Antioxidant potential of zinc-flavonol complex studied in streptozotocin-diabetic rats

Background: Diabetic oxidative stress coexists with a reduction in the antioxidant status, which can further increase the deleterious effects of free radicals. Zinc is an essential trace element with significant antidiabetic activity. However, the acceptance of zinc compounds as promising therapeutic antidiabetic agents has been slowed due to concerns regarding chronic toxicity. Recently, we have designed, synthesized and characterized a novel zinc flavonol complex and evaluated its antidiabetic efficacy in streptozotocin (STZ)-diabetic rats. The aim of the present study was to evaluate the role of the zinc flavonol complex in the antioxidant status of diabetic rats. Methods: Diabetes was induced in rats by i.p. injection of STZ. Diabetic rats were then treated with the zinc flavonol complex (5 mg/kg, p.o.) for 30 days. The extent of oxidative stress was assessed by determining lipid peroxide levels, pancreatic tissue antioxidant enzyme activities and plasma concentrations of non-enzymatic antioxidants. In addition, nuclear levels of nuclear factor (NF)-kappa B p65, pancreatic nitric oxide (NO), and plasma levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta and IL-6 were determined. Pancreatic tissues were examined histologically. Results: Oral treatment with the zinc-flavonol complex significantly improved antioxidant levels and alleviated levels of oxidative stress markers. Furthermore, significant increases were seen in NF-kappa B p65, NO, TNF-alpha, IL-1 beta and IL-6 levels. Histological observations revealed that the zinc flavonol complex effectively protects pancreatic beta-cells against oxidative damage. Conclusion: The results of the present study indicate that the zinc flavonol complex has an antioxidative and anti-inflammatory role in the diabetic milieu.