IBIMOL   23987
INSTITUTO DE BIOQUIMICA Y MEDICINA MOLECULAR PROFESOR ALBERTO BOVERIS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Vascular effects of flavan-3-ols: direct antioxidant mechanisms in vitro and ex vivo
Autor/es:
LITTERIO MC; GORZALCZANY SB; FRAGA CG; GALLEANO M
Lugar:
Buenos Aires
Reunión:
Congreso; VIII Meeting of the Society Free Radical Biology and Medicine; 2013
Institución organizadora:
Society for Free Radical in Biology and Medicine-South American Group
Resumen:
Flavonoids are one of the most abundant family of polyphenols present in human diet. Flavan-3-ols (a subfamily of flavonoids) consumption has been associated with improved endothelial function and decreased blood pressure. Being the benefits of flavan-3-ols on human health often ascribed to their antioxidant activities, we analyzed their ability to scavenge free radicals. (-)-Epicatechin and (+)-Catechin, flavan-3-ols of nutritional relevance, were evaluated as peroxyl radical (ROO) scavengers by an EPR technique. Both compounds were highly efficient scavenging ROO as indicated by the calculated second order rate constants. However, the reaction rate of flavan-3-ols was significantly lower than those for physiological compounds (glutathione, ascorbate and uric acid), considering the intracellular/plasma concentrations. As scavengers in vitro, both flavan-3-ols showed a CE50 ≈ 0.3 µM. Nevertheless, when scavenging capacity was measured ex vivo, in aorta rings, it was necessary a higher flavan-3-ol concentration to be effective. Incubation of aortic rings with flavan-3-ols showed a 2-fold increase in endothelial nitric oxide synthase phosphorylation at Ser1177, which is an activation site of the enzyme. These results suggest that based on kinetic considerations, specific mechanisms (such as post-translational modifications of proteins) instead of unspecific antioxidant mechanisms should be responsible of the beneficial vascular effects ascribed to flavan-3-ols in humans and animal models.