A simple and efficient ultrasonic-assisted extraction of bioactive compounds from raw Bupleuri Radix and vinegar-baked Bupleuri Radix was developed and optimized by using quantitative analysis of multi-components by a single-marker combined with response surface methodology approaches. The quantitative analysis of multi-components by a single-marker analytical method based on high-performance liquid chromatography coupled with a photodiode array detector was established and applied to determine the contents of six bioactive compounds in raw Bupleuri Radix and vinegar-baked Bupleuri Radix. In order to maximize extraction of six bioactive compounds in raw Bupleuri Radix and vinegar-baked Bupleuri Radix, the ultrasonic-assisted extraction conditions were obtained by the response surface methodology coupled with Box–Behnken design. The conditions of ultrasonic-assisted extraction were found to be effective for the extraction of bioactive compounds from raw Bupleuri Radix and vinegar-baked Bupleuri Radix. The test results showed that the difference in saikosaponins contents in these samples was obvious; a quantitative analysis of saikosaponins will contribute significantly to improving the quality control of raw Bupleuri Radix and vinegar-baked Bupleuri Radix. In conclusion, the designed protocol is suitable for the quality control of raw Bupleuri Radix and vinegar-baked Bupleuri Radix.

Rhubarb is a Chinese traditional medicine. Ninety-four compounds belonging to five different classes of compounds (anthraquinone, anthrones, stilbenes, flavonoids and acylglucosides) have so far been identified in rhubarb. These constituents are effective in purgative, clearing heat-fire, removing toxic materials from the body, cooling blood and promoting blood circulation. Recent studies have shown that the appropriate processing methods may directly impact on its remedial activities and chemical compositions. Here, we provide a comprehensive review of the chemical compositions, pharmacological activities and processing methods of rhubarb.