Abstract: In this study,ultrasonication was employed to extract bioactive components from Hypericum.japonicum Thunb.ex Murray (Hypericaceae).The optimal conditions for ultrasonic extraction of Hypericaceae were determined by response surface methodology.Three independent variables were chosen based on single factor tests.Box-Behnken design was applied to evaluate the effects of three independent variables (ultrasonic time,ethanol concentration,ultrasonic temperature) on the extraction yield of total flavonoid compound (TFC),total phenolic compound (TPC) and their scavenging activity to DPPH and ABTS⁺ free radicals.The analysis of variance (ANOVA) showed that the contribution of quadratic model was significant for the responses.The 3D response surfaces were plotted from the mathematical model.The optimized extraction conditions based on combination responses were as follows:ultrasonic time of 48.89 min,ethanol concentration of 63.72% and ultrasonic temperature of 66.92 ℃.Under the optimized condition,TFC,TPC,%DPPHsc and %ABTSsc were determined to be 105.06 mg RE/g DW,51.75 mg GAE/g DW,58.81% and 64.99%,respectively.The experimental values agreed with the predicted ones by analysis of variance (AVOVA).It indicated high fitness of four models used and the success of using response surface methodology for the optimization of the extraction conditions.

Key words: Hypericum japonicum, total flavonoid compound, total phenolic compound, DPPH, ABTS, response surface methodology