Optimization of Ultrasonic-assisted Extraction Process of Flavonoids from Damiana by Response Surface Methodology and Its Antioxidant Activity

The purpose of this study was to determine the optimal extraction process conditions for flavonoids from damiana. Taking the extraction rate of flavonoids as an indicator, the effects of factors such as ultrasonic time, temperature, ultrasonic power, and material-to-liquid ratio on the extraction rate of damiana flavonoids were investigated through experiments. Through response surface tests, a regression mathematical model was established and variance analysis was performed to determine the best conditions for extracting turner grass flavonoids. At the same time, the scavenging rate of DPPH free radicals and ABTS free radicals and reducing power were used as indicators to evaluate the antioxidant activity of the crude extract of damiana flavonoids. The results showed that the optimal extraction process conditions were ultrasound time 42 min, temperature 70 ℃, ultrasound power 320 W, and ethanol volume fraction 82%. Under these conditions, the extraction rate of damiana flavonoids reached 94.4%. Tests showed that the IC₅₀ values of flavonoids of damiana in scavenging DPPH free radicals and ABTS free radicals were 0.0283 and 0.0272 mg/mL, respectively. The reducing force were stronger than V_C. This optimized process is feasible, and flavonoids from damiana have good antioxidant properties.