Simultaneous LC-MS Analysis and of Wogonin and Oroxylin A in Rat Plasma, and Pharmacokinetic Studies After Administration of the Active Fraction from Xiao-Xu-Ming Decoction

摘要

A rapid and specific high-performance liquid chromatographic method coupled with electrosproy ionization mass spectrometric detection has been developed and validated for identification and quantification of wogonin and oroxylin A in rat plasma. Wogonin, oroxylin A, and diazepam (internal standard) were extracted from plasma samples by liquid-liquid extraction with ethyl acetate. Chromatographic separation was achieved on a C-18 column with acetonitrile-0.6% aqueous formic acid 35:65 (vlv) as mobile phase at a flow rate of 0.2 mL min(-1). Detection was performed with a single-quadrupole mass spectrometer in selected-ion-manitoring (SIM) mode. Linearity was good within the concentration range 14.4-360 ng mL(-1) for wogonin and 10.8-271 ng mL(-1) for oroxylin A; the correlation coefficients (r(2)) were 0.9999. The intra-day and inter-day precision, as RSD, was below 12.4%, and accuracy ranged from 81.1 to 111.9%. The lower limit of quantification was 14.4 ng mL(-1) for wogonin and 10.8 ng mL(-1) for oroxylin A. This method was successfully used in the first pharmacokinetic study of wogonin and oroxylin A in rat plasma after oral administration of the active fraction from Xiao-xu-ming decoction.