A hyperbranched β-d-glucan with compact coil conformation from Lignosus rhinocerotis sclerotia

An alkali-soluble polysaccharide was extracted from Lignosus rhinocerotis sclerotia (LRP). Its structural characteristics were determined by GC–MS, FT-IR, GC, 1D and 2D NMR combined with Smith degradation and methylation analysis. The LRP had a (1   →   3)-β- d -Glcp backbone with every three residues bearing a (1   →   6)-linked and hyperbranched side chain that contained three (1   →   6)-β- d -Glcp residues as secondary main chain and two terminal β- d -Glcp residues linked at O3. The degree of branching was 0.76 from GC–MS analysis, implying a highly branched structure for LRP. The M w , < S 2 > z 1/2 , R h and [ η ] values of LRP in 0.25   M LiCl/DMSO were measured by SEC-MALLS-Vis-RI combination technology to be 2.88   ×   10 5   g/mol, 30.36   nm, 22.34   nm and 131.50   ml/g, respectively. Furthermore, the exponent α of [ η ] –M w , β of < S 2 > z 1/2 –M w , the fractal dimension d f and molecular parameter ρ were determined to be 0.20, 0.33, 2.50 and 1.36, demonstrating that the LRP was a hyperbranched polysaccharide and adopted a compact coil conformation in LiCl/DMSO.