Ex-vivo and in-vivo antithrombotic effect of triflavin, an RGD-containing peptide.

Triflavin, an Arg-Gly-Asp-containing snake venom peptide, inhibits platelet aggregation through the blockade of fibrinogen binding to the activated platelets. It binds to fibrinogen receptors associated with the glycoprotein IIb/IIIa complex with a Kd value of 7 x 10(-8) M. In this study, we found that 125I-triflavin reached the maximal binding to human platelets within 5 min at 25 degrees C. In addition, when triflavin was intravenously administered at 1.0 mg kg-1 to rabbits, it reversibly impaired the platelet aggregation of platelet-rich plasma caused by ADP (20 microM) ex-vivo over 30 min. The platelet counts of the experimental rabbits remained unchanged. Triflavin was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice when administered intravenously at a dose of 2 micrograms g-1. Therefore, triflavin was proven to be an effective antithrombotic agent in preventing ADP-induced acute pulmonary thromboembolism in mice and impairing reversibly the platelet function of rabbits when given intravenously.