Antidiabetic activity of isoquercetin in diabetic KK -Ay mice

Background: Tartary buckwheat bran is an important natural source of quercetin and isoquercetin. Quercetin and isoquercetin are both powerful alpha-glucosidase inhibitors. Although the IC50 of isoquercetin as alpha-glucosidase inhibitor was much higher than that of quercetin, the bioavailability of isoquercetin was higher than that of quercetin. Hence, we are interested in the antidiabetic effect of isoquercetin in diabetic KK -A(y) mice. Methods: The hypoglycemic effect of isoquercetin in a type 2 diabetic animal model (KK-A(y) mice) was studied. Isoquercetin was administrated at doses of 50, 100 and 200 mg/kg for 35 days. Results: It was found that fasting blood glucose concentration was decreased with the 200 mg/kg group (p < 0.01) the most efficient compared with the diabetic control group. In addition, there was significant decrease in plasma C-peptide, triglyceride, total cholesterol and blood urea nitrogen levels after 35 days. Meanwhile, glucose tolerance was improved, and the immunoreactive of pancreatic islets beta-cells was promoted. Conclusions: These results suggest that isoquercetin had a regulative role in blood glucose level and lipids, and improved the function of pancreatic islets. Isoquercetin may be useful in the treatment of type 2 diabetes mellitus.