Role of allium sativum in the protection against oxidative stress and associated biochemical changes in streptozotocin-induced diabetes in rats

Oxidative stress is involved in both pathogenesis and complications of diabetes. The need to identify agents with a potential for preventing such damage and complication has assumed great importance. The present study was devoted to the assessment of the effect of chronic oral administration of raw garlic homogenate on oxidative stress and associated biochemical changes in streptozotocin [STZ]-induced diabetic rats. Male Sprague- Dawley rats weighing 180-200 g were used. Rats were divided into four groups 6 rats each. Group 1: is a control group in which rats received only 0.5 ml of vehicle [citrate buffer pH 4.5] as a single intraperitoneal [i.p.] dose. Group II: in which rats were treated orally with 20% raw garlic homogenate in distilled water in a dose of 500 mg/kg once a day for 30 days. Group III: rats were treated with 0.5 ml 2.4% solution STZ in citrate buffer in a single i.p. dose of 60 mg/kg. Group IV: rats were treated with 0.5 ml 2.4% solution STZ in citrate buffer in a single i.p. dose of 60 mg/kg, plus orally with 20% raw garlic homogenate in distilled water in a dose of 500 mg/kg once a day for 30 days. Blood aliquots were collected for serum separation. Serum levels of glucose, aspartate aminotransferase [AST], alanine aminotransferase [ALT], alkaline phosphatase [ALP], bilirubin, urea and creatinine as well as total cholesterol, LDL-cholesterol, VLDL-cholesterol and triglycerides were evaluated. HDL-cholesterol was also determined. The animals were then sacrificed and specimens were taken from the liver and kidney tissues and tissue homogenates were separated for determination of oxidative stress and antioxidant parameters such as malondialdehyde [MDA], reduced glutathione [GSH] and catalase [CAT] levels. Chronic oral administration of raw garlic homogenate produced a significant reduction in the serum levels of glucose[P<0.01], AST [P<0.05], ALT[P<0.05], ALP [P<0.05], bilirubin [P<0.01], urea [P<0.01] and creatinine [P<0.05] in STZ-induced diabetic rats. Furthermore,there was a significant decrease in total serum cholesterol [P<0.05], LDL-cholesterol [P<0.01], VLDL-cholesterol [P<0.05], and triglycerides [P<0.05] and a significant increase in HDL-cholesterol [P<0.01] as compared to STZ -induced diabetic group. On the other hand, hepatic and renal MDA were significantly reduced, [P<0.01] and [P<0.05], respectively. Also, there was a significant increase in both hepatic [P<0.01] and renal [P<0.05] GSH levels and catalase activity [P<0.001] as compared to STZ-induced diabetic rats. Chronic oral administration of raw garlic homogenate attenuates oxidative stress and associated biochemical changes in STZ-induced diabetic rats