Abstract: The extraction technology of total flavonoids from supercritical CO2 extraction residue of Humulus lupulus was optimized by using singel factor and orthogonal test.The optimal extraction conditions are determined as follows:50% ethanol as extraction solvent,the ratio of materiel to 50% ethanol 1:25(g/ml),circumfluence temperature 70℃,and circumfluence time 2.5 h,and extraction rate reaches 68.09 mg/g dry Humulus lupulus under the above conditions.The results of antioxidative experiment showed that the flavonoids extracts has stronger DPPH freed radical scavenging activity(IC50 5.73 μg/ml) than ascorbic acid(IC50 8.79 μg/ml) and rutin(14.84 μg/ml),and it has stronger reducing capacity(EC50 0.158 mg/ml) than rutin(0.252 mg/ml),but weaker than ascorbic acid(0.103 mg/ml);It also has stronger inhibition rate on MDA produced by lipid-peroxidation induced by Fe2+-H2O2 in mouse liver homogenate than rutin.As a conclusion,the total flavonoids from supercritical CO2 extraction residue of Humulus lupulus has strong antioxdant capacity.

Key words: supercritical CO2 extraction residue, total flavonoids from Humulus lupulus, extraction technology, DPPH free radical, reducing capacity, lipid peroxidation