Alkali-soluble polysaccharides from mushroom fruiting bodies improve insulin resistance.

Insulin resistance is the main cause of type 2 diabetes. Polysaccharide is one of the main active components in mushrooms. Some mushroom polysaccharides have been reported to have beneficial effects against type 2 diabetes. However, the structural features and mechanisms of polysaccharides with hypoglycemic activity have not been elucidated. In this paper, six alkali-soluble total polysaccharides, six neutral polysaccharides and six acidic polysaccharides were extracted and purified from mushrooms fruiting bodies of different species. The effects of these polysaccharides on improving insulin resistance were compared using high fatty acids and glucose-induced hepatocytes. Among them, the neutral polysaccharide AAMP-N of Armillaria mellea fruiting body showed the most significant activity, indicating that mannogalactoglucan is the main active domain. AAMP-N enhanced insulin sensitivity in vitro. Also AAMP-N lowered blood glucose, and modulated lipid metabolism in db/db mice. In addition, AAMP-N protected damaged pancreatic islets in mice. Our results demonstrated the role of natural polysaccharides from mushrooms in the improvement of insulin sensitivity and lipid metabolism, and provided basis for the development of mushroom polysaccharides as hypoglycemic healthy food.