The objectives of this study were to investigate the antithrombotic effect and physiological mechanism of
okanin, a
flavonoid monomer in Coreopsis tinctoria Nutt. The antithrombotic effects of
okanin were determined by the
anticoagulant activity test in vitro and in vivo, the
venous thrombosis and arterial
thrombosis test in rats. To study the antithrombotic physiological mechanisms of
okanin, UV spectrophotometer and
enzyme-linked
immunosorbent assay (ELISA) were used to determine the effects of three concentrations of
okanin on the contents of 6-keto-prostaglandin F1α (6-Keto-PGF1α),
thromboxane B2 (TXB2),
endothelin-1 (ET-1),
antithrombin III (AT-Ⅲ),
protein C (PC) and
von willebrand factor (vWF) in the plasma of rats with arterial
thrombosis; ELISA was used to detect the effects of
okanin on the contents of
plasminogen (PLG),
tissue plasminogen activator (t-PA) and type-1
plasminogen activator inhibitor (PAI-1) in the plasma of mice and Chinese white rabbits. The results showed that
okanin could prolong the coagulation time in vitro and in vivo of animals (P < 0.01 in the high dose group) and the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) of human venous blood (ATPP of medium dose group P < 0.01; PT, TT P < 0.05. P < 0.01 in the high dose group); inhibit the maximum platelet aggregation rate of rabbits (P < 0.05 in the low dose group; P < 0.01 in the medium and high dose groups), decrease the dry and wet weight of
venous thrombosis and the wet weight of
common carotid artery thrombosis in rats (low dose group, P < 0.05; medium and high dose groups, P < 0.01); increase the levels of 6-Keto-PGF1α, AT-Ⅲ, PLG and t-PA in animal plasma; decrease the levels of TXB2, ET-1, vWF and
PAI-1 in animal plasma. It is concluded that
okanin can significantly inhibit
thrombosis, and its physiological mechanisms were related to affecting the activation of related
coagulation factors in endogenous and exogenous coagulation pathways, affecting the physiological characteristics of platelets, repairing damaged vascular endothelial cells and enhancing the activity of the fibrinolytic system.