Selective extraction of glabridin from Glycyrrhiza glabra crude extracts by sulfobutylether-β-cyclodextrin in a ternary extraction system

Glabridin is the active ingredient in Glycyrrhiza glabra, which is widely used in medicine and cosmetics. A ternary solvent extraction system containing a water-soluble β-cyclodextrin (β-CD) derivative was explored for selective extraction of glabridin. The effects of the extraction solvent type and ratio, β-CD derivatives type and concentration, crude extract concentration, and temperature on the distribution behavior were investigated to determine the optimal extraction system, which consisted of a 0.1 mol/L sulfobutylether-β-cyclodextrin (SBE-β-CD) aqueous phase and an n-octanol: n-hexane (50:50, V: V) organic phase. SBE-β-CD showed the strongest encapsulation ability toward glabridin among the tested β-CD derivatives. Multi-stage centrifugal fractional extraction under the ideal extraction conditions was used to continuously and specifically separate glabridin from the Glycyrrhiza glabra crude extract. The yield and purity of glabridin reached 97% and 95%, respectively. This technique, combining the SBE-β-CD extractant and fractional extraction, provides an effective, high yield, high purity, eco-friendly and low-cost method to separate glabridin from the crude extract.