Pharmacokinetic study and metabolite identification of the bidesmosidic triterpenoid saponin BTS-1 in rat plasma

Assays based on high-performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC–MSn) have been developed and validated for the determination and metabolite identification of the bidesmosidic triterpenoid saponin, BTS-1 (3-O-β-d-galactopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→3)]-β-d-glucuronopyranosyl gypsogenin 28-O-α-l-arabinopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranoside), in rat plasma. The assay was successfully applied to a pharmacokinetic study in rats given a single oral dose of BTS-1 (400 mg/kg). The results indicated that the compound was rapidly absorbed (Tmax=1.28±0.29 h, Cmax=37.4±5.6 µg/mL) and slowly eliminated (t1/2=13.2±6.6 h). In addition, secondary glycosides and aglycones of BTS-1 were detected and identified. Since these metabolites are known to be active α-glucosidase inhibitors, they probably play an important role in mediating the pharmacological effects of the saponin.

Graphical abstractHPLC and LC–MSn methods were developed for the determination of the bidesmosidic triterpenoid saponin BTS-1 and identification of its metabolites in rat plasma. Inactive BTS-1 can be metabolized to secondary glycosides and aglycones with α-glucosidase inhibitory activity in vivo.Figure optionsDownload full-size imageDownload as PowerPoint slide