title: Effects of bergamottin on human and monkey drug-metabolizing enzymes in primary cultured hepatocytes.
abstract: We investigated the effect of bergamottin, a major furanocoumarin in grapefruit juice, on phase I and phase II drug-metabolizing enzymes using cultured human and monkey hepatocytes. Both cultured systems were compared and evaluated for the direct effects of bergamottin as well as control treatments on liver enzymes. Treatment of hepatocytes with 0.1, 1, 5, and 10 microM bergamottin resulted in a concentration-dependent reduction in CYP3A4 activity (40-100%) in both human and monkey cells, as measured by testosterone 6 beta-hydroxylase activity. Bergamottin was potent at eliciting these inhibitory effects at both basal and induced states of CYP3A. Bergamottin (5 microM) completely inhibited alpha-naphthoflavone-induced ethoxyresorufin O-dealkylase (EROD) and methoxyresorufin O-dealkylase (MROD) activities in human hepatocytes and caused a 100% decrease in EROD activity in monkey hepatocytes. A 48-h exposure of cultured human hepatocytes to bergamottin resulted in increased levels of immunoreactive CYP3A4, CYP1A1, and CYP1A2 proteins, and CYP3A4, CYP1A1, CYP1A2, CYP2B6, and UDP-glucuronosyl transferase mRNAs. There was only a 20 to 30% reduction in glucuronidation and sulfation of 4-methylumbelliferone in human hepatocytes by 10 microM bergamottin and no effect on conjugation in the monkey hepatocytes. These results suggest that bergamottin causes both inhibition of CYP3A and CYP1A1/2 enzymatic activities and induction of correspondent proteins and mRNAs.
authors.affiliation: Department of Drug Safety Evaluation, Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA.
authors.forename: Yuan Hua
authors.initials: YH
authors.lastname: Wen
authors.forename: Jasminder
authors.initials: J
authors.lastname: Sahi
authors.forename: Ellen
authors.initials: E
authors.lastname: Urda
authors.forename: Shaila
authors.initials: S
authors.lastname: Kulkarni
authors.forename: Kelly
authors.initials: K
authors.lastname: Rose
authors.forename: Xianxian
authors.initials: X
authors.lastname: Zheng
authors.forename: Jacqueline F
authors.initials: JF
authors.lastname: Sinclair
authors.forename: Hongbo
authors.initials: H
authors.lastname: Cai
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Strom
authors.forename: Vsevolod E
authors.initials: VE
authors.lastname: Kostrubsky
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D032083:Citrus paradisi / Q000737:chemistry; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics / Q000378:metabolism; D065702:Cytochrome P-450 CYP2B6; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D011564:Furocoumarins / Q000494:pharmacology*; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D010089:Oxidoreductases, N-Demethylating / Q000235:genetics / Q000378:metabolism
chemical_list: D011564:Furocoumarins; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585599:CYP2B6 protein, human; C104464:CYP3A protein, human; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D065702:Cytochrome P-450 CYP2B6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D010089:Oxidoreductases, N-Demethylating; D014453:Glucuronosyltransferase; C068337:bergamottin