Picropodophyllotoxin Suppresses Factor Xa Activity, Platelet Aggregation, and Arterial Thrombosis.

Picropodophyllotoxin (PPT), a naturally occurring tyrosine kinase inhibitor derived from Podophyllum hexandrum roots, is well recognized for its anticancer potential. The present study was designed to determine whether PPT exerts antithrombotic effects and to elucidate the underlying mechanisms. A range of functional assays were employed, including coagulation time measurements, platelet aggregation tests, evaluations of factor Xa activity and production, nitric oxide (NO) level assessments, and protein expression analyses. Our results demonstrated that PPT prolonged the clotting time of human platelet-poor plasma to an extent comparable to that of rivaroxaban, a reference anticoagulant, and effectively suppressed platelet aggregation induced by ADP or the thromboxane A2 mimetic U46619. Mechanistically, PPT inhibited the phosphorylation of PLCγ2 and PKC, as well as intracellular calcium mobilization-key events in platelet activation. It also downregulated the surface expression of the adhesion molecules P-selectin and PAC-1. In endothelial cells, PPT enhanced NO production while reducing endothelin-1 secretion following stimulation with ADP or U46619. Furthermore, PPT suppressed both the enzymatic activity and the cellular production of coagulation factor Xa in endothelial cells and blocked FXa-induced platelet aggregation. In murine models of thromboembolism, PPT administration significantly accelerated thrombus resolution, reduced thrombus burden and size, and improved survival rates. Collectively, these findings establish that PPT possesses potent antithrombotic activity, operating through prolongation of clotting time, inhibition of platelet aggregation, and suppression of factor Xa function-effects comparable to those of standard anticoagulants. This multifaceted mechanism positions PPT as a promising candidate for thrombosis therapy with a potentially favorable side-effect profile.