Measurement of xenobiotic carbonyl reduction in human liver fractions.

Carbonyl reducing enzymes are involved in the metabolism of endogenous as well as xenobiotic molecules. Enzymes that catalyze the reversible oxidoreduction of aldehyde and ketone moieties include alcohol dehydrogenases, aldo-keto reductases, quinone reductases, and short-chain dehydrogenases/reductases. These enzymes differ with respect to subcellular location, cofactor dependence, and susceptibility to chemical inhibitors. Thus, it is possible to assess the relative contributions of these enzyme systems in the hepatic metabolism of a particular xenobiotic through simple in vitro experiments with commercially available reagents. The approaches described in this unit assume the availability of analytical procedures for measuring the parent compound and metabolites, such as HPLC with radiochemical, UV, or MS detection. Thus, the purpose of this unit is to outline methods for the study of the enzymatic carbonyl reduction of a drug development candidate or other xenobiotic molecule of interest.