Response surface optimization of enzyme-assisted extraction of total flavonoids fromwisteria and study on hydroxyl radicals scavenging effectAuthor(s): LiHui-duan
The response surface methodology (RSM) and Box-Benhnken Design (BBD) were employed to optimize the extraction conditions of total flavonoids from Wisteria. The hydroxyl radicals scavenging and inactivity scavenging and inhibiting effect of Wisteria total flavonoids were also studied in this paper. The total flavonoids were extracted from Wisteria neck, leaf, flower and fruit clip by using enzyme-assisted ethanol refluxing. According to the single-factor experimental results, Enzyme concentration of 0.15~0.25mg·mL-1, enzymatic pH of 5 ~ 7, enzymatic temperature of 45 ~ 65! and enzymatic times of 1.5 ~ 2.5h were selected as the independent variables and scope for BBD. The preferred extract conditions optimized by RSM. Hydroxyl radicals scavenging and inhibiting effect of Wisteria extracts were also measured. The optimum extract conditions optimized by RSM and BBD were enzyme concentration of 0.23 mg·mL-1; enzymatic pH of 6, enzymatic temperature of 64 ! and times for 2.0h with responding extraction ratio of 0.94% for Wisteria neck, 4.60% for Wisteria leaf, 3.32% for Wisteria flowers and 5.16% for Wisteria fruit clip. The experimental extraction ratio matched well with the calculated values by solving the multiple regression equation. It confirms that the fitted quadratic model has a predictive effect on target extracts. The scavenging effect on hydroxyl radicals displayed a significant dose-effect relationship for Wisteria flavonoids, but it showed a weaker scavenging effect compare to BHT with the same concentration.