Effect of quercetin-rich onion peel extracts on arterial thrombosis in rats.

The aim of this study was to examine whether oral supplementation of quercetin-rich onion peel extract (OPE) influences blood coagulation and arterial thrombosis in Sprague-Dawley (SD) rats. 24 male rats, 5 weeks old, were divided into three groups with different diets (C: control, 2mg OPE: chow diet with 2mg OPE supplementation, 10mg OPE: chow diet with 10mg OPE supplementation) for 6 weeks. Blood coagulation parameters including prothrombin time (PT), activated partial thromboplastin time (aPTT) and platelet aggregation were examined. The OPE did not affect blood cholesterol levels but significantly decreased blood triglyceride and glucose levels. PT, aPTT and platelet aggregation were not significantly different among all tested groups. However, in vivo arterial thrombosis was significantly delayed in groups that were fed 2mg and 10mg OPE diets compared to the control group. In addition, the OPE greatly diminished thrombin-induced expression of tissue factor in human umbilical vein endothelial cells (HUVECs), a coagulation initiator. In addition, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways activated by thrombin treatment were prevented by the OPE pre-treatment. These results indicate that OPE may have anti-thrombotic effects through restricting the induced expression of tissue factor via down-regulating mitogen-activated protein kinase (MAPK) activation upon coagulation stimulus, leading to the prolongation of time for arterial thrombosis.