Optimized microwave-assisted extraction of bioflavonoids from bark using response surface methodology.

Bioflavonoids are of great interest due to their health-benefitting properties and possible protection against certain types of diseases. A microwave-assisted extraction (MAE) method was investigated for maximum retention of total bioflavonoids from bark (AMB). Response surface methodology (RSM) using central composite design were employed for obtaining the best possible combination of MAE process parameters including microwave power (400-900 W), liquid/solid ratio (20-40 ml/g), extraction time (20-40 min) and ethanol concentration (60-100%). Optimum conditions of extraction under which predicted maximum bioflavonoids yield of 152.74 mg QE/g DW and antioxidant activity of 75.33% in close proximity with the experimental values were: microwave power 728 W, liquid/solid ratio 24.70 ml/g, extraction time 39.86 min and ethanol concentration 70.36%. Satisfactory statistical parameters (R), ANOVA for the model and lack-of-fit testing provided an adequate mathematical description of the MAE of bioflavonoids with high antioxidant activity. Therefore, MAE of AMB using RSM could be termed as a time-saving and an efficient method resulting to high yield with increased antioxidant activity. Also, HPLC analysis of AMB revealed the presence of bioflavonoids viz., naringin, quercetin and apigenin; which may be further extensively studied for use as therapeutics against various health issues.