Tetrastigma hemsleyanum Polysaccharides as Natural Inhibitors of Platelet Thrombosis via GPIIb/IIIa and MAPK Pathways

Background Thrombosis, driven by abnormal platelet activation and fibrin clot formation, is a key pathological basis of cardiovascular disorders. Polysaccharide-based agents, such as heparin, possess distinct antithrombotic activities. Tetrastigma hemsleyanum polysaccharide (THP) exhibits notable anti-inflammatory properties. However, its antithrombotic potential remains unexplored. Purpose This work intended to explore the antithrombotic and antiplatelet activities of THP5, a novel acidic glucuronic acid-containing galactomannan isolated from THP, and to elucidate its molecular targets and mechanisms of platelet interaction. Methods The antithrombotic activity of THP5 was tested in vivo using a mouse model of κ-carrageenan-induced thrombosis. In vitro platelet function assays determined its antiplatelet effects. Platelet protein targets were identified via pull-down, liquid chromatography-mass spectrometry (LC-MS/MS), and surface plasmon resonance (SPR) analyses. Comparative studies with the GPIIb/IIIa inhibitor tirofiban were performed in κ-carrageenan- and FeCl 3 -induced thrombosis models. Proteomic profiling and bleeding risk assessments were conducted to investigate underlying mechanisms and safety. Results THP5 markedly reduced thrombus formation, attenuated inflammatory responses, and alleviated vascular injury in vivo. In vitro , it protected endothelial cells from LPS-induced damage and strongly inhibited platelet activation. GPIIb/IIIa was identified as a direct binding target of THP5, and proteomic analysis revealed modulation of the MAPK signaling pathway. Compared with tirofiban, THP5 demonstrated comparable efficacy with a lower bleeding risk. Conclusion THP5 exerts potent antithrombotic effects by directly targeting GPIIb/IIIa and modulating PKCα-MAPK-dependent platelet activation, supporting its potential as a safe and effective therapeutic candidate for thrombotic disorders.