Separation of ginsenosides from Panax notoginseng intensified with Ionic liquids

Ginsenoside is one of the main bioactive substances of Panax notoginseng, which belongs to terpene compounds and has high medicinal value. To improve the separation efficiency of ginsenosides, the ionic liquid (IL) solvents were screened from 720 ILs database for the extraction and separation of six main ginsenosides (Rg1, Rb1, Rg2, Rb2, Rb3 and Rd) from Panax notoginseng based on the concept of infinite activity coefficient and COSMO-SAC thermodynamic model. The ionic liquids, namely 1-ethyl-3-methylimidazolium bromide ([C2mim]Br), 1-butyl-3-methylimidazolium bromide ([C4mim]Br) and 1-ethyl-3-methylimidazolium acetate ([C2mim][Ac]), were selected and mixed with methanol at different ratios to make novel composite solvents, and the extraction efficiency of Panax notoginseng saponins was then determined experimentally. The results showed that the selected IL solvents could sharply promote the separation efficiency of ginsenosides. The separation efficiency increases with the increase of IL concentration in mixed solvent. When the molar concentration of [C2mim]Br, [C4mim]Br and [C2mim][Ac] in methanol mixed solvent was 0.1, the extraction efficiencies of total ginsenosides from Panax notoginseng were 62.77%, 23.86% and 79.53% respectively, which were 59.25%, 20.34% and 76.01% higher than ones only using methanol solvent. Instead of using an aqueous IL solution and the ultrasonic extraction technique, an IL-organic mixed solvent with heating reflux extraction was presented. Meanwhile, a combination of theoretical and experimental methods was first proposed to screen the solvent for the separation of ginsenosides, and sharply reduce the experimental work and cost compared ones only based on experiment. This work could provide a general guide for the extraction of bioactive components from natural products and biomass with high efficiency.