Study on Basic Structure and Antioxidant Activity of Polysaccharides from Three Edible Fungi

In this study, polysaccharides from Lentinus edodes, Auricularia auricula and the waste from the corners of Dictyophora rubrovolvata were extracted by water extraction and alcohol precipitation, and separated and purified by Sevag reagent and dialysis. The molecular weight, functional groups, glycosidic bond and three helix structure of three edible fungi polysaccharides were analyzed by ultraviolet spectrophotometer, high performance gel permeation chromatography (HPGPC), infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR) and Congo red experiment. The antioxidant capacity of polysaccharides from three edible fungi was evaluated by scavenging 1,1-diphenyl-2-trinitrophenylhydrazine free radical (DPPH·) and hydroxyl free radicals (OH·) and the total reducing power of Fe³⁺, and the basic structure and antioxidant activity of the three edible fungi were compared and analyzed. The results showed that the three edible fungus polysaccharides had good homogeneity, and the molecular weight distribution was in the order of tens of thousands and millions. The three edible fungus polysaccharides contained similar functional groups, which were the acidic polysaccharides with configuration both α and β, and all of them had triple helix structure. In addition, the three edible fungus polysaccharides had good antioxidant activity in the range of experimental concentration. When the concentration was 1.0 and 3.0 mg/mL, the DPPH and OH radical scavenging ability of Dictyophora rubrovolvata polysaccharide was better than that of Lentinus edodes and Auricularia auricula polysaccharide, up to 66.86% and 35.69%, their IC₅₀ value were 0.010 and 0.195 mg/mL. In conclusion, there was no significant difference in the basic structure of polysaccharides from the three kinds of edible fungi, but there was a great difference in antioxidant activities, which laid a foundation for industrial production of extracting edible fungi polysaccharides from the waste of Dictyophora rubrovolvata.