In Vitro and in Vivo Pharmacological Characterization of BM-613 [N-n-Pentyl-N′-[2-(4′-methylphenylamino)-5-nitrobenzenesulfonyl]urea], a Novel Dual Thromboxane Synthase Inhibitor and Thromboxane Receptor Antagonist

Abstract

Thromboxane A 2 (TXA 2 ) 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 TP␣ and TP␤, occur in humans. TXA 2 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-NЈ-[2-(4Ј-methylphenylamino)-5-nitrobenzenesulfonyl]urea], a new combined TXA 2 receptor antagonist and TXA 2 synthase inhibitor. It exhibits a strong affinity for human platelet TP receptors (IC 50 ϭ 1.4 nM), TP␣ and TP␤ expressed in COS-7 cells (IC 50 ϭ 2.1 and 3.1 nM, respectively), and TPs expressed in human coronary artery smooth muscle cells (IC 50 ϭ 29 M). BM-613 shows a weak ability to prevent contraction of isolated rat aorta (ED 50 ϭ 1.52 M) and guinea pig trachea (ED 50 ϭ 2.5 M) induced by TXA 2 agonist U-46619 (9.11-dideoxy-9.11-methanoepoxy-prostaglandin F 2 ). Besides, BM-613 antagonizes TP␣ (IC 50 ϭ 0.11 M) and TP␤ (IC 50 ϭ 0.17 M) calcium mobilization induced by U-46619 and inhibits human platelet aggregation induced by U-46619 (ED 50 ϭ 0.278 M), arachidonic acid (ED 50 ϭ 0.375 M), and the second wave of ADP. BM-613 also dose dependently prevents TXA 2 production by human platelets (IC 50 ϭ 0.15 M). 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 TXA 2 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.Thromboxane A 2 (TXA 2 ) is a key lipid mediator characterized by several implications in physiological homeostasis, including platelet aggregation and vascular and bronchial smooth muscle constriction (Hamberg et al., 1975;Moncada and Vane, 1978). An overproduction of TXA 2 has been associated with many pathological states such as myocardial infarction, thrombosis and thrombotic disorders, unstable angina, pulmonary embolism, shock, atherosclerosis, preeclampsia, and asthma (Dogné et al., 2004a).TXA 2 is a metabolite of arachidonic acid (AA), a 20-carbon

Synthesis and Pharmacological Evaluation of Novel Nitrobenzenic Thromboxane Modulators as Antiplatelet Agents Acting on Both the Alpha and Beta Isoforms of the Human Thromboxane Receptor

“…These affinities, expressed as the percentage displacement of [ 3 H]SQ29,548, were all in the nanomolar range and were comparable to that of the reference compounds 1 and 2 (Figure ) used throughout this study. The affinities of 1 and 2 were in the same range of order of previously published data …”

“…The overall aim of this study was to evaluate a series of novel nitro-substituted benzene sulfonamide derivatives as pharmacological antagonists of the TPα and TPβ isoforms of the human TXA 2 receptor. Consequently, we synthesized several analogues of 1 (BM-573) and 2 (BM-613, both structures are presented in Figure ), two potent TP antagonists characterized by a nitrobenzenic ring bearing a sulfonylurea moiety. − The binding affinities of each TP isoform for each test compound was assessed through competition binding studies in COS-7 cell lines transiently transfected with respective plasmids encoding TPα or TPβ. Experiments were initially performed at a single concentration (1 nM) of the 35 novel test compounds or reference compounds, 1 and 2 .…”

Pharmacological Characterization of 2NTX-99 [4-Methoxy-N1-(4-trans-nitrooxycyclohexyl)-N3-(3-pyridinylmethyl)-1,3-benzenedicarboxamide], a Potential Antiatherothrombotic Agent with Antithromboxane and Nitric Oxide Donor Activity in Platelet and Vascular Preparations

“…2NXT-99 inhibited TXA 2 synthesis, either in the absence or presence of aortic rings (70 -80% at 10 M), and in the latter situation increased PGI 2 synthesis (approximately 3-fold at 10 M), as shown by other TX synthase inhibitors (Gresele et al, 1991;Buccellati et al, 2002). 2NTX-99 inhibited U46619-induced platelet aggregation, thus showing a profile similar to dual TX synthase inhibitors-TP antagonists (Gresele et al, 1989;Hanson et al, 2005). To assess the thromboxane A 2 receptor antagonist properties of 2NTX-99, we performed classic competition experiments in a recombinant system expressing the TP␣ receptor (it would have been the same using the TP␤ because the two isoforms are identical for the first 328 residues and differ only in the Cterminal tail of no relevance for ligand binding).…”

Adventures in vascular biology: a tale of two mediators

“…This led to the synthesis of thromboxane receptor antagonists, some of which would also possess thromboxane synthase inhibitory activity. Several of these compounds were developed and launched as drugs and others are still under clinical evaluation (Ishizuka et al 2003;Dogne et al 2004;Hanson et al 2005). However, their potential superiority over aspirin has never been fully investigated due, at least in part, to the great success of the use of small doses of aspirin in anti-thrombotic therapy.…”