Antithrombotic potential of Lippia alba: A mechanistic approach

Ethnopharmacological relevance: Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson is traditionally used in Brazil as an adjunct in the relief of mild anxiety, as an antispasmodic, and as an antidyspeptic. This medicinal species was included in the Phytotherapeutic Form of the Brazilian Pharmacopeia 2nd edition (2021) and has already been described as the most used medicinal plant in a study with patients from an Anticoagulation Clinic in Brazil. Meanwhile, no studies were found that support the safety of the use of L. alba in patients using anticoagulants, a drug with several safety limitations.Aim of the study: Provide scientific evidence to ensure the safety of the concomitant use of L. alba and warfarin and support the management of these patients by evaluating its in vitro anticoagulant effect and chemical composition. And, as a timely complementation, evaluate the potential of this medicinal species in the devel-opment of new antithrombotics.Methods: The chemical profile of L. alba derivatives was analyzed by chromatographic methods such as Ultra -Performance Liquid Chromatography (UPLC) coupled with electrospray ionization mass spectrometry (ESI-MS), qualitative UPLC using Diode-Array Detection, and Thin Layer Chromatography. The anticoagulant activity was evaluated by the innovative Thrombin Generation Assay by Calibrated Automated Thrombogram method and using traditional coagulometric tests: prothrombin time, activated partial thromboplastin time, and plasma fibrinogen measurement.Results: Extracts and fractions prolonged the coagulation time in all the tests and reduced thrombin formation in thrombin generation assay. Coagulation times with the addition of ethanloic extract (2.26 mg/mL) was 17.78s, 46.43s and 14.25s respectively in prothrombin time, activated partial thromboplastin time and fibrinogren plasma measurement. In thrombin generation test, this same extract showed ETP as 323 nM/min compared to control (815 nM/min) with high tissue factor and 582 nM/min compared to control (1147 nM/min) using low tissue factor. Presence of flavonoids, phenylpropanoids, and triterpenes were confirmed by chromatographic methods and 13 compounds were identified by UPLC-ESI-MS. Based on these results and on the scientific literature, it is possible to propose that phenylpropanoids and flavonoids are related to the anticoagulant activity observed.Conclusion: The results demonstrate the in vitro anticoagulant activity of L. alba, probably due to the activation of intrinsic and extrinsic pathways. It is concluded, then, that there is a potential for interaction, which needs to be further studied, between L. alba and warfarin. Also, this medicinal species shows a great potential for use in the development of new antithrombotics.