Characterization of the multiple absorbed constituents in rats after oral administration of Chai-Huang decoction by liquid chromatography coupled with electrospray-ionization mass spectrometry.

A rapid, sensitive, and specific method by high-performance liquid chromatography (HPLC) coupled to diode-array detection (DAD) and tandem mass spectrometry (MS) techniques was developed for the identification of absorbed constituents and their metabolites in rats after the oral administration of a Chai-Huang decoction (CHD), which consists of Bupleurum chinense and Scutellaria baicalensis in the proportion 1 : 1 (w/w). By comparing their retention times and MS data with those of authentic compounds and published data, a total of 14 compounds were identified in the CHD samples. In addition, eleven and seven compounds were characterized in the urine and serum samples of the rats, respectively. The results indicated that the main absorbed constituents were chrysin-6-C-arabinosyl-8-C-glucoside, chrysin-6-C-glucosyl-8-C-arabinoside, baicalin, wogonin-5-O-glucoside, oroxylin A-7-O-glucuronide, wogonoside, saikosaponin A, saikosaponin C, saikosaponin D, baicalein, and wogonin. These compounds might be responsible for the curative effects of the CHD. The findings demonstrated that the proposed method could be used to rapidly and simultaneously analyze and screen the multiple absorbed bioactive constituents in a formula of traditional Chinese medicines (TCM). This is very important not only for the pharmaceutical discovery process and the quality control of crude drugs but also to explain the mechanisms of action of TCM.