Antioxidant and immunobiological activity of water-soluble polysaccharide fractions purified from Acanthopanax senticosu

A water-soluble polysaccharide obtained from Acanthopanax senticosus leaves (ASL), was fractionated by DEAE-Sepharose fast-flow column chromatography, and purified by Sephadex G-75 gel-permeation column chromatography. The characteristics of ASP-2-1 were determined by chemical analysis, high-performance capillary electrophoresis (HPCE), high-performance gel-permeation chromatography (HPGPC). The results show that ASP-2-1 contained 89.47% carbohydrate, 7.45% uronic acid, 2.16% protein and seven kinds of monosaccharides including rhamnose, xylose, glucose, mannose, arabinose, galactose and glucuronic acid in a molar ratio of 7.45:18.63:25.15:0.93:8.35:2.79:5.69, with an average molecular weight of about 14,573 Da. Furthermore, the immunobiological and antioxidant activities, in vitro, of ASP-2-1 were evaluated by MIT (3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide) assay and ferric-reducing antioxidant power assay (FRAP), 2,2-dipheny1-1-picrylhydrazyl (DPPH center dot), superoxide radical (O-center dot(2)-) and hydroxyl radical ((OH)-O-center dot) free radical-scavenging assay, respectively. The results showed that ASP-2-1 exhibited significantly higher immunomodulatory activities against the lymphocyte proliferation in vitro, pronounced reductive power (FRAP value: 785.1 mu M at 0.2 mg/ml), strong hydroxyl radical (89.56% at 1 mg/m1) scavenging activity, moderate superoxide radicals (65.32% at 1 mg/ml) and DPPH radicals (68.9% at 1 mg/ml) scavenging activities. ASP-2-1 should be explored as a novel and potential natural antioxidant and immunostimulating agent for use in functional foods or medicine. (C) 2011 Elsevier Ltd. All rights reserved.