Development of an ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry method for comparative pharmacokinetics of six triterpenoids in rat plasma and application to different forms of Phytolacca acinosa

Phytolacca acinosa is an herb for treatment of ascites and tumor. Two forms of P. acinosa, i.e. raw and vinegar-processed herb, have been used in clinic. However, pharmacokinetic difference between the two forms of P. acinosa has not been fully understood. Herein, a comparative pharmacokinetic method based on liquid chromatography with tandem mass spectrometry was developed for quantification of six bioactive triterpenoids, including esculentoside H, esculentoside T, esculentoside A, esculentoside B, phytolaccagenic acid, and phytolaccagenin in rat plasma after oral administration of different forms of P. acinosa. Separation was performed on an Acquity BEH C-18 column (1.7 mu m, 2.1 mm x 50 mm). The method was validated over a linear range of 2.0-5000 ng/mL. Intraday and interday bias were within +/- 5%. Besides, all triterpenoids were stable in plasma during different storage conditions. The described method was successfully applied to a comparative pharmacokinetic study of raw and vinegar-processed P. acinosa in rats. Notably, double peak phenomenon for six triterpenoids of P. acinosa was observed for the first time. AUC(0 -> t) and C-max values of esculentoside H, esculentoside T, phytolaccagenic acid, and phytolaccagenin were significantly lower in vinegar-processed group than that of raw group, indicating the oral bioavailability of the four triterpenoids was decreased after vinegar processing.