Physicochemical profiles and antioxidant capacities of lingzhi ( Ganoderma lingzhi ) polysaccharides under different extraction regimes

Polysaccharides (GLPs) were extracted from the fruiting bodies of Ganoderma lingzhi using an optimised water-extraction and alcohol-precipitation method. Two homogeneous fractions (GLP1 and GLP2) were purified, and their molecular weights, monosaccharide compositions, and antioxidant activities were characterised via high-performance liquid gel permeation chromatography (GPC) and ion chromatography. GPC analysis determined the molecular weights of GLP1 and GLP2 to be 4.352 × 104 Da and 2.261 × 104 Da, respectively. Both fractions were primarily composed of glucose, along with mannose, rhamnose, arabinose, fucose, galactose, xylose, and glucuronic acid, albeit with varying molar ratios. Notably, the crude polysaccharide fraction exhibited superior antioxidant activity compared to the purified fractions, achieving DPPH and hydroxyl radical scavenging rates of 71.5% and 80.0% at concentrations of 2.5 mg/mL and 3.5 mg/mL, respectively. These findings establish a foundation for the development of GLPs in functional foods and pharmaceuticals.