Abstract:Response surface methodology was used to optimize the extraction conditions of total flavonoids from Toona sinensis leaves by ultrasound-assisted ethanol extraction.The extraction rate of total flavonoids was determined by three factors：liquid -to -material ratio，extraction time and ethanol concentration.The bacteriostatic effects of the ethanol extract of total flavonoids on three tested bacteria（Escherichia coli，Bacillus subtilis and Staphylococcus aureus）were also investigated.The results showed that the optimal extraction conditions were as follows：the liquid-to-material ratio was 41 ∶1（mL/mg），the extraction time was 36 min and ethanol concentration of 65%.Under these conditions，the experimental extraction yield of total flavonoids from leaves was 38.96 mg/g，which was close to the theoretical value of 38.59 mg/g.In addition，the inhibition of total flavonoids from Toona sinensis leaves on Staphylococcus aureus was the most significant，and the bacteriostatic zone of the original solution was 16 mm.This study provided theoretical basis for further research and resource utilization development of Toona sinensis.