A galactomannoglucan derived from Agaricus brasiliensis: Purification, characterization and macrophage activation via MAPK and IκB/NFκB pathways

•A novel galactomannoglucan was extracted from Agaricus brasiliensis.•It exerted significant effect on macrophage proliferation and activation.•It is a potent inducer in activating mitogen-activated protein kinase pathway.•It is involved in inhibitor of nuclear factor-kappa B/nuclear factor-kappa B pathway. In this study, a novel galactomannoglucan named as TJ2 was isolated from Agaricus brasiliensis with microwave extraction, macroporous resin, ion exchange resin and high resolution gel chromatography. TJ2 is composed of glucose, mannose and galactose in the ratio 99.2:0.2:0.6. Infrared spectra (IR), methylation analysis and nuclear magnetic resonance spectra indicated that TJ2 mainly contained a β-(1→3) – linked glucopyranosyl backbone. Interestingly, TJ2 significantly promoted RAW264.7 cell proliferation, and was able to activate the cells to engulf E. coli. In addition, TJ2 induced the expression of Interleukin 1β (IL-1β), Interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and cyclooxygenase-2 (Cox-2) in the cells. TJ2 also promoted the production of nitric oxide (NO) by inducing the expression of inducible nitric oxide synthase (iNOS). Moreover, TJ2 is a potent inducer in activating the mitogen-activated protein kinase (MAPK) and inhibitor of nuclear factor-kappa B (IκB)/nuclear factor-kappa B (NFκB) pathways.