Extraction Structural Properties And Antioxidant Activities Of Polysaccharide From Pholiota Nameko

Polysaccharides,as one of the main bioactive components of Pholiota nameko,had been reported to possess antioxidant,antitumor,immunomodulatory and antidiabetic activities.One of the main aims of this study was to optimizethe extraction conditions of polysaccharides extracted by hot water from pholiota nameko.Another is to elucidate the structure and bio-activity of this polysaccharide.The experimental results were given as follows:In this paper,the optimum extraction conditions of polysaccharides extracted by hot water from pholiota nameko were determined by single-factor test.and orthogonal test.According extracting temperature,extracting time,ratio of water to pholiota nameko and the times of extraction were influencing on extraction rate of polysaccharides,the optimum extraction parameters of experiment were as follows:temperature was 85? time was 2 h,ratio of water to pholiota nameko was 1:40(g/mL).By using this condition test,pholiota nameko polysaccharide reached 24.55±0.10%.In this research,a polysaccharide named PNP was extracted by hot water extraction and ethanol precipitation from fruit bodies of Pholiota nameko.It was isolated and purified by Sephadex G-200,the total sugar content of purified PNP was 95.299±0.21%and the molecular weight was 1.89×103 kDa.The structural features of PNP were investigated by UV spectrophotometer,specific rotation determination,FT-IR,periodate oxidation-Smith degradation,methylization analysis,Congo red and so on.The results showed that the optical rotation of PNP was +120° and that it had atriple-helical structure.Besides,PNP was mainly composed of glucose and mannose at the molar ratio of 4.24:1.00.The backbone of PNP was composed of(1 ?3)-linked-Glc and(1 ? 3)-linked-Man whereas the branches of(1?3,6)-linked-Glc,(1?3,6)-linked-Man,T-Glc and polyphenols.It indicated that PNP was a complex of polysaccharides and polyphenols.In vitro antioxidant results suggested that PNP was processed with certain scavaging capacity against DPPH radical,Hydroxyl radical and Superoxide radical.A highest inhibition rate of 70.65±0.31%was observed against hydroxyl radical.