Vitamin E (alpha-tocopherol) acts as a chain-breaking antioxidant by:
- A Chelating iron and copper to prevent Fenton reaction
- B Activating superoxide dismutase in the mitochondrial matrix
- C Donating a hydrogen atom to lipid peroxyl radicals, stopping the chain reaction of lipid peroxidation ✓
- D Reducing hydrogen peroxide via its peroxidase activity
Correct answer: C. Donating a hydrogen atom to lipid peroxyl radicals, stopping the chain reaction of lipid peroxidation
Explanation
Vitamin E is a lipid-soluble antioxidant embedded in biological membranes; it donates a hydrogen atom (H•) to lipid peroxyl radicals (LOO•), converting them to non-reactive lipid hydroperoxides and generating the relatively stable tocopheroxyl radical, thereby terminating lipid peroxidation chain reactions. Vitamin C can regenerate tocopherol from tocopheroxyl radical. Iron chelation is the mechanism of desferrioxamine. SOD and peroxidase activities are separate enzymes.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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