Preparation And Anti-t2dm-ir Effects Of Flavonoid Rich Extract From Urtica Dentata Hand

Objective:To investigate the hypoglycemic and hypolipidemic effects of the flavonoid rich extract of Urtica dentata Hand(UDH) in a type 2 diabetic model related insulin resistance.Methods: The total flavones from the acetic ether extracts of Urtica dentata Hand were prepared by alkali extraction and acid precipitation methods and identified by color reaction of flavonoid, then quantitated by the standard curve. High-fat diet (HFD)and low dose streptozotocin (STZ) induced induced type 2 diabetic model was set up in BALB/c mice. The flavonoid rich extract (FRE) of UDH was administered orally at different doses (25, 100 mg/kg) every day and the level of blood glucose was observed. After 28 days, the activity of SOD, content of TG, TC, MDA in serum was detected. ELISA method was used to evaluate the levers of insulin. Pancreas tissues were taken for histopathologic analysis by H&E dyeing and the livers were also taken out to investigate the protein expression of insulin receptor and peroxisome proliferator-agonist receptorγ(PPAR-γ) using weternblot analysis.Result: A type 2 diabetic model was established by high-fat fed and STZ-injected. After 4 weeks'daily oral administration of FRE,a significant decrease on blood glucose levels in mice (P<0.01) was observed, and histopathology results revealed that there were no differences between groups. FRE at the dose of 25 mg/kg (FRE25) was found to be more effective on lowering serum total cholesterol, triglycerides and insulin resistance indices after 4 weeks'treatment. FRE25 significantly improved glucose tolerance (GTT) (P<0.05) as well. Normal appearance of pancreas was observed in all the mice and the level of insulin showed no significant changes except for the mice treated with FRE at the dose of 100 mg/kg(FRE100) and there was no marked changes in comparison to normal control in levels of SOD or MDA. Meanwhile, western blot analysis was used to investigate the protein expression of insulin receptor and peroxisome proliferator-agonist receptorγ(PPAR-γ). It was found that the expression of insulin receptor increased significantly in FRE25 treated mice. Conclusion:Therefore, our findings suggest that FRE could prevent mice from developing hyperglycemia and hyperlipemia by elevating insulin receptor and enhancing the activity of insulin not by stimulating the clearance of free radical. From the present study, we have indentified that flavonoids existed in the extract which is proved to have hypoglycemic and hypolipemic effect, on the other hand developed a insulin resistant type 2 diabetes model which is suitable for pharmacological screening and molecular mechanism study.