Triazolo and imidazo dihydropyrazolopyrimidine potassium channel antagonists.

Previously disclosed C6 amido and benzimidazole dihydropyrazolopyrimidines were potent and selective blockers of IKur current. Syntheses and SAR for C6 triazolo and imidazo dihydropyrazolopyrimidines series are described. Trifluoromethylcyclohexyl N(1) triazole, compound 51, was identified as a potent and selective Kv1.5 inhibitor with an acceptable PK and liability profile.

Arylsulfonamidopiperidone derivatives as a novel class of factor Xa inhibitors.

The design, synthesis and SAR of a novel class of valerolactam-based arylsulfonamides as potent and selective FXa inhibitors is reported. The arylsulfonamide-valerolactam scaffold was derived based on the proposed bioisosterism to the arylcyanoguanidine-caprolactam core in known FXa inhibitors. The SAR study led to compound 46 as the most potent FXa inhibitor in this series, with an IC(50) of 7 nM and EC(2×PT) of 1.7 µM. The X-ray structure of compound 40 bound to FXa shows that the sulfonamide-valerolactam scaffold anchors the aryl group in the S1 and the novel acylcytisine pharmacophore in the S4 pockets.

Pyrrolidine amides of pyrazolodihydropyrimidines as potent and selective KV1.5 blockers.

Design and synthesis of pyrazolodihydropyrimidines as KV1.5 blockers led to the discovery of 7d as a potent and selective antagonist. This compound showed atrial selective prolongation of effective refractory period in rabbits and was selected for clinical development.

Dihydropyrazolopyrimidines containing benzimidazoles as K(V)1.5 potassium channel antagonists.

Dihydropyrazolopyrimidines with a C6 heterocycle substituent were found to have high potency for block of K(V)1.5. Investigation of the substitution in the benzimidazole ring and the substituent in the 5-position of the dihydropyrazolopyrimidine ring produced 31a with an IC50 for K(V)1.5 block of 0.030muM without significant block of other cardiac ion channels. This compound also showed good bioavailability in rats and robust pharmacodynamic effects in a rabbit model.

Cyanoguanidine-based lactam derivatives as a novel class of orally bioavailable factor Xa inhibitors.

The N,N'-disubstituted cyanoguanidine is an excellent bioisostere of the thiourea and ketene aminal functional groups. We report the design and synthesis of a novel class of cyanoguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The SAR studies led to the discovery of compound 4 (BMS-269223, K(i)=6.5nM, EC(2xPT)=32muM) as a selective, orally bioavailable FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models. The X-ray crystal structure of 4 bound in FXa is presented and key ligand-protein interactions are discussed.

Aroylguanidine-based factor Xa inhibitors: the discovery of BMS-344577.

We report the design and synthesis of a novel class of N,N'-disubstituted aroylguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The structure-activity relationships (SAR) investigation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC(50)=4 nM, EC(2xPT)=7 microM). However, the potent CYP3A4 inhibition activity (IC(50)=0.3 microM) of 22 precluded its further development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the discovery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC(50)=9 nM, EC(2xPT)=2.5 microM), which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models.

Pyrano-[2,3b]-pyridines as potassium channel antagonists.

The design and synthesis of a series of highly functionalized pyrano-[2,3b]-pyridines is described. These compounds were assayed for their ability to block the I(Kur) channel encoded by the gene hKV1.5 in patch-clamped L-929 cells. Six of the compounds in this series showed sub-micromolar activity, the most potent being 4-(4-ethyl-benzenesulfonylamino)-3-hydroxy-2,2-dimethyl-3,4-dihydro-2H-pyrano[2,3b]-pyridine-6-carboxylic acid ethyl-phenyl-amide with an IC(50) of 378 nM.

Dihydropyrazolopyrimidine inhibitors of K(V)1.5 (I(Kur)).

A series of dihydropyrazolopyrimidine inhibitors of K(V)1.5 (I(Kur)) have been identified. The synthesis, structure-activity relationships and selectivity against several other ion channels are described.

Synthesis and evaluation of acylguanidine FXa inhibitors.

A series of acylguanidine derivatives were prepared and investigated as inhibitors of Factor Xa (FXa). These compounds were made by guanidine acylation with carboxylic acids using carbonyl diimidazole (CDI) as the coupling reagent. Conditions for the rapid synthesis and purification of these compounds are described along with their ability to inhibit FXa. The best FXa inhibitor is 1 with a FXa IC(50) of 6 nM.

Potent non-nitrile dipeptidic dipeptidyl peptidase IV inhibitors.

The synthesis and structure-activity relationships of novel dipeptidyl peptidase IV inhibitors replacing the classical cyanopyrrolidine P1 group with other small nitrogen heterocycles are described. A unique potency enhancement was achieved with beta-branched natural and unnatural amino acids, particularly adamantylglycines, linked to a (2S,3R)-2,3-methanopyrrolidine based scaffold.

Small molecule mitochondrial F1F0 ATPase hydrolase inhibitors as cardioprotective agents. Identification of 4-(N-arylimidazole)-substituted benzopyran derivatives as selective hydrolase inhibitors.

In this paper we show that 4-aryl-CH2-imidazole-substituted benzopyran compounds with 3S,4R-stereochemistry are cardioprotective by inhibiting the F1F0 mitochondrial ATP hydrolase. Compounds (e.g., 13) with 3R,4S-stereochemistry act as mitochondrial KATP openers. This resulted from an inversion of stereochemistry for the F1F0 mitochondrial ATP hydrolase vs mitochondrial KATP. Structure-activity relationships for the inhibition of mitochondrial ATP hydrolase are also delineated. It is not clear how 13 (3R,4S) can selectively inhibit the hydrolytic activity of the F1F0 mitochondrial enzyme without interfering with the synthase activity.

Discovery of ((S)-5-(methoxymethyl)-7-(1-methyl-1H-indol-2-yl)-2-(trifluoromethyl)-4,7-dihydropyrazolo[1,5-a]pyrimidin-6-yl)((S)-2-(3-methylisoxazol-5-yl)pyrrolidin-1-yl)methanone as a potent and selective I(Kur) inhibitor.

Previously disclosed dihydropyrazolopyrimidines are potent and selective blockers of I(Kur) current. A potential liability with this chemotype is the formation of a reactive metabolite which demonstrated covalent binding to protein in vitro. When substituted at the 2 or 3 position, this template yielded potent I(Kur) inhibitors, with selectivity over hERG which did not form reactive metabolites. Subsequent optimization for potency and PK properties lead to the discovery of ((S)-5-(methoxymethyl)-7-(1-methyl-1H-indol-2-yl)-2-(trifluoromethyl)-4,7-dihydropyrazolo[1,5-a]pyrimidin-6-yl)((S)-2-(3-methylisoxazol-5-yl)pyrrolidin-1-yl)methanone (13j), with an acceptable PK profile in preclinical species and potent efficacy in the preclinical rabbit atrial effective refractory period (AERP) model.

Triphenylphosphine oxide is a potent and selective inhibitor of the transient receptor potential melastatin-5 ion channel.

Transient receptor potential melastatin-5 (TRPM5) is a calcium-gated monovalent cation channel expressed in highly specialized cells of the taste bud and gastrointestinal tract, as well as in pancreatic ß-cells. Well established as a critical signaling protein for G protein-coupled receptor-mediated taste pathways, TRPM5 also has recently been implicated as a regulator of incretin and insulin secretion. To date, no inhibitors of practical use have been described that could facilitate investigation of TRPM5 functions in taste or secretion of metabolic hormones. Using recombinant TRPM5-expressing cells in a fluorescence imaging plate reader-based membrane potential assay, we identified triphenylphosphine oxide (TPPO) as a selective and potent inhibitor of TRPM5. TPPO inhibited both human (IC50 = 12 µM) and murine TRPM5 (IC50 = 30 µM) heterologously expressed in HEK293 cells, but had no effect (up to 100 µM) on the membrane potential responses of TRPA1, TRPV1, or TRPM4b. TPPO also inhibited a calcium-gated TRPM5-dependent conductance in taste cells isolated from the tongues of transgenic TRPM5(+/)⁻ mice. In contrast, TPP had no effect on TRPM5 responses, indicating a strict requirement of the oxygen atom for activity. Sixteen additional TPPO derivatives also inhibited TRPM5 but none more potently than TPPO. Structure-activity relationship of tested compounds was used for molecular modeling-based analysis to clarify the positive and negative structural contributions to the potency of TPPO and its derivatives. TPPO is the most potent TRPM5 inhibitor described to date and is the first demonstrated to exhibit selectivity over other channels.

Design, structure-activity relationships, X-ray crystal structure, and energetic contributions of a critical P1 pharmacophore: 3-chloroindole-7-yl-based factor Xa inhibitors.

An indole-based P1 moiety was incorporated into a previously established factor Xa inhibitor series. The indole group was designed to hydrogen-bond with the carbonyl of Gly218, while its 3-methyl or 3-chloro substituent was intended to interact with Tyr228. These interactions were subsequently observed in the X-ray crystal structure of compound 18. SAR studies led to the identification of compound 20 as the most potent FXa inhibitor in this series (IC(50) = 2.4 nM, EC(2xPT) = 1.2 microM). An in-depth energetic analysis suggests that the increased binding energy of 3-chloroindole-versus 3-methylindole-containing compounds in this series is due primarily to (a) the more hydrophobic nature of chloro- versus methyl-containing compounds and (b) an increased interaction of 3-chloroindole versus 3-methylindole with Gly218 backbone. The stronger hydrophobicity of chloro- versus methyl-substituted aromatics may partly explain the general preference for chloro- versus methyl-substituted P1 groups in FXa, which extends beyond the current series.

Benzopyran sulfonamides as KV1.5 potassium channel blockers.

K(V)1.5 blockers have the potential to be atrium-selective agents for treatment of atrial fibrillation. The benzopyrans provide a template for the synthesis of potent and selective K(V)1.5 blockers.

Amino(methyl) pyrrolidines as novel scaffolds for factor Xa inhibitors.

The design and synthesis of a novel class of amino(methyl) pyrrolidine-based sulfonamides as potent and selective FXa inhibitors is reported. The amino(methyl) pyrrolidine scaffolds were designed based on the proposed bioisosterism to the piperazine core in known FXa inhibitors. The SAR study led to compound 15 as the most potent FXa inhibitor in this series, with an IC(50) of 5.5 nM and PT EC(2x) of 1.7 microM. The proposed binding models show that the pyrrolidine cores are in van der Waals contact with the enzyme surface, and the flexibility of amino(methyl) pyrrolidines allows the two nitrogen atoms to anchor both the P1 and P4 groups to fit similarly in the S1 and S4 pockets.

Synthesis and biological activity of 5-aryl-4-(4-(5-methyl-1H-imidazol-4-yl)piperidin-1-yl)pyrimidine analogs as potent, highly selective, and orally bioavailable NHE-1 inhibitors.

A series of potent inhibitors of the sodium hydrogen exchanger-1 (NHE-1) is described. Structure-activity relationships identified the 3-methyl-4-fluoro analog 9t as a highly potent (IC50 = 0.0065 microM) and selective (NHE-2/NHE-1=1400) non-acylguanidine NHE-1 inhibitor. Pharmacokinetic studies showed that compound 9t has an oral bioavailability of 52% and a plasma half life of 1.5 h in rats. Because of its promising potency, selectivity, and a good pharmacokinetic profile, compound 9t was selected for further studies.

Ketene aminal-based lactam derivatives as a novel class of orally active FXa inhibitors.

N,N'-Disubstituted ketene aminals are good bioisosteres of thiourea functional groups. We report the design and synthesis of a novel class of ketene aminal-based lactam derivatives as potent and orally active FXa inhibitors.

Tryptamine and homotryptamine-based sulfonamides as potent and selective inhibitors of 15-lipoxygenase.

A series of inhibitors of mammalian 15-lipoxygenase based on tryptamine and homotryptamine scaffolds is described. Compounds with aryl substituents at C-2 of the indole core of tryptamine and homotryptamine sulfonamides (e.g., 37a-p) proved to be potent inhibitors of the isolated enzyme. Selected compounds also demonstrated desirable inhibition selectivities over isozymes 5- and P-12-LO.

Pharmacologic profile of the selective mitochondrial-K(ATP) opener BMS-191095 for treatment of acute myocardial ischemia.

ATP-sensitive potassium channel (K(ATP)) openers as a class protect ischemic myocardium. The protective effects are independent of vasodilator activity and effects on action potential shortening, actions typically associated with sarcolemmal K(ATP) activation. BMS-191095 is a novel mitochondrial K(ATP) opener which protects ischemic myocardium while having no electrophysiologic or vasodilator effects (determined in vitro and in vivo). The cardioprotective effects were determined in isolated rat hearts subjected to ischemia and reperfusion. Protective effects were deduced from increased time to contracture formation during ischemia, improved reperfusion recovery of contractile function, and reduced reperfusion LDH release. The cardioprotective effects of BMS-191095 were observed at concentrations at which this compound selectively opened cardiac mitochondrial K(ATP) channels. This effect was consistent with the pharmacologic profile of this agent. The protective effects were abolished by mitochondrial K(ATP) inhibition. Unlike first-generation K(ATP) openers, BMS-191095 is expected to protect ischemic myocardium with little hemodynamic sequelae and without any proarrhythmic potential. BMS-191095 is potentially useful clinically as a cardioprotective agent. It is also a useful tool for basic research.