Orthogonal experiment was used to optimize the extraction conditions of Flammulina velutipes mycelia polysaccharides (FvP). Four independent variables (ratio of water to raw material, initial pH value, extracting temperature, and extracting time) were taken into consideration. A yield of FvP of 2.19% was obtained under an optimized condition (ratio of water to material of 50:1, initial pH value of 6.0, extracting temperature of 85℃, and extracting time of 6 h). Subsequently, antioxidative properties of FvP-2 (crude polysaccharides) and FvP-3 (deproteinized polysaccharides) prepared from F. velutipes mycelia were evaluated by monitoring the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and hydroxyl radical scavenging activity, together with antitumor activity against the human hepatocellular carcinoma BEL-7402 cells. DPPH scavenging rate of 65.85% and hydroxyl radical scavenging rate of 71.24% were obtained at 200 μg/mL of FvP-3. The inhibition rate of BEL-7402 cells was up to 45% at 640 μg/mL of FvP-2. These results suggested that FvP possesses potent antioxidant and antitumor properties. The polysaccharide may be useful as a functional food additive and an antioxidant and antitumor agent.
IntroductionMushrooms have been valued as edible and medicinal resources, and antitumor substances have been identified in many mushroom species. Polysaccharides, as one of the most important components isolated from mushrooms, have been correlated with multiple pharmacological activities, such as antioxidant, immunomodulatory, reducing blood lipid and antitumor activities. Flammulina velutipes, one of the most popular edible mushrooms, has being under a large-scale artificial cultivation and increasingly consumed in Japan and China owing to its high nutritional values and attractive taste (Smiderle et al., 2008). It has attracted considerable attention in the fields of its biological activities (Fu et al., 2002;Shi et al., 2012, Wasser, 2002. It was reported that the polysaccharides from the fruiting bodies of F. velutipes have been proved to be beneficial in immunomodulatory, antioxidant, antitumor and biological activity on hepatocytes (Leung et al., 1997;Ohkuma et al., 1983;Pang et al., 2007;. Several polysaccharides have been isolated from F. velutipes, and their pharmacological efficacies were investigated . For example, an antitumor polysaccharide with the structure of 1,3-glucan was isolated from cytoplasms of the fruiting bodies of F. velutipes (Ikekawa et al., 1982). An alkaline-soluble polysaccharide prepared from the cell wall of F. velutipes was reported to have immunomodulatory and antitumor activities against sarcoma SC180 (Leung et al., 1997). However, few studies on the bioactive of F. velutipes mycelia polysaccharides (FvP) were investigated. Furthermore, there are few investigations focusing on the effect of FvP on the proliferation of human hepatocellular cancer cells .Various methods are applied to increase the extraction efficiency of polysaccharides from mushrooms, including selection of proper sol...