Thromboxane A2 (TXA2) is a key mediator of platelet aggregation and smooth muscle contraction. Its action is mediated by its
G protein-coupled receptor of which two
isoforms, termed TPalpha and TPbeta, occur in humans. TXA2 has been implicated in pathologies such as
cardiovascular diseases,
pulmonary embolism,
atherosclerosis, and
asthma. This study describes the pharmacological characterization of
BM-613 [N-n-pentyl-N'-[2-(4'-methylphenylamino)-5-nitrobenzenesulfonyl]
urea], a new combined TXA2 receptor antagonist and TXA2 synthase inhibitor. It exhibits a strong affinity for human platelet
TP receptors (IC50 = 1.4 nM), TPalpha and TPbeta expressed in COS-7 cells (IC(50) = 2.1 and 3.1 nM, respectively), and TPs expressed in human coronary artery smooth muscle cells (IC50 = 29 microM).
BM-613 shows a weak ability to prevent contraction of isolated rat aorta (ED50 = 1.52 microM) and guinea pig trachea (ED50 = 2.5 microM) induced by TXA2 agonist
U-46619 (9.11-dideoxy-9.11-methanoepoxy-prostaglandin F2). Besides,
BM-613 antagonizes TPalpha (IC50 = 0.11 microM) and TPbeta (IC50 = 0.17 microM)
calcium mobilization induced by
U-46619 and inhibits human platelet aggregation induced by
U-46619 (ED50 = 0.278 microM),
arachidonic acid (ED50 = 0.375 microM), and the second wave of
ADP.
BM-613 also dose dependently prevents TXA2 production by human platelets (IC50 = 0.15 microM). In a rat model of
ferric chloride-induced
thrombosis,
BM-613 significantly reduces weight of formed
thrombus by 79, 49, and 28% at 5, 2, and 1 mg/kg i.v., respectively. In conclusion,
BM-613 is a dual and potent
TP receptor antagonist and TXA2 synthase inhibitor characterized by a strong antiplatelet and antithrombotic potency. These results suggest that
BM-613 could be a potential therapeutic
drug for thrombotic disorders.