Análisis de las interacciones de polifenoles con el receptor GPllb/llla plaquetario y de sus efectos inmunomoduladores sobre células sanguíneas circulantes

Abstract

Nowadays many active ingredients extracted from plants are used successfully in therapeutic indications, but their mechanism of action is still unknown. This is the case of some polyphenols such as flavonoids and coumarins, which have antiplatelet properties with some peculiarities. Some flavonoids such as diosmin are used as phlebotonics products and improve vascular permeability. This could suggest that if some prostaglandins control platelet aggregation, perhaps those drugs would behave as antiplatelet agents. These facts are related to inflammatory processes, so we also consider the possibility of relevant biochemical studies concerning a possible effect on the main cellular mediators that influence these processes. For this reason, and to clarify some aspects related to the mechanism of action of flavonoids and coumarins on platelet aggregation and modulation of proinflammatory mediators, we studied the platelet receptor occupancy of GPIIb/IIIa for such products by flow cytometry and the modulation of proinflammatory cytokines by ELISA. Flavonoids and coumarins assayed are naringin, naringenin, esculetin, coumarin and fraxetin. The results of the platelet receptor occupancy of GPIIb/IIIa show that all products are able to bind to this receptor although with a low occupancy rate. The assay of platelets morphology by flow cytometry shows that flavonoids and coumarins studied present antiplatelet activity. Naringin 2mM has the highest activity (90%). Naringenin, esculetin and fraxetin 2mM, have an antiplatelet effect around 50%. Coumarin gets the lowest results (25%). The study of modulation of proinflammatory cytokines by ELISA shows that flavonoids and coumarins studied are able to inhibit the production of IL-1β, TNF-α, IL-6 and IL-8 and therefore also intervene indirectly, by monocytes, over decreased platelet aggregation. About a possible relationship between chemical structure and pharmacological activity, we suggest the glycoside flavone exerts a higher antiplatelet activity than the aglycone, which is more active over inhibition of cytokines. Also, the presence of ortho phenolic hydroxyl coumarin in the structure could cause higher antiplatelet activity with esculetin and fraxetin than with coumarin. However, the greater inhibitory effect on some cytokines production, except on TNF-α, is exerted by coumarin.