In vitro Metabolism of Humantenine in Liver Microsomes from Human, Pig, Goat and Rat

Background: Gelsemium elegans Benth（G. elegans） is a well-known toxic plant. Alkaloids are main active components of G. elegans. Currently, the metabolism of several alkaloids, such as gelsenicine, koumine, and gelsemine, has been widely studied. However, as one of the most important alkaloids in G. elegans, the metabolism of humantenine has not been studied yet. Methods: In order to elaborate on the in vitro metabolism of humantenine, a comparative analysis of its metabolic profile in human, pig, goat and rat liver microsomes was carried out using high-performance chromatography/quadrupole time-of-flight mass spectrometry (HPLC/QqTOF-MS) for the first time. Results: Totally, ten metabolites of humantenine were identified in liver microsomes from human (HLMs), pig (PLMs), goat (GLMs) and rat (RLMs) based on the accurate MS/MS spectra. Five metabolic pathways of humantenine, including demethylation, dehydrogenation, oxidation, dehydrogenation and oxidation, and demethylation and oxidation, were proposed in this study. There were qualitative and quantitative species differences in the metabolism of humantenine among the four species. Conclusions: The in vitro metabolism of humantenine in HLMs, PLMs, GLMs and RLMs was studied by a sensitive and specific detection method based on HPLC/QqTOF-MS. The results indicated that there were species-related differences in the metabolism of humantenine. This work might be of great significance for the further research and explanation of species differences in terms of toxicological effects of G. elegans.