Characterization, hypolipidemic and antioxidant activities of degraded polysaccharides from Ganoderma lucidum

The aim of this work is to characterize the primary structure and physicochemical properties of natural polysaccharides (GLP) and degraded polysaccharides (GLP_UD) from Ganoderma lucidum, and evaluate their hypolipidemic and antioxidant activities. The results of particle size distribution and scanning electron microscopy (SEM) showed that Ganoderma lucidum polysaccharides were effectively degraded by ultrasonic method. GLP_UD was composed of the same monosaccharide units as GLP but with different molar ratios. Infrared spectra and NMR showed that the primary structure of polysaccharides had not been changed by ultrasonic degradation. Meanwhile, the thermal stability of polysaccharides increased after ultrasonic treatment. After administration by GLP and GLP_UD four weeks, body weight, visceral index, atherosclerosis index (AI) and biochemical indicators in serum and in liver were determined. The results showed that GLP_UD had stronger hypolipidemic and antioxidant activities than GLP. GLP_UD was more effective than the GLP for reducing AI, total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C), raising high density lipoprotein (HDL-C) (p < 0.01), reducing malondialdehyde (MDA) content, as well as increasing the glutathione peroxidase (GSH-Px) in mice serum, increasing superoxide dismutase (SOD) activity and reducing MDA content in liver (p < 0.05 or p < 0.01). In addition, the histopathological observations of mice livers showed that GLP_UD could significantly improve lipid metabolism disorder in hepatocytes. Thus, GLP_UD might be tested as a more effective hypolipidemic drug.