Validated UHPLC–MS/MS method for simultaneous determination of four triterpene saponins from Akebia trifoliata extract in rat plasma and its application to a pharmacokinetic study

Saponin PH, akemisaponins E, saponin PJ₁ and scheffoleoside A, the main bioactive triterpene saponins of Chinese traditional medicine Akebia trifoliata, contribute to its diuretic pharmacological activity. Because of interactions of the multiple ingredients in vivo, pharmacokinetic studies of multiple triterpenes after administration of A. trifoliata extract are essential to clarify their pharmacological effects. The purpose of this study was to develop an efficient and sensitive UHPLC–MS/MS method for simultaneous determination of these four triterpene saponins in rat plasma. The biosamples were prepared by liquid–liquid extraction with n‐butanol. The chromatographic separation was performed on a Phenomenex Luna^® C₁₈ (150 × 2 mm, 3 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 0.5 mL/min. The MS/MS system was operated in a negative multiple reaction monitoring mode, and the precursor–product ion transitions were optimized as m/z 941.6 → 471.1 for saponin PH, 941.7 → 471.2 for akemisaponins E, 1089.7 → 601.1 for saponin PJ₁, 957.6 → 487.4 for scheffoleoside A and 799.5 → 637.3 for ginsenoside Rg₁ (Rg₁, internal standard). Method validation parameters (calibration curve linearity, lower limit of detection, recovery, matrix effect, intra‐ and inter‐day precision) were within the acceptable ranges. This is the first reported on the UHPLC–MS/MS detection of saponin PH, akemisaponins E, saponin PJ₁ and scheffoleoside A, and applied to a preclinical pharmacokinetic study after oral administration of A. trifoliata extract in rats. This study provides a basis for clinical application and further development of A. trifoliata extract.