Simultaneous determination of multiple components in rat plasma and pharmacokinetic studies at a pharmacodynamic dose of Xian-Ling-Gu-Bao capsule by UPLC-MS/MS

Xian-Ling-Gu-Bao capsule (XLGB) is an effective traditional Chinese medicine prescription (TCMP) that is used for the prevention and treatment of osteoporosis in China. A rapid, simple, efficient and stable method based on UPLC-MS/MS technology was developed for simultaneous determination of multiple components of XLGB in rat plasma. Mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI). For twenty-one selected quantitative prototypes, all calibration curves showed favourable linearity (r>0.9932) in linear ranges. The lower limits of quantification (LLOQs) were 2 ng/mL for psoralen (PL), 2.5 ng/mL for asperosaponin VI (AS), 1 ng/mL for isopsoralen (IPS) and sweroside (SW), 0.5 ng/mL for magnoflorine (MA), bavachinin (BVN), tanshinone IIA (TA), timosaponin BII (TBII) and icaritin (ICT), 0.1 ng/mL for epimedin B (EB) and epimedin C (EC), 0.05 ng/mL for icariin (IC), isobavachalcone (IBC), psoralidin (PD), bavachin (BV), bavachalcone (BC), epimedin A (EA) and isobavachin (IBV), 0.02 ng/mL for neobavaisoflavone (NEO) and icariside I (ICI) and 0.01 ng/mL for icariside II (ICII). The intra-day and inter-day (low, medium, high) precision (relative standard deviation) for all analytes was less than 8.63%, and the accuracies (as relative error) were in the range of -12.45% to 8.91%. Extraction recoveries and matrix effects of analytes and IS were acceptable. All analytes were stable during the assay and storage in plasma samples. The validated method was successfully applied to the pharmacokinetics (PK) studies of the twenty-one prototypes at pharmacodynamic doses (0.3 and 1 g/kg/day). In addition, dynamic profiles of 28 metabolites (phase II conjugates: 23 glucuronide conjugates, 2 sulfate conjugates and 3 glucuronide or sulfate conjugates) were also monitored by their area/IS area-time curves. As a result, coumarins, prenylated flavonoids from Psoraleae Fructus, alkaloids and prenylated flavonol glycosides from Epimedii Herba, and iridoid glycosides, triterpenoid saponins from Dipsaci Asperoidis Radix were considered to be the key effective substances of XLGB due to their high exposure and appropriate pharmacokinetic features. This is the first report to reveal pharmacodynamic ingredients by a reversed pharmacodynamic (PD) - pharmacokinetics (PK) study.