Study on antioxidant activity of polysaccharides with different molecular weights from Pyropia yezoensis in vitro

Abstract:

In this research,polysaccharides from Pyropia yezoensis were separated by four ultrafitration membranes in different molecular weight cut-off(MWCO) to obtain five parts of relative molecular weight :PPⅠ(MW≥100 000), PPⅡ(MW:50 000-100 000), PPⅢ(MW:10 000-50 000), PPⅣ(MW:5 000-10 000) and PPⅤ(MW≤5 000),for further study,the antioxidant activity of PP with different molecular weights was determined. The results showed that PP with different molecular weights all have antioxidant capacity in the experimental concentration range of PP,they all have good hydroxyl radical(·OH) scavenging activity, superoxide anion(·O₂^-) radical scavenging effects and DPPH radical scavenging activity, and scavenging rate increased with increasing concentration of polysaccharides, showing a dose-effect relationship; antioxidant activity was related to the size of its relative molecular weight, and the antioxidant activity of small molecular polysaccharide PPⅤ(MW≤ 5 000) was best, significantly higher than the greater molecular weight PPⅠ(MW≥100 000). Ultrafiltration technology could achieve good separation of PP, it could be used as a new method for the development and utilization of the active component from Pyropia yezoensis, and the PP of MW below 5 000 was the main active component and worthy of exploitation in future.