Post on 29-Dec-2015
transcript
Fe
Hb
Other cells
Cyt P 450
superoxideMet Hb
H2O2
NADPH oxidase
SOD
Neutro phils
Glu perRBC
Habe
r-wei
ss
catalaseH2O
OH. H2O
xanthine oxidase
bacteria
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Physiological Stimuli that Form Free radicals
• Normal respiration – O. , H2O2, HOCL, NO
• Transition metals present inside our body when are in free form behave as free radicals. Fe2+, Cu+
• Body cells-– Endothelium (NO,NO2) – Macrophages (NO2)
• Ageing• Phagocytosis or biogenetics • Oxidation of foods and endogenous compounds. • Transportation of substances for energy production.• Breakdown of drugs by body-CCl3
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Pathological Stimuli that Form Free radicals
Radiation, Ultraviolet rays, X-raysBreaks the water inside our body: H2O =H+ + OH-
Emotional stress Sunlight Stress Toxins Pollution Exercise Food additives Environmental Chemicals Synthetic materials Household cleaners Solvents Pesticides,Herbicides
SmokingSmoking 10 Quad Trillion free radicals 10 Quad Trillion free radicals
per cigarette!per cigarette!
Free radicalsSuperoxide, O2
· -
Hydroxyl radical, OH ·
Peroxyl, ROO ·Alkoxyl, RO ·
Hydroperoxyl, HO2 ·
Nitric oxide, NO .
Nitrous oxide, NO2 .
Free radicals - physiological function
• NADPH-oxidase of leukocytes against bacteria (ROS/RNS)
• Signal molecules-first messenger second messenger information net-This info net function is affected by the redox state of cells
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Actions of Free radicals
• Lipid peroxidation.• Alteration of the enzyme and
receptor proteins. • Fracturing on the cell nucleus
resulting in single strand DNA damage.• Damages LDL
Lipid Peroxidation
• Initiation
ROOH + metal (n)+ ROO. + metal(n-1) + H+
X . +RH R . +XH• Propagation
R . + O2 ROOH + R.
• Termination
ROO. + ROO. ROOR + O2
ROO. + R . ROOR
R . + R . RR
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• This chain reaction may produce diseases like: –Carcinogenesis.–Myocardial reperfusion injury.– Shock related injury.–Arteriosclerosis.–Rheumatoid arthritis.–Adult respiratory diseases.–Diabetes.–Obesity.– Lipid abnormality. Etc.
ANTI-OX
PRO-OX
SODGSH
Vit C, ECarotenoidO-
2OH NOH2O2
An imbalance between the prooxidants and the antioxidants of the organism, in favour of the former lead to disease
Ideal Antioxidants
SafetyAntioxidant effectivenessOff-odor, Off-colorStability to pH and food processingAvailability, CostNon-adsorbableEffective in low concentrationFat-solubleMechanism of Antioxidants•Hydrogen donation •Formation of a complex between the lipid radical and the antioxidant radical (free radical acceptor).
Antioxidants-enzymatic
• Glutathione peroxidase(for hydroperoxides) H2O2 + 2GSH GSSG + 2H2O
• Catalase2H2O2 H2O + O2
• Superoxide dismutase (SOD) for superoxide O2
- + O2- + 2H+ H2O2 + O2
Antioxidants-non enzymatic- fixed in membranes ( -tocopherol, -carotene, coenzyme Q 10)
- out of membranes (ascorbate, transferrin, bilirubin, dihydrolipoic acid (DHLA), Flavonoids)
• carotenoids, -carotene, vitamin A-removing the radicals from lipids
• glutathione (GSH, GSSG)-in all mammalian cells (1-10 mmol/l)-important redox buffer
• 2 GSH GSSG + 2e- + 2H+
ROS elimination, stabilisation in reduction form ( SH- groups, tocopheryl and ascorbate regeneration)-substrate of glutathione peroxidases
• Lipoic acid (lipoate)-tocopheryl and ascorbate regeneration• melatonin-lipophilic ; hydroxyl radicals scavenger• Selenium:influence to vitamin E resorption, part of selenoproteins• Zinc-cell membrane stabilisation, Fe antagonist• thioredoxin
Superoxide dismutaseUrateVitamin EVitamin CQuercetin
Anthocyanin
R.
ROO.
ROOH
Fe2+
O2
Free radical
Fe3+
RO.
OROO.
O2
Donates H+
CatalaseGlutathione peroxidaseSinglet oxygen quencher-Transition metal chelators (Phosphoric acid, Citric acid, Ascorbic acid, Ethylene-Diamine-Tetra-Acetate (EDTA), haptoglobin, hemopexin, albuminDiethylene diamine tetra acetate(DTPA)
Transferin for Fe, Ceruloplasmin for Cu
Vitamin C (ascorbic acid)• Ascorbic acid can easily give up two hydrogen
with their electrons, thereby becoming dehydroascorbic acid.
• Molecules with unpaired electrons (free radicals) combine vitamin C to form . Gives up electrons very easily when they are needed-recycle themselves over and over again.
• Helps to reactivate Vitamin E• Protects oxygen and iron from oxidation.
AscAscH
O
OH
OHO
O
OH
R+ RH+
O
O
HO
O
OH
O
Glutathione/Selenium Redox Cycleto Regenerate Vitamin C
Reduced Glutathione
(GSSG)Oxidized Glutathione
Oxidized Vitamin C(Ascorbate)
Vitamin C(Ascorbic Acid)
Selenium
Thioredoxin ReductaseGlutathione Reductase
Vitamin E- Membrane bound
alpha tocopherol radical
alpha-tocopherol + free radical
Membrane bound
alpha-tocopherol
H+
Vit C
Flavanoids as “Super Antioxidants.” • antiviral, antiallergic, anti-inflammatory,
antithrombogenic and anticarcinogenic effects.• Scavenge for free radicals associated with oxygen and
iron; or by inhibiting oxidative enzymes.• Over 4000 flavanoids have been found, fall in four
different groups: flavones, flavanones, catechins, and anthocyanins.
• Found in: certain fruits, flowers, roots, stems, tea, wine, grains and vegetables.
Phyto chemicals
Food Phytochemical(s)
Allium vegetables(garlic, onions, chives, leeks) Allyl sulfides
Cruciferous vegetables(broccoli, cauliflower,cabbage, Brussels sprouts,kale, turnips, bok choy,kohlrabi)
Indoles/glucosinolates-Sulfaforaphane, Isothiocyanates/thiocyanates,Thiols
Solanaceous vegetables(tomatoes, peppers) Lycopene
Umbelliferous vegetables(carrots, celery, cilantro,parsley, parsnips)
Carotenoids-PhthalidesPolyacetylenes
Compositae plants (artichoke) Silymarin
Citrus fruits(oranges, lemons, grapefruit)Glucarates
Monoterpenes (limonene)Carotenoids
Other fruits (grapes, berries,cherries, apples, cantaloupe,watermelon, pomegranate)
Ellagic acid-Phenols Flavonoids (quercetin)
Beans, grains, seeds-(soybeans, oats, barley, brownrice, whole wheat, flax seed)Protease inhibitors
Flavonoids (isoflavones) Phytic acid, Saponins
Herbs, spices (ginger, mint,rosemary, thyme, oregano,sage, basil, tumeric, caraway,fennel)
Gingerols –Flavonoids,Monoterpenes (limonene)
Licorice root-Green tea,Polyphenols Glycyrrhizin Catechins
•Tomato-against cancer by protecting DNA from oxidative damage
•Broccoli sprouts -phytochemical –sulforaphane
•Garlic -allicin
•Apples-flavonoids
•Soybeans-flavonoids
•resveratrol
• Citrus fruits(vit C) Don’t throw it. The wine bottle is full of antioxidants
• 20 times stronger antioxidant then Vitamin C and 50 times stronger then Vitamin E.
• Found in: Grape seed, Red Wine, Pine Bark (Pycnogenol), grape skin, peanut skin, and some white wines and fruits.
Oligomeric Proanthocyanidins(Bioflavanoids)
Lung Cancer
Prostate Cancer
Macular Degeneration & Cataracts
Osteoarthritis
Rheumatoid Arthritis
Skin Cancer & Melanoma
Photo-aging (wrinkles)
Stroke, Alzheimer’sParkinson’s
PeriodontitisEmphysema Coronary Heart Disease
Alcohol &Viral Liver Diseases
Diabetes
Hypertension &Chronic Kidney Disease
Colo-rectal CancerPeripheral Vascular Disease
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Role of Antioxidants in Carcinogenesis
Reactive O2+
O2-Derived Free Radicals
Oxidized basesin DNA
Normal cell
Lipid peroxidationin cell membranes
Cell repairExposure of DNACell DeathLipid Peroxides
DNA Repair
Normal Cell
Mutations Cell DeathNo Repair
CompensatoryCellularHypoproliferation
Less regulation of cellgrowth & differentiation
Cell Hyperproliferation
Exposure of DNA
Further Mutations
Antioxidant Scavengers &
Enzyme Systems
Assessment of free radical damage and antioxidant
status• Protein oxidation-fluorescence spectroscopy• Lipid peroxidation-Diene conjugates : early marker of
lipid peroxidation 235 – 255 mm• Thiobarbituric acid - Absorbance measured at 532 nm
or 553 nm• Measurement of enzymes: Superoxide Dismutase,
catalase, Glutathione peroxidase in bloodOXYGEN RADICAL ABSORBANCE CAPACITY Standard assay for measuring antioxidant capacity of
foods and supplements. Foods with high ORAC is said to have high antioxidant
capacity.
Oxidative stress markers
Lipoperoxidation markers:malondialdehyde (MDA), conjugated diens,
isoprostanesOxidative damage to protein markers :protein hydroperoxidesOxidative damage to DNA :modified nucleosidesAntioxidant determination:ascorbate,tocopheryl,glutathion