# Antiplatelet Activity of Phenolic Compounds-Fortified Merlot Wine and Pure Phenolic Compounds
## 4 Discussion
The results suggest that our extract does not inhibit platelet activation through glycoprotein VI (GPVI), which is the main collagen receptor, while its activity seems to be related to activation pathways through purinergic receptors and PAR1 (ADP and TRAP-6, respectively) [26]. F8 also inhibited the expression of p-selectin induced by the three agonists and the expression of GPIIb/IIA induced by ADP. Similar results were shown by [PERSON] et al., 2000; a procyanidin-enriched cocoa drink together with the administration of dealcohlized red wine resulted in a significant reduction in platelet activation (p-selectin and GPIIb/IIa) [32]. However, we would need additional studies to elucidate the way by which the wine extract induces the inhibition of platelet aggregation. Also, it was observed that individual phenolic compounds exhibit antiplatelet effects, with quercetin being the most prominent against the three agonists studied, while gallic acid did not show any antiplatelet effect. In addition to antiplatelet activity, the expression of the cell adhesion molecule p-selectin, which is associated with the risk of atherosclerosis and vascular disease, was assessed. Both the F8 wine sample and some of the phenolic compounds evaluated showed the ability to inhibit agonist-induced p-selectin expression, suggesting that this mechanism could contribute to the regulation of platelet aggregation. Research on the synergistic, additive, and antagonistic effects between phenolic compounds is also relevant to understanding how to optimize their use in therapeutic applications. Overall, these results support the importance of phenolic compounds in promoting a healthy diet and their potential benefit for cardiovascular health [33; 34]. Previous studies have shown that binary combinations of phenolic compounds have additive or antagonistic effects on the DPPH [14]. In this study, ten combinations of five independent phenolic compounds were evaluated to understand how they interact and whether they exhibit synergistic, additive, or antagonistic effects in inhibiting platelet aggregation. The phenolic compounds analyzed were quercetin, epicatechin, catechin, caffeic acid, and gallic acid. In our case, when platelet aggregation was stimulated with TRAP-6, there was an antagonistic effect, both for the flavonoid-flavonoid and flavonoid-phenolic acid binary combinations; the Querc/Epicat and Epicat/Cat mixtures showed a slight inhibition effect,and this was less than the independent quercetin. On the other hand, when aggregation was stimulated with ADP, the flavonoid-flavonoid and flavonoid-phenolic acid binary combinations generally showed a synergistic effect, while phenolic acid-phenolic acid had an antagonistic effect. When we studied the ADP-stimulated platelet aggregation of the individual pure compounds, caffeic acid and quercetin showed antiplatelet activity; as expected, the quercetin mixtures showed antiplatelet potential, as did the Cat/Gallic and Cat/Caffeic combinations. While a synergistic effect was observed against collagen, all combinations had activity, in fact, more potent than the independent compounds. Although gallic acid had no activity against collagen, the combinations of this phenolic acid with other phenolic acids (caffeic acid) and flavonoids (quercetin, epicatechin, and catechin) potentiated the inhibition of platelet aggregation, showing the synergistic effect of these mixes. It has been reported that when gallic acid is mixed with another phenolic compound, the 3-OH substitution results in a higher torsion angle and loss of coplanarity [14; 35]. Some investigations have also observed that there is oxidation in the combination of phenolic compounds, which could generate an effect on the antiplatelet capacity of the ions (antagonism/additive) [36; 37]. This research provides valuable insights into the interactions between phenolic compounds and their impact on the inhibition of platelet aggregation.