IDENTIFICATION OF NOVEL N-GLUCURONIDES IN RAT BILE AFTER ADMINISTRATION OF 450191-S, A 1H-1, 2, 4-TRIAZOLYL BENZOPHENONE DERIVATIVE

Abstract

5-[(2-Aminoacetamido) methyl]-1-[p-chloro-2-(o-chlorobenzoyl) phenyl]-N, N-dimethyl-1H-s-triazole-3-carboxamide hydrochloride dihydrate (450191-S) is a ring-opened derivative of 1, 4-benzodiazepine, which is activated by desglycylation and subsequent cyclization. After 450191-S administration, rat bile contained three novel conjugates which released active metabolites possessing the 1, 4-benzodiazepine structure through β-glucuronidase hydrolysis. Since the released metabolites have no functional groups to conjugate with glucuronic acid, we speculated that the aglycone might be the ring-opened form of 1, 4-benzodiazepine which spontaneously cyclizes after the release of glucuronic acid. This possibility was tested by chemically reducing the ketone group of the ring-opened 1, 4-benzodiazepine glucuronate conjugates, which would prevent the spontaneous ring closure reaction after the release of the glucuronic acid moiety. The NaBH₄ reduction of the ketone of the benzophenone moiety of the conjugates and subsequent treatment with β-glucuronidase allowed identification of the reduced aglycones with authentic samples using gas chromatography-mass spectrometry.