Morin activates the Nrf2-ARE pathway and reduces oxidative stress-induced DNA damage in pancreatic beta cells.

Oxidative stress is an important factor contributing to the pathogenesis of diabetes and its complications. In our earlier study, we demonstrated the antidiabetic efficacy of morin by regulating key enzymes of carbohydrate metabolism in diabetic rats. The present study was designed to assess the antigenotoxic potential of morin in pancreatic β-cells, using the COMET assay. To explore its potential mechanisms of action, three genotoxic agents, HO which induces DNA damage by the generation of reactive oxygen species, streptozotocin (STZ) by RNS and Methyl methanesulfonate (MMS) by DNA alkylation was used. We found that STZ and HO- induced genotoxicity was dose dependently reduced by morin as assessed by DNA tail length, tail moment, DNA content and olive moment. Since the protective property was found to be specific against oxidative DNA damage, we explored the molecular mechanism underlying morin-induced Nuclear factor erythroid 2-related factor 2 (Nrf2) activation in pancreatic β-cells as assessed by ARE-driven downstream target genes with Luciferase reporter assay. In addition, morin inhibited intracellular free radical generation as assessed by using DCFDA and increased the intra cellular antioxidants viz, superoxide dismutase and catalase in INS-1E cells. In addition, morin attenuated glucose-stimulated insulin secretion following exposure to oxidative stress by STZ (P<0.05). Collectively, our data provide evidence that morin protects pancreatic β-cells against oxidative stress-induced DNA damage by activating the Nrf2 signaling pathway.