Polysaccharide from rubescens: extraction, optimization, characterization and antioxidant activities

In this work, rubescens polysaccharide was extracted and extraction conditions were optimized with the response surface method (RSM). The extracted polysaccharide was structurally elucidated and its antioxidant activity was investigated. The best extraction conditions were as follows: the solvent-solid ratio was 33.33 : 1, the extraction temperature was 87.70 °C and the extraction time was 2.59 h. Under optimum conditions, the predicted yield of the polysaccharide was 11.92%. The preliminary structural characteristics were analyzed by HPLC, X-ray, and FT-IR. Results showed that the polysaccharide composition was mannose : glucose : galactose : xylose : arabinose = 2.27 : 4.65 : 2.57 : 1 : 1.85. In addition, the rubescens polysaccharide possessed typical characteristic absorption peaks of polysaccharides. During the antioxidant experiments, the rubescens polysaccharide showed great reducing capacity and strong antioxidant activities on DPPH, ABTS, and hydroxyl radicals. This proved that rubescens polysaccharide has the potential to be a resource for the development of natural antioxidants. Rubescens has become a research object highly valued by the international oncology community and by western institutions for the research and development of new drugs due to its excellent anti-tumor activity. The research on the extraction of polysaccharide from rubescens provides a technical reference for the further utilization of rubescens resources. Hot-water extraction has the advantages of simple operation, easy access to materials and mild extraction conditions, and it can better preserve the original biological activity of the polysaccharide. The research on the antioxidant activity of rubescens polysaccharide provides theoretical support for its use as a natural antioxidant.