Study on Extraction of Total Flavonoids from Licorice with Ultrasonic Assistance and Oxidation Resistance

The extraction technology of flavonoids in the licorice was studied according to the orthogonal design in this paper.The optimum extraction process of total flavonoids from Licorice wasthe concentration of ethanol 75 %,ratio of material to liquid 1∶25,ultrasonic frequency 350 W,ultrasonic time 25 min.The average extraction rate of flavonoids was 1.943 %.Total flavonoids from licorice has the ability to reduce oxygen radicals and the hydroxyl radicals.When the solution concentration is 1.129 6 mg/mL,the scavenging rate of crude flavonoids on hydroxyl radical reached 55.73 %,the removal rate of crude flavonoids to clear superoixide radical(O2-·)is 50 %.Suggesting that it would be an effctive natural free radical scavenger.