Characterization of N-benzylcarbazole and its metabolites from microsomal mixtures by tandem mass spectrometry.

The metabolism of N-benzylcarbazole (NBC) was studied in vitro using hamster hepatic microsomes to establish whether the corresponding amide is formed. This work was carried out in order to see if the extremely low pka characteristic of such a benzylic amine would allow the formation of the carbonyl derivative. No amide formation was observed. However, a number of metabolic products were detected using HPLC, including the oxidative debenzylation products, namely carbazole and benzaldehyde, together with 2 phenolic isomers of NBC. These products were tentatively characterized by their UV spectra using a rapiscan UV detector connected to HPLC equipment. The structural characterization of these 4 metabolites, together with unchanged substrate, was carried out using desorption electron impact tandem mass spectrometry (DEI-MS/MS) on a hybrid instrument with EBQ1Q2 configuration.