Abstract: Taking the seeds of Chenopodium quinoa as the research object, based on ultrasonic time, solid-liquid ratio, and negative pressure of single factor experiment, combined with the characterization results of SEM of Chenopodium quinoa powder, the optimal extraction process condition of flavonoids from Chenopodium quinoa was obtained by response surface optimization. The crude extract of flavonoids from Chenopodium quinoa was extracted with ethyl acetate and purified by the silica gel column （The eluent was acetone） to obtain the flavonoids with high purity, which was tested for antioxidant activity in vitro. The results showed that the best process parameter for the extraction of flavonoids from Chenopodium quinoa by ultrasonic-negative pressure was ultrasound time of 27 min, solid-liquid ratio of 1:36（g/mL） and negative pressure of 0.059 MPa. The extraction rate （5.31 ± 0.038） mg/g was close to the predicted extraction value of 5.28 mg/g. The factors affecting the extraction rate of flavonoids from Chenopodium quinoa were solid-liquid ratio> negative pressure> ultrasonic time. The antioxidant activity of flavonoids from Chenopodium quinoa was positively correlated with the concentration, and the greater the concentration, the stronger the antioxidant capacity. At a concentration of 0.25 mg/mL, the scavenging rate of the DPPH radical reached （89.5 ± 0.430）%.

Key words: flavonoids from Chenopodium quinoa, ultrasonic-negative pressure method, single factor experiment, response surface optimization, antioxidant activity