Hypoglycemic and hypolipidemic action of Du-zhong (Eucommia ulmoides Oliver) leaves water extract in C57BL/KsJ-db/db mice

The anti-diabetic efficacy of Du-zhong (Eucommia ulmoides Oliver) leaves water extract (WDZ) was investigated in type 2 diabetic animals. The WDZ was given to C57BL/KsJ-db/db mice as a dietary supplement based on 1% dried whole Du-zhong leaves (0.187 g WDZ/100 g standard diet) for 6 weeks. The WDZ supplementation significantly lowered the blood glucose level and enhanced the glucose disposal in an intraperitoneal glucose tolerance test. The plasma insulin and C-peptide levels were significantly higher in the WDZ group than in the control group, while the glucagon level was lower. The hepatic glucokinase activity was significantly higher in the WDZ group, whereas, the glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities were significantly lower. The WDZ supplementation also significantly lowered the hepatic fatty acid synthase, HMG-CoA reductase and ACAT activities compared to the control group, while it elevated the lipoprotein lipase activity in the skeletal muscle. The WDZ also altered the plasma and hepatic lipid levels by lowering the cholesterol and triglyceride concentrations, while elevating the plasma HDL-cholesterol level. Therefore, these results suggest that WDZ may partly ameliorate hyperglycemia and hyperlipidemia with type 2 diabetes through increasing glycolysis, suppressing gluconeogenesis and the biosynthesis of fatty acid and cholesterol in the liver.