Total saponin from Korean Red Ginseng inhibits binding of adhesive proteins to glycoprotein IIb/IIIa via phosphorylation of VASP (Ser(157)) and dephosphorylation of PI3K and Akt

BACKGROUND: Binding of adhesive proteins (i.e., fibrinogen, fibronectin, vitronectin) to platelet integrin glycoprotein IIb/IIIa (αIIb/β(3)) by various agonists (thrombin, collagen, adenosine diphosphate) involve in strength of thrombus. This study was carried out to evaluate the antiplatelet effect of total saponin from Korean Red Ginseng (KRG-TS) by investigating whether KRG-TS inhibits thrombin-induced binding of fibrinogen and fibronectin to αIIb/β(3). METHODS: We investigated the effect of KRG-TS on phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and dephosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt, affecting binding of fibrinogen and fibronectin to αIIb/β(3), and clot retraction. RESULTS: KRG-TS had an antiplatelet effect by inhibiting the binding of fibrinogen and fibronectin to αIIb/β(3) via phosphorylation of VASP (Ser(157)), and dephosphorylation of PI3K and Akt on thrombin-induced platelet aggregation. Moreover, A-kinase inhibitor Rp-8-Br-cyclic adenosine monophosphates (cAMPs) reduced KRG-TS-increased VASP (Ser(157)) phosphorylation, and increased KRG-TS-inhibited fibrinogen-, and fibronectin-binding to αIIb/β(3). These findings indicate that KRG-TS interferes with the binding of fibrinogen and fibronectin to αIIb/β(3) via cAMP-dependent phosphorylation of VASP (Ser(157)). In addition, KRG-TS decreased the rate of clot retraction, reflecting inhibition of αIIb/β(3) activation. In this study, we clarified ginsenoside Ro (G-Ro) in KRG-TS inhibited thrombin-induced platelet aggregation via both inhibition of [Ca(2+)](i) mobilization and increase of cAMP production. CONCLUSION: These results strongly indicate that KRG-TS is a beneficial herbal substance inhibiting fibrinogen-, and fibronectin-binding to αIIb/β(3), and clot retraction, and may prevent platelet αIIb/β(3)-mediated thrombotic disease. In addition, we demonstrate that G-Ro is a novel compound with antiplatelet characteristics of KRG-TS.