anticoagulant activity of selected medicinal plants: potential interactions with warfarin and development of new anticoagulants.

Objectives: Warfarin is the most widely used anticoagulant in the world, but it has several limitations including its narrow therapeutic range, need for dose adjustment and high potential for interactions. The simultaneous use of other drugs or even medicinal plants and certain foods could interfere with its therapeutic activity. In this context, this study aims to investigate the anticoagulant potential and phytochemical constitution of 17 plants selected from a previous clinical cross-sectional study (2014), that investigated the habits of plant utilization among patients taking warfarin.

Methods: Ethanol extracts and essential oils were evaluated, , as to their effect in the prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests. Four species that presented aPTT >50 s were selected for phytochemical evaluation.

Results: Thirteen of the 17 plants selected demonstrated a significant anticoagulant effect in at least one of the evaluated parameters. (PT=14.75 and aPTT=53.15), (aPTT=51.25), (PT=14.90 and aPTT=52.10), and (aPTT=50.55) showed greater anticoagulant potential compared to normal plasma pool (PT=12.25 and aPTT=37.73). Chemical profiles of these four species were obtained, and certain compounds were identified: rosmarinic acid from and isoorientin from .

Conclusions: Thus, the results of this study could be a useful indicator for clinical practice towards the possibility of interaction between these plants and anticoagulants, although further clinical research is needed taking into consideration the limitations of studies. These findings also suggest that further research into the action of these plants could be of real clinical value in identifying potential alternative anticoagulant therapies.