Extraction Optimization, Composition Analysis, and Antioxidation Evaluation of Polysaccharides from White Jelly Mushroom, Tremella fuciformis (Tremellomycetes)

We investigated the sonication-assisted extraction (SAE) conditions of Tremella fuciformis polysaccharides. Single-factor experiments showed that the optimal sonication intensity was 6 W/cm(2); the other SAE conditions were further optimized using response surface experimental design. A Box-Behnken experiment exhibited that the optimal SAE conditions were temperature, 85 degrees C; ratio of liquid to solid, 46 mL/g; and sonication time, 2 hours. The maximal polysaccharide yield (8.95 g/100 g) was obtained under the optimal extraction conditions. Polysaccharides extracted by sonication or traditional hot water extraction (TWE) were further separated and purified using DEAE-Sepharose and Sephadex G-100 column chromatography. Polysaccharide fractions (SAE-1, SAE-2, TWE-1, and TWE-2) were obtained; their molecular weights were 9.85 x 10(4), 6.64 x 10(4), 4.75 x 10(5), and 2.81 x 10(5) Da, respectively. The total sugar content of SAE-1 and SAE-2 was lower and the protein and nucleic acid contents were higher than those of TWE-1 and TWE-2. In addition, SAE-1 and SAE-2 showed stronger Fe2+-chelating activities and superoxide radical scavenging activities than TWE-1 and TWE-2. This suggests that polysaccharides extracted by sonication possess high antioxidant activities.