Calycosin extracted from Astragalus membranaceus root inhibits platelet activation and thrombus formation: Insights from in vivo and in vitro experiments.

Platelets, which mediate hemostasis, have been implicated in cardiovascular diseases such as myocardial infarction and stroke. Calycosin, a flavonoid extracted from the root of Astragalus membranaceus, has diverse biological effects, including anticancer, anti-inflammatory, and antidiabetic effects. Whether calycosin inhibits platelet activation and thrombus formation is unclear. The present study explored the mechanisms underlying the potential antiplatelet and antithrombotic effects of calycosin. Platelet aggregation assays, flow cytometry, and Western blotting were performed to analyze the antiplatelet effects of calycosin. Thrombus formation in mouse mesenteric vessels was investigated to analyze the antithrombotic effects of calycosin. Calycosin selectively inhibited collagen-induced platelet aggregation and glycoprotein VI-mediated downstream signaling, including pathways involving phospholipase Cγ2 and protein kinase C. Additionally, calycosin attenuated the activation of protein kinase B and mitogen-activated protein kinase and further suppressed collagen-induced granule release, calcium mobilization, and glycoprotein IIb/IIIa activation. In vivo experiments revealed that calycosin prevented pulmonary thromboembolism and delayed thrombus formation in mouse mesenteric vessels, without affecting hemostasis. This study is the first to demonstrate that calycosin effectively prevents platelet activation and thrombus formation, partly by targeting glycoprotein VI-mediated signaling, without affecting hemostasis. These findings highlight the therapeutic potential of calycosin for cardiovascular diseases.