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

Abstract

The present study was designed to investigate the structure and immunomodulatory activity of a polysaccha- ride. 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 nutri- tional 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 substi- tuted 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 applica- tion of C. cibarius as a valuable source for functional food.