Vitamin E becomes a tocopheroxyl radical after donating its phenolic hydrogen to a lipid peroxyl radical. Which nutrient directly regenerates vitamin E from this radical, allowing continued chain-breaking activity?

• A Vitamin C (ascorbic acid) ✓
• B Beta-carotene
• C Riboflavin (FAD)
• D Niacin (NAD+)

Explanation

Ascorbic acid reduces the tocopheroxyl radical back to alpha-tocopherol at the membrane-water interface, becoming semidehydroascorbate itself, which is then recycled by dehydroascorbate reductase using GSH. This vitamin E-vitamin C coupling explains their synergistic antioxidant action. Beta-carotene is itself a lipid-phase singlet oxygen quencher and cannot reduce tocopheroxyl, and riboflavin and niacin have no direct role in this specific recycling step.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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