Search

p300 and its paralog CBP can acetylate histones and other proteins and have been implicated in a number of diseases characterized by aberrant gene activation, such as cancer. A novel, highly selective, orally bioavailable histone acetyltransferase (HAT) domain inhibitor has been identified through virtual ligand screening and subsequent optimization of a unique hydantoin screening hit. Conformational restraint in the form of a spirocyclization followed by substitution with a urea led to a significant improvement in potency. Replacement of the hydantoin moiety with an oxazolidinedione followed by fluoro substitution led to A-485 , which exhibits potent cell activity, low clearance, and high oral bioavailability., Competing Interests: The authors declare the following competing financial interest(s): This study was sponsored by AbbVie. AbbVie contributed to the study design, research, and interpretation of data, writing, reviewing, and approving the publication. M.R.M., T.M.H., R.M.R., R.Man., H.L., K.D.B., L.L., and A.L. are employees of AbbVie. D.M., E.A.K., K.K., P.d.V., and J.W.L were employees of Acylin, which provided assets to Abbvie at the time of the study. R.Mar. and P.A.C. are co-founders of Acylin and consultants for AbbVie.

The design and enzyme activities of a novel class of imidazo[2,1-b]thiazoles is presented., (Copyright 2010 Elsevier Ltd. All rights reserved.)

A series of non-amide-linked 6-substituted-2-naphthamidine urokinase plasminogen activator (uPA) inhibitors are described. These compounds possess excellent binding activities and selectivities with significantly improved pharmacokinetic profiles versus previously described amide-linked inhibitors.

Several 8-substituted 2-naphthamidine-based inhibitors of the serine protease urokinase plasminogen activator (uPA) are described. Direct attachment of five-membered saturated or unsaturated rings improved inhibitor performance; substitution with sulfones further improved binding profiles. Combination of these substituents or of previously described NH-linked heteroaromatic rings with 6-phenyl amide substituents provided further enhancements to potency and selectivity.

The preparation and assessment of biological activity of 6-substituted 2-naphthamidine inhibitors of the serine protease urokinase plasminogen activator (uPA, or urokinase) is described. 2-Naphthamidine was chosen as a starting point based on synthetic considerations and on modeling of substituent vectors. Phenyl amides at the 6-position were found to improve binding; replacement of the amide with other two-atom linkers proved ineffective. The phenyl group itself is situated near the S1' subsite; substitutions off of the phenyl group accessed S1' and other distant binding regions. Three new points of interaction were defined and explored through ring substitution. A solvent-exposed salt bridge with the Asp60A carboxylate was formed using a 4-alkylamino group, improving affinity to K(i) = 40 nM. Inhibitors also accessed two hydrophobic regions. One interaction is characterized by a tight hydrophobic fit made with a small dimple largely defined by His57 and His99; a weaker, less specific interaction involves alkyl groups reaching into the broad prime-side protein binding region near Val41 and the Cys42-Cys58 disulfide, displacing water molecules and leading to small gains in activity. Many inhibitors accessed two of these three regions. Affinities range as low as K(i) = 6 nM, and many compounds had K(i) < 100 nM, while moderate to excellent selectivity was gained versus four of five members of a panel of relevant serine proteases. Also, some selectivity against trypsin was generated via the interaction with Asp60A. X-ray structures of many of these compounds were used to inform our inhibitor design and to increase our understanding of key interactions. In combination with our exploration of 8-substitution patterns, we have identified a number of novel binding interactions for uPA inhibitors.

Background: Human urokinase-type plasminogen activator has been implicated in the regulation and control of basement membrane and interstitial protein degradation. Because of its role in tissue remodeling, urokinase is a central player in the disease progression of cancer, making it an attractive target for design of an anticancer clinical agent: Few urokinase inhibitors have been described, which suggests that discovery of such a compound is in the early stages. Towards integrating structural data into this process, a new human urokinase crystal form amenable to structure-based drug design has been used to discover potent urokinase inhibitors., Results: On the basis of crystallographic data, 2-naphthamidine was chosen as the lead scaffold for structure-directed optimization. This co-crystal structure shows the compound binding at the primary specificity pocket of the trypsin-like protease and at a novel binding subsite that is accessible from the 8-position of 2-napthamidine. This novel subsite was characterized and used to design two compounds with very different 8-substituents that inhibit urokinase with K(i) values of 30-40 nM., Conclusions: Utilization of a novel subsite yielded two potent urokinase inhibitors even though this site has not been widely used in inhibitor optimization with other trypsin-like proteases, such as those reported for thrombin or factor Xa. The extensive binding pockets present at the substrate-binding groove of these other proteins are blocked by unique insertion loops in urokinase, thus necessitating the utilization of additional binding subsites. Successful implementation of this strategy and characterization of the novel site provides a significant step towards the discovery of an anticancer clinical agent.

Endothelins, ET-1, ET-2, and ET-3 are potent vasoconstricting and mitogenic 21-amino acid bicyclic peptides, which exert their effects upon binding to the ET(A) and ET(B) receptors. The ET(A) receptor mediates vasoconstriction and smooth muscle cell proliferation, and the ET(B) receptor mediates different effects in different tissues, including nitric oxide release from endothelial cells, and vasoconstriction in certain vascular cell types. Selective antagonists of endothelin receptor subtypes may prove useful in determining the role of endothelin in various tissue types and disease states, and hence as therapeutic agents for such diseases. The pyrrolidine carboxylic acid A-127722 has been disclosed as a potent and ET(A)-selective antagonist, and is currently undergoing clinical trials. In our efforts to find antagonists with altered selectivity (ET(A)-selective, ET(B)-selective, or nonselective), we investigated the SAR of the 2-substituent on the pyrrolidine. Compounds with alkyl groups at the 2-position possessed ET(A) selectivity improved over A-127722 (1400-fold selective), with the best of these compounds showing nearly 19,000-fold selectivity.

We have discovered a novel class of endothelin (ET) receptor antagonists through pharmacophore analysis of the existing non-peptide ET antagonists. On the basis of this analysis, we determined that a pyrrolidine ring might replace the indian ring in SB 209670. The resultant compounds were readily prepared and amenable to extensive SAR studies. Thus a series of N-substituted trans,trans-2-(4-methoxyphenyl)-4-(1,3-benzodioxol-5-yl)pyrroli din e-3- carboxylic acids (8) have been synthesized and evaluated for binding at ET(A) and ET(B) receptors. Compounds with N-acyl and simple N-alkyl substituents had weak activity. Compounds with N-alkyl substituents containing ethers, sulfoxides, or sulfones showed increased activity. Much improved activity resulted from compounds where the N-substituents were acetamides. Compound 17u (A-127722) with the N,N-dibutylacetamide substituent is the best of the series. It has an IC(50)=0.36 nM for inhibition of ET-1 radioligand binding at the ET(A) receptor, with a 1000-fold selectivity for the ET(A) vs the ET(B) receptor. It is also a potent inhibitor (IC(50)=0.16 nM) of phosphoinositol hydrolysis stimulated by ET-1, and it antagonized the ET-1-induced contraction of the rabbit aorta with a pA(2)=9.20. The compound has 70% oral bioavailability in rats.

The aim of this study was the discovery of nonpeptide renin inhibitors with much improved oral absorption, bioavailability, and efficacy, for use as antihypertensive agents. Our prior efforts led to the identification of A-74273 [1,R = 3-(4-morpholino)propyl], with a bioavailability of 26 +/- 10% [10 mg/kg intraduodenally (id), dog]. In vivo metabolism studies of A-74273 showed that the morpholino moiety underwent metabolic degradation. Computer modeling of A-74273 bound to renin indicated that the C-terminus was involved in a hydrogen-bonding network. New C-terminal groups were examined in two series of nonpeptides for effects on renin binding potency, lipophilicity (log P), and aqueous solubility. Those groups which possessed multiple hydrogen-bonding ability (3,5-diaminotriazole, cyanoguanidines, morpholino) provided particularly potent renin binding. Intraduodenal bioavailabilities of selected compounds, evaluated in rats, ferrets, and dogs, were higher for inhibitors with moderate solubility as well as moderate lipophilicity, in general. Although the absolute values varied substantially among species, the relative ordering of the inhibitors in terms of absorption and bioavailability was reasonably consistent. Such well absorbed inhibitors (e.g. 41, 44, and 51) were demonstrated as highly efficacious hypotensive agents in the salt-depleted dog. We report here the discovery of a series of efficacious nonpeptide renin inhibitors based on the 3-azaglutaramide P2-P4 replacement, the best of which showed id bioavailabilities > 50% in dog.

A-74273 is a nonpeptidic, potent inhibitor of human and canine renin (IC50 = 3.1 and 43 nM, respectively, in plasma at pH 7.4) and has been shown to be orally active in dogs. To determine the hemodynamic mechanism underlying this renin inhibitor's hypotensive activity, the cardiac and hemodynamic effects of A-74273 were studied in sodium-depleted and sodium-replete pentobarbital-anesthetized dogs. Vehicle [5% dextrose in water (V, D5W), n = 8] or a single dose of A-74273 was administered intravenously (i.v.) as a bolus followed by a 30-min infusion (one tenth the bolus dose per minute). Baseline mean arterial pressure (MAP) was similar among all treatment groups, but baseline plasma renin activity (PRA) was increased in the sodium-depleted dogs as compared with the sodium-replete dogs. In sodium-depleted dogs (n = 7-8/dose), MAP decreased maximally as compared with baseline by 4 +/- 1, 19 +/- 3, and 23 +/- 3% during infusion of A-74273 at doses of 0.001, 0.01, and 0.1 mg/kg/min, respectively (p < 0.05 vs. baseline or V). The two highest infusion doses also produced significant reductions (p < 0.05 vs. baseline and V) in systemic vascular resistance (SVR, 21 +/- 2 and 25 +/- 2%) and left ventricular end-diastolic pressure (LVEDP, 40 +/- 8 and 47 +/- 12%). In sodium-replete dogs (n = 4/dose), an infusion dose of 0.01 mg/kg/min elicited no hemodynamic response, whereas 0.1 mg/kg/min reduced MAP by 13 +/- 2% (p < 0.05 vs. baseline) and SVR by 7 +/- 6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous studies with peptidic renin inhibitors have shown that high intravenous (i.v.) doses can induce unexpectedly large decreases in blood pressure (BP) that appear to be independent of plasma renin inhibition. A-74273 represents a new class of potent and orally bioavailable nonpeptidic renin inhibitors. We evaluated the BP effects of this renin inhibitor administered orally (p.o.) or i.v. at high doses to conscious salt-depleted dogs. Administration of A-74273 at 30 and 60 mg/kg p.o. (n = 6 per dose) produced similar maximum reductions in BP (-40 +/- 4 vs. -46 +/- 5 mm Hg) despite the occurrence of greater plasma drug concentrations at the higher dose. Duration of hypotension, however, was increased (p < 0.05) from 9 h at 30 mg/kg to 18 h at 60 mg/kg. The initial depressor response to 10 and 30 mg/kg i.v. doses of A-74273 (n = 6 per dose) was comparable, although duration and overall BP response was greater at 30 mg/kg i.v. No BP responses to A-74273 were noted in salt-replete dogs (n = 5). The hypotension produced by 30 mg/kg p.o. A-74273 was completely reversed by norepinephrine (NE 5 micrograms/kg/min; n = 5) or isotonic saline (4 ml/min/kg, n = 5) infusion. These studies demonstrate that high doses of A-74273 result in predictable BP responses that are renin-dependent and reversible. Therefore, large decreases in BP with high doses is not an attribute common to all renin inhibitors but appears to be a function of the structural characteristics specific to a particular compound.

We describe the development of a series of soluble, potent, and bioavailable nonpeptide renin inhibitors. These inhibitors derived from a series of novel nonpeptide renin inhibitors which were recently identified in our laboratories, by alteration of the nature of the C-terminus (P2') of the molecules. Introduction of basic substituents into modified hydroxyethylene dipeptide isosteres gave inhibitors with improved solubility as well as improved potency against human plasma renin. In addition, these modifications produced inhibitors which displayed markedly improved intraduodenal bioavailability in both the ferret and cynomolgus monkey. We also present data which demonstrate excellent efficacy in the monkey for A-74273 (65), with an intraduodenal bioavailability of 16 +/- 4% in the monkey, compared to 1.7 +/- 0.5% for the dipeptide renin inhibitor enalkiren (A-64662, 75). A-74273 is an example of a nonpeptide inhibitor which possesses a good balance of the desirable properties of potency, solubility, and lipophilicity and which is well absorbed into the intestine.

A series of nonpeptidic human renin inhibitors with a 4-methoxymethoxypiperidinylamide at the P4 position of the molecule exhibited slow tight binding to the enzyme. Replacement of the methoxymethoxy moiety on the piperidine ring with H, OH, methoxyethyl, propyloxy or n-butyl eliminated the effect. The inhibition was partially reversed by prolonged dialysis at 4 degrees C, arguing against formation of a covalent bond in the tightened complex.