Abstract: Hericium erinaceus β-glucan (HEBG) was obtained from the fruiting body of H. erinaceus by water extraction and alcohol precipitation. The primary structure of HEBG was characterized by high performance liquid chromatography (HPLC), gas chromatography (GC), infrared spectroscopy (IR), periodate oxidation, Smith degradation, methylation analysis and nuclear magnetic resonance (NMR) analysis. The solution properties of HEBG were investigated by viscosity measurement and Congo red tests, and its microstructure was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that HEBG was a homogeneous polysaccharide composed of β-D-glucose (Glu). Periodate oxidation, Smith degradation, methylation analysis and NMR analysis indicated that the HEBG backbone consisted of 1,3-β-D-Glu residues and the branches were composed of 1,6-β-D-Glu residues with a molar ratio of 1,3-β-D-Glu to 1,6-β-D-Glu residues of 1:1. The intrinsic viscosity and Congo red tests showed that the dilute HEBG solution had both a random coil and triple helix structure, and the random coil structure of the polysaccharide and the branching structure of its molecular chain were more clearly observed by SEM and AFM. The molecular chain diameter was (0.55 ± 0.11) nm and the width was 1.9 nm. This study provides the rationale for an in-depth study of the biological activity and structure-activity relationship of H. erinaceus β-glucan.

Key words: Hericium erinaceus, β-glucan, structure characterization, dilute solution properties