Electrophilic xenobiotics are detoxified by conjugation with reduced glutathione. The final urinary metabolite excreted after sequential processing of this conjugate in the kidney is called:
- A Hippuric acid
- B Mercapturic acid ✓
- C Ornithine conjugate
- D Glucuronide
Correct answer: B. Mercapturic acid
Explanation
Glutathione S-transferases attach GSH to electrophiles; the gamma-glutamyl and glycine residues are then removed and the cysteine residue is N-acetylated, yielding a mercapturic acid excreted in urine. Hippuric acid arises from glycine conjugation of benzoic acid, a separate pathway, so it is the tempting distractor. This pathway explains depletion of glutathione stores during high electrophile load.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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