Optimization of microwave-assisted extraction for picroside I and picroside II from Picrorrhiza kurroa using Box-Behnken experimental design

The response surface methodology was employed to study the optimization of microwave-assisted extraction of picroside I and picroside II from Picrorrhiza kurroa Royle rhizomes. The effects of solid to solvent ratio, and extraction temperature, time and solvent on the yields of picroside I and picroside II have been investigated using Box-Behnken experimental design. The experimental data were fitted to second-order polynomial equations using multiple regression analysis and analyzed using the appropriate statistical method. By solving the regression equation and analyzing 3-D plots, the optimum extraction conditions were found to be: solid to solvent ratio, 10: 90 (w/v); temperature, 60 °C; and extraction time, 60 s. Under the optimal conditions, the yields of picroside I and picroside II are 41.23 and 6.12 mg·g−1 feed respectively, which are in good agreement with the predicted values. The ratio of solid to solvent significantly affects the yields of picroside I and picroside II. Application of microwaveassisted extraction of picroside I and picroside II from P. kurroa would dramatically reduce extraction time and solvent consumption.