PT  - JOURNAL ARTICLE
AU  - J M te Koppele
AU  - E J van der Mark
AU  - J C Olde Boerrigter
AU  - J Brussee
AU  - A van der Gen
AU  - J van der Greef
AU  - G J Mulder
TI  - alpha-Bromoisovalerylurea as model substrate for studies on pharmacokinetics of glutathione conjugation in the rat. I. (Bio-) synthesis, analysis and identification of diastereomeric glutathione conjugates and mercapturates.
DP  - 1986 Dec 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 898--904
VI  - 239
IP  - 3
4099  - http://jpet.aspetjournals.org/content/239/3/898.short
4100  - http://jpet.aspetjournals.org/content/239/3/898.full
SO  - J Pharmacol Exp Ther1986 Dec 01; 239
AB  - In order to find a model substrate for kinetic characterization of glutathione conjugation in vivo alpha-bromoisovalerylurea (BIU) was studied. After administration of racemic [14C]urea BIU to rats, two radioactive metabolites were found in bile by high-performance liquid chromatography. The identity of these metabolites was established by various methods. Based on the hydrolytic activity of gamma-glutamyltranspeptidase (presence of the gamma-glutamyl moiety), high resolution nuclear magnetic resonance (isovaleryl and glutathionyl moieties) and fast atom bombardment mass spectrometry (molecular weight and fragmentation pattern), they were identified as glutathione conjugates of BIU. Because both conjugates in bile had these characteristics in common they must be diastereomers. Incubation of BIU with glutathione in the presence of rat liver cytosol resulted in formation of the same diastereomeric glutathione conjugates. Chemical synthesis of the diastereomers confirmed their identity. The major urinary excretion products of [14C]urea BIU in the rat were identified as diastereomeric mercapturates. A convenient chromatographic separation of the diastereomeric glutathione conjugates and the mercapturic acids is described. Electrochemical detection was used to determine the presence of the thioethers in both urine and bile. Pharmacokinetic results on BIU conjugation are described in the accompanying paper.