Comparative pharmacokinetics of aloe-emodin, rhein and emodin determined by liquid chromatography-mass spectrometry after oral administration of a rhubarb peony decoction and rhubarb extract to rats

This study aimed to clarify the rationality of herbaceous compatibility of a rhubarb peony decoction (Da-Huang-Mu-Dan-Tang, RPD) by comparing the pharmacokinetics of aloe-emodin, rhein and emodin in rats' plasma after oral administration of RPD and rhubarb extract. A rapid, sensitive LC-MS method was developed and validated for the determination of the plasma concentrations of the three analytes after oral administration RPD and rhubarb extract. The developed method was successfully applied to a pharmacokinetic study of aloe-emodin, rhein and emodin in rats' plasma after oral administration. Compared with administration of single rhubarb, the C-max of rhein in RPD was decreased significantly (p < 0.05). Meanwhile, the T-1/2 of aloe-emodin and emodin were increased significantly (p < 0.05) after administration of RPD. In addition, the T-max of rhein and emodin were also increased significantly (p < 0.05) in RPD. These results indicated that the absorption of rhein in rats was suppressed after oral administration RPD. Moreover, The time for rhein and emodin to reach the peak concentration was delayed and the elimination of aloe-emodin and emodin was also postponed in RPD. This study could provide a meaningful basis for evaluating the clinical application of traditional Chinese medicine in terms of pharmacokinetics.