Metabolism of S-Benzyl O-Ethyl Phenylphosphonothioate (Inezin^®) by Mycelial Cells of Pyricularia oryzae

Abstract

Gas-liquid chromatographic study revealed that organophosphorus fungicide Inezin^®, (S-benzvl O-ethyl phenylphosphonothioate) was metabolized to O-ethyl hydrogen phenylphosphonothioate or ethyl hydrogen phenylphosphonate by mycelial cells of Pyricularia oryzae. Metabolic fate of the removed benzyl or benzylthio group was further studied by labeling benzene ring of benzyl radical of the fungicide with ¹⁴C, and dibenzyl disulfide, benzvl alcohol, toluene-α-sulfonic acid and benzoic acid were found as metabolites by ion exchange chromatography and thin-layer chromatography. Gas-liquid chromatographic study also ascertained that a part of Inezin was hydroxylated at m-position of the benzene ring of benzvl radical, but o- or p-hydroxylation of benzyl radical was not seemed to occur.
No significant difference was found in metabolism of the fungicide between susceptible and resistant clones of the fungi.