METABOLISM OF THE BUTYLCARBAMOYL MOIETY OF BENOMYL IN RAT

The metabolism of the butylcarbamoyl group was studied in the rat. [14C]Benomyl-1-carbamoyl-n-[1-3H]butyl was fed orally, and 24 hr later 40% of the 14C was found both in the urine and in the respired carbon dioxide. During the same period, 55-69% of the tritium was recovered in the urine. S-(n-Butylcarbamoyl)cysteine and S-(n-butylcarbamoyl)-N-acetylcysteine were found in the 24-hr urine and constituted 6-9% and 23-28%, respectively, of the tritium in that urine. A conjugate of butylamine, containing 42-47% of the tritium in the urine, was tentatively identified as the N-glucuronide derivative. The butylcarbamoyl group of benomyl is readity transferred to glutathione in vitro. N, N′-dibutylurea, an in vitro decomposition product of benomyl, was not found in the urine of animals fed benomyl. When dibutylurea was fed to rats, 11-14% of the compound was recovered unchanged in the urine. © 1979.