Study on microwave and ultrasonic-assisted extraction of flavonoids in the sweetpotato leaves

The total flavonoid in sweetpotato leaves was extracted by microwave and ultrasonic- assisted extraction method. By single factor and orthogonal experiment, the microwave and ultrasound- assisted extraction technology was studied to gain the flavonoids from sweetpotato leaves. The optimized extraction process and related technological parameters were determined as follows:the ethanol mass fraction 80%, supersonic wave power 300 W, the ultrasonic time 3min, microwave power 150 W, the microwave time 3min, the ratio of material to solvent 1∶60. The extraction quantity of flavonoids from sweetpotato leaves could reach8.61%. The polyamide column chromatography was selected to separate the flavonoids. Firstly, ethanol gradient solution was used to elute at the speed of 2mL/min. Secondly, the elution concentrated point-like of each concentration of ethanol was collected. Thirdly, the composition of the flavonoids were confirmed and dried. Then, the weight of each composition in the flavonoids was confirmed. In conclusion, the content of quercetin was under 1.62%.