Category: other
Aliases: 5-geranyloxypsoralen, BG, bergamottine
Furanocoumarin from grapefruit (Citrus paradisi) peel oil and juice — the principal active component behind the grapefruit/CYP3A4 food-drug interaction. Mechanism-based (suicide) inactivator of intestinal CYP3A4: K_I = 7.7 µM, k_inact = 0.3 min⁻¹ on purified CYP3A4 (He 1998 PMID:9548795); K_I = 40 µM, k_inact 0.05-0.08 min⁻¹ in HLM (Tassaneeyakul 2000 PMID:10860553). Inactivation is irreversible — recovery requires de novo CYP3A4 synthesis (~24-72 h), which is why a single glass of grapefruit juice perturbs first-pass metabolism for the rest of the day. The clinically dominant effect is on enterocyte CYP3A4 (intestinal first-pass), not hepatic. Co-furanocoumarin 6′,7′-dihydroxybergamottin (DHB) is more potent in vitro (K_I 5.56 µM) and faster-onset.