A 45-year-old man with hereditary hemochromatosis develops hepatic fibrosis. Hepatocyte injury is attributed to a reactive species generated when ferrous iron (Fe2+) reacts with hydrogen peroxide inside cells. Which species is produced by this reaction?

• A Superoxide radical
• B Nitric oxide
• C Singlet oxygen
• D Hydroxyl radical ✓

Explanation

The Fenton reaction converts hydrogen peroxide to the hydroxyl radical using ferrous iron: Fe2+ plus H2O2 yields Fe3+, hydroxyl ion, and hydroxyl radical. The hydroxyl radical is the most reactive oxygen species in biological systems and attacks DNA, lipids, and proteins indiscriminately. Superoxide is instead produced by incomplete reduction of oxygen in mitochondria, and singlet oxygen arises from photoexcitation of molecular oxygen, not from iron catalysis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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