Characterization and antioxidant activity of two low-molecular-weight polysaccharides purified from the fruiting bodies of Ganoderma lucidum

Two low-molecular-weight polysaccharides, GLPL1 and GLPL2, purified from a crude Ganoderma lucidum polysaccharide preparation GLPP were investigated for their physicochemical properties, structure characterization and antioxidant activities. The results indicated that GLPL1 was a glucan with an average molecular weight of 5.2 kDa, while GLPL2 was composed of glucose, galactose and mannose in a ratio of 29:1.8:1.0 with the average molecular weight of 15.4 kDa. GLPL1 and GLPL2 had similar structure characteristic which contained linkages such as →3)-Glcp-(1→, →4)-Glcp-(1→, →6)-Glcp-(1→, →3,6)-Glcp-(1→, and →4,6)-Glcp-(1→ in the percentage ratio of 21.9:20.3:23.7:24.0:3.7 and 23.0:34.6:7.0:14.1:3.0 in the backbone or branches, respectively. Antioxidant results showed that both GLPL1 and GLPL2 exhibited antioxidant activities while GLPL1 was more effective in free radicals scavenging and Fe2+ chelating. Low-molecular-weight polysaccharide seems to play an important role in the exploration of natural antioxidants in food industry and pharmaceuticals.