Structural characterization and biological activities of a novel polysaccharide containing N-acetylglucosamine from Ganoderma sinense.

A novel homogeneous heteropolysaccharide (GSPB70-S) with a molecular weight of 2.87 kDa was isolated from Ganoderma sinense. Structural analysis showed that GSPB70-S was composed of glucose, glucosamine, mannose, and galactose with a molar ratio of 12.90:3.70:2.26:1.00. The repeating structure units of GSPB70-S were characterized by the combined application of chemical methods and nuclear magnetic resonance. GSPB70-S contains a backbone of →3)- β -D-Glcp-(1 → 4)- α -D-GlcpNAc-(1 → 4)- α -D-Manp-(1 → 3)- β -D-Glcp-(1→, with branches of β-D-Glcp-(1→, α-D-GlcpNAc-(1 → and →4)- α -D-Galp-(1→. Scanning electron microscope (SEM) showed that GSPB70-S presented a long strip shape with different thicknesses, and there were many lamellar substances on the surface. Biological research showed that GSPB70-S inhibited the activity of α-glucosidase in vitro, increased the viability of RAW 264.7 macrophages, and promoted the release of NO. In addition, GSPB70-S showed good abilities to scavenge free radicals. • A novel polysaccharide (GSPB70-S) was isolated from Ganoderma sinense , and its proposed structure units were established. • N -acetylglucosamine was first found in the polysaccharide of Ganoderma sinense. • GSPB70-S could significantly inhibit α -glucosidase activity, with the IC 50 value of 0.006 mg/mL. • GSPB70-S could prominently increase the viability of RAW264.7 macrophages and promote the release of NO. • GSPB70-S has the potential to be developed as a hypoglycemic drug or immunomodulator. [ABSTRACT FROM AUTHOR]