Structural analysis and macrophage activation of a novel β-glucan isolated from Cantharellus cibarius

The present study was designed to investigate the structure and immunomodulatory activity of a polysaccharide. A novel acidic β-glucan (WCCP-A-b; molecular weight, 7.3 kDa) was purified from the fruiting bodies of the edible mushroom Cantharellus cibarius, which possesses high nutritional values. WCCP-A-b was composed primarily of glucose (89.7%) and glucuronic acid (8.8%). Methylation and nuclear magnetic resonance analysis suggested that WCCP-A-b contained β-D-1,6-glucan as its main chain, which was substituted at O-3 by β-1,3-D-Glcp oligosaccharides or a single-unit of β-Glcp residues. Minor β-1,4-D-GlcpA residues may also be present in the side chains. The degree of branching was ~20.9%. Moreover, WCCP-A-b possessed a macrophage activating effect by promoting the secretion of nitric oxide, TNF-α and IL-6 in a dose-dependent manner. At a cellular mechanistic level, WCCP-A-b activated macrophages via the MAPK signaling pathway. The present results provided useful information for supporting further investigations on the structure-activity association of polysaccharides from C. cibarius, and indicated that the novel β-glucan may be a potent natural immunomodulator, thus promoting the application of C. cibarius as a valuable source for functional food.