Which antioxidant vitamin is a lipid-soluble, chain-breaking antioxidant that donates a hydrogen atom to quench lipid peroxyl radicals in cell membranes, and is regenerated by vitamin C?
- A Vitamin E (alpha-tocopherol) ✓
- B Vitamin A (retinol)
- C Vitamin K
- D Coenzyme Q10 (ubiquinol)
Correct answer: A. Vitamin E (alpha-tocopherol)
Explanation
Alpha-tocopherol (vitamin E) is incorporated into cell membranes and lipoproteins where it intercepts lipid peroxyl radicals (LOO•) by donating a phenolic hydrogen, generating a tocopheroxyl radical. Ascorbate (vitamin C) reduces the tocopheroxyl radical back to tocopherol at the membrane-aqueous interface, restoring antioxidant capacity. This synergistic cycle makes vitamins E and C the primary extramitochondrial antioxidant defence against lipid peroxidation.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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