Abstract: In this paper,the optimum extraction process and antioxidant activity in vitro of total flavonoids from Polygonum perfoliatum L. was researched.The effects of extraction temperature,extraction time,ratio of material to liquid and ethanol concentration on extraction rate were investigated by single factor and response surface methodology.According to the experimental results,the optimized extraction conditions were got,which were listed as following,extraction temperature was 79.86 ℃,extraction time was 2.03 h,ethanol concentration was 51.64%,ratio of material to liquid was 1∶59,shear times was 7 times,shear temperature was 50 ℃,and the extraction rate of flavonoids under the above conditions was 8.37%.In addition,the in vitro antioxidant activities of the total flavonoids was investigated by measuring clearance abilities of O₂^-·,1,1-diphenyl-2-trinitrophenylhydrazine (DPPH·) and ·OH.The results showed that the total flavonoids had good antioxidant activity.When the concentration of total flavonoids was 8 mg/mL,the scavenging rates of DPPH·, O₂^-· and·OH were between 68%-90%.

Key words: Polygonum perfoliatum L., flavonoids, high shear, antioxidant