title: Clotrimazole, but not dexamethasone, is a potent in vitro inhibitor of cytochrome P450 isoforms CYP1A and CYP3A in rainbow trout.
abstract: The effects of clotrimazole (CLO) and dexamethasone (DEX), both detected in the aquatic environment, were assessed on inhibition of cytochrome P450 (CYP450) in hepatic microsomes of rainbow trout. Activity of three CYP450 isoforms: ethoxyresorufin O-deethylase (EROD; CYP1A), 7-benzyloxy-4-trifluoromethylcoumarin O-debenzylase (BFCOD; CYP3A) and p-nitrophenol hydroxylase (PNPH; CYP2E1-like protein) was investigated in the presence of four concentrations of CLO and DEX. Clotrimazole in a concentration range of 1-100μM decreased the activity of EROD and BFCOD. The inhibition was reversible, as pre-incubation of the microsomes with CLO, before addition of the substrate, had no effect. EROD activity was non-competitively inhibited with a Ki of 0.5μM, and BFCOD activity revealed competitive inhibition with a Ki of 0.04μM. The relatively low Ki for CLO inhibition of EROD and BFCOD activity may indicate that the ability of CYP1A and CYP3A to metabolize xenobiotics is reduced in the presence of CLO. PNPH activity was not affected by CLO. DEX showed no inhibitory potency on any investigated reaction. CLO, but not DEX, inhibited EROD and BFCOD activity by different mechanisms.
authors: University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zatisi 728/II, Vodnany 389 25, Czech Republic. vburkina@frov.jcu.cz
authors: Viktoriia
authors: V
authors: Burkina
authors: Vladimir
authors: V
authors: Zlabek
authors: Galia
authors: G
authors: Zamaratskaia
mesh_terms: D000818:Animals; D003022:Clotrimazole / Q000737:chemistry / Q000494:pharmacology*; D019363:Cytochrome P-450 CYP1A1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003907:Dexamethasone / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D017686:Oncorhynchus mykiss / Q000378:metabolism*
chemical_list: D065691:Cytochrome P-450 CYP2E1 Inhibitors; D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D019392:Cytochrome P-450 CYP2E1; D019363:Cytochrome P-450 CYP1A1; D051544:Cytochrome P-450 CYP3A; D003022:Clotrimazole
keywords: 7-benzyloxy-4-trifluoromethylcoumarin; 7-benzyloxy-4-trifluoromethylcoumarin O-debenzylase; 7-benzyloxyquinoline; BFC; BFCOD; BQ; BzRes; CLO; CYP1A; CYP2E1-like protein; CYP3A; Clotrimazole; DBF; DEX; Dexamethasone; EROD; P450; PNP; PNPH; Rainbow trout; benzyloxyresorufin; clotrimazole; cytochrome P450; dexamethasone; dibenzylfluorescein; ethoxyresorufin O-deethylase; p-nitrophenol; p-nitrophenol hydroxylase