Angelique Arcambal
University of Reunion, France
Title: Protective antioxidant effects of polyphenols extracted from the French medicinal plant Antirhea borbonica on cerebral endothelial cells exposed to diabetes-related hyperglycemia
Biography
Biography: Angelique Arcambal
Abstract
Type-2 diabetes promotes vascular complications, leading to neurological disorders such as stroke. Indeed, hyperglycemia alters the blood-brain barrier integrity by deregulating the cerebral endothelial cell function. Oxidative stress may play a causal role. Thus, the biological effect of plant polyphenols known to exert antioxidant capacities is of high interest. We evaluated the effect of polyphenols from the medicinal plant Antirhea borbonica referred in the French Pharmacopeia for antidiabetic properties, on the production of redox and vasoactive markers from cerebral endothelial cells exposed to hyperglycemia. Polyphenols extracted from Antirhea borbonica were identified by UPLC-MS method. Then, their action on murine bEnd.3 cerebral endothelial cells exposed to hyperglycemia was determined by measuring the intracellular levels of free radicals (DCFH-DA assay), SOD activities (enzymatic assay) and the production of redox and vasoactive molecules (RT-qPCR, DAF-FM assay). We found that Antirhea borbonica exhibited a high content (4%, w/w) of polyphenols including caffeic acid, chlorogenic acid, kaempferol and quercetin. Plant polyphenols decreased hyperglycemia-induced production of free radicals and NADPH oxidase 4 gene expression. Moreover, plant polyphenols counteracted the deregulation of Cu/ZnSOD activity and Nrf2 redox transcriptional factor gene expression mediated by hyperglycemia. Preconditioning of cells with specific inhibitors targeting the signaling molecules JNK, ERK, PI3K and NFκB modulated hyperglycemia-induced oxidative stress and showed their possible involvement in polyphenol action. Polyphenols also abrogated hyperglycemia-mediated down-regulation of the intracellular levels of NO vasodilatator. Interestingly, caffeic and chlorogenic acids detected among the major polyphenols of Antirhea borbonica exerted similar protective effects. Collectively, these findings demonstrated that polyphenols extracted from Antirhea borbonica protected cerebral endothelial cells against hyperglycemia-mediated oxidative stress. Further studies are in progress to evaluate the in vivo benefits of plant polyphenols on a mouse model exposed to hyperglycemia and middle cerebral artery occlusion to mimic a cerebral ischemia during type-2 diabetes.