IJCS | Volume 32, Nº2, May/June 2019

242 Figure 2 - Electrochemical Index (EI) chart representing the sum of the I pa /E pa (A) rates and differential pulse voltammograms (B) obtained using carbon paste electrode for analysis of C (RJ) ( ─ ) and F (--) (SP), which presented the highest and the lowest potential of antioxidant activity, respectively. The white (...) was achieved in 0.01 M pH 7 sodium phosphate buffer. Britto Junior et al. Antioxidant and vasodilatory action of grape juices Int J Cardiovasc Sci. 2019;32(3)238-246 Original Article Regarding the mechanism of action, all juice samples tested revealed a major participation in the endothelial NO in the induction of relaxation, as L-NAME nearly completely inhibited relaxation (Figure 4). Only the RS (2) sample showed no difference (p > 0.05) after inhibition of NO with L-NAME, revealing an action mechanism unrelated to NO release by the vascular endothelium. Discussion The greatest finding of this study is that the grape juices marketed in Brazil do not have the same functional properties. Its antioxidant capacities, phenolic compound concentration and vasodilator activity are different among samples tested fromdifferent regions. Moreover, the vasodilatory capacity of grape juice is not equivalent to the red wine-induced dilation, except for one sample (obtained from RJ). To investigate some factors that may influence the antioxidant power and health-related benefits of different grape juices produced in Brazil, the sampling included juices from different geographical locations. The first finding is that the samples have different antioxidant properties, which can also be seen in other beverages such