Identification of the in vitro Anticholinesterase Metabolite of Methyl Parathion1

Abstract

Heretofore it has been assumed that phosphate analogs are formed during in vitro activation of phosphorothionate insecticides. To test this hypothesis. highly purified methyl parathion was incubated with liver microsomes from male white rats (Rattus norregicus albinos) XADH₂, and pH 7.7 borax buffer at room temperature ami atmosphere. The formation of a potent cholinesterase inhibiting metabolite was demonstrated by manometric assay. The compound was isolated by column chroma tography and was shown to be methyl para-oxon hy infrared spectroscopy, thus confirming the hypothesis.