Response Surface Methodology for Optimization of Ultrasound-Assisted Extraction of Flavonoids from Radix Puerariae

Response surface methodology was employed to optimize the ultrasound-assisted extraction of flavonoids from Radix Puerariae.The effects of extraction time,solid-to-liquid ratio,and temperature on the extraction yield of flavonoids were studied by one-factor-at-a-time method.A regression model for the yield of flavonoids was established using a Box-Behnken design involving the above three factors at three levels.The results showed that the optimal extraction conditions were as follows: distilled water as extraction solvent,extraction time of 43 min,solid-to-liquid ratio of 1:10(g/mL),and temperature of 68 ℃.Under these conditions,the observed yield of flavonoids was 5.28% in comparison with the predicted yield of 5.36%,and the relative error was only 1.49%,suggesting that the optimal extraction conditions are reliable.