The purpose of this study is to evaluate the capacity of lycopene against diabetes-induced oxidative damage in Wistar rats. Thirty Wistar rats of both sexes, twenty-five of which were diabetic, were used. Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ) 60 mg/kg body weight and it was confirmed by the elevated blood glucose ≥200 mg/dl after three days. The rats were divided randomly into groups 1 to 6, each containing 5 rats. Group 1 (Normal control) and Group 2 (Diabetic control) rats were administered 0.5 ml of olive oil; Groups 3, 4, and 5 rats were, respectively, administered 10, 20, and 40 mg/kg body weight of lycopene, while Group 6 rats were administered 2 mg/kg body weight of Glibenclamide. All administrations were done orally and once daily for twenty-eight days. At the end of the treatment, serum levels of antioxidant enzymes, cortisol and malondialdehyde (MDA) were determined. Administration of graded doses of lycopene to diabetic animals significantly (P<0.05) decreased the blood glucose concentration after four weeks of treatment when compared to diabetic untreated animals. Serum levels of cortisol and MDA (index of oxidative stress) were reduced while there were up-regulated activities of serum endogenous enzymes (superoxide dismutase, catalase and glutathione peroxidase) in diabetic animals treated with all doses of lycopene when compared with diabetic untreated animals. Overall, lycopene attenuated the biomedical alterations in STZ-induced diabetic Wistar rats. Lycopene therefore possesses antioxidant activity at the doses tested in this study.
Key words: Lycopene, diabetes mellitus, oxidative stress, cortisol, malondialdehyde, catalase, glutathione peroxidase.