Structural analysis and macrophage activation of a novel β‑glucan isolated from <i>Cantharellus cibarius</i>

Abstract

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 <i>Cantharellus cibarius</i>, 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‑Glc<i>p</i> oligosaccharides or a single‑unit of β‑Glc<i>p</i> residues. Minor β‑1,4‑D‑Glc<i>p</i>A 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 <i>C. cibarius</i>, and indicated that the novel β‑glucan may be a potent natural immunomodulator, thus promoting the application of <i>C. cibarius</i> as a valuable source for functional food.