The 'chain reaction' of lipid peroxidation is initiated by which free radical and propagated by which species?

• A Superoxide anion (O2·−) directly oxidizing membrane lipids
• B Hydrogen peroxide directly cleaving C–C bonds in fatty acid chains
• C Nitric oxide acting as the chain-carrying radical
• D Hydroxyl radical (·OH) initiating; peroxyl radicals (ROO·) propagating ✓

Explanation

Lipid peroxidation is initiated when the hydroxyl radical (·OH) abstracts a hydrogen atom from a polyunsaturated fatty acid, generating a lipid radical (L·). This reacts with O2 to form a lipid peroxyl radical (LOO·), which propagates the chain by abstracting hydrogens from adjacent lipids. Superoxide is not reactive enough to initiate this directly; H2O2 is not itself a radical; NO primarily reacts with superoxide to form peroxynitrite rather than acting as a chain carrier.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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