Optimization of the ultrasound-assisted extraction for phenolic compounds content and antioxidant activity of Cortex fraxini using response surface methodology

In this study, for the first time, optimized phenolic compounds and antioxidant properties were derived from the extraction process of Cortex fraxini (CFR) using response surface methodology. Four factors and three levels of Box-Behnken (BBD) were used to study the extraction time (X 1 ), extraction temperature (X 2 ), ethanol concentration (X 3 ), and solvent-material ratio (X 4 ). The analysis of variance (ANOVA) revealed that temperature and solvent-material ratio had a relatively large effect on the response. The optimal combination of phenolic compounds and antioxidant activity was obtained with the optimal conditions of X 1  = 1.629 h, X 2  = 53.367 ℃, X 3  = 60.971% (v/v), and X 4  = 45.582 mL/g under ultrasonic assisted extraction (UAE). The experimental parameters were consistent with the predicted values. Caffeic acid, erucic acid, ferulic acid and p-hydroxycinnamic acid and other 19 phenolic acids were characterized by high performance liquid chromatography-mass spectrometry (HPLC–MS). The results of this study indicate that optimization of the extraction process is essential for the accurately determined measurement of phenolic components and antioxidants in CFR for its industrial applications.