The pyrrolidinoindoline alkaloid Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling

Abstract

Aim: Psm2, one of the pyrrolidinoindoline alkaloids isolated from whole Selaginella moellendorffii plants, has shown a potent antiplatelet activity. In this study, we further evaluated the antiplatelet effects of Psm2, and elucidated the underlying mechanisms. Methods: Human platelet aggregation in vitro and rat platelet aggregation ex vivo were investigated. Agonist-induced platelet aggregation was measured using a light transmission aggregometer. The antithrombotic effects of Psm2 were evaluated in arteriovenous shunt thrombosis model in rats. To elucidate the mechanisms underlying the antiplatelet activity of Psm2, ELISAs, Western blotting and molecular docking were performed. The bleeding risk of Psm2 administration was assessed in a mouse tail cutting model, and the cytotoxicity of Psm2 was measured with MTT assay in EA.hy926 cells. Results: Psm2 dose-dependently inhibited human platelet aggregation induced by ADP, U4619, thrombin and collagen with IC 50 values of 0.64, 0.37, 0.35 and 0.87 mg/mL, respectively. Psm2 (1, 3, 10 mg/kg) administered to rats significantly inhibited platelet aggregation ex vivo induced by ADP. Psm2 (1, 3, 10 mg/mL, iv) administered to rats with the A-V shunt dose-dependently decreased the thrombus formation. Psm2 inhibited platelet adhesion to fibrinogen and collagen with IC 50 values of 84.5 and 96.5 mg/mL, respectively, but did not affect the binding of fibrinogen to GPIIb/IIIa. Furthermore, Psm2 inhibited AktSer473 phosphorylation, but did not affect MAPK signaling and Src kinase activation. Molecular docking showed that Psm2 bound to phosphatidylinositol 3-kinase β (PI3Kβ) with a binding free energy of -13.265 kcal/mol. In addition, Psm2 did not cause toxicity in EA.hy926 cells and produced only slight bleeding in a mouse tail cutting model. Conclusion: Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling. Psm2 may be a lead compound or drug candidate that could be developed for the prevention or treatment of thrombotic diseases.

Ligustrazine inhibits platelet activation via suppression of the Akt pathway

“…Platelet activation may be induced by a variety of agonists, including AdP and TXA2, which are released from the granules of activated platelets. TXA2 exerts its function through interaction with the thromboxane receptor, contributing to the amplification of the initial platelet activation, which therefore is a principal target for most currently-used antiplatelet agents (31)(32)(33). Although different agonists induce platelet activation through different mechanisms by respectively binding to their specific receptors, they all result in an elevation of intracellular ca 2+ concentration [(ca 2+ )i], an event termed ca 2+ mobilization (34).…”

Circulating microRNA expression and their target genes in deep vein thrombosis

“…In this process, phosphor-Akt can further active endothelial nitric oxide synthase, and ultimately facilitate the migration of ECs, [ 41 ] which is critical to the regulation of vascular homeostasis and angiogenesis. Su et al [ 42 ] pointed out that the inhibition of PI3K signaling could be a promising curative target for thrombotic diseases. An experiment on rat DVT models indicated that overexpressed miR-126 induced an increase in PI3K and phosphor-Akt.…”

Pharmacological actions of miltirone in the modulation of platelet function

“…The main targets of the commercially available anti-platelet medicine include ADP receptors, integrin αIIbβ3, and cyclooxygenase but without GPVI and PAR. Upon GPVI activation, the adjacent Src family kinases will initiate the downstream Syk/PLCγ2/PKC signaling [24][25][26]. Miltirone inhibited collagen-and CRP-induced platelet activation in a concentration-dependent manner.…”