title: Clotrimazole, an inhibitor of benzo[a]pyrene metabolism and its subsequent glucuronidation, sulfation, and macromolecular binding in BALB/c mouse cultured keratinocytes.
abstract: The effect of the antifungal imidazole compound, clotrimazole, on the metabolism of benzo[a]pyrene (BP) was studied in cultured keratinocytes prepared from BALB/c mouse epidermis. Varying concentrations of clotrimazole added to the cultured keratinocytes resulted in a dose-dependent inhibition of the activities of the microsomal cytochrome P-450-dependent monooxygenases aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase. The major organic solvent-soluble metabolites of BP identified in the cultured cells were trans-7,8-dihydro-7,8-dihydroxybenzo[a]pyrene (BP-7,8-diol), 9-hydroxybenzo[a]pyrene (9-OH-BP), and 3-hydroxybenzo[a]pyrene (3-OH-BP), although small amounts of trans-4,5-dihydro-4,5-dihydroxybenzo[a]pyrene, BP-quinones, and trans-9,10-dihydroxybenzo[a]pyrene were also present. The major organic solvent-extractable metabolites of BP found in the extracellular culture medium were primarily the diols with smaller quantities of phenols and quinones. The major water-soluble metabolites of BP present both intracellularly and extracellularly were glucuronide conjugates of 3-OH-BP, 9-OH-BP, and benzo[a]pyrene-3,6-dione and to a lesser extent sulfate conjugates (primarily of the BP-7,8-diol). Clotrimazole inhibited the generation of organic solvent-soluble and water-soluble conjugates in a dose-dependent manner. The in vitro metabolism of BP by microsomes prepared from control and benz[a]anthracene (BA)-induced cultured keratinocytes was also inhibited by clotrimazole with greater inhibitory effect on BA-induced keratinocytes especially with respect to the formation of diols and quinones. The enzyme-mediated covalent binding of BP to mouse keratinocyte DNA and protein was also substantially diminished by clotrimazole in a dose-dependent fashion. These results indicate that clotrimazole, a widely used drug for the management of a variety of superficial dermatophyte infections of the skin, is a potent inhibitor of cytochrome P-450-dependent transformation of polycyclic aromatic hydrocarbons in cultured murine keratinocytes. This system offers a convenient approach for studies as inhibitors of carcinogen metabolism in the epidermis.
mesh_terms: D000818:Animals; D001551:Benz(a)Anthracenes / Q000494:pharmacology; D001564:Benzo(a)pyrene / Q000378:metabolism*; D002478:Cells, Cultured; D003022:Clotrimazole / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System; D004790:Enzyme Induction / Q000187:drug effects; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism; D005965:Glucuronates / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology*; D046911:Macromolecular Substances; D051379:Mice; D008807:Mice, Inbred BALB C; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D010105:Oxygenases / Q000037:antagonists & inhibitors; D013431:Sulfates / Q000378:metabolism
chemical_list: D001551:Benz(a)Anthracenes; D005965:Glucuronates; D007093:Imidazoles; D046911:Macromolecular Substances; D013431:Sulfates; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System; C030935:benz(a)anthracene; D010105:Oxygenases; D003022:Clotrimazole