Citrus sinensis: Antithrombotic potential and safety concerns involving possible interactions based on in vitro coagulometric tests

Background: Citrus sinensis, popularly called sweet orange, is widely used in Brazil for its calming properties, particularly in treating anxiety and insomnia, even among patients using warfarin. However, there is no scientific data supporting the safe concurrent use of both. Objective: To access the in vitro activity of C. sinensis ethanolic extract (EtEXT) and its fractions on blood clotting. Methods: The study used activated partial thromboplastin time (aPTT), prothrombin time (PT) and plasma fibrinogen measurement (PF), and thrombin generation test (TGT) to evaluate the effects. TGT, a highly sensitive assay, investigates overall changes in the hemostatic system and can evaluate the qualitative micromolecular chemistry of C. sinensis EtEXT and its fractions. Results: The EtEXTs of sweet orange leaves and their fractions were added to plasma pools at concentrations of 1.67 mg/ml, 2.26 mg/ml, and 2.86 mg/ml. Presence of phenolics as coumarins, flavonoids and tannins, as well as triterpenes was confirmed. At all concentrations, the extract increased PT and aPTT while decreasing PF and TGT, except for the hexane fraction. Conclusion: Our findings provide scientific evidence supporting both patient care in the context of warfarin use and the potential development of new antithrombotics. The leaves of sweet orange exhibited in vitro anticoagulant effects, likely due to interference in both extrinsic (EXT-path) intrinsic (INT-path) coagulation pathways. The function of the identified substances in these effects was also discussed, as well as the potential for using this extract in developing antithrombotic agents.