Soil transformation of acetochlor via glutathione conjugation

Abstract

Acetochlor and acetochlor S-glutathione conjugate were degraded in soil with respective half-lives of 7 days and 30 min to a similar distribution of identical metabolites. Degradation of acetochlor-glutathione conjugate appears to be initiated by γ-glutamyl transpeptidase, and the addition of γ-glutamyl transpeptidase inhibitors effectively retarded the soil degradation of both acetochlor and its glutathione conjugate. The addition of a γ-glutamyl transpeptidase inhibitor to the soil caused the accumulation of acetochlor-glutathione conjugate as a transient metabolite of acetochlor and thereby facilitated its detection. These results suggested that conjugation of acetochlor with glutathione is an initial pathway of metabolism in soil. Acetochlor-glutathione conjugate was further degraded in soil to acetochlor S-cysteine conjugate, which was shown to be a key intermediate in the formation of the major acidic metabolites of acetochlor in soil.