Résumé
OBJECTIVE: To optimize the ultrasonic-assisted extraction process of isoflavones from Pueraria lobata (Wild.) Ohwi using response surface methodology and measure the reducing power. METHODS: On the basis of single factor experiments, a four factors and five levels Box-Behnken experiment was designed. Then the reducing power of isoflavones was measured. RESULTS: The optimum conditions for the ultrasonic-assisted extraction process of isoflavone from Pueraria lobata (Wild.) Ohwi at ultrasonic power of 300 W were as follows: ethanol concentration 75%, liquid-solid ratio 35 mL · g-1, extraction time 35 min, and treatment temperature 50℃. Under the optimum conditions, the yield of polysaccharide from Pueraria lobata (Wild.) Ohwi was 24.18%, and the relative error between experimental value and predicted value was only 3.02%; the EC50 of the reducing power of isoflavones reached 0.135 mg · mL-1. CONCLUSION: The response surface methodology is suitable for regression analysis and optimization of the ultrasonicassisted extraction of polysaccharide from Pueraria lobata (Wild.) Ohwi.