Objective: To optimize extraction process of total flavonoids from Punica granatum leaves by response surface methodology and investigate its in vitro antioxidant activity. Method: On basis of single factor tests and Box-Behnken principle

response surface methodology was used to optimize extraction conditions with ethanol concentration

solid-liquid ratio

ultrasonic power and time as factors

yield of total flavonoids as index.DPPH and·OH scavenging assays were carried out to verify in vitro antioxidant activity of total flavonoids from P. granatum leaves. Result: Optimum extraction conditions were ethanol concentration of 59.8%

solid-liquid ratio of 1 : 16.3

ultrasonic power of 221 W

extraction time of 33.45 min;under these conditions

yield of total flavonoids was 0.433%.When the concentration of sample was 0.6-1.0 g·L-1

scavenging rates of DPPH radical and·OH were high

which approached vitamin C. Conclusion: Application of this simple and workable technology to extract total flavonoids from P. granatum leaves can improve extraction efficiency

total flavonoids shows a relatively high antioxidant activity.