Characterization and immunomodulatory effects of glucans from Pleurotus albidus, a promising species of mushroom for farming and biomass production

Polysaccharides from a number of mushroom species are recognized as functional food ingredients with potential health benefits, including immunomodulatory effects. In this study, polysaccharides extracted from the basidiome with cold water (BaCW), hot water (BaHW), and hot alkali (BaHA) solution, and exo- (MyEX) and endopolysaccharides (MyEN) from the submerged culture of Pleurotus albidus, a promising species for farming and biomass production, were analyzed for their chemical composition and structure and immunomodulatory effects on macrophages. Compositional (HPAEC-PAD and HPSEC-RID/MWD) and structural (FT-IR, 1D- and 2D-NMR) analyses identified BaCW and MyEX as β-(1,6)-branched β-(1,3)-glucans, BaHW and MyEN as α-(1,3)-(1,2)-branched α-(1,6)-glucans, and BaHA as a mixture of α-(1,6)- and β-(1,3)-glucans. BaCW and MyEX stimulated the production of tumor necrosis factor alpha (TNF-α) and nitric oxide (NO), but not interleukin-6 (IL-6), and decreased phagocytosis of zymosan particles. In contrast, BaHW and MyEN induced TNF-α, NO and IL-6 production, and increased zymosan phagocytosis, while BaHA displayed intermediary effects in comparison the other polysaccharides. In conclusion, the basidiome and the submerged culture of P. albidus are sources of easily extractable α- and β-glucans with potential immunomodulatory effects.