[Glucose- lowering effect of Trametes orientalis polysaccharides in hyperglycemic and hyperlipidemic mice]

To explore the glucose-lowering effect of the polysaccharide fractions of Trametes orientalis.

The crude polysaccharides of T. orientalis were chromatographed on DEAE cellulose column using H2O and 0.5 mol/L NaCl solution as the eluent and DEAE-water and DEAE-salt with high polysaccharide contents were collected. The two fractions were separated using Sephadex G-100 gel column to obtain 4 polysaccharide fractions TOPW-1, TOPW-2, TOPS-1, and TOPS-2. The anti-oxidation activity of the polysaccharide fractions was investigated with ABTS method. The fractions TOPW-1 and TOPS-1 with consistent UV detection signals were collected and HPGPC was used to determine their relative molecular mass. The monosaccharide composition in homogeneous TOPW-1 was determined by acid hydrolysis combined with HPLC. The in vitro inhibitory activities of TOPW-1 and TOPS-1 against DPP4, adipocyte glucose intake and lipase activity were tested to preliminarily assess their glucose-lowering effect. In a mouse model of hyperglycemic and hyperlipidemic, the glucose-lowering effect of TOPS-1 (0.1, 0.2, and 0.4 g/kg) and its effect on blood lipid metabolism were investigated in comparison with Xiaoke pills (5 pills/kg) and Danshen tablets (0.5 g/kg).

TOPW-1 was a homogeneous polysaccharide composed mainly of D-mannose, D-glucose, D-galactose, and D-fucose, with weak antioxidant and hypoglycemic effects. TOPS-1 was not a single polysaccharide and at the concentration of 500 μg/mL showed an high ABTS clearance rate (90.15%). In the mouse model of hyperglycemia and hyperlipidemia, treatment with TOPS-1 (0.2 g/kg) enhanced the activity of lipase and significantly reduced fasting glucose level and serum contents of total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol without causing death in the mice. The glucose-lowering effects of TOPS-1 was not significant at the low (0.1 g/kg) or high (0.4 g/kg) dose, and a high dose tended to increase the mortality of the mice.

T. orientalis polysaccharides have anti-oxidation, glucose-lowering and lipid-lowering effects in mice, and their glucose-lowering effect is probably medicated by reducing oxidative stress and ameliorating lipid metabolism disorder.