Abstract:In order to study the extraction process of total flavonoids from Syzygium jambos leaves and their antioxidant activity，microwave-assisted extraction was used to extract total flavonoids from these leaves.Based on single-factor methodology，the response surface methodology was designed to optimize the extraction process of total flavonoids from Syzygium jambos leaves，with ethanol volume fraction，liquid-material ratio，microwave power，and microwave time as independent variables and total flavonoid extraction rate as the dependent variable.Results showed that the optimum extraction conditions were as follows：ethanol volume fraction 59%，liquid-material ratio 53∶1（mL/g），microwave power 400 W，and microwave time 3.9 min.The extraction rate of total flavonoids from Syzygium jambos leaves was 5.13% under these conditions.In vitro antioxidant activity was also investigated，which showed that the IC50values of total flavonoids from Syzygium jambos leaves were 120 μg/mL and 9.19 μg/mL for hydroxyl radicals and 1，1-diphenyl-2-picrylhydrazyl（DPPH）free radicals，respectively.Total flavonoids from Syzygium jambos leaves had strong scavenging ability for DPPH free radicals and some scavenging ability for hydroxyl radicals.