Free radicals are unstable molecules that can cause harm through reactions with other compounds. They are produced through normal cellular processes but also environmental sources like radiation and pollution. Free radicals can damage DNA, proteins, and lipids, potentially contributing to aging and diseases. Antioxidants like vitamins C and E can help defend against free radical damage by donating electrons to the free radicals to make them stable. The free radical theory of aging proposes that accumulation of free radical damage to cellular components over time is a major factor in the aging process.

1. Free Radical; Defense From Aging
Rajkumar Kirtania
M.Sc,4th semester
Regd. No.-240313020
Exam Roll No -151303020
INDIAN INSTITUTE OF ENGINEERING
SCIENCE AND TECHNOLOGY,SHIBPUR
DEPT. OF CHEMISTRY

2.  Free Radicals.
 Various Sources.
 Harmful Effect.
 Defense via Antioxidant.
CONTENT 2

3. Free Radicals are molecules with an unpaired electron and are important
intermediates in natural processes.
Involving cytotoxicity, control of vascular tone, and neurotransmission.
Free radicals are very unstable and react quickly with other compounds,
and try to capture the needed electron to gain stability.
A chain reaction thus gets started.
FREE RADICAL 3

4. How Free Radicals Form 4

5. Sources of free Radicals
Cellular
Sources
Enzymic
Sources
Environmental
Sources
Mitochondria
Endoplasmic
reticulum
Cytochrome
oxidases
Xanthine
oxidase
Ionizing
radiation
Pollution
Membrane
NADPH
Oxidases
Source of Free Radical
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6. Environmental sources
Exposure to ionizing radiations like gamma rays, x-rays, and ultraviolet
rays excite the electrons in many atoms, thereby generating large
amounts of free radicals.
H2O U.V. Rays HO▪ + H+
 Oxygen free radicals in the atmosphere considered as pollutants
 Interaction with chemicals, automobile exhausts fumes, smoking of
cigarettes, cigars, beedie
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7. Harmful Effect of Free Radical
Cancer
Cerebrovascular disease
Heart disease &Stroke
Diabetes mellitus
Sunburn
Cerebrovascular disease.
Osteoporosis
Crohn's disease
Behcet's disease
Arteriosclerosis & atherosclerosis
Senility
Aging
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8. FREE RADICAL THEORY OF AGING
 In 1956s Dr. Denham Harman proposed that-
Cells continuously produce free radicals by normal metabolism and oxidation of organic
compounds and these free radicals damage cellular macromolecules ( like DNA , lipid
, proteins ) and due accumulation of these damage over time period cause aging.
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9. Mitochondrial free radical theory of aging
In 1972s, Denham Harman modified his theory-
 About 95% energy of a cell is produce in mitochondria and about 97% - 99% of
oxygen is use in energy formation and 1%- 3% oxygen is utilize in reactive oxygen
species formation.
 It states that reactive oxygen species (ROS ) are produce in mitochondria during
ETC cycle and they cause damage to macromolecules including lipid , protein,
DNA of mitochondria and nucleus which lead to aging .
DNA Damage
RNA damage
Protein Damage
Lipid Damage
Reactive
species
AGING
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10.  Formation of thymine dimer
Oxidative damage to DNA
Modification of purines – 8-hydroxy-deoxyguanosine
Marker of the oxidative damage to DNA
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11. Antioxidant Vitamins --
 Vitamin E-It is a fat soluble vitamin and prevent peroxidation of
lipid by donating of electrons to free radicals
In absence of vitamin ‘E’ In presence of vitamin ‘E’
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12. Vitamin C:Vitamin C protects watery components in the body (fluid in the blood) against free radical
damage.
 Vitamin C also is especially good at stopping free radicals air pollution and cigarette smoke.
 In addition, vitamin C may also restore oxidized vitamin E to its active state
 Ascorbic acid is special because it can transfer a single electron, owing to the resonance-stabilized nature of its
own radical ion called, semidehydroascorbate. The net reaction is…
RO • + C6H7O6
− → RO- + C6H7O6
• → → ROH + C6H6O6
 It suppresses the formation of carcinogens i.e. cancer.
 protecting tissues against oxidative damage.
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13. CONCLUSION
 To Avoid Exposure Of Free Radical ,we Should Avoid Sunshine & Our Diet
Should Be Full Of Vitamins With an Antioxidant
 Monitoring and rapid detection of free radical is necessary to combat the spread of
various diseases
 So if we can intensify our knowledge regarding free radicals & go deep into it we
can easily prove the proverb “PREVENTION IS BETTER THAN CURE”
Prevention Is Better Than Cure
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14. References
 Wikipedia
 C. J. Rhodes, An overview of the role of free radicals in biology.
 CRC Handbook of Free Radicals and Antioxidants, 1989, 1: 209-221.
 P, Larsen, "Aging and resistance to oxidative damage in Caenorhabditis
elegans". Proc Natl Acad Sci U S A, 1993, 90 (19):8905-9.
 Exercise, Oxidative Damage and Effects of Antioxidant Manipulation
(review). Journal of Nutrition, 1992, 122(3): 766-73.
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15. ACKNOWLEDGEMENT
I would like to acknowledge
 My project supervisor, Dr. Jhuma Ganguly,
 Head of the department Prof. P. K. Nandi,
 All the teachers of our department ,
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