Effect of Pleurotus tuber-regium polysaccharides supplementation on the progression of diabetes complications in obese-diabetic rats.

In this study, the effect of mushroom extracellular polysaccharides on fatty acid composition and liver peroxisome proliferator-activated receptor-alpha (PPAR-α) expression in obese-diabetic rats was investigated, and distinguished the association among anti-obesity, hypoglycemic and hypolipidemic properties. Extracellular polysaccharides from three different strains of Pleurotus tuber-regium were extracted and labeled as HP (high-percentage), MP (medium-percentage) and LP (low-percentage). Obese- diabetes (OD) was induced by chronic high-fat diet plus streptozotocin (STZ) injections. Simultaneously to the diet, polysaccharides were orally administered to OD groups (20 mg/kg body weight/8-week), and categorized into OD+HP, OD+MP and OD+LP groups (n = 10/group), respectively. High-fat diet plus STZ-induced hyperglycemia was prominently attenuated by polysaccharides. Increased fatty acid component n-6/n-3 ratio in liver and plasma of obese-diabetic rats was attenuated, while, reduced MUFA/ PUFA and MUFA/SFA ratios were restored (P < 0.01) with polysaccharides treatment. Furthermore, elevated serum total cholesterol, triglycerides and low-density lipoprotein (LDL) concentrations were controlled, and parallel restoration of decreased high-density lipoprotein (HDL) levels were found with polysaccharides supplementation. This hypolipidemic property might be associated with up-regulated liver PPAR-α mRNA expression and protein levels (P < 0.01). These findings concluded that stable fatty acid components and activated PPAR-α by polysaccharides may contribute to its hypoglycemic and hypolipidemic properties. Therefore, P. tuber-regium could be considered as nutritional supplement to treat diabetic complications.

Pleurotus tuber-regium Polysaccharides Attenuate Hyperglycemia and Oxidative Stress in Experimental Diabetic Rats.

Pleurotus tuber-regium contains polysaccharides that are responsible for pharmacological actions, and medicinal effects of these polysaccharides have not yet been studied in diabetic rats. We examined the antidiabetic, antihyperlipidemic, and antioxidant properties of P. tuber-regium polysaccharides in experimental diabetic rats. Forty rats were equally assigned as diabetic high-fat (DHF) diet and polysaccharides treated DHF groups (DHF+1P, DHF+2P, and DHF+3P, 20 mg/kg bodyweight/8-week). Diabetes was induced by chronic low-dose streptozotocin injections and a high-fat diet to mimic type 2 diabetes. Polysaccharides (1P, 2P, and 3P) were extracted from three different strains of P. tuber-regium. Fasting blood glucose and glycosylated hemoglobin (HbA1c) levels substantially decreased, while serum insulin levels were restored by polysaccharides treatment compared to DHF. Furthermore, plasma total cholesterol, triglycerides, and low-density lipoprotein levels were significantly (P < 0.01) lower in polysaccharide groups. High-density lipoprotein levels were attenuated with polysaccharides against diabetes condition. Polysaccharides inhibited (P < 0.01) the lipid peroxidation index (malondialdehyde), and restored superoxide dismutase and glutathione peroxidase activities in the liver of diabetic rats. The antihyperglycemic property of polysaccharides perhaps boosts the antioxidant system that attenuates oxidative stress. We emphasize that P. tuber-regium polysaccharides can be considered as an alternative medicine to treat hyperglycemia and oxidative stress in diabetic rats.