Solid–liquid extraction of protopine from Fumaria officinalis L.—Experimental study and process optimization

Optimization of the protopine batch extraction from Fumaria officinalis was studied by experimental design. Several parameters were first studied in order to measure their influence on batch extraction thus enabling to choose the most accurate model. A response surface method design that allows investigating the simultaneous variations of the three main parameters (percentage of ethanol in solvent, temperature, solid–liquid weight ratio) was used to evaluate the influence of experimental parameters and their interactions on the extraction yield of protopine. The central composite design (CCD) used for the analysis of treatment combinations showed that a second-order polynomial regression model was in good agreement with the experimental results, with a coefficient of determination of 0.998 and a Fischer test of 1.0. First, this model was validated by variance analysis and experimental checking, then the optimal conditions and the significance of the effects of the parameters were determined. The maximum yield was obtained by using graphical methods and the optimal conditions were obtained when using ethanol 50% (w/w) at a temperature of 79 °C with a 3% solid–liquid (w/w) ratio. Under these optimal conditions, the weight of protopine extracted from 100 g of F. officinalis was about 230 mg.