Sequential extraction and separation using ionic liquids for stilbene glycoside and anthraquinones in Polygonum multiflorum

In recent years, ionic liquids (ILs) have received more attentions in green extraction and separation process as a kind of novel environment-friendly solvent, and their application in the field of natural products needs to be extended. In this paper, a new method of the sequential extraction for stilbene glycoside and anthraquinones from Polygonum multiflorum was developed for the first time and different ionic liquids was used and compared. It was found two benzothiazolium ILs including [BBth][Br] and [HBth][p-TSA] had good selectivity and high efficiency. In addition, the important extraction conditions were also investigated and optimized. Compared with the traditional acid/alcohol-water extraction process, the extraction assisted by ionic liquid not only can obtain higher yield in shorter time, but also can realize the selective extraction for two different kinds of constituents with less consumption. Furthermore, the recovery of target compounds and recycling of ionic liquid were also studied and it was found that solvent extraction combined with cation-exchange resin had the ideal recovery performance.