Preparation of Plant ExtractThe fruits of jambolana were first washed well and pulp was removed from the seeds. Seeds were washed several times with distilled water to remove the traces of pulp from the seeds. The seeds were dried at room temperature. The kernel of the seeds was selectively separated from the seed coat. The kernel was powdered in an electrical grinder and stored at 5°C until further use. Kernel powder (100 g) was extracted with petroleum ether (60-80°C) to remove lipids. It was then filtered and the residue was extracted with 95% ethanol by Soxhlation. Ethanol was evaporated in a rotary evaporator at 40-50°C under reduced pressure. The yield of kernel was Ϫ3.2 g/100 g. Animals Male albino Wistar rats, weighing about 150-180 g obtained from Tamil Nadu Veterinary and Animal Sciences University, Chennai, India were used for the present investigations. The animals were maintained on standard rat Oxidative stress plays an important role in chronic complications of diabetes. In the present study the antioxidant effect of oral administration of ethanolic extract of Eugenia jambolana seed kernel on tissue antioxidant enzymes and lipid peroxidation in liver and kidney of streptozotocin-induced diabetic rats was evaluated. Administration of seed kernel to diabetic rats significantly decreased the levels of blood glucose, glycosylated hemoglobin and increased body weight gain, plasma insulin and hemoglobin. The diabetic rats showed the low activities of superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione content in liver and kidney, which were restored to near normal levels by treatment with the seed kernel extract. The increased levels of lipid peroxidation and hydroperoxides in diabetic rats were reverted back to near normal levels after the treatment with seed kernel extract. Diabetic rats treated with seed kernel extract restored almost normal architecture of liver and kidney and were confirmed by histopathological examination. The present study reveals the efficacy of Eugenia jambolana seed kernel in the amelioration of diabetes, which may be attributed to its hypoglycemic property along with its antioxidant potential. The antioxidant effect of Eugenia jambolana seed kernel was also compared with glibenclamide, a standard hypoglycemic drug.