Purpose: To develop a more green, efficient and low cost process for the extraction of steroidal
saponins from
Dioscorea zingiberensis
C. H. Wright.
Methods: Six kinds of ionic liquids with different cations and anions were evaluated. In addition, the
extraction parameters of the ionic liquid based ultrasonic/microwave extraction were studied. In order to
quantify the total saponin content accurately, all steroidal saponins were converted into diosgenin and
quantified with an appropriate HPLC procedure. IL-UMAE under optimal conditions was compared with
heat reflux extraction (HRE) and ultrasonic assisted extraction (UAE).
Results: 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm]BF4) solution at concentration of 0.5 mol
L-1 was selected as extraction solvent. The optimum conditions were as follows: solvent to solid ratio
15:1, microwave power 500 W and extraction time 8 min. Under these optimal conditions, the highest
extraction yield of diosgenin 10.24 ± 0.31 mg g-1 was obtained. It took only 8 min to obtain the 91.67 %
content of diosgenin obtained by traditional HRE. Extracting on time was shortened from 120 min to 8
min.
Conclusion: Compared with traditional methods, IL-UMAE method uses Ionic liquid-solvent which
greatly shortens the extraction time. IL-UMAE as a simple, effective and environmentally friendly
approach shows a broad prospect for active ingredient extraction.
