Metabolism of the Herbicide Pyrazolate in Rats

Abstract

Metabolism of pyrazolate, 4-(2,4-dichlorobenzoyl)-l,3-dimethylpyrazol-5-yl p-toluenesulfonate was studied in rats given a single oral dose or 11 consecutive daily doses, using 14C-preparations labeled at the 3rd position of the pyrazole ring or uniformly at the chlorinated benzene ring. Dosed radiocarbons were almost completely eliminated from the body within several days, and no specific tissues accumulated radiocarbons. Pyrazolate was hydrolyzed in the gastrointestinal tract to give p-toluenesulfonic acid (PTSA) and 4-(2,4-dichlorobenzoyl)-l,3-dimethyl-5-hydroxypyrazole; i.e., destosyl pyrazolate (DTP), which was further metabolized and excreted mainly into urine, whereas unchanged pyrazolate was excreted into feces at a ratio clearly depending on a dose. Metabolism of DTP involved hydroxylation of the 3-methyl group and subsequent oxidation to carboxyl group, demethylation of the 1-methyl group, cleavage of 2,4-dichlorobenzoyl linkage, and conjugation. © 1987, Pesticide Science Society of Japan. All rights reserved.