Dibenzothiophene sulphoxidation: a new and fast high-performance liquid chromatographic assay of mixed-function oxidation

Abstract

1. Dibenzothiophene (DBT) was used as a model substrate of hepatic microsomal mixed-function oxidases. Liver microsomes from Aroclor-induced rats oxidatively transformed this substrate to DBT-5-oxide and subsequently to DBT-5-dioxide. These metabolites were identified by mass spectrometry after incubation of perdeuterated DBT.

2. A simple and fast h.p.l.c. method for determination of the metabolites using u.v. detection at 225 nm is described.

3. Optimal reaction conditions were determined. The apparent K_m and the V_max were, respectively, 85 μM and 8.25 nmol of DBT-5-oxide/min per mg protein.

4. The effects of the inducers phenobarbitone, 3-methylcholanthrene and DBT itself on hepatic DBT-metabolizing activity in rats were determined.

5. DBT, an important constituent of petroleum products, might serve as a useful substrate of aromatic hydrocarbon mono-oxygenase.