Ethanolic Extract of Leaves of Newbouldia laevis Attenuates Glycosylation of Hemoglobin and Lipid Peroxidation in Diabetic Rats

Abstract

Diabetes is one of the major health problems around the world and the incidence of this metabolic disorder is on the increase. Current therapeutic interventions have not done much in preventing complications of diabetes. Therefore this study investigated the effect of ethanolic extract of Newbouldia laevis leaves (NLet) on lipid peroxidation and glycosylation of hemoglobin, which are pathological indicators of diabetes mellitus. Diabetes was induced in Wistar rats by intravenous injection of streptozotocin (60 mg kg^-1). Diabetic rats were then treated orally with NLet for 28 days. After the treatment, the concentration of Malondialdehyde (MDA) in the liver, kidney and pancreas of the rats was estimated. Fasting blood glucose was determined and oral glucose tolerance test was also carried out. Other groups of STZ-diabetic rats were treated for 8 weeks and percentage glycosylated hemoglobin (HbA1c) was measured. Fasting blood glucose of treated diabetic rats significantly (p<0.05) decreased in a dose-dependent manner when compared with untreated diabetic control rats. After oral glucose load, blood glucose level reached a peak at 60 min. In both non-diabetic and diabetic rats, treatment with the extract significantly (p<0.01) reduced the blood glucose level at 120 and 180 min. The percentage total hemoglobin glycated in diabetic rats significantly reduced (p<0.05) after the 8-week treatment with NLet. MDA concentration in the liver, kidney and pancreas of diabetic rats was also dose-dependently reduced by the extract. At 300 and 500 mg kg^-1, the reduction was significant (p<0.05) compared with the diabetic control. The effects of NLet were comparable to those observed with glibenclamide. The results of this study suggest that NLet can prevent the complications of diabetes that result from glycation of hemoglobin and lipid peroxidation.