RESUMO
A combination of inductively coupled plasma mass spectrometry (ICP-MS) and electrospray ionization mass spectrometry (ESI-MS) was deployed for the metabolite profiling and metabolite identification of a new antituberculosis compound (R207910, also known as TMC207) that is currently in drug development. R207910 contains one bromine atom, allowing the detection by ICP-MS. Fluctuations in the Br sensitivity caused by the HPLC gradient were counteracted by the use of species-unspecific isotope dilution. In order to evaluate the method developed, the results obtained were compared with those acquired via radioactivity detection. HPLC-ESI-MS was used for the structural identification of R207910 and its metabolites. The (79)Br/(81)Br isotope ratio is also valuable in the search for metabolites in the complex background of endogenous compounds obtained using HPLC-ESI-MS analyses. Data-dependent scanning using isotope recognition with an ion trap mass spectrometer or processing of Q-Tof data provides HPLC-ICP-MS-like "bromatograms". The combination of accurate mass measurements and the fragmentation behavior in the MS(2) spectra obtained using the Q-Tof Ultima mass spectrometer or MS(n) spectra acquired using the LTQ-Orbitrap allowed structural characterization of the main metabolites of R207910 in methanolic dog and rat faeces extracts taken 0-24 h post-dose.
Assuntos
Antituberculosos/análise , Bromo/química , Espectrometria de Massas/métodos , Quinolinas/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Administração Oral , Animais , Antituberculosos/administração & dosagem , Antituberculosos/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Diarilquinolinas , Cães , Desenho de Fármacos , Isótopos , Masculino , Estrutura Molecular , Quinolinas/administração & dosagem , Quinolinas/metabolismo , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Mass defect, neutral loss and isotope filtration techniques were applied to electrospray ionization mass spectrometry (ESI-MS) data obtained for in vivo and in vitro samples of drug metabolism studies. A combination of these post-acquisition processing techniques was shown to be more powerful than the use of one of these tools alone for the detection in complex matrices of metabolites of candidate drugs with a characteristic isotope pattern (e.g. containing bromine, chlorine, or a high proportion of radiolabeled drug ((12)C/(14)C)) or characteristic neutral losses. In combination with 'all-in-one' data acquisition this methodology is able to perform software-driven constant neutral loss scanning for an unlimited number of mass differences at any time after analysis. Highly selective MS chromatograms were obtained with excellent correlation with their corresponding radiochromatograms.