A Study Of The Anti-diabetic Effects And Mechanism Of Cydonia Oblonga Mill Leaf Total Flavonoid

Objective: To observe the effects of the total flavonoids of Cydonia Oblonga Mill leaf(thereinafter referred to as COM) on the blood glucose and lipids of experimental diabetic rats.Methods:1. The rats were given a high-carbonhydrate and high-fat diet for four weeks and built as experimental diabetic models with small-dose peritoneal injections of STZ. The models were then randomly divided into the following groups- model, Metformin(200mg/kg), high(160mg/kg), medium(80mg/kg), and low(40mg/kg) dosage of total flavonoids of the COM leaf. Healthy rats from the same source were selected as contrasts. After 5 weeks of intragastric administration, we observed the effects of the two types of extract on fasting blood glucose(FBG), glycosylated serum protein(GSP) and serum insulin(INS) of diabetic rats, and measured serum TC, TG, HDL-C and LDL-C with automatic biochemistry analyser. 2. Changes in the levels of SCr, SOD, MDA and GSH-PX in the serum of rats in each group were measured, along with the levels of ALT and AST, the levels of MDA, IL-6 and TNF-α and the activity of SOD. Liver and kidney indexes were calculated to study the effects of COM extract on the functions of the liver and kidney of diabetic rats. Meanwhile, pathologic examinations were conducted on the liver and kidney tissue. 3. Levels of 24-hour microalbuminuria(m ALB) and of TXB2 and 6-keto-PGF1α in blood plasm were measured in each group.Results:After five weeks of medication, 1. High dosage of total flavonoids of the COM extract could inhibit the decrease in the rats’ weight and significantly lower the liver and kidney coefficient of diabetic rats(P<0.01). 2. Compared with the models, medium and high dosage of total flavonoids of the COM leaf extract could reduce the level of total cholesterol(TC), triglyceride(TG), and low density lipoprotein-cholesterol(LDL-C) inthe blood serum(P<0.01), and MDA levels in the blood serum(P<0.01). Each group of the total flavonoid extract of the COM leaf could considerably inhibit the activity of ALT and AST(P<0.05, P<0.01). Medium and high dosage of the COM leaf extract could enhance the activity of GSH-PX(P<0.05). 3. Medium and high dosage of total flavonoids of the COM leaf extract could considerably reduce the level of FBG(P<0.05), and a high dosage could dramatically lower the level of serum insulin(P<0.01), and could reduce the level of GSP(P<0.05).Conclusion:Total flavonoids of the COM leaf could have the capacity of reducing the level of blood glucose and lipid, and could improve the blood glucose and lipid disorders in the diabetic rats.