Characterization of 2-amino-1-benzylbenzimidazole and its metabolites using tandem mass spectrometry

Toxicol Lett. 1995 Jun;78(1):25-33. doi: 10.1016/0378-4274(94)03231-u.


We have investigated the in vitro hamster hepatic microsomal metabolism of the amino-azaheterocycle, 2-amino-1-benzylbenzimidazole (ABB). Three major metabolites were isolated and structurally characterized, using a combination of off-line HPLC, in conjunction with both electron ionization and fast atom bombardment ionization tandem mass spectrometry. ABB was shown to be debenzylated to afford 2-aminobenzimidazole (AB), as well as N- and C-oxidized to give 1-benzyl-N2-hydroxyaminobenzimidazole (BHB) and 2-amino-1-benzyl-hydroxybenzimidazole, respectively. The possible reasons for formation of the exocyclic hydroxylamine BHB are discussed. Furthermore, ABB is proposed as a suitable model compound for investigating parameters that control formation of toxic hydroxylamines derived from amino-azaheterocycles.

MeSH terms

  • Animals
  • Benzimidazoles / chemistry
  • Benzimidazoles / metabolism*
  • Chromatography, High Pressure Liquid
  • Cricetinae
  • Hydroxylamines / metabolism
  • In Vitro Techniques
  • Male
  • Mass Spectrometry
  • Mesocricetus
  • Microsomes, Liver / metabolism*
  • Oxides / metabolism
  • Spectrometry, Mass, Fast Atom Bombardment


  • Benzimidazoles
  • Hydroxylamines
  • Oxides
  • 2-amino-1-benzylbenzimidazole