Study on hypoglycemic effect and mechanism of total flavonoids of Propolis in STZ diabetic rats

Objective: To study hypoglycemic effect and mechanism of the total flavonoids of Propolis (TFP) in the STZ diabetic rats.

Methods: The model of type 2 diabetic rats was induced by high-fat diet feeding for 4 weeks combined with intraperitoneal injection of streptozotocin (STZ). Then the rats without above-mentioned treatment were selected as the normal control group,the diabetic rats were randomly divided into four groups by blood glucose, the model control group, high doses (240 mg/kg), medium doses (120 mg/kg) and low doses (60 mg/kg) TFP groups. The TFP preparation was intragastric administration given to rats in TFP groups. The model control rats were treated intragastric administration with 0.5% sodium carboxymethyl cellulose (CMC-Na) for 4 weeks. The rats were fed with high fat diet during treatment. 12 hours after the last administration, glucose (GLU), total cholesterol (TC), triglyceride (TG), high density lipoprotein( HDL-C), low density lipoprotein LDL-C), glycated hemoglobin (GHb), serum insulin INS), C-peptide (C-P), superoxide dismutase( SOD), malondialdehyde (MDA), glutathione (GSH), tumor necrosis factor-alpha (TNF-alpha), free fatty acid (FFA), nitric oxide (NO), and hepatic glycogen were determined.

Results: Compared with the normal group, the levels of GLU, TC, TG, HDL-C, FFA, TNF-alpha, NO, MDA and GHb in serum were increased significantly in the model control group (P < 0.05-P < 0.001), the levels of HDL-C, INS, C-P, SOD and GSH in serum and hepatic glycogen in hepatic tissue were decreased significantly (P < 0.01 or P < 0.001). The levels of all above indexes of high and medium doses groups were improved significantly compared with the model control group (P < 0.05-P < 0.01).

Conclusions: TFP can significantly decrease the level of blood glucose,improve the glucose and lipid metabolism and inhibit insulin resistance in STZ diabetic rats.