Isolation, structural characterization and immunoregulatory activity of a novel acidic polysaccharide from Ganoderma sinense.

This research was the first to successfully isolate and purify three polysaccharides, referred to as GSPA60-1, GSPA60-2, and GSPA60-3, from Ganoderma sinense using simulated gastric juice extraction. The polysaccharides were characterized using conventional chromatographic methods as well as spectroscopic techniques. The three polysaccharides exhibited distinct differences in morphology, molecular weight, and monosaccharide composition. The immunomodulatory effects of these polysaccharides were systematically assessed. According to bioactivity assays, GSPA60-3 demonstrated a stronger immunomodulatory effect than GSPA60-1 and GSPA60-2, prompting further analysis of its structure and properties. GSPA60-3 consisted mainly of →6)-β-D-Glcp-(1→, →3,6)-β-D-Glcp-(1→, and →4)-β-D-Manp-(1 → residues, with terminal β-D-GlcpA-(1→. Moreover, in vitro experiments demonstrated that GSPA60-3, at a low dose of 40 μg/mL, significantly enhanced the phagocytic activity of RAW264.7 cells and increased the secretion of NO, iNOS, TNF-α, IL-6, and IL-1β. The activation of macrophages by GSPA60-3 was mediated through the TLR-2/TLR-4 and MAPK/Akt/NF-κB signaling pathways. Our findings collectively characterized GSPA60-3 as a well-defined acidic polysaccharide with notable immunomodulatory effects, suggesting its potential as a dietary supplement for boosting immune function and preventing cancer.