Simultaneous determination of vitexin-4''-O-glucoside and vitexin-2''-O-rhamnoside from hawthorn leaves flavonoids in rat plasma by HPLC method and its application to pharmacokinetic studies

The present study was to investigate the pharmacokinetics of the two similar flavonoid glycosides, vitexin-4"-O-glucoside (VGL) and vitexin-2"-O-rhamnoside (VRH) in rats after intravenous administration of hawthorn leaves flavonoids (HLF). Blood samples were collected via tail vein at time intervals after drug administration and the plasma concentrations of the studied ingredients were analyzed by HPLC after the plasma protein was precipitated directly with methanol. VGL and VRH were successfully separated using a C-18 column with a UV detection at 330nm and a mobile phase of methanol-acetonitrile-tetrahydrofuran-0.5% acetic acid (1:1:19.4:78.6, v/v/v/v). The assay linearities of VGL and VRH were confirmed over the range 0.23-138.42 and 0.36-218.49 mu g/ml, respectively. The accuracy and precision of the two analytes at high, medium and low concentration were within the range of -3.13% to 3.51 % and below 4%, the mean assay recoveries of them (n = 5) ranged from 96.87% to 10 1.75% and 96.88% to 103.51 % for intra- and inter-day assays and the mean extraction recoveries of them (n = 5) varied from 92.68% to 95.74% for VGL and 93.45% to 99.26% for VRH, respectively. After intravenous administration of HLF to rats over the doses range of 10-40 mg/kg, the plasma concentration-time curves of VGL and VRH were both conformed to the three-compartment open pharmacokinetic model and linear pharmacokinetic characteristics. (c) 2007 Elsevier B.V. All rights reserved.