Resveratrol, a natural phytoalexin: a therapeutic promise for metabolic disorders in streptozotocin-nicotinamide induced type 2 diabetic rats

ABSTRACT

Resveratrol, a natural phytoalexin, has demonstrated a wide variety of biological activities, which make it a good candidate for treatment of diabetes mellitus. The present study was aimed to evaluate the properties of resveratrol [RSV] as an antidiabetic agent in streptozotocin-nicotinamide [STZ-NIC] induced Type2 diabetes model. Furthermore, the antidiabetic nature of resveratrol was compared with glyclazide, an oral standard antidiabetic drug. This study includes 40 male albino rats divided into 5 groups control, control+resveratrol, diabetic, diabetic+resveratrol and diabetic+ glyclazide. The antidiabetic effect of oral administration of RSV [5mg kg/b.wt] for 45days was evidenced from the improvement in the levels of blood glucose, glycosylated hemoglobin and the calculated homeostasis model assessment of insulin resistance. The significant decrease [p<0.05] in plasma insulin level exhibited in the diabetic rats was not affected by RSV treatment, indicating that the hypoglycemic effect of RSV is independent of insulin. The altered activities of key enzymes of carbohydrate metabolism such as glucokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase and glycogen synthase in liver tissues of diabetic rats were all significantly reverted [p<0.05] to near normal levels by administration of RSV. Hyperlipidemia observed in the diabetic group of rats was markedly alleviated by oral treatment with RSV. Lastly, STZ-NIC induced diabetic rats orally treated with RSV had significantly lower [p<0.05] plasma homocystein level and significantly higher [p<0.05] serum folic acid and vit. B12 levels than the untreated ones indicating improvement in the endothelial function in those rats. The present study suggests that STZ-NIC induced diabetes is an excellent model for type2 diabetes, and that RSV is an effective therapeutic agent for treatment of type 2 diabetes mellitus