Antidiabetic Activity of Polysaccharides from Tuberous Root of Liriope spicata var. prolifera in KKAy Mice

Tuberous root of Liriope spicata var. prolifera has been widely used as a traditional Chinese medicine for the treatment of diabetes. The present study investigated the antidiabetic effect and the potential mechanisms of two new polysaccharides (LSP1, LSP2) and the total polysaccharides (TLSP), isolated from the tuberous roots. Upon the intragastric administration in obese insulin-resistant diabetic KKAy mice for 28 days, TLSP, LSP1, and LSP2 all caused a remarkable decrease of fasting blood glucose and significant improvement of insulin resistance and serum lipid metabolism in diabetic mice. In addition, liver histological analysis showed that TLSP, LSP1, and LSP2 significantly ameliorated the hepatocyte hypertrophy and decreased the lipid accumulation in the mice liver. Further experiments suggested that TLSP, LSP1, and LSP2 effectively inhibited hepatic gluconeogenesis and increased hepatic glycolysis and hepatic glycogen content. Furthermore, the mechanistic analysis showed the increased expression of insulin-receptor α subunit, insulin-receptor substrate-1, phosphatidylinositol 3-kinase, and peroxisome proliferators-activated receptors γ. These results suggested that TLSP, LSP1, and LSP2 manifest strong antidiabetic activity, therefore hold a great promise for therapeutic application in diabetic therapy and other related metabolic disorders

Hypoglycemic Activity and Antioxidative Stress of Extracts and Corymbiferin from Swertia bimaculata In Vitro and In Vivo

The present study was to investigate the anti-diabetic activities of Swertia bimaculata. Based on the glucose consumption of S. bimaculata extractsand different fractions (petroleum, dichloromethane, ethyl acetate, n-butanol and water extracts) in 3T3-L1 adipocyte assay, ethanol (ETH) and dichloromethane (DTH) extracts had the most effective potency. Furthermore, ETH, DTH and corymbiferin (the most abundant component of DTH) were evaluated for anti-diabetic effects in high fat and sucrose fed combined with low dose streptozocin induced diabetic rats. DTH and corymbiferin displayed remarkable anti-diabetic activities. The fasting blood glucose levels were significantly decreased, while the serum insulin levels were obviously increased. The oral glucose tolerance was also improved. The lowed serum total cholesterol, low density lipoprotein (LDL) and triglyceride levels and increased ratio of HDL (high density lipoprotein)/LDL were observed. The insulin sensitivity was improved on the basis of increased expressions of insulin-receptor substrate-2, phosphatidylinositol 3-kinase and Ser/Thr kinase AKT2. And also DTH and corymbiferin improved antioxidant capacity and carbohydrate metabolism in diabetic rats, along with the improvement of histopathology of livers and pancreatic β cells. Corymbiferin was one of active constituents, responsible for anti-diabetic properties. Therefore, S. bimaculata could be considered as an alternative agent against diabetes mellitus