Abstract: Flavonoids was extracted from Longan Pericarp by microwave-assisted method and its antioxidant activities were measured.The conditions of extraction were optimized by orthogonal test design L₉(3⁴).The results showed the optimum conditions as follows:Longan Pericarp(1 g) was soaked in 30 mL of 70% ethanol at 30 ℃ water bath for 30min after being dealt with 480 W microwave for 20 s.The flavonoids yield was 3.465%.Then its antioxidant activity was evaluated by three different assays in vitro.Comparing with the scavenging ability of Vc,it had better function to nitrite system.However the inhibition of the extract to lipid peroxidation of yolk lipoprotein and hydroxyl radical was lower than that of butylated hydroxytoluene(BHT) and Vc,respectively.

Key words: Longan Pericarp, microwave-assisted extraction, flavonoids, antioxidant activity