Pharmacokinetic and metabolic studies of ginsenoside Rb3 in rats using RRLC-Q-TOF-MS

Ginsenoside Rb3 is one of major ginsenosides in Panax ginseng with effect on cardio-vascular and central nervous system. The aim of this study is to develop a rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method for pharmacokinetic study of ginsenoside Rb3 and simultaneous determination of metabolites in rats. The results showed that the concentration-time profile of ginsenoside Rb3 conformed to a two-compartment pharmacokinetic model after intravenous administration at the dosage of 2.0 mg/kg for rats. The mean plasma elimination half-lives were 13.77 ± 1.23 min and 2045.70 ± 156.20 min for the distribution and exterminate phases t1/2α and t1/2β. In the metabolic study, prototype ginsenoside Rb3 and deglycosylation metabolites were characterized by comparison with the retention time of the standard compounds, accurate mass measurement and the characteristic fragment ions obtained from MS/MS. Two major metabolites Mb1 and M2' were tentatively identified in rat urine samples after intravenous administration, and four possible metabolites Mb1, F2, M2' and CK were detected in rat feces samples after oral administration. The deglycosylation was found to be the major metabolic pathways of ginsenoside Rb3 in rat. The in vivo metabolic pathway of ginsenoside Rb3 was summarized.