Ultrasonic-extraction of phenolic compounds from Phyllanthus urinaria: optimization model and antioxidant activity

Abstract Ultrasonic-assisted extraction technique was used to extract phenolic compounds from Phyllanthus urinaria and response surface methodology was used to optimize the extraction parameters including ultrasonic time (X1), ethanol concentration (X2) and solid-liquid ratio (X3). A mathematical model of the tree parameters for the high extraction yield (Y) was established. Antioxidant activity of the phenolic compounds was investigated by DPPH free radicals, ABTS free radicals, hydroxyl free radicals and reducing power assay with vitamin C as a control. The results showed that the independent variables (X1, X2 and X3) and the interaction terms (X1X3 and X2X3) had a significant effect on the extraction yield. The effect of the variables on the extraction yield was in the order of X3, X1 and X2. The optimal extraction process was X1 of 34 min, X2 of 46.5% and X3 of 1:63 g/mL, and the extraction yield was 9.59%, which was well matched with the predicted value. The antioxidant activity assay indicated that the phenolic compounds from Phyllanthus urinaria have a good antioxidant activity.