Validated UPLC-MS/MS method for simultaneous quantification of eight saikosaponins in rat plasma: Application to a comparative pharmacokinetic study in depression rats after oral administration of extracts of raw and vinegar-baked Bupleuri Radix.

A sensitive and efficient UPLC-MS/MS method was developed and validated for simultaneous quantification of eight saikosaponins (SSa, SSb1, SSb2, SSb3, SSb4, SSc, SSd and SSf) in rat plasma. Furthermore, comparative pharmacokinetic profiles of these sakosaponins were investigated, following oral administration of extracts of raw and vinegar-baked Bupleuri Radix to depression rats. Biosamples were processed with liquid-liquid extraction technique using ethyl acetate. Chromatographic separation was accomplished on Waters BEH C18 UPLC column. 0.05% formic acid in water and acetonitrile as mobile phase was used at a flow rate of 0.40mL/min. The analytes and internal standard, digoxin, were detected using negative ion electrospray ionization in multiple reaction monitoring mode. The lower limit of quantification was less than 0.62ng/mL for the each analyte. The validation parameters investigated, which were specificity, precision, accuracy, matrix effect, recovery and stability, were well within acceptable limits. Results showed that for some of analytes, AUC0-t and Cmax were significantly different after oral administration of extracts of raw and vinegar-baked Bupleuri Radix. Moreover, the pharmacokinetic study in pathological state could provide more useful information to guide the clinical usage of Bupleuri Radix.