CHARACTERIZATION OF 2-AMINO-1-BENZYLBENZIMIDAZOLE AND ITS METABOLITESUSING TANDEM MASS-SPECTROMETRY

We have investigated the in vitro hamster hepatic microsomal metabolis m of the amino-azaheterocycle, 2-amino-1-benzylbenzimidazole (ABB), Th ree major metabolites were isolated and structurally characterized, us ing a combination of off-line HPLC, in conjunction with both electron ionization and fast atom bombardment ionization tandem mass spectromet ry. ABB was shown to be debenzylated to afford 2-aminobenzimidazole (A B), as well as N- and C-oxidized to give 1-benzyl-N-2-hydroxyaminobenz imidazole (BHB) and 2-amino-1-benzyl-hydroxybenzimidazole respectively , The possible reasons for formation of the exocyclic hydroxylamine BH B are discussed. Furthermore, ABB is proposed as a suitable model comp ound for investigating parameters that control formation of toxic hydr oxylamines derived from amino-azaheterocycles.