Optimization of Extraction and Antioxidant Activities of Triterpenic Acids from Blacked Jujube by Response Surface Methodology

Objective: Blacked jujube was used as raw materials to study the extraction conditions and antioxidant activity of triterpenic acids. Methods: The ultrasonic extraction process of triterpenic acids from blacked jujube was optimized by single factor and Box-Behnken response surface experiments. The antioxidant activity of before and after purification of triterpenic acids were evaluated by determining the scavenging capacity of DPPH and ABTS⁺ free radicals and total reducing power. Results: The optimum extraction parameters were as follows: 50% ethanol concentration, liquid-solid ratio 23:1 mL/g, ultrasonic time 30 min, ultrasonic power 300 W. Under these conditions, the yield of triterpenoid acids was 1.313±0.01 mg/g. The half inhibitory concentration (IC₅₀) for scavenging of DPPH· and ABTS⁺· of crude and purified triterpenoid acids from blacked jujube were 0.571, 0.053, 0.186 and 0.059 mg/mL, respectively. The total reducing power showed a certain dose effect relationship with the sample concentration. Conclusions: The process was simple, reasonable and feasible. The triterpenic acids of blacked jujube would have a good antioxidant activity.