Abstract: Objective:The physical and chemical characteristics and the antioxidant of acidic polysaccharide extracted from cyanobacteria of Chaohu was studied in order to be availably used as profitable resource.Methods:CHAP was fractionated by DEAE-52 anion-exchange chromatography and was further purified by Sephadex G-150.HPLC, UV, IR, and EC etc. were used for the analyses of purity，molecular weight, monosaccharide constituents，spectroscopic characteristics and the antioxidant of CHAP.Results:The purity of CHAP was high.The mean molecular weight of CHAP was 2.209×105.monosaccharide constituents of CHAP are D(+) xylose(31.8341%), D-rhamnose (4.36%), D-galactose (17.53%), L-arabinose(12.77%), glucose(23.82%)and unknown monosaccharide.Infrared spectrum showed that CHAP was main pyranose-polysaccharides and had β-glycosidic in its molecule structure, and there was a characteristic absorb peak of α-D-galactopyranosyl in it.The results showed that CHAP could significantly decrease the DPPH and superoxide anion radicals.The rate could arrived 60.71% and 74.74.However,the CHAP had little scavenging effect on OH,the rate was less than 10%.All that can availably used as profitable data for resource utilization of CHAP.

Key words: Cyanobacteria of Chaohu, acidic polysaccharide, physical and chemical characteristics, antioxidant activity