Simultaneous determination and pharmacokinetics of five rhubarb anthraquinones in dog plasma by HPLC after orally administration the rhubarb extract.

Rhubarb is widely used in the treatment of obstipation, gastrointestinal indigestion and other diseases in China and other Asian countries for thousands of years. Anthraquinones are the major group of polyphenol constituents including aloe-emodin, rhein, emodin, chrysophanol and physcion. In order to evaluate the pharmacokinetics of five rhubarb anthraquinones, a high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method for simultaneous determination of aloe-emodin, rhein, emodin, chrysophanol and physcion in dog plasma was established. Solid phase extraction (SPE) was applied to the extraction and purification of samples. The calibration curves of five anthraquinones showed good linearity with r greater than 0.9925. The average extraction recoveries, examined at three concentration levels, carried from 92.1% to 102.3%, and the accuracies ranged from 87.7% to 102.5% with precision (RSD) <10%. The pharmacokinetic paremeters of five anthraquinones were investigated systematically after orally administration the rhubarb extract. Five anthraquinones were rapidly absorbed and Tmax for aloe-emodin, rhein, emodin, chrysophanol and physcion was at 0.75, 1.50, 0.75, 1.0 and 2.0 h respectively. The Cmax of five anthraquinones was 0.031, 3.39, 0.27, 0.036 and 0.032 μg/mL while the AUC of five anthraquinones was 0.35 ± 0.058, 32.22 ± 8.29, 2.97 ± 0.66, 0.43 ± 0.10 and 0.41 ± 0.12 mg h/L, respectively.