Extraction of bioactive ginseng saponins using aqueous two-phase systems of ionic liquids and salts

In this research, two types of aqueous two-phase systems (ATPS) based on n-alkyl-tropinium and n-alkyl-quinolinium bromide ionic liquids (ILs) + salt + water have been developed and studied experimentally at different temperature. The binodal curves are fitted to nonlinear Merchuk relationship. For both investigated ILs, the longer the cation alkyl chain is, the greater its ability for ATPSs formation is; meanwhile the ability of the potential salts used for phase separation was compared and sorted, and high temperature was not beneficial to form these tropinium/quinolinium ILs-based ATPSs. On the basis of above results, the new method of extraction for ginsenosides from crude extracts of Panax Ginseng C. A. Mey using IL-ATPS was developed for the first time. Under appropriate conditions, a relatively high extraction efficiency (99.5%), partition coefficient (K = 651) and selective enrichment for total saponins could be obtained. Furthermore, the target ginsenosides can be recovered from the IL-rich phase and the enrichment is conducive to improve their antioxidant activity. Above research is expected to provide meaningful reference for the separation of similar bioactive compounds.