Molinate sulphoxide, an oxidation metabolite of molinate, is cleaved in vitro by Japanese carp liver cytosol fraction, indicating the presence of GSH-S-transferase activity, since cleavage of the sulphoxide is dependent on the amount of supernatant protein and GSH in the assay medium. 2. Molinate mercapturate was identified as a major metabolite recovered from bile of carp treated with molinate. 3. The structure of the mercapturate was established by co-chromatography with an authentic standard in three t.l.c. systems and by mass spectrometry.
