Solubility Water soluble Fat soluble Ascorbate , uric acid, flavenoids , Cysteine , transferins α - Tocopherol , Caratenoids , bilirubin

21. 5. Structures they protect DNA Protein Lipid Superoxide bismutase-1 & 2, glutathione peroxidase , DNA repair enzymes, reduced gluththione , cysteine Sequestration of transition metals by preventive Antioxidants Vitamin-E, Vitamin-c, carotenoids , glutathione

22. 6. Origin Exogenous Endogenous Cartenoids , ascorbic acid, tocopherols , polyphenols Catalase , superoxide dismutase, glutathione

23. There are several nutrients in food that contain antioxidants- Vitamin C, vitamin E, and beta carotene are among the most commonly studied dietary antioxidants. Vitamin C is the most important water-soluble antioxidant in extracellular fluids & it helps to neutralize ROS in the water or aqueous phase before it can attack the lipids. Vitamin E is the most important lipid soluble antioxidant. It is important as the chain-breaking antioxidant within the cell membrane. Antioxidants from food

24. Vit E It can protect the membrane fatty acids from lipid peroxidation . Beta carotene and other carotenoids also have antioxidant properties. Carotenoids work in synergy with vitamin E.

25. Apart from diet, the body also has several antioxidant mechanisms that can protect itself from ROS mediated damage. The antioxidant enzymes – Glutathione peroxidase , catalase , and superoxide dismutase (SOD) are such enzymes & They require micronutrient cofactors such as selenium, iron, copper, zinc, and manganese for their activity. Antioxidants within the human body

26. Functions of Antioxidants Antioxidants such as vit -c & vit -E boost our immune system. Certain phytochemicals have beneficial effect on heart diseases. Antioxidants lower the level of LDL- Cholesterol, thus preventing plaque deposition in the blood vessels. It is beneficial in cancer prevention. antioxidants neutralize substances that can damage the genetic material by oxidation.

27. Vitamins as antioxidants Carotenes – is one of four antioxidants that are vital for our general health & wellbeing. There are 4 carotene compounds:- α - Carotene, β - carotene, γ - carotene, δ - carotene . α - Carotene & β - carotene are the powerful antioxidants . Much like beta, alpha- carotene is found in foods like- carrots, sweet potatoes, kiwi, spinach, broccoli, mango, etc..