Optimization of Extraction Parameters of Phenolic Antioxidants from Leaves of Capparis spinosa Using Response Surface Methodology

Optimization of antioxidant assay (2,2-dipheynl-1-picrylhydrazy (DPPH) scavenging assay), total phenol content (TPC), and total flavonoid content (TFC) from leaves of Capparis spinosa were investigated using response surface methodology (RSM). The conditions investigated were ethanol concentration (20-80 %, ethanol/water, v/v), extraction temperature (30-65 A degrees C), and solvent to material ratio 20:50 (v/w). A rotatable Box-Behnken design (BBD) consisting of 15 experimental runs with three replicates at the center point were applied by second-order polynomial models. The results of RSM showed that the highest extraction efficiency was obtained in 49 % ethanol, 51.8 A degrees C, and 50 (v/w) ratio of solvent to material. Under optimum conditions, the corresponding values for TPC, TFC, and antioxidant assay were 27.44 (mg gallic acid equivalent (GAE) g(-1) dry weight (DW)), 26.07 (mg quercetin g(-1) DW), and 85.74 (DPPHsc%), respectively. Comparison of predicted and observed data through the chi-square (X (2)) values demonstrated that RSM models was useful for predicting of responses. In addition, the higher R (2) values (R (2) > 0.998) showed that models could efficiently predict the yield of responses.