TY - JOUR T1 - Specific and enantioselective sulfoxidation of an aryl-trifluoromethyl sulfide by rat liver cytochromes P-450. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 877 LP - 881 VL - 20 IS - 6 AU - E Benoit AU - T Cresteil AU - J L Riviere AU - P Delatour Y1 - 1992/11/01 UR - http://dmd.aspetjournals.org/content/20/6/877.abstract N2 - Evidence based on thermal stability and enzyme inhibition data suggests that the sulfoxidation of the drug toltrazuril by rat liver microsomes is catalyzed by different cytochromes P-450. Pretreatment of rats by different inducers--phenobarbital, 3-methylcholanthrene, dexamethasone, and triacetyloleandomycin--results in a 2.1-, 2.6-, 2.9-, and 1.8-fold increase, respectively, in the rate of sulfoxidation. The highest increase (8.4-fold) was observed after treatment of microsomes from triacetyloleandomycin-treated animals by potassium ferricyanide. Castration and aging also modify the sulfoxidase activity. The relative rate of formation of the two toltrazuril enantiomers [(A)- and (B)-sulfoxides] depends on the source of the microsomes, suggesting that different cytochromes P-450 have different stereoselectivities. ER -