Potential Antidiabetic and Hypolipidemic Effects of Propolis Extract in Streptozotocin-induced Diabetic Rats

Free radicals have been implicated in the pathogenesis of diabetes mellitus leading to various complications including atherosclerosis. Propolis was reported to have oxygen radical scavenging activity. The present study was designed to investigate the possible antidiabetic, hypolipidemic and antioxidant effects of ethanolic extract of propolis (EEP). Type capital I, Ukrainian diabetes was induced in rats by injection of streptozotocin (STZ) in a dose of 60 mg/kg bwt, i.p. for 3 consecutive days. After 5 weeks of STZ injection, there were an apparent reduction in the animal body weight amounting to 21% and significant increases in serum glucose (184%), triglycerides (63%), total cholesterol (43%) and low density lipoprotein-cholesterol (LDL-C) (148%) with a concomitant decrease in serum high density lipoprotein-cholesterol (HDL-C) (51%) as compared to the control normal group. In addition, there was significant elevation in pancreatic lipid peroxides measured as malondialdehyde (MDA) and serum nitric oxide (NO) amounting to 185% and 224%, respectively with marked reduction in serum reduced glutathione (GSH) and catalase (CAT) (66% and 31%, respectively) and pancreatic superoxide dismutase (SOD) (54%) in STZ-treated rats. On the other hand, oral daily treatment of animals with EEP in a dose of 200 mg/kg bwt for a period of 5 weeks ameliorated STZ-induced alterations in the animal body weight as well as in serum glucose, lipids, lipoproteins, NO, GSH & CAT and pancreatic MDA & SOD. In conclusion, propolis extract offers promising antidiabetic and hypolipidemic effects that may be mainly attributed to its potent antioxidant potential. Further studies will be needed in future in order to determine which one(or more) of its active constituents has the main antidiabetic and hypolipidemic effects.