Evaluation of Antiplatelet Activity of Phenolic Compounds by Flow Cytometry

Platelets play a pivotal role in coagulation, or clot formation, resulting in haemostasis, after endothelium injury. Disturbance of platelet activation may lead to pathologic thrombosis. Platelet activation and aggregation are common factors in atherothrombotic events, critical in the atherothrombotic process, and cardiovascular diseases. Several drugs are being used for antiplatelet therapy to prevent and/or treat atherosclerosis and cardiovascular diseases. Synthetic antiplatelet drugs hold possible undesired health consequences (cardiovascular diseases, carcinogenicity, etc.), advocating their replacement with natural, effective, and non-toxic compounds. Many phenolic compounds are created as secondary metabolites of plants, are found in many fruits and vegetables, and constitute a wide family of high-added-value molecules. Their biological activities include antioxidant, anti-platelet, and anti-inflammatory action. Based on the above, we examined five phenolic compounds (ellagic acid, ferulic acid, gallic acid, quercetin, and kaempferol) for their effect on platelet reactivity in whole blood samples using flow cytometry. Quantification of activated platelet marker CD62-P by flow cytometry showed that all five compounds inhibited platelet activation in vitro, induced by adenosine diphosphate (ADP) and collagen. Interestingly, based on the IC50 values obtained for expression of CD62-P, among ellagic, ferulic, and gallic acid, gallic acid showed significantly higher inhibition than the other two. Kaempferol found to be a more potent inhibitor than quercetin, following previously reported results from aggregometry. Results obtained from our flow cytometry screening indicate antiplatelet activity from novel phenolic compounds and their potential use as drugs for thrombosis and cardiovascular diseases.