Metabolism of [ring-U-14C] agaritine by precision-cut rat, mouse and human liver and lung slices

Agaritine {(β-N-[γ-l(+)glutamyl]-4-hydroxymethylphenylhydrazine)} is present in the common cultivated mushroom Agaricus bisporus and several agaritine derivatives have been shown to produce tumours in experimental animals. In this investigation the metabolism of [ring-U-14C]agaritine has been studied in precision-cut rat, mouse and human liver slices and in precision-cut rat and mouse lung slices. To confirm the functional viability of the tissue slice preparations, the metabolism of 7-ethoxycoumarin was also studied. Liver and lung slices from all species metabolized 50 μM 7-ethoxycoumarin to 7-hydroxycoumarin, which was conjugated with D-glucuronic acid and sulfate. Incubation of rat, mouse and human liver slices, and rat and mouse lung slices with 25 μM [14C]agaritine resulted in a time-dependent formation of metabolite(s), which bound covalently to tissue slice proteins. Agaritine metabolite covalent binding was greater in mouse liver than in rat and human liver slices and was greater in mouse lung than in rat lung slices. No correlation was observed between agaritine metabolite covalent binding and tissue slice γ-glutamyltransferase activity. Additional studies with mouse liver slices showed that [14C]agaritine was also metabolized to a number of unknown polar metabolites. These results demonstrate that agaritine can be metabolized by enzymes present in mammalian liver and lung.