Phenolic fractions from nine <italic>Trifolium</italic> species modulate the coagulant properties of blood plasma <italic>in vitro</italic> without cytotoxicity towards blood cells.

Abstract: Objective: The study covers an evaluation of the influence of extracts (1–50 μg/ml), isolated from aerial parts of nine <italic>Trifolium</italic> L. species (i.e. <italic>T. alexandrinum</italic>,<italic> T. fragiferum</italic>,<italic> T. hybridum</italic>,<italic> T. incarnatum</italic>,<italic> T. pallidum</italic>,<italic> T. pratense</italic>,<italic> T. resupinatum</italic> var. <italic>majus</italic>,<italic> T. resupinatum</italic> var. <italic>resupinatum</italic> and <italic>T. scabrum</italic>) on haemostatic properties of blood plasma. Methods: The clot formation and fibrinolysis assay (CFF), blood clotting times, the extrinsic and intrinsic coagulation pathway‐dependent polymerization of plasma fibrin were measured. The effects of plant extracts on amidolytic activity of thrombin were also evaluated and compared with argatroban, an antithrombotic drug. Cytotoxicity was assessed in a model of blood platelets and as the viability of peripheral blood mononuclear cells. Key findings: While no changes in blood clotting times or fibrinolytic properties of blood plasma were found, some fractions impaired the blood plasma coagulation induced by the intrinsic coagulation pathway. Reduction in the maximal velocity of fibrin polymerization was also observed in the clot formation and fibrinolysis assay. No cytotoxicity of <italic>Trifolium</italic> extracts towards the investigated cells was recorded. Conclusions: The most efficient anticoagulant activity in plasma was found for <italic>T. fragiferum</italic> and <italic>T. incarnatum</italic> extracts, while the <italic>T. alexandrinum</italic> fraction was the most effective inhibitor of thrombin amidolytic activity. [ABSTRACT FROM AUTHOR]