title: Effects of hydroxyl group numbers on the B-ring of 5,7-dihydroxyflavones on the differential inhibition of human CYP 1A and CYP1B1 enzymes.
abstract: Flavonoids are polyphenols composed of two aromatic rings (A, B) and a heterocyclic ring (C). In order to determine the effects of the number of hydroxyl groups in the B-ring of the flavonoids on human cytochrome P450 (CYP) 1 family enzymes, we evaluated the inhibition of CYP1A-dependent 7-ethoxyresorufin omicron-deethylation activity by chrysin, apigenin and luteolin, using bacterial membranes that co-express human CYP1A1, CYP1A2, or CYP1B1 with human NADPH-cytochrome P450 reductase. Chrysin, which possesses no hydroxyl groups in its B-ring, exhibited the most pronounced inhibitory effects on CYP1A2-dependent EROD activity, followed by apigenin and luteolin. On the contrary, CYP1A1-mediated EROD activity was most potently inhibited by luteolin, which is characterized by two hydroxyl groups in its B-ring, followed by apigenin and chrysin. However, all of the 5,7-dihydroxyflavones were determined to similarly inhibit CYP1B1 activity. Chrysin, apigenin, and luteolin exhibited a mixed-type mode of inhibition with regard to CYP1A2, CYP1B1, and CYP1A1, with apparent Ki values of 2.4, 0.5, and 2.0 microM, respectively. These findings suggested that the number of hydroxyl groups in the B-ring of 5,7-dihydroxyflavone might have some influence on the degree to which CYP1A enzymes were inhibited, but not on the degree to which CYP1B1 enzymes were inhibited.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Sang Bum
authors.initials: SB
authors.lastname: Lee
authors.forename: Song-Kyu
authors.initials: SK
authors.lastname: Park
authors.forename: Hwan Mook
authors.initials: HM
authors.lastname: Kim
authors.forename: Young In
authors.initials: YI
authors.lastname: Park
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Dong
mesh_terms: D047310:Apigenin / Q000737:chemistry / Q000494:pharmacology; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics / Q000378:metabolism; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D065633:Cytochrome P-450 CYP1B1; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D047311:Luteolin / Q000737:chemistry / Q000494:pharmacology; D009251:NADPH-Ferrihemoprotein Reductase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D065609:Cytochrome P-450 CYP1A2 Inhibitors; D004791:Enzyme Inhibitors; D005419:Flavonoids; D010078:Oxazines; D011994:Recombinant Proteins; C043561:chrysin; C007649:ethoxyresorufin; D047310:Apigenin; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D065633:Cytochrome P-450 CYP1B1; D009251:NADPH-Ferrihemoprotein Reductase; D047311:Luteolin