Two polysaccharide fractions, SGP I-b and SGP II-b, were purified from the fruiting bodies of Suillus granulatus. The assayed relative molecular masses of SGP I-b and SGP II-b were approximately 17.31 and 10.16 kDa, respectively. SGP I-b consisted of fucose, mannose, glucose, and galactose, whereas SGP II-b consisted of rhamnose, fucose, mannose, glucose, and galactose. The structures of SGP I-b and SGP II-b were preliminarily analyzed through methylation analysis and nuclear magnetic resonance spectroscopy. The results of in vitro antioxidant assays revealed that SGP II-b demonstrated good scavenging ability for hydroxyl and DPPH radicals but poor reduction capacity and scavenging for superoxide anions. SGP I-b did not exhibit any significant antioxidant activities. SGP II-b could also significantly increase lymphocyte proliferation in vitro, however, SGP I-b had no significant effect.
Practical applicationsSuillus granulatus is a wild, edible medicinal fungus distributed in Northeastern China. S. granulatus polysaccharides (SGP) already be prove have special bioactivities. In the current study, SGP were purified and characterized, and the antioxidant activities and immunomodulatory effects were also assayed. Our work will contribute to the utilization of SGP as natural antioxidants and/or immunity-enhancing agents in food and pharmaceutical industries.