Structural characterization and immunomodulating activity of a complex glucan from spores of Ganoderma lucidum

A polysaccharide with a molecular weight of 1.26 x 10(5), obtained from the sporoderm-broken spores of Ganoderma lucidum, was purified by anion-exchange and gel-permeation chromatography. This polysaccharide had a strong effect on suppressing the antibody production and the Con A or LPS induced lymphocyte proliferation in mice. Chemically, the structure of the polysaccharide was identified by methylation analysis, 1 D, 2 D NMR and ESI-MS spectroscopic studies of the native one and of the oligosaccharide fragments generated by partial acid hydrolysis, Smith degradation, and acetolysis. It was concluded that the intact polysaccharide was a complex beta-D-glucan consisting of a (1-->6)-linked backbone chain, in which every other glucosyl residue was substituted at C-3 or C-4 with mono-, di- and trisaccharide branches.