HPLC-MS/MS method for the determination and pharmacokinetic study of six compounds against rheumatoid arthritis in rat plasma after oral administration of the extract of Caulophyllum robustum Maxim.

Caulophyllum robustum Maxim (CRM) is a well-known traditional Chinese medicine (TCM) mainly present in the northeast, northwest and southwest regions of China, which is belong to the family Berberidaceae. The roots and rhizomes of CRM have been used as a famous TCM for the treatment of rheumatoid arthritis (RA). The selective, sensitive and accurate high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the determination and pharmacokinetic study cauloside H, leonticin D, cauloside G, cauloside D, cauloside C and magnoflorine in rat plasma was developed and validated in this paper. Chromatographic separation was achieved by using a Waters ACQUITY UPLC HSS T3 (100 mm × 2.1 mm, 1.7 μm) with gradient elution using a mobile phase consisting of acetonitrile and 0.1 % formic acid in water at a flow rate of 0.4 mL/min. The detection was performed in multiple reaction monitoring (MRM) mode and electrospray ionization (ESI) in positive and negative modes. The linearity, precision, accuracy, extraction recovery, matrix effects and stability were assessed to validate the current high-performance liquid chromatography/mass spectrometry (HPLC-MS) assay. Good linearity was achieved for each analyte with a correlation coefficient (r2 ) > 0.99). All the precision (RSD) data were less than 12.20 %, the accuracies ranged from -12.39 % to 10.55 %, the recovery rates from the rat plasma ranged from 85.48%-98.69 %, and the matrix effects ranged from 80.96 % to 91.35 %. The validated approach was successfully applied to study the pharmacokinetic characteristics of saponins and alkaloids in plasma after administering CRME to rats, and this assay provides a platform for studying the active components of multicomponent traditional Chinese medicines and provides useful information for further clinical studies.