The antithrombotic activity of the active fractions from the fruits of Celastrus orbiculatus Thunb through the anti-coagulation, anti-platelet activation and anti-fibrinolysis pathways.

Traditional Chinese medicine Celastrus orbiculatus Thunb (C. orbiculatus) with peel and seeds is mainly composed of flavonoids, sesquiterpenes and tripenes. According to the Traditional Chinese medicine standard of Liaoning province (2009), it has been long used to invigorate blood circulation.To identify the antithrombus fraction and components of C. orbiculatus, and to investigate the underlying mechanisms.

The antithrombus effects of C. orbiculatus fractions were evaluated in vitro by plasma recalcification time (PRT). The antithrombus effect of NST-50, the most effective fraction, was further investigated in acute pulmonary embolism (APE) mice and FeCl₃-induced carotid arterial thrombus rats. Bleeding assessment was also carried out to assess the side effects of NST-50. In addition, the content of total flavonoids and active components of NST-50 was also quantified.

Nine flavonoids were detected in NST-50 as main components with the content of 44.70%. Next, NST-50 was found with significant anticoagulation activity by prolonging the plasma recalcification time (PRT), activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) and decreasing the content of fibrinogen (FIB). Furthermore, NST-50 administration markedly suppressed the level of TXB₂ and PAI-1, while significantly up-regulated the level of 6-keto-PGF_1a and t-PA (p < 0.05).

The results demonstrated that NST-50 could be valuable in clinical application against acute coronary syndrome, venous thromboembolisms and cerebrovascular thrombosis. It was possible that the anticoagulation action of NST-50 could be related to the regulation of TXA₂ - PGI₂ and t-PA - PAI-1 pairs.