Antidiabetic effects of Swertia macrosperma extracts in diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Swertia macrosperma is a traditional folk medicine used for its anti-hepatitis, antipyretic and antidotal effects as "Dida" or "Zangyinchen" in Tibet, Yunnan and Guizhou province for a long time, and it has been reported for its anti-diabetic effects in a Chinese patent. Swertia macrosperma was reported rich in xanthones, iridoids, seco-iridoids and their glycosides, several of which had been documented as potential antidiabetic agents. The objective of this study was to investigate the antidiabetic effect of Swertia macrosperma in diabetic rats. MATERIALS AND METHODS: This study was designed firstly to evaluate the effect of Swertia macrosperma on glucose consumption in HepG2 cells. Based on the result in HepG2 cells, the antidiabetic effect of ethanol extract (EE) and n-butanol extract (BE) were investigated in diabetic rats induced by high fat fed and streptozotocin. The effects of EE and BE on fasting blood glucose, oral glucose tolerance test, serum insulin, glycosylated hemoglobin, serum lipid level, serum antioxidant parameters, glucokinase, glucose-6-phosphatase activities and glycogen content in liver tissue were measured, histology examination of pancreatic tissue was also carried out. RESULTS: After 4 weeks treatment with EE and BE, apparently decreased fasting blood glucose concentrations were observed in these treated groups, compared with the diabetic control groups. Additionally, improvement in serum antioxidant parameters and lipid profile were evidenced clearly. Moreover, EE and BE had effects of protecting the pancreatic ß-cells and stimulating insulin secretion from the remaining pancreatic ß-cells, evidenced by pancreatic histology examination. Increased glucokinase activity and decreased glucose-6-phosphatase activity were observed in liver. CONCLUSION: The results of in vivo and in vitro experiment suggested that EE and BE of Swertia macrosperma had excellent effects on controlling the hyperglycemia and hyperlipidemia in diabetic rats.

In vitro and in vivo anti-diabetic activity of Swertia kouitchensis extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Swertia kouitchensis has long been used as a folk medicine to treat hepatitis and diabetes in central-western China. Therefore, this study was aimed to evaluate the anti-diabetic activity of the plant ethanol extract. MATERIALS AND METHODS: Firstly, the extract was tested for its inhibitory activity on α-amylase and α-glucosidase in vitro. Following that, insulin secretion test in NIT-1 cell was performed. Then, oral sucrose or starch tolerance test of the extract were carried out in normal mice. After that, acute effect of the extract was executed in normal and streptozotocin-induced (60 mg/kg) diabetic mice. Eventually, long term effect of the extract was performed in diabetic mice for 4 weeks. Oral glucose tolerance test and biochemical parameters were estimated at the end of the study. RESULTS: Swertia kouitchensis extract could remarkably inhibit the activity of α-amylase and α-glucosidase and stimulate insulin secretion in vitro. And also the extract displayed anti-hyperglycemic activity, improved antioxidant capacity, ameliorated the hyperlipidemia and carbohydrate metabolism in diabetic mice. CONCLUSIONS: Swertia kouitchensis exhibits considerable anti-diabetic activity and metabolic alterations in diabetic mice. These results provide a rationale for the use of Swertia kouitchensis to treat diabetes mellitus.