Abstract: Crude polysaccharides from Actinidia arguta Sieb. et Zucc. fruits were extracted by hot water extraction and ethanol precipitation, deproteinized and defatted and the yield of crude polysaccharides was found to be 1.41%. The crude polysaccharide extract was separated by DEAE-cellulose 52 ion exchange chromatography to obtain four fractions (Ⅰ, Ⅱ, Ⅲ and Ⅳ). Complete separation of fractions Ⅱ and Ⅲ was achieved by Sephadex G-200 column chromatography. The antioxidant activity of fraction Ⅱ was investigated by measuring free radical scavenging activity. Polysaccharide fraction II was found to have strong radical scavenging activity against DPPH and alkyl radicals with an IC50 of 0.497 mg/mL and 0.547 mg/mL, respectively. Its radical scavenging activity increased with increasing concentration within the concentration range investigated and the scavenging rate at a concentration of 1 mg/mL was 86.4% and 87.1% for DPPH and alkyl radicals, respectively, which was comparable to that of vitamin C. Moreover, this fraction also had radical scavenging activity against hydroxyl radical with an IC50 of 0.668 mg/mL in a concentration-dependent manner but was inferior to vitamin C. However, its radical scavenging activity against superioxide anion radical was weak. Based on the above results, we conclude that polysaccharide fraction Ⅱ has potent antioxidant activity.

Key words: Actinidia arguta Sieb. et Zucc., polysaccharides, antioxidant activity, free radical, scavenging rate