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

Abstract

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.

Keywords

• Triterpenoid saponin
• BTS-1
• HPLC
• LC–MSn
• Pharmacokinetic study
• Metabolite identification
• Rat plasma