Tag: Antioxidant

Antioxidant

Antioxidant

Q. 1

Allopurinol is used in organ preservation as:

 A

Antioxidant

 B

Preservative

 C

Free radical scavenger

 D

Precursor for energy metabolism

Q. 1

Allopurinol is used in organ preservation as:

 A

Antioxidant

 B

Preservative

 C

Free radical scavenger

 D

Precursor for energy metabolism

Ans. C

Explanation:

Free radical scavenger [Ref http://www.essentialpharma.com/Eghtesad5-18-07.ppt%5D

Organ preservation is the supply line for organ transplantation. Currently, the liver, pancreas, and kidney can be successfully preserved for up to two days by flushing the organs with the University of Wisconsin (UW) solution and storing them at hypothermia (0-5° C). The UW solution is effective because it uses a number of cell impermeant agents (lactobionic acid, raffinose, hydroxyethyl starch) that prevent the cells from swelling during cold ischemic storage. Additionally, the UW solution contains glutathione, allopurinol and adenosine, agents that may stimulate recovery of normal metabolism upon reperfusion by augmenting the antioxidant capacity of the organs (glutathione) or by stimulating high-energy phosphate generation (adenosine) upon reperfusion and allopurinol as free-radical scavenger.

  • Glutathione——— as antioxidant
  • Adenosine——– as precursor for energy metabolism
  • Allopurinol —– as free-radical scavenger

Q. 2

Which of the following elements is known to influence the body’s ability to handle oxidative stress?

 A

Calcium

 B

Iron

 C

Potassium

 D

Selenium

Q. 2

Which of the following elements is known to influence the body’s ability to handle oxidative stress?

 A

Calcium

 B

Iron

 C

Potassium

 D

Selenium

Ans. D

Explanation:

Selenium is essential to the production of glutathione peroxidase, a constituent of the antioxidant defence system. 

Ref: Harper’s Biochemistry, 26th Edition, Pages 88, 166, 496 ; Ghai Essential Pediatrics 6th, Edition, Page 131

 


Q. 3

The following are biological antioxidants which act against the free radicals formed inside the body, EXCEPT:

 A

Selenium

 B

Glycine

 C

Uric acid

 D

Ascorbic acid

Q. 3

The following are biological antioxidants which act against the free radicals formed inside the body, EXCEPT:

 A

Selenium

 B

Glycine

 C

Uric acid

 D

Ascorbic acid

Ans. B

Explanation:

The peroxides that are formed by radical damage to lipids in membranes and plasma lipoproteins are reduced to hydroxy fatty acids by glutathione peroxidase, a selenium-dependent enzyme (hence the importance of adequate selenium intake to maximize antioxidant activity). Ascorbate, uric acid and a variety of polyphenols derived from plant foods act as water-soluble radical trapping antioxidants, forming relatively stable radicals that persist long enough to undergo reaction to non-radical products. Ubiquinone and carotenes similarly act as lipid-soluble radical-trapping antioxidants in membranes and plasma lipoproteins. Lipid peroxides are also reduced to fatty acids by reaction with vitamin E.
 
Ref: Bender D.A. (2011). Chapter 45. Free Radicals and Antioxidant Nutrients. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper’s Illustrated Biochemistry, 29e.

Quiz In Between


Q. 4

Which of the following elements is known to influence the body’s ability to handle oxidative stress?

 A

Calcium

 B

Iron

 C

Potassium

 D

Selenium

Q. 4

Which of the following elements is known to influence the body’s ability to handle oxidative stress?

 A

Calcium

 B

Iron

 C

Potassium

 D

Selenium

Ans. D

Explanation:

D i.e. Selenium 

Selenium in the form of ‘selenocysteine’ is a component of enzyme glutathione peroxidaseQ. ‘Glutathione peroxidase serve to protect proteins, cell membranes, lipid and nucleic acids from oxidant molecules’. Glutathione prevents oxidation of hemoglobin to methemoglobinQ.


Q. 5

Which of the following reduces oxidative stress except

 A

Superoxide dismutase

 B

Catalase

 C

Glutathione peroxidase

 D

Xanthine oxidase

Q. 5

Which of the following reduces oxidative stress except

 A

Superoxide dismutase

 B

Catalase

 C

Glutathione peroxidase

 D

Xanthine oxidase

Ans. D

Explanation:

D i.e. Xanthine oxidase


Q. 6

Which of the following act as antioxidants:

 A

Glutathione peroxidase

 B

Vit. C

 C

Selenium

 D

All

Q. 6

Which of the following act as antioxidants:

 A

Glutathione peroxidase

 B

Vit. C

 C

Selenium

 D

All

Ans. D

Explanation:

 All Correct – A,B & C

Quiz In Between


Q. 7

Allopurinol is used in organ preservation as:

 A

Antioxidant

 B

Preservative

 C

Free radical scavenger

 D

Precursor for energy metabolism

Q. 7

Allopurinol is used in organ preservation as:

 A

Antioxidant

 B

Preservative

 C

Free radical scavenger

 D

Precursor for energy metabolism

Ans. C

Explanation:

Ans is c i.e. Free radical scavenger 

Organ preservation is the supply line for organ transplantation. Currently, the liver, pancreas, and kidney can be successfully preserved for up to two days by flushing the organs with the University of Wisconsin (UW) solution and storing them at hypothermia (0-5° C). The UW solution is effective because it uses a number of cell impermeant agents (lactobionic acid, raffinose, hydroxyethyl starch) that prevent the cells from swelling during cold ischemic storage. Additionally, the UW solution contains glutathione, allopurinol and adenosine, agents that may stimulate recovery of normal metabolism upon reperfusion by augmenting the antioxidant capacity of the organs (glutathione) or by stimulating high-energy phosphate generation (adenosine) upon reperfusion and allopurinol as free-radical scavenger.

  • Glutathione            as antioxidant
  • Adenosine              as precursor for energy metabolism
  • Allopurinol              as free-radical scavenger

Q. 8

All of the following are antioxidant except:

September 2005

 A

Vitamin A

 B

Vitamin B

 C

Vitamin C

 D

Vitamin E

Q. 8

All of the following are antioxidant except:

September 2005

 A

Vitamin A

 B

Vitamin B

 C

Vitamin C

 D

Vitamin E

Ans. B

Explanation:

Ans. B: Vitamin B

Antioxidants are a group of compounds that help to protect the body from the formation and elimination of free radicals. Free-radicals are formed from exposure to sunlight and pollution and also as a byproduct of cell metabolism. Alcohol, cigarette smoke, stress and even diet also affect the level of free-radical development in the body. Excellent antioxidants include Vitamin A, Vitamin E, Vitamin C, zinc, selenium, ginkgo biloba, grape seed extract, and green tea extract.


Q. 9

Antioxidant vitamin ‑

 A

Vitamin A

 B

Ascorbic acid

 C

Vitamin E

 D

All of the above

Q. 9

Antioxidant vitamin ‑

 A

Vitamin A

 B

Ascorbic acid

 C

Vitamin E

 D

All of the above

Ans. D

Explanation:

Quiz In Between


Q. 10

Role of selenocystein is important in ‑

 A

Hydroxylation of dopamine

 B

Oxidation of drugs

 C

Antioxidant mechanism

 D

None of the above

Q. 10

Role of selenocystein is important in ‑

 A

Hydroxylation of dopamine

 B

Oxidation of drugs

 C

Antioxidant mechanism

 D

None of the above

Ans. C

Explanation:

Ans. is ‘c’ i.e., Antioxidant mechanism


Q. 11

All are antioxidant except ‑

 A

Vitamin A

 B

Catalase

 C

Cystein

 D

Glutamine

Q. 11

All are antioxidant except ‑

 A

Vitamin A

 B

Catalase

 C

Cystein

 D

Glutamine

Ans. D

Explanation:

Ans. is ‘d’ i.e., Glutamine


Q. 12

Drug with beta adrenergic blocking, with antioxidant, with calcium channel blocking, with alpha 1 antagonist activity is ‑

 A

Esmolol

 B

Carvedilol

 C

Nebivolol

 D

Levobunolol

Q. 12

Drug with beta adrenergic blocking, with antioxidant, with calcium channel blocking, with alpha 1 antagonist activity is ‑

 A

Esmolol

 B

Carvedilol

 C

Nebivolol

 D

Levobunolol

Ans. B

Explanation:

Ans. is ‘b’ i.e., Carvedilol

Carvedilol

  • Carvedilol is a β1 + β2 + α1 adrenoceptor blocker with α : β blocking property of 1 : 9.
  • It has antioxidant and antimitotic property.
  • It produces peripheral vasodilation due to α-1 blockade as well as calcium channel blockade (direct effect).
  • It is used in hypertension and angina.
  • It is used as cardioprotective in CHF.
  • t1/2 is 2-8 hrs.
  • It is eliminated through liver and kidney.
  • It causes orthostatic hypotension.

Quiz In Between


Q. 13

Antioxidant property is seen in

 A

Chromium

 B

Selenium

 C

Magnesium

 D

Iron

Q. 13

Antioxidant property is seen in

 A

Chromium

 B

Selenium

 C

Magnesium

 D

Iron

Ans. B

Explanation:

Ans. is `b’ i.e., Selenium 


Q. 14

True about Glutathione except

 A

Tripeptide

 B

Formed from glutamic acid, glycine, cysteine

 C

Act as antioxidant in reduced state

 D

All of the above

Q. 14

True about Glutathione except

 A

Tripeptide

 B

Formed from glutamic acid, glycine, cysteine

 C

Act as antioxidant in reduced state

 D

All of the above

Ans. D

Explanation:

Ans. is `d’ i.e., All of the above 

Glutathione

  • Glutathione is a tripeptide of glutamie acid, cysteine, and glycine. The molecule has a sulfhydryl (-SH) or thiol group on the cysteine, which accounts for its strong electron-donating character.
  • It exists in two forms : reduced glutathione or GSH. In the reduced state, the thiol group of cysteine is able to donate a reducing equivalent (H+ e-) to other unstable molecules, such as reactive oxygen species. In donating an electron, glutathione itself becomes reactive, but readily reacts with another reactive glutathione to form glutathione disulfide (GSSG) or oxidized glutathione. GSH can be regenerated from GSSG by the enzyme glutathione reductase.
  • While all cells in the human body are capable of synthesizing glutathione, liver glutathione synthesis has been shown to be essential. The liver is the largest GSH reservoir.
  • Because of its reducing property, reduced glutathione has potent antioxidant action.

Functions :

  • GSH is an extremely important cell protectant. It directly reduces reactive hydroxyl free radicals, other oxygen centered free radicals, and radical centers on DNA and other biomolecules.
  • GSH is the essential cofactor for many enzymes which require thiol-reducing equivalents, and helps keep redox-sensitive active sites on enzymes in the necessary reduced state. GSH is used as a cofactor by ‑
  • Multiple peroxidase enzymes, to detoxify peroxides generated from oxygen radical attack on biological molecules;
  • Transhydrogenases, to reduce oxidized centers on DNA, proteins, and other biomolecules; and
  • Glutathione S-transferases (GST) to conjugate GSH with endogenous substances (e.g., estrogens) and to exogenous electrophiles (e.g., arene oxides, unsaturated carbonyls, organic halides), and diverse xenobiotics.
  • GSH is a primary protectant of skin, lens, cornea, and retina against radiation damage, and the biochemical foundation of P450 detoxication in the liver, kidneys, lungs, intestinal epithelia, and other organs.
  • GSH acts as a carrier in transport of certain amino acids across membranes in the kidney.
  • Glutathione (GSH) participates in leukotriene synthesis.

Q. 15

Which of the following Vitamin is an antioxidant‑

 A

Vitamin D

 B

Vitamin E

 C

Vitamin K

 D

Vitamin B1

Q. 15

Which of the following Vitamin is an antioxidant‑

 A

Vitamin D

 B

Vitamin E

 C

Vitamin K

 D

Vitamin B1

Ans. B

Explanation:

Ans. is ‘b’ i.e., Vitamin E 

Vitamin E (a-Tocopheroll

  • Vitamin E is sometimes described as anti-sterility vitamin.
  • However, its anti-sterility function is seen only in some animals and not in human beings.
  • Vitamin E activiy is present in several tocopherols, the most important being a-, (3-, y- and 6- tocopherol. a Tocopherol is the most abundant and is taken as the standard.
  • The most important function of vitamin E in human beings is to act as an anti-oxidant.
  • It prevents the oxidation of other antioxidants, .e.g, carotenes, vitamin A and vitamin C.
  • Vitamin E is the lipid-soluble antixodant in cell membranes and plasma lipoproteins.
  • The main function of vitamin E is as a chain-breaking, free radical-trapping antioxidant in cell membranes and plasma lipoproteins by reacting with lipid peroxide radicals formed by peroxidation of polyunsatured fatty acid. o Vitamin E prevents rancidity of fats due to its antioxidant action.

Antioxidant vitamins are :-

  1. Vitamin -A (carotenes) Vitamin – C
  2. Vitamin – E

Quiz In Between


Q. 16

The main function of Vitamin C in the body is 

 A

Coenzyme for energy metabolism

 B

Regulation of lipid synthesis

 C

Involvement as antioxidant

 D

Inhibition of cell growth

Q. 16

The main function of Vitamin C in the body is 

 A

Coenzyme for energy metabolism

 B

Regulation of lipid synthesis

 C

Involvement as antioxidant

 D

Inhibition of cell growth

Ans. C

Explanation:

Ans. is ‘c’ i.e., Involvement as antioxidant 

Vitamin C (Ascorbic acid)

  • Ascorbic acid (Vitamin C) is also called antiscorbutic factor. It is very heat labile, especially in basic medium.
  • Ascorbic acid itself is an active form. Maximum amount of vitamin C is found in adrenal cortex.
  • Ascorbic acid functions as a reducing agent and scavanger of free radicals (antioxidant). Its major functions are:-
  • In collagen synthesis : – Vitamin C is required for post-translational modification by hydroxylation of proline and lysine residues converting them into hydroxyproline and hydroxylysine. Thus vitamin C is essential for the conversion of procollagen to collagen, which is rich in hydroxyproline and hydroxylysine. Through collagen synthesis, it plays a role in formation of matrix of bone, cartilage, dentine and connective tissue.
  1. Synthesis of norepinephrine from dopamine by dopamine-(3-monoxygenase (dopamine-f3-hydroxylase) requires Vitamin C.
  2. Carnitine synthesis
  3. Bile acid synthesis :- 7-ct-hydroxylase requires vitamin C.
  4. Absorption of iron is stimulated by ascorbic acid by conversion of ferric to ferrous ions.
  5. During adrenal steroid synthesis, ascorbic acid is required during hydroxylation reactions.
  6. Tyrosine metabolism : – Oxidation of P-hydroxy-phenylpyruvate to homogentisate.
  7. Folate metabolism : – Folic acid is converted to its active form tetrahydrofolate by help of Vitamin C.

Q. 17

All have antioxidant property except

 A

Catalase

 B

Glutathione peroxidase

 C

Phosphorylase

 D

Superoxide dismutase

Q. 17

All have antioxidant property except

 A

Catalase

 B

Glutathione peroxidase

 C

Phosphorylase

 D

Superoxide dismutase

Ans. C

Explanation:

Ans. is ‘c’ i.e., Phosphorylase 

  • There are two types of antioxidant systems :‑

1. Enzymatic antioxidant system

  1. This include
  2. Catalase
  3. Superoxide dismutase (SOD)
  4. Glutathione peroxidase

2. Non-enzymatic antioxidant system

  1. This is further subdivided into
  2. Vitamins : Vitamin E, Vitamin A & beta carotene, Vitamin C.
  3. Minerals : Selenium, Copper, Zinc, Manganese
  4. Tissue proteins : Transferrin, ferritin, lactoferrin, ceruloplasmin
  5. Amino acids : Glutathione, Cysteine

Q. 18

Which of the following has antioxidant property‑

 A

Selenium

 B

Copper

 C

Zinc

 D

All

Q. 18

Which of the following has antioxidant property‑

 A

Selenium

 B

Copper

 C

Zinc

 D

All

Ans. D

Explanation:

Ans. is ‘d i.e., All             

  • The activity of the antioxidant enzymes depends on supply of minerals :‑
  1. Manganese
  2. Copper
  3. Zinc
  4. Selenium
  • Manganese, copper and zinc are required for the activity of superoxide dismutase. 
  • Selenium is required for the activity of glutathione peroxidase.

Quiz In Between


Q. 19

Glutathione requires which vitamin to act as antioxidant ‑

 A

Vitamin E

 B

Niacin

 C

Vitamin C

 D

Vitamin A

Q. 19

Glutathione requires which vitamin to act as antioxidant ‑

 A

Vitamin E

 B

Niacin

 C

Vitamin C

 D

Vitamin A

Ans. B

Explanation:

Ans. is ‘b’ i.e., Niacin 


Q. 20

All are true about vitamin E except ‑

 A

Act as antioxidant

 B

Prevent lipid peroxidation of cell membrane

 C

Water soluble vitamin

 D

Chemically tocopheral

Q. 20

All are true about vitamin E except ‑

 A

Act as antioxidant

 B

Prevent lipid peroxidation of cell membrane

 C

Water soluble vitamin

 D

Chemically tocopheral

Ans. C

Explanation:

Ans. is ‘c’ i.e., Water soluble vitamin 

  • Vitamin E is a fat soluble vitamin (not water soluble).
  • All other options are correct.

Quiz In Between



Antioxidant

Antioxidant


ANTIOXIDANT

  • Molecule that prevent oxidation of other molecule.
  • Oxidative stress produces free radical,contribute to diseases.
  • It is measured by  BAP Test and d-ROMs test.

NATURAL AND SYNTHETIC ANTIOXIDANT

Antioxidant Source
Vitamin C Citrus Fruits
Vitamin E Vegetable Oil
Polyphenolic (resveratol and Flavoniod) Fruits, Red wine, Tea,Choclate, Orgeno, Coffe, Olive oil,Soy
Careteniods (lycopene carotene, lutien) Fruits Vegetable egg
Synthetic Propylgallate, Butylated Hydroxyanisole, Butylated Hydroxytoulene, Tertiarbutylhydroquinone.

CLASSIFICATION OF ANTIOXIDANTS

  1. ANTIOXIDANT ENZYMES
    1. Catalase
    2. Glutathione peroxidase
    3. Glutathione reductase
    4. Super oxide dismutase(both Cu -Zn and Mn)
  2. METAL BINDING PROTIENS
    1. Ceruloplasmin
    2. Ferritin
    3. Lactoferrin
    4. Metallotheinein
    5. Transferrin
    6. Hemoglobib
    7. Myoglobin
  3. Bilirubin
  4. Caroteniod
    1. Beta Carotene
    2. Alpha carotene
    3. Lutien
    4. Lycopene
    5. Zeaxanthin
  5. Vitamins A,C,E,D
  6. Uric acids
  7. Thiols
  8. Other-Copper, Selenium,Zinc,Alpha lipoic acid,Glutathione

MECHANISM OF ACTION

  • Vit. E prevents peroxidation of membrane phosphor lipids
  • Vit.C reactivate oxygen and scavenges free radicals
  • Super oxide dismutase reduces superoxide.
  • Catalase and glutathione convert hydrogen peroxide.

 What are antioxidants used for?

  •  Antioxidants may play a role in the management or prevention –
  1. Some cancers
  2. Macular degeneration
  3. Alzheimer’s diseases
  4. Some arthritis-related conditions.
  • Destroys free radicals.
  • Promote growth of healthy cell.
  • Support immune system

ANTIOXIDATIVE STRESS

  • Strong reducing acid binds to deitary minerals(iron,zinc)
  • Prevent their absorbtion
  • Examples are oxalic acid, tannins and phytic acid, which are high in plant-based diets.
  • Nonpolar antioxidants such as eugenol have toxicity limits.
  • examples are oxalic acid, tannins and phytic acid, which are high in plant-based diets

Exam Important

ANTIOXIDANT

  • Molecule that prevent oxidation of other molecule.

NATURAL AND SYNTHETIC ANTIOXIDANT

Antioxidant Source
Vitamin C Citrus Fruits
Vitamin E Vegetable Oil
Polyphenolic (resveratol and Flavoniod) Fruits, Red wine, Tea,Choclate, Orgeno, Coffe, Olive oil,Soy
Careteniods (lycopene carotene, lutien) Fruits Vegetable egg
Synthetic Propylgallate, Butylated Hydroxyanisole, Butylated Hydroxytoulene, Tertiarbutylhydroquinone.

CLASSIFICATION OF ANTIOXIDANTS

  1. ANTIOXIDANT ENZYMES
    1. Catalase
    2. Glutathione peroxidase(selenium imp.component)
    3. Glutathione reductase
    4. Super oxide dismutase(both Cu -Zn and Mn)
  2. METAL BINDING PROTIENS
    1. Ceruloplasmin
    2. Ferritin
    3. Lactoferrin
    4. Metallotheinein
    5. Transferrin
    6. Hemoglobib
    7. Myoglobin
  3. Bilirubin
  4. Caroteniod
    1. Beta Carotene
    2. Alpha carotene
    3. Lutien
    4. Lycopene
    5. Zeaxanthin
  5. Vitamins A,C,E,D
  6. Uric acids
  7. Thiols
  8. Other-Copper, Selenium,Zinc,Alpha lipoic acid,Glutathione

MECHANISM OF ACTION

  • Vit. E prevents peroxidation of membrane phosphor lipids
  • Vit.C reactivate oxygen and scavenges free radicals
  • Super oxide dismutase reduces superoxide.
  • Catalase and glutathione convert hydrogen peroxide.
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