| Objective: The present study was to investigate the anti-diabetic effect ofpotentilla flavone on alloxan-induced diabetic mice and streptozotocin-induceddiabetic rats, and to explore the anti-diabetic effect and its mechanisms of potentillaflavone.Methods: 1 .Mice were initated with intervenous injection 65mg/kg alloxan toestablish diabetic model mice, the alloxan-diabetic mice and normal mice wereequally divided into 10 groups according to body weight and FBG. Different polarityfraction were given intragastrically for successive 15 days,once a time. Fast bloodsugar was measured using GOD method to screen anti-diabetic active component.2. A main flavonoid constituent, named potentilla flavone of the anti-diabeticactive fraction F were isolated by the methods of silica gel column chromatographyand preparative high performance(HPLC). Anti-diabetic effects were observed byusing alloxan-induced diabeticmice, screen anti-diabetic active constituent.3. Diabetic animal models were induced by the intervenous injection of alloxan(70mg·kg-1) in mice, the alloxan-diabetic mice and normal mice were equally dividedinto 7 groups. The above groups were given intragastrically the potentilla flavone forsuccessive 15 days and then blood samples were taken to determine blood glucose,TG and TC. Made the pancreatic gland pathological section to observe pancreasorganization through optics microscope. Pathologic changes of pancreatic tissues ineach group were observed.4. Male type 2 diabetic model rats were induced by feeding with high glucose andfat diet together with intervenous injection of 35mg/kg STZ and then intragastricallythe potentilla flavone for 10 weeks. Then we observed the effects of the testedcomponent on glycometabolism, lipid metabolism, oral glucose tolerance, pancreaspathomorpholgoy change, serum SOD, MDA level in diabetic mice.5. According to the purpose of the experiment, type 1 diabetic model was inducedby STZ(60mg/kg)in rats and then intragastrically given the potentilla flavone for 4weeks. Then the effects of the tested component on glycometabolism, lipidmetabolism, antioxidation capability, pancreas pathomorpholgoy change in diabeticrats were observed.Results: 1 .In the anti-diabetic experiment, fraction F revealed significantlypoglycemic effect comparing with the phenformin group(P＜0.01),and their reduction rates were 32.97% for the fraction F group and 33.30% for the phenformin group.This observation suggests that potentilla flavone is an anti-diabetic active fraction.2. A main constituent was isolated from the fraction F. By using spectroscopicmethod, the strueture was elucidated as a flavonoid, named poteniilla flavone. Inthe anti- diabetic experiment, potentilla flavone revealed the significanthypoglycemic effect in alloxan-induced diabetic mice, its reduction rate of bloodglucose was 52.19%, and reduction rate of phenformin group was 29.26%. The aboveobservation suggests that potentilla flavone is an anti-diabetic active constituent.3. The results showed that potentilla flavone can decrease significantly the levelof the blood sugar, TG and TC. The observation indicated potentilla flavone candecrease blood sugar and improve the lipid decompensation in mice. Pathologic resultof pancreas islet indicated that potentilla flavone has repair effects. potentilla flavonehas the effect of decreasing blood glucose and serum lipid of the diabetic mice butshows no effects on blood glucose and serum lipid of normal mice. The FBG andTC,TG level in trans-potentilla flavone and cis-potentilla flavone-treated group withsame dosage show no difference. The result of morphyology pancreas isletβcellshow that it can restore the histology structure of damaged pancreas isletβcell.4. Diabetic model rats were induced by combination of high-fat-sugar diet for 8weeks and low dose streptozotocin (STZ, 30mg/kg iv) injection in SD rats. Diabeticrats were randomly divided into 5 groups and normal group. After being given drugsor distilled water for 10 weeks, the levels of FBG, serum lipid, serum MDA and theactivity of SOD were measured. The blood sugar in rat at 0, 30, 60, 120 and 180minute after taking glucose were measured. Furthermore, pathologic changes ofpancreatic tissues in each group were observed. Experimental results indicate thatpotentilla flavone can lower blood glucose levels and significantly lower the level ofserum cholesterol, triglyceride and increase high-density lipoprotein level. Thepotentilla flavone group is able to enhance the SOD activity, reduce the production ofMDA(P＜0.05, P＜0.01) and lower 30, 60, 120 and 180min BG after OGTT ascompared with the diabetic model group, the difference is significant(P＜0.05). HEstaining of pancreas shows that potentilla flavone can improve pancreatic injury indiabetic mice.5. The results showed that potentilla flavone can improve glycometabolism bydecreasing the level of FBG and increasing hepatic glycogen content. The content oftotal cholesterol, LDL-C, FFA level was rectified and HDL-C content in serum increased, so lipid metabolism was improved. Promote the antioxidant capability byincreasing the activity of SOD and low the content of MDA in serum of diabetic rats.The research results suggest that potentilla flavone can improve glycometabolismand lipid metabolism, promote antioxidant capability, protect the islet cell injury thatwas induced by streptozotocin and improve the impaired glucose tolerance. Therefore,potentilla flavone will be expected to develop a promising natural product to treatdiabetic mellitus and its complications. |
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