Optimization of antioxidant extraction from Persicaria barbata leaves using response surface methodology (RSM)

Abstract

Optimization of antioxidant capacity from Persicaria barbata leaf extract was conducted using response surface methodology (RSM). The conditions investigated were 90 - 150 min extraction time (x1), 60 - 75%v/v ethanol concentration (x2) and 30 - 50 v/w liquid-to-solid ratio (x3) while a fixed extraction temperature at 95 °C was chosen. The quality of fit to the second-order polynomial models was confirmed based on the coefficient of determination of 0.9581. Box-Behnken experimental design indicated that models can significantly (p< 0.05) express more than 80% ( > 0.80) of the response variation. The order of factors influencing the response value of antioxidant capacity was ethanol concentration, extraction time and liquid-to-solid ratio, respectively. The optimal extract condition for maximum antioxidant capacity was 120 min of extraction time, 60% (v/v) of ethanol concentration, 40: 1 mL/g of liquid-to-solid ratio and extraction temperature at 95 °C. The ascorbic acid equivalent antioxidant capacity (AEAC) value obtained from experiment was 93.825 ± 0.15 mg AEAC/ g of dried plant.