Effects of Oral Aged Garlic Extract (AGE) on Indicators of Diabetes and Oxidative Stress in Streptozotocin‐Induced Diabetic Rats

Abstract

The anti‐diabetic and antioxidant effects of oral administration of aged garlic extract (AGE) were studied in diabetic rats. Diabetes was induced by IP injection of streptozotocin (60mg/kg, STZ), and a fasting blood sugar >300 mg/dl indicated diabetes. AGE (Wakunaga‐Kyolic, USA) was administered orally at a dose of 600 mg/kg daily for 8 weeks. Diabetic rats were divided into 2 groups, diabetic control and AGE‐treated diabetic. A normal, saline‐treated, control group was also included. STZ‐induced diabetic rats lost significant weight during the experiment with AGE‐treated rats maintaining their initial weights. Blood glucose as well as serum cholesterol and triglycerides were significantly elevated in diabetic rats, and significantly lowered by AGE treatment. Serum insulin level was decreased nearly 30‐fold in diabetic rats and was increased significantly by AGE treatment; while serum fructosamine was increased about 2.5 fold in diabetic rats with a marked decrease in AGE‐treated diabetic rats. Significant decreases in total antioxidant levels (26‐39%) and catalase activity (50‐71%) were observed in serum, kidneys and livers of diabetic rats with significant recovery in AGE‐treated animals. In contrast, lipid peroxidation (MDA levels) increased in kidneys (57%) and livers (44%) of diabetic rats and was significantly lowered in AGE‐treated diabetic rats. Protein levels in serum, liver and kidneys were significantly lowered in diabetic rats with increased levels in AGE‐treated rats. Thus, oral AGE treatment was effective in ameliorating oxidative stress and other indicators of diabetes in STZ‐induced diabetic rats. The study was supported by KU grant #SL 06/13.