Biotransformation of diethenylbenzenes. II. Metabolic pattern of 1,4-diethenylbenzene.

The metabolism of 1,4-diethenylbenzene in the rat was followed by gas chromatographic-mass spectrometric analysis of urine using three different derivatization procedures: (i) methylation-acetylation; (ii) methylation-trimethylsilylation; (iii) methylation followed by conversion into trimethylsilyloximes. Fifteen metabolites were found in the urine of rats dosed with a single intraperitoneal injection of 1,4-diethenylbenzene (300 mg/kg). Nine of them were identified in our previous study [I. Lindhart et al., Xenobiotica, 19 (1989) 645], but the other six have not previously been reported. New metabolites, namely, 1-ethenyl-4-(1-hydroxyethyl)benzene, 4-(1,2-dihydroxyethyl)benzoic acid, (4-carboxymethylphenyl)acetylglycine, N-acetyl-S-[2-carboxy-1-(4-ethenylphenyl)ethyl]-L-cysteine, and two isomeric beta-D-glucosiduronates derived from 1-(4-ethenylphenyl)ethane-1,2-diol, were identified by mass spectrometry of their derivatives and comparison of them with the spectra of analogous metabolites of styrene and 4-methylstyrene. Acetylation of methylated urine extracts seems to be the most suitable derivatization procedure, but a combination of at least two procedures is needed if the virtually complete metabolic pattern of diethenylbenzene is to be obtained. Possible routes of biotransformation leading to the newly identified metabolites are discussed.