Stereoisomerism metabolites found in rats after oral administration of timosaponin B-II using HPLC-Q-TOF-MS and NMR methods

Abstract

Timosaponin B-II (TB-II), a representative furostanol saponin from Rhizoma Anemarrhenae, has been used to treat diabetes and senile dementia. To better understand the action mechanism of TB-II, it is indispensable to study its metabolism profile in vivo. A HPLC-Q-TOF-MS and NMR methods for the analysis of TB-II and its metabolites in rat urine has been developed. Five derivatives of TB-II including one novel compound (timosaponin BIII-d) were synthesized and used as the reference compounds. In rat urine, a total of 13 metabolites were identified after oral administration of TB-II and eight of them were confirmed by NMR. The metabolic pathways of TB-II were mainly deglycosylation, F-ring isomerization, and even stereoisomerism at C₂₅. It is important for understanding metabolism of TB-II in rats to clarify its metabolic pathways in vivo, which will also provide useful information and reference for similar study in humans. Moreover, the metabolites could contribute to obtain better compounds than TB-II for the development of new drugs in the future.