Ultrasound assisted extraction of total phenolics from Cassia auriculata leaves and evaluation of its antioxidant activities

Abstract

The present study investigated the optimization of ultrasound assisted total phenolics extraction from Cassia auriculata leaves by Response surface methodology (RSM). A three-level four-factor Box–Behnken design (BBD) was used to illuminate the optimal points of ultrasound assisted extraction (UAE) process variables, extraction time (5,10,15min), pH (5,6,7), solvent concentration (40,50,60%) and ultrasonic power (30,40,50W) for obtaining maximum total phenolics with better antioxidant activities. C. auriculata extracts obtained from UAE in RSM experiments were evaluated in terms of total phenolics content (TPC), FRAP (Ferric reducing antioxidant power) and DPPH (1,1′-diphenyl-2-2′-picrylhydrazyl) radical scavenging activities as responses. Second-order polynomial models for TPC, FRAP and DPPH were build by using the coefficients obtained from regression analysis. ANOVA statistics showed that pH had significant effect on TPC, DPPH and FRAP antioxidant activities. The predicted optimum levels of extraction time 5min, pH 6.2, solvent concentration 60% and power 50W showed maximum TPC, FRAP and DPPH activities of 59.68 (mgGAE/g), 96.2 (mM Fe2+/g) and 90.5% respectively. Validation experiments results had good agreement with the predicted responses by RSM. Results of this study implied that UAE was the better method for TPC extraction from C. auriculata leaves with good antioxidant activities which can be used as natural antioxidant in pharmaceutical and food industries.