Inhibitory Effects of Calycosin on Thrombus formation via Regulation of Cyclic Nucleotides in Collagen-induced Platelets

While physiological platelet activation is fundamental for hemostasis, its aberrant hyperactivity contributes significantly to the pathogenesis of cardiovascular diseases, including stroke, atherosclerosis, and thrombosis.Thus, identifying novel modulators of platelet function is a key focus for cardiovascular therapy.Calycosin, a major isoflavone derived from Astragalus membranaceus, possesses well-documented anti-inflammatory and antioxidant properties.However, its specific regulatory mechanism involving cyclic nucleotide elevation in platelets has remained elusive.This study investigated the impact of calycosin on collagen-induced platelet activation and thrombus formation.Our findings revealed that calycosin significantly increased intracellular levels of cAMP and cGMP, subsequently triggering the phosphorylation of VASP and IP 3 R-substrates for cAMP-and cGMP-dependent kinases, respectively.The phosphorylation of IP 3 R effectively inhibited the mobilization of cytosolic Ca 2+ , while phosphorylated VASP led to the inactivation of the surface glycoprotein αIIb/β 3 , thereby blocking fibrinogen binding.Consequently, calycosin suppressed thrombin-mediated fibrin clot formation.Taken together, these results suggest that calycosin may serve as a promising candidate agent for the prevention and treatment of cardiovascular disorders associated with excessive platelet activation and thrombosis, at least in part through a mechanism consistent with cAMP/cGMP-associated signaling.Future studies using pathway-specific inhibitors will be needed to establish direct mechanistic causality.