Introduction to free radicals, antioxidants, types of antioxidants, biological importance and protective role of certain important antioxidants in diseases.

1. PRESENTED BY,
AYESHA NAZEER
1ST MPHARM (PHARMACOLOGY)
20PP215
SRINIVAS COLLEGE OF
PHARMACY

2. 1. INTRODUCTION
2. CLASSIFICATION
3. MAJOR ANTIOXIDANTS FOUND IN PLANTS
4. BIOLOGICAL ROLE OF ANTIOXIDANTS
5. ROLE OF ANTIOXIDANTS IN PHARMACOTHERAPY
6. REFERENCES
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3. Free radicals are an atom or molecule that bears an unpaired electron and is extremely reactive.
 Play central role in cell injury and cell death mechanism.
 When they overwhelm the body’s ability to regulate them, leads to oxidative stress.
 Capable of engaging in rapid change reaction that destabilize other molecules and generate
many more free radicals.
 Examples of free radicals, Hydroxyl radical, Superoxide anion radical, Singlet oxygen,
Hydrogen peroxide, Nitric oxide, Peroxynitrite.
 Antioxidants are present in various type of eatables like grains, oats, fruits, vegetables that are
easily available in the market so the people take antioxidant in their diet and taking
antioxidant-rich diet is very helpful for the body to decrease the risk of various disorders.
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4. An antioxidant is a substance that when present in low concentrations
relative to the oxidizable substrate, significantly delays or reduces oxidation of
the substrate.
Antioxidants get their name because they combat oxidation.
They are substance that protect other chemicals of the body from damaging
oxidation reactions by reacting with free radicals and other reactive oxygen
species.
A.K.A free radical scavengers
Oxidation is a chemical reaction that transfer electrons or hydrogen from a
substance to an oxidizing agent.
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5. 5

6. Antioxidants can be classified based on:
1) Types
2) Mode of action
3) Location
4) Solubility
5) Structures they protect
6) Origin
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7. Antioxidants
Enzymatic
Superoxide dismutase, glutathione peroxidase, reductase, transferase,
catalase Antioxidants
Non-enzymatic
Nutrient
Non-nutrient
alpha tocopherol, beta
carotene, ascorbate,
selenium
ceruloplasmin, transferrin,
uric acid.
CLASSIFICATION BASED ON TYPES:
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8. Chain breaking
mechanism
Antioxidant donates an
electron to free radical
present in system 
conversion of harmful
agent to harmless
Eg: beta carotene,
vitamin C, vitamin E, α-
Tocopherol
ss
Scavenging
initiating radicals
Scavenging initiating radicals
are the compounds that act
in an aqueous phase to
compete with free radicals
by mechanism of trapping
them.
Superoxide
dismutase(SOD),
γ-Tocopherol
Chelating
Chelating agents
which chelate metallic
ions such as copper
and iron and enhance
action of other
antioxidants ascorbic
acid, tocopherol.
Citric acid, phytic acid.
CLASSIFICATION BASED ON MECHANISM OF ACTION:
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9. CLASSIFICATION BASED ON LOCATION:
INTRACELLULAR
• Superoxide Dismutase- SOD-1 & 2, catalase,
peroxidase, DNA repair enzymes.
EXTRACELLULAR
• SOD 3, reduced glutathione, Ascorbate,
Carotenoids, Uric acid.
MEMBRANE
ASSOCIATED
• α-Tocopherol.
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10. solubility
Water-soluble
Ascorbate, Uric acid,
Thiols, Flavonoids,
Cysteine, Transferrin
Lipid-soluble
Alpha tocopherols,
Carotenoids,
bilirubin.
OTHER CLASSIFICATIONS:
Origin
Exogenous(from diet)
Carotenoids, Ascorbic
acid, Tocopherols,
Polyphenols
Endogenous
Catalase, Superoxide
dismutase,
Glutathione
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11. SOD1&2, Glutathione peroxidase, DNA repair enzymes,
reduced glutathione, cysteine.
DNA
Sequestration of transition metals by chelating agents
Protein
Alpha tocopherols, Ascorbate, carotenoids, glutathione
Lipids
CLASSIFICATION BASED ON STRUCTURES THEY PROTECT:
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12. 12

13. 13

14. 1. Enzymes
1.1 Superoxide Dismutase (SODs):
• SOD isoenzyme are present in chloroplasts, cytosol and in mitochondria.
• It catalyses the decomposition of superoxide into hydrogen peroxide and
oxygen.
• Catalase decomposes the hydrogen peroxide formed to oxygen and water.
1.2 Glutathione:
• Participating directly in the neutralisation of free radicals and reactive
oxygen compounds.
• Maintaining of exogenous antioxidant such as vitamin C & E in their reduced
forms.
1.3 Glutathione Peroxidase:
• Glutathione Peroxidase uses glutathione as substrate and catalyses the
reduction of hydrogen peroxide and lipid hydro peroxide
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15. 2. Mineral:
• Minerals are elements that originate in the soil and can’t be usually created by living things.
• Selenium in the only mineral produced by plants.
• The richest plant sources of selenium is Brazil nut.
3. Low Molecular Weight & High Molecular Weight Compounds:
• HMW compounds includes albumin, ceruloplasmin and transferrin.
• LMW antioxidant are divided into
Lipid soluble Polyphenols, Tocopherols & ascorbic acid.
Water soluble Some Polyphenols.
Both types of these compounds act as reducing agents, free radical scavengers and quenchers
of singlet oxygen formation.
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16. 3. Carotenes:
• A carotene is one of four antioxidant that are vital our general health and wellbeing.
• α-carotene, γ-carotenes, δ-carotenes and β-carotenes types of carotenes.
• α&β carotenes are the powerful antioxidant. (provitamin A)
• β –carotene is an anti aging micronutrient and play a significant role in reducing the effects of
certain illness such as heart disease, decreased immune function, cataracts, cancer.
4. Vitamins
4.1 Ascorbic acid (Vit-C):
• Its an hydrophilic antioxidant.
• Neutralisation of H2O2.
• Maintain healthy collagen in skin.
• Repair damaged tissue, healthy teeth and bones, immune system.
• As a free radical fights against cataracts, arthritis, heart disease, cancer & oxidation.
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17. Vitamin C functions as anti-inflammatory, and helps the body fight against inflammatory
diseases including fibromyalgia, chronic fatigue, angina, bronchitis, constipation and diabetes.
4.2 Tocopherols (Vit-E)
• Vitamin E is primary fat-soluble antioxidant nutrient.
• Vitamin E resides in fatty tissues, especially cell walls and membranes.
• It helps to protect the stability and integrity of cellular tissues membranes throughout the
body by preventing free radical (lipid peroxidation) damage.
• Improves skin conditions.
• Improves appearance of scars.
• Protecting the body’s membrane.
• Maintaining healthy blood vessels.
• thinning blood in body.
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18. 5.Hormone as antioxidant:
5.1 Melatonin:
• Its powerful antioxidant that can easily cross cell membrane and the blood
brain barrier.
• It doesn’t undergo redox cycling.
• Melatonin cant be reduced to its former state as it forms stable compounds
after reacting with free radical.
• It has been referred as a terminal or suicidal antioxidant
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19. 6. Essential Oils as Antioxidant:
These are the class of volatile oils obtained by steam distillation and these may
be extracted from plants, flowers, barks and seeds.
Advantages:
 Due to their small molecular size, they can easily penetrate the skin tissue.
 As essential oils are lipid soluble they are capable of penetrating the
membrane easily even in conditions when oxygen deficiency is present.
 They serve as powerful antioxidant & they prevent mutants and oxidants in
cells.
 including lavender (Lavendular angustifolia), peppermint (Mentha piperita),
rosemary (Rosmarius officinalis), lemon (Citrus limon), grapefruit (Citrus
paradise).
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20.  To counter the harmful effects of free radicals, antioxidants defence mechanism operates to
detoxify or scavenge theses free radicals.
 Boost up immune system.
 Prevent the neurodegenerative disorder.
 Prevent DNA damage and therefore have anticarcinogenic effects.
 Promotes the cardiovascular health.
 Antioxidants can decrease LDL and cholesterol, Increases HDL and blood pressure.
 Promotes the eye health and prevent macular degeneration, cataract and other degenerative
disorder.
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21. 1. Antioxidants: a protection against heart disease
Antioxidants from dietary sources are good enough for the treatment of heart problems. As the scientists
state that the main reason for cardiovascular disease is due to high concentration of oxidative stress also
called as high concentration of oxygen radicals in the body.
Free radicals can trap a low-density lipoprotein (LDL) and start the arrangement of plaque.
Vitamin A, Beta-carotenoids and Vitamin E are the antioxidants that are very important for the treatment of
cardiovascular diseases. They are very important to convert the oxidative free radicals to inactive form.
The source of those components are apricots, peaches, broccoli, pumpkin, melons, carrots, spinach and
sweet potato.
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22. 2. Antioxidants: as anticancer agent
Cancer is a very critical disorder in the society.
Cancer is caused by free radicals that initiate the cancerous cells to grow into the body.
Antioxidants also known as "free radicals scavengers” are used to neutralize the free radicals so
the cell growth prevents in itself.
Phytochemicals like lycopene, lutein are used to prevent cancer. Tomato soups, tomato
products, watermelon etc are lycopene-rich substances which are helpful in the fight against
cancer .
These antioxidants are given protection against mouth cancer, stomach cancer, colon cancer and
prostate cancer .
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23. 3. Antioxidants : as protection against ocular diseases
In the adult persons, oxidative mechanism plays an important role in case of eye diseases. There are
two most common causes of visual impairment in adults
(1) muscular degeneration
(2) cataract.
Antioxidants such as lutein and zeaxanthin, vitamin C, vitamin E and zinc, have been related to
reducing the risk of certain serious eye diseases like age-related macular degeneration and cataracts.
You can find these antioxidants in green leafy vegetables, fruits, nuts and a lot of other foods.
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24. 4. Antioxidants in neurodegenerative disorders
Neurodegenerative diseases (NDD) are a group of illness with diverse clinical importance and etiologies.
Growing body of evidence implicates free radical toxicity, radical induced mutations and oxidative enzyme
impairment and mitochondrial dysfunction due to congenital genetic defects in clinical manifestations of
NDD.
There is two mechanism to prevent the patient from neurodegenerative disorder
(1) exogenous mechanism
(2) endogenous mechanism.
In an endogenous mechanism, there is an elimination of free radicals takes place by decrease the lipid per
oxidation.
Endogenous antioxidants are glutathione peroxidase (cofactor of selenium), superoxidase dismutase
(cofactor of cu/zn).
Antioxidants are useful in preventing various neurodegenerative disorders like Alzheimer's disorder,
Parkinson disorder, Huntington's disease.
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3. Irshad M, Chaudhuri PS. Oxidant–antioxidant system: role and significance in human body.
Indian J Exp Biol. 2002;40:1233-9
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