CHIRAL SULFOXIDATION OF ALBENDAZOLE BY THE FLAVIN ADENINE DINUCLEOTIDE-CONTAINING AND CYTOCHROME P450-DEPENDENT MONOOXYGENASES FROM RAT-LIVER MICROSOMES

The enantioselectivity of the in vitro sulfoxidation of the prochiral drug albendazole was investigated in rat river microsomes. When biolog ical material obtained from control rats and phenobarbital-, 3-methylc holanthrene-, or dexamethazone-pretreated rats was subjected to specif ic immunological and chemical inhibitors, it was shown that two main e nzymatic systems-cytochrome P450s and flavin-containing monooxygenase (FMO)-were responsible for the sulfoxidation. Purified FMO from rat li ver was used to study the enantioselectivity of this enzyme in the sul foxidation of albendazole. The enantiospecificity of FMO is the revers e of that of the P450s. Nevertheless, each P450 isoenzyme involved in this reaction presents its own individual stereoselectivity.