Biotransformation of dimethoate by cell culture systems

Dimethoate O,O-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate] was oxidatively metabolized by primary human embryonic lung cells in culture. Over 95% of the recovered radioactivity after incubation with ¹⁴C-labeled dimethoate resulted from oxidative metabolites, with the remainder being water soluble. Thus, oxidative metabolism of dimethoate predominated over hydrolytic metabolism in the cell culture system, in contrast to the whole rat where the opposite is true. The sequence of reactions was similar to that found in rats. Dimethoate was desulfurated to yield dimethoxon and both compounds were N-demethylated. Metabolism of dimethoate in mouse fibroblast L-929 cell cultures revealed up to 35% of dimethoate carboxylic acid as the only compound other than dimethoate present.