Thromboxane A2 receptor antagonism in man and rat by a sulphonylcyanoguanidine (BM-144) and a sulphonylurea (BM-500).

Torasemide, a loop diuretic, has been reported to relax dog coronary artery precontracted by thromboxane A2 (TXA2), an endogenous prostanoid involved in cardiovascular and pulmonary diseases. N-cyano-N'-[[4-(3'-methylphenylamino)pyrid-3-yl]sulphonyl] homopiperidinoamidine (BM-144) and N-isopropyl-N'-[5-nitro-2-(3'-methylphenylamino)-benzenesulphon yl]urea (BM-500), chemically related to torasemide, have been examined for their TXA2 antagonism. The affinity (IC50, the concentration resulting in 50% inhibition) of BM-144 and BM-500 for the TXA2 receptor of washed platelets from man was 0.28 and 0.079 microM, respectively. This is better than for sulotroban (IC50 = 0.93 microM) but less than for SQ-29548 (IC50 = 0.021 microM), two TXA2 antagonists used as reference. The aggregation of platelets from man induced by arachidonic acid was prevented by BM-144 (IC50 = 9.0 microM) and by BM-500 (IC50 = 14.2 microM). Similar results were obtained by use of U-46619, a TXA agonist, as aggregating agent (BM-144, IC50 = 12.9 microM and BM-500, IC50 = 9.9 microM). The contracting effect of U-46619 on rat stomach strip was abolished by BM-144 (IC50 = 1.01 microM) and BM-500 (IC50 = 2.54 microM). Both drugs (BM-144: IC50 = 0.12 microM and BM-500: IC50 = 0.19 microM) also relaxed rat aorta precontracted by U-46619; both were more potent than sulotroban (IC50 = 1.62 microM). The two torasemide derivatives (100 microM) did not significantly affect the myo-stimulating effect of some prostaglandins (PGE2, PGI2, PGF2alpha) or aorta contraction elicited by KCl (30 mM). They did not modify rat diuresis after administration of a 30-mg kg(-1) dose. In conclusion, BM-144 and BM-500 can be regarded as novel non-carboxylic TXA2 receptor antagonists and offer a novel template for the design of more potent molecules.

Pharmacomodulation of torasemide led to original diuretic, neuroprotective, anticonvulsant and antithrombotic drugs.

Pharmacomodulation of torasemide, a diuretic sulfonylurea, led to the discovery of two novel diuretics, a sulfonylthiourea (BM 20) and a sulfonylcyanoguanidine (BM 106). BM 27, a lipophilic sulfonylurea, exhibited neuroprotective properties associated to an anticonvulsant activity. As BM 27, two lipophilic sulfonythioureas (BM 11 and BM 34) revealed an anticonvulsant profile similar to that of phenytoin. Finally the synthesis of torasemide derivatives led to the development of a sulfonylcyanoguanidine (BM 144) with a thromboxane A2 antagonist potency.

Platelet antiaggregant methoxyphenylthienyl ketoxime ethers: synthesis and structure-activity relationships.

Some new oximinoalkanoic (n = 2,3,4) esters and acids derived from methoxyphenylthienyl ketones have been synthesized and evaluated in vitro for their inhibitory effects on arachidonic acid-induced human platelet aggregation. Of the eighteen oximinoethers tested the most active derivatives, which were four times more active as aspirin, belonged to the para methoxy series with Z configuration and n = 2 or 3.