抄録
The metabolism of an organophosphorus fungicide, Kitazin P® (S-benzyl O, O-diisopropyl phosphorothioate) by mycelia of Pyricularia oryzae, the rice blast fungus, was studied by using 32P- and 35S-doubled-labeled, 35S-labeled and non-labeled compounds.
The mycelia incorporated the fungicide from the medium, metabolized most of it to water-soluble metabolites and released them into the medium. The main metabolite from Kitazin P was identefied as O, O-diisopropyl hydrogen phosphorothioate by ion-exchange chromatographic separation of double-labeled metabolites. S-Benzyl O-isopropyl hydrogen phosphorothioate, diisopropyl hydrogen phosphate and/or isopropyl dihydrogen phosphate were suspected to be minor metabolites. From the toluene-soluble fraction several metabolites were separated by thin-layer chromatography. The most eminent metabolite among them was found to be the m-hydroxy derivative of Kitazin P by thin-layer chromatographic identification of the labeled metabolite and gas-liquid chromatographic identification of the metabolite and its methylated and acetylated products with respective authentic samples. The o- and p-hydroxy derivatives were not found in the metabolites.
No significant difference in the rate and extent of metabolism was found between susceptible and resistant clones against the fungicide, when its concentration was below the growth-inhibitory concentration to the both clones.
