Chronic administration of Satsuma mandarin fruit (Citrus unshiu Marc.) improves oxidative stress in streptozotocin-induced diabetic rat liver.

Fruits and vegetables contain numerous antioxidants such as carotenoids, vitamins, and phenolic phytochemicals. Recent studies have demonstrated that antioxidants may reduce the risk for diabetes or its complications. In this study, we investigated the effects of the chronic administration of Satsuma mandarin fruit on an antioxidant defense system in streptozotocin (STZ)-induced diabetic rat liver. After a ten-week administration of Satsuma mandarin, antioxidant enzymes and glutathione levels in the liver were evaluated. The superoxide dismutase (SOD), catalase, and glutathione-peroxidase (GPx) activities, and glutathione level in the STZ-induced diabetic rats liver decreased significantly compared with those in the age-matched normal rats. The glutathione-reductase (GR) activities did not differ significantly between these two groups. In contrast, the SOD, GR, and glutathione levels in the Satsuma mandarin (1% or 3%) diet-fed STZ-diabetic rat livers were significantly higher than those in the normal diet-fed STZ-diabetic rat livers. In addition, although the serum alanine aminotransferase and gamma-glutamyl-aminotransferase concentrations of normal diet-fed STZ-diabetic rats were significantly higher than those of the age-matched normal rats, these increments of serum liver enzymes were diminished by the chronic administration of Satsuma mandarin. These results suggest that Satsuma mandarin may act as a suppressor against liver cell damage and inhibit the progression of liver dysfunction induced by chronic hyperglycemia.