Anti-inflammatory and intestinal microbiota modulation properties of Ganoderma lucidum β-d-glucans with different molecular weight in an ulcerative colitis model

This study systematically investigated the therapeutic effects and the corresponding mechanisms of β-D-glucans from Ganoderma lucidum (G. lucidum) with different molecular weights (Mws) on ulcerative colitis (UC). Results showed that three β-d-glucans (GLPS, GLPN and GLPW) from G. lucidum with different Mws exhibited the significant activities on the reduction of typical symptoms of UC by regulating inflammatory cytokine levels, modulating intestinal immunity, improving intestinal microbiota and metabolism of short-chain fatty acids (SCFAs) in the dextran sulfate sodium (DSS)-induced mice model. Among them, the effects of the microwave assisted degraded fraction (GLPW) mainly containing two fractions with smaller Mw (1.33 × 104 and 3.51 × 103 g/mol) on the regulation of inflammatory factors and SCFAs metabolism were found to be comparable to those of GLPN with medium Mw (3.49 × 104 g/mol), and superior to those of GLPS with large Mw (2.42 × 106 g/mol). The effect of GLPW on regulation of intestinal microbiota was even better than that of GLPN. These findings suggested that lowering Mw by means of physical degradation could improve the anti-inflammatory activities of G. lucidum β-d-glucans. The analysis of anti-inflammatory mechanism also provided a feasible and theoretical basis for potential use of degraded β-d-glucans in the prevention and treatment of UC.