Interaction of bisphenol A with rat hepatic cytochrome P450 enzymes

The effect of bisphenol A (BPA) on the kinetics of cytochrome P450 (P450)-d ependent monooxygenases in rat liver microsomes was studied. Testosterone 1 6 beta-hydroxylase (TS16BH) and testosterone 2 alpha-hydroxylase (TS2AH) ac tivities were extensively inhibited by BPA at 100 mu M (69% and 74%, respec tively). The inhibition type was mixed for both P450-dependent monooxyganas es. The K-i of TS16BH and TS2AH from Lineweaver-Burk plots were 25.9 and 24 .9 mu M, respectively. The activities of acetanilide 4-hydroxylase (AA4H), 7-ethoxycoumarin O-deethylase (ECOD), bufuralol 1'-hydroxylase (BF1'H), chl orzoxazone 6-hydroxylase (CZ6H) and testosterone 6 beta-hydroxylase (TS6BH) were also effectively inhibited by BPA at 100 mu M (43-52%). The inhibitio n type of these P450-dependent monooxygenases was mixed or uncompetitive, a nd the K(i)s (50.5-88.5 mu M) were higher than those of TS 16BH and TS2AH. By contrast, the values of IC50 and K-i of testosterone 7 alpha-hydroxylase (TS7AH) and lauric acid omega-hydroxylase (LAOH) for BPA were >1000 mu M. These results suggest that BPA interacts with rat hepatic CYP1A2, CYP2A2, C YP2B2, CYP2C11, CYP2D1, CYP2E1 and CYP3A2 in vitro. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.