Erythropoietic protoporphyria (EPP) causes immediate burning pain on sun exposure. Beta-carotene is used as adjunctive therapy. What is its mechanism of action?

• A Induces hepatic ALAS1 to bypass the block
• B Quenches singlet oxygen and reactive oxygen species ✓
• C Chelates excess protoporphyrin in skin
• D Stabilises ferrochelatase enzyme activity

Explanation

Beta-carotene acts as a singlet oxygen quencher, reducing the phototoxic damage caused by accumulated protoporphyrin IX in EPP. It does not alter enzyme activity or chelate porphyrins. This is a symptomatic treatment that increases sunlight tolerance but does not correct the underlying ferrochelatase deficiency.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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