Abstract:

Flavonoid with antioxidant activity was extracted from Soutellaria barbata based on single factor experiments.
A Box-Behnken design involving four factors at three levels each was used to determine the optimum extraction conditions
using flavonoid yield as the response. The optimal extraction conditions were obtained as follows: extraction solvent, 75%
ethanol; liquid to material ratio, 40:1 (mL/g); extraction time, 80 min; and ultrasonic power, 220 W. Under the optimized
conditions, the yield of flavonoid was 11.53%. The antioxidant activity was evaluated based on 1,1-diphenyl-2-picrylhydrazyl
(DPPH) radical scavenging capacity, hydroxyl free radical scavenging capacity and reducing power. The results showed that
the flavonoid from S. barbata had good antioxidant activity.

Key words: Soutellaria barbata, flavonoid, response surface analysis, antioxidant activity