Anti-diabetic and anti-oxidant potential of aged garlic extract (AGE) in streptozotocin-induced diabetic rats

BACKGROUND Although aged garlic extract (AGE) shares some active components with fresh garlic and in spite of its palatability and milder side effects, the anti-diabetic and related anti-oxidant properties of AGE have not been investigated extensively, and the reported findings are inconsistent. This study investigated the anti-diabetic effects of 3 incremental doses of AGE in streptozotocin (STZ)-induced diabetic rats (fasting blood sugar > 20 mM). METHOD Diabetic rats were divided into a control diabetic group (CD) and AGE-treated diabetic group (AGE-D). The AGE-D was divided into 3 groups and accordingly treated with AGE i.p. at 100, 300 and 600 mg/kg daily for 8 weeks. A control normal group (CN) was also included for reference. RESULTS Compared to the CN group, the CD group showed significant loss of body weight (over 50 %); and decreased serum insulin concentration (10 fold) and total anti-oxidant level and catalase activity (45-70 %) in serum, kidney and liver. Conversely, the CD rats had an elevated blood glucose (nearly 4 fold), serum cholesterol (nearly 2 fold) and triglycerides (>2 fold), erythrocyte glycated hemoglobin (GHb, 3 fold) and kidney and liver lipid peroxidation (MDA levels). Treatment with AGE positively reversed the diabetic changes in the targeted parameters to levels significantly lower than those measured in the CD group and the degrees of attenuation were almost dose dependent especially with the two higher doses. CONCLUSION AGE exhibits a dose-dependent ameliorative action on indicators of diabetes in STZ-induced diabetic rats.