Inhibitory effects of isoscopoletin on thrombus formation via regulation of cyclic nucleotides in collagen-induced platelets

Abstract

An essential component of the hemostatic process during vascular damage is platelet activation. However, many cardiovascular diseases, such as atherosclerosis, thrombosis, and myocardial infarction, can develop due to excessive platelet activation. Isoscopoletin, found primarily in plant roots of the genus Artemisia or Scopolia, has been studied to demonstrate potential pharmacological effects on Alzheimer's disease and anticancer, but its mechanisms and role in relation to thrombus formation and platelet aggregation have not yet been discovered. This research investigated the effect of isoscopoletin on collagen-induced human platelet activation. As a result, isoscopoletin strongly increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in a concentration-dependent manner. In addition, isoscopoletin greatly phosphorylated inositol 1,4,5-triphosphate receptor (IP3R) and vasodilator-stimulated phosphoprotein (VASP), known substrates of cAMP-dependent kinase and cGMP dependent kinase. Phosphorylation of IP3R by isoscopoletin induced Ca2+ inhibition from the dense tubular system Ca2+ channels, and VASP phosphorylation was involved in fibrinogen binding inhibition by inactivating αIIb/β3 in the platelet membrane. Isoscopoletin finally reduced thrombin-induced fibrin clot production and finally reduced thrombus formation. Therefore, this research suggests that isoscopoletin has strong antiplatelet effects and is likely to be helpful for thrombotic diseases involving platelets by acting as a prophylactic and therapeutic agent.