Biotransformation of a fungicide ethaboxam by soil fungus Cunninghamella elegans

Metabolism of a new fungicide ethaboxam by soil fungi was studied. Among the fungi tested, Cunninghamella elegans produced metabolites from ethaboxam, which were not found in the control experiments. M5, a major metabolite from ethaboxam, was firmly identified as N-deethylated ethaboxam by LC/MS/MS and NMR. N-Deethylated ethaboxam has been found as a single metabolite in in vitro metabolism with rat liver microsomes. M1 was proved to be 4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboxamide (ETC) by comparing with the authentic compound. In addition, M2, M3, and M4, and M6 were tentatively identified by LC/MS/MS as hydroxylated and methoxylated ethaboxams, respectively. Production of the major metabolite, N-deethylated ethaboxam, by the fungus suggested that C. elegans would be an efficient eukaryotic microbial candidate for evaluating xenobiotic-driven mammalian risk assessment.