Structure and chain conformation of bioactive β-D-glucan purified from water extracts of Ganoderma lucidum unbroken spores

Two polysaccharide fractions (GLSB50 and GLSB70) with total sugar content of 82.07 wt% and 53.79 wt%, respectively, were obtained from the water extracts of unbroken Ganoderma lucidum spores by sequential ethanol precipitation treatment. Compared with GLSB70. GLSB50 exhibited better activity on stimulation of humoral immune responses in immunosuppressed mice. A novel beta-D-glucan (GLSB50A-III-1) with weight average molecular weight (M-w) of 1.93 x 10(5) g/mol was purified from GLSB50 through chromatography separation. The exponent alpha value of Mark-Houwink-Sakurada equation was calculated to be 0.13, indicating that GLSB50A-III-1 presented globular spheres conformation in aqueous solution. Structural analysis showed that GLSB50A-III-1 mainly consisted of (1 -> 3), (1 -> 4), (1 -> 6)-linked beta-D-glucose residues in the backbone, with two single beta-D-Glcp attached at 0-6 of beta-(1 -> 3) and beta-(1 -> 4)-linked residues separately as side chains. The repeat unit of GISB50A-III-1 was deduced as follows: [GRAPHICS] . (C) 2021 Published by Elsevier B.V.

Automated summary

Two polysaccharide fractions (GLSB50 and GLSB70) were obtained from Ganoderma lucidum spores, with GLSB50 showing better activity in stimulating humoral immune responses in immunosuppressed mice. A novel β-D-glucan (GLSB50A-III-1) was purified from GLSB50, with structural analysis revealing it mainly consisted of β-D-glucose residues.