Preparation And Biological Activity Of Low Molecular Weight Chitosan

The conditions of decomposing chitosan by metal-coordination controlled oxidative method were optimized. The optimal conditions are as follows: control raw material chitosan 0.5g, 1% HAc solution 30mL, the time of degradation 1.5h, the temperature of degradation 45℃, hydrogen peroxide 1 mL (concentration 30% ), copper acetate 80 mg. The degradation products of chitosan under this condition was separated by 732 cationic exchange column chromatography, low molecular weight chitosan with high quality was prepared, and the yield achieved 60﹪～70﹪.Sephadex G-25 gel filtration chromatography, DNS terminal group analysis, mass spectrometric analysis and thin layer chromatography results indicated that the low molecular weight chitosan had a narrow distribution in molecular weights, and its polymerization degree was about 4, which separated and prepared by 732 cationic exchange column chromatography.The low molecular weight chitosan could inhibit Bacillus subtilis and Phytophthora infestans markedly, however, it inhibit E.coli faintly. The clearance rate of 0.625mg/mL of this product on superoxide anions achieved 63.3% , and the clearance rate on hydroxyl free radicals achieved 91.8% when its concentration was 1.25 mg/mL. 2mg/mL of the low molecular weight chitosan could suppressed Human Hela cell remarkably, the suppress rate was about 67% under experimental conditions.