Radical scavenging activities of polysaccharides in three Nostoc species

The radical scavenging activities of polysaccharides in three Nostoc species were investigated employing three in vitro systems. The result showed that they all have a concentration-dependent scavenging effect on superoxide anion radical and hydroxyl radical. N. commune,with a high inhibition rate of 72.3% at 40 mu g/mL, was the most effective scavenger on superoxide radical, while that were 46.7% and 35.5% of N. sphaeroides and N. flagelliforme respectively. Moreover, N. flagelliforme showed an excellent capacity on hydroxyl radical scavenging. Its maximal scavenging effect was 74.3% at the test concentration of 30 mu g/mL, while 49.0% and 46.7% were N. sphaeroides and N. commune's, respectively. However, three Nostoc polysaccharides had no significant effect on DPPH radical scavenging