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.
Keywords: Cantharellus cibarius; polysaccharide; glucan; structural analysis; macrophage activation.