Antihyperglycaemic, antilipid peroxidative and antioxidant effects of gallic acid on streptozotocin induced diabetic Wistar rats

The present study aims to evaluate the antihyperglycaemic, antilipid peroxidative and antioxidant effects of gallic acid on streptozotocin induced diabetic male Wistar rats. To induce diabetes mellitus, rats were injected with streptozotocin intraperitoneally at a single dose of 40 mg/kg. Streptozotocin induced diabetic rats showed significant ( P < 0.05) increase in the levels of blood glucose, glycosylated haemoglobin and significant ( P < 0.05) decrease in the levels of plasma insulin, body weight and total haemoglobin. Diabetic rats also showed significant ( P < 0.05) decrease in the activity of hepatic hexokinase and significant ( P < 0.05) increase in the activities of glucose-6-phosphatase and fructose-1, 6-bisphosphatase. The pancreatic thiobarbituric acid reactive substances and lipid hydroperoxides were significantly ( P < 0.05) increased and the activities of pancreatic superoxide dismutase, catalase and glutathione peroxidase were significantly ( P < 0.05) decreased in diabetic rats. Oral treatment with gallic acid (10 and 20 mg/kg) daily for a period of 21 days showed significant ( P < 0.05) protective effects on all the biochemical parameters studied. Histopathology of pancreas confirmed the protective effects of gallic acid in diabetic rats. In vitro study also revealed the potent antioxidant effect of gallic acid. Thus, the study shows the antihyperglycaemic, antilipid peroxidative and antioxidant effects of gallic acid on streptozotocin induced diabetic rats. The effect exerted by 20mg/kg body weight of gallic acid was more effective than 10 mg/kg body weight of gallic acid.