Antithrombotic activity of 12 table grape varieties. Relationship with polyphenolic profile.

The synthesis of tissue factor (TF) by monocytes/macrophages activated by inflammatory agents is of utmost importance in the pathogenesis of thrombotic diseases and substances inhibiting TF synthesis represent novel and promising antithrombotics. We investigated the effect of 12 table grape varieties (white, red and black) on TF synthesis and the possible relation with the phenolic profile. The ability of grape skin extracts (GSEs) to inhibit TF was evaluated in whole blood and isolated mononuclear cells challenged with endotoxin. TF expression was assayed by functional and immunological assays. All GSEs inhibited TF synthesis but with a different efficiency, red grapes being the most active. By correlation analysis, the compounds showing the strongest association with TF-inhibiting activity were quercetin and cyanidin. However, no single polyphenol was able to inhibit TF synthesis as efficiently as the crude grape extracts, unless it was combined with at least another compound, suggesting a synergism.