Optimization of Ultrasonic Assisted Extraction of Flavonoids From Bupleurum chinense by Response Surface Methodology and Its Antioxidant Activity

Taking Bupleurum chinense as the test material, extraction of total flavonoids from Bupleurum chinense by assisted with ultrasound was studied, the extraction process was optimized through single factor test and response surface test.The clear ability of total flavonoids to DPPH free radicals and ABTS+ free radicals and the content of total flavonoids in different parts of Bupleurum chinense Maxim were studied, in order to provide reference for the development and utilization of Bupleurum chinense.The results showed that the experimental model was very significant（P＜0.000 1）,and the goodness of fit between the predicted value of the model and the true value was good（R~2=0.972 2）.The optimum extraction conditions of ultrasonic assisted extraction of total flavonoids from Bupleurum chinense by response surface methodology were as follows, ultrasonic temperature 57 ℃,ultrasonic power 170 W,solid-liquid ratio 1∶156 mg·mL^-1,ethanol concentration 74%.The yield of total flavonoids from Bupleurum chinense was 8.21%,which was in good agreement with the predicted value（8.17%）.The order of total flavonoids content in different parts of Bupleurum chinense was leaf＞stem＞root.Total flavonoids from different parts had strong scavenging effects on DPPH free radicals and ABTS+ free radicals.