Extraction, purification and properties of water-soluble polysaccharides from mushroom Lepista nuda

Lepista nuda has high nutritional and medicinal value, especially has high antioxidant, antitumor and antiviral activities. Based on results of single factor experiment, response surface methodology was used to optimize the extraction conditions of polysaccharides (LNP). Macroporous resin D301 was used to decolorization, and its technological conditions were determined by orthogonal experiment. In addition, two novel polysaccharides (LNP-1, LNP-2) were purified by DEAE Cellulose-52 and Sephadex G-150 chromatography. The molecular weight of LNP-1 is 11,703Da, mainly composed of mannose, glucose, galactose, xylose, arabinose and fucose, while the molecular weight of LNP-2 is 13,369Da, mainly composed of mannose, glucose, galactose, arabinose and fucose. The polysaccharide contents of crude LNP, LNP-1 and LNP-2 were 70.60%, 87.71% and 81.20% respectively, and the protein contents were 1.72%, 0.97% and 0.68% respectively. Their sulfuric contents were 3.39%, 5.02% and 8.64%, and uronic acid contents were 3.66%, 5.56% and 6.80%, respectively. Further studies showed that their ability to chelate iron ions, scavenge DPPH (1,1‑diphenyl‑2‑picrylhydrazyl) free radicals and scavenge superoxide anion radicals were 70.09%, 55.94% and 36.64% respectively. They showed strong ability to scavenge free radicals in a concentration-dependent manner. LNP is expected to be developed as a new efficacy factor in the food industry.