Hepatic metabolism of skatole in pigs by cytochrome P4502E1

High concentrations of skatole in fat are a major cause of boar taint in intact male pigs. Skatole is metabolized in the liver, and this metabolism could affect concentrations of skatole in fat. In this study, we evaluated the involvement of cytochrome P450, in particular cytochrome P4502E1, in skatole metabolism in pig liver. Liver microsomes from F4 European Wild Pig x Swedish Yorkshire intact male pigs were incubated in a buffer containing NADPH, NADH, and skatole. Several skatole metabolites were detected by HPLC, including 6-hydroxyskatole (pro-MII), 3-hydroxy-3-methyloxyindole (MIII), and five others not identified in this study. Inhibitors of P450 were added to microsomal incubations, and their effect on the formation of skatole metabolites and skatole disappearance was evaluated. The general cytochrome P450 inhibitors SKF 525A, at a concentration of .2 mM and metyrapone, at a concentration of .1 mM decreased the formation of pro-MII (P = .001) to 38.2 and 11.6%, respectively, of that of controls. The SKF 525A also reduced the synthesis of MIII and three other metabolites, whereas metyrapone only reduced the disappearance of skatole and synthesis of pro-MII. Inhibitors specific for cytochrome P4502E1 were more effective in reducing the formation of skatole metabolites than SKF 525A and metyrapone. Chlorzoxazone and diallyl sulfide reduced (P = .001) the synthesis of pro-MII to 9.7 and 30.9% of the control rate. The formation of most of the other skatole metabolites and disappearance of skatole were also reduced with these inhibitors. These results indicate that skatole is metabolized in pig liver to pro-MII and other metabolites by cytochrome P4502E1.