Caffeic Acid Diminishes the Production and Release of Thrombogenic Molecules in Human Platelets

Caffeic acid (CA) is a well-known to inhibit thrombogenic thromboxane A 2 (TXA 2 ) production, but there are no reports for the supply and usage of its precursor arachidonic acid (AA) and the release of serotonin, another thrombogenic molecule. In this study, we investigated the effect of CA on the phosphorylation of AA supply enzymes [cytosolic phospholipase A 2α (cPLA 2α ), and phospholipase C γ2 (PLC γ2 )] and AA utilization enzymes [cyclooxygenase (COX)-1, TXA 2 synthase (TXAS)] in collagen-activated human platelets. p38 MAPK phosphorylation associated with TXA 2 production and c-Jun NH 2 -terminal kinase 1 (JNK1) phosphorylation associated with serotonin release were also determined. CA inhibited collagen-induced TXA 2 production in a dose-dependent manner. It acted by counteracting the phosphorylation of AA release enzyme (PLC γ2 ) and AA utilization enzymes (COX-1 and TXAS) without affecting p38 MAPK and cPLA 2α in collagenactivated human platelets. CA decreased collagen-released serotonin by inhibiting JNK1 phosphorylation. Therefore, our data demonstrate that CA might protect TXA 2 - and serotonin-mediated thrombogenesis.