Conformationally restricted indolopiperidine derivatives as potent CCR2B receptor antagonists.

The preparation and biological evaluation of a series of indolopiperidine CCR2B receptor antagonists possessing a conformationally restricted C-5 linker chain in combination with a restricted piperidine ring are described. Compared to the parent compound 1, analogue 8 shows a dramatic improvement in selectivity against a range of 5-HT and dopaminergic receptors.

1-(Arylpiperazinylamidoalkyl)-pyrimidones: orally active inhibitors of lipoprotein-associated phospholipase A(2).

The lipophilic 1-substituent in a series of 1-((amidolinked)-alkyl)-pyrimidones, inhibitors of recombinant lipoprotein-associated phospholipase A(2), has been modified to give inhibitors of high potency in human plasma and enhanced physicochemical properties. Phenylpiperazineacetamide derivative 23 shows very promising oral activity.

Lipoprotein-associated PLA2 inhibition--a novel, non-lipid lowering strategy for atherosclerosis therapy.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a serine lipase that is associated with low density lipoprotein (LDL) in human plasma. Substrates include oxidised phosphatidylcholine (PC), which is hydrolysed by Lp-PLA2 to lyso-PC and oxidised fatty acids. Both products are bioactive and proinflammatory, and implicated in monocyte infiltration into the developing plaque, deposition of foam cells, and plaque progression and instability. Lp-PLA2 has recently been shown to be a risk factor for coronary events in previously asymptomatic, hypercholesterolaemic men. A series of azetidinones was designed as potent and selective inhibitors of this enzyme; SB-222657 inhibited release of the chemotactic cleavage products from oxidised LDL, and SB-244323 reduced atherosclerotic plaque development in a 3 month rabbit study. A series of pyrimidones has been designed from a screening hit, and nanomolar inhibitors identified. Oral efficacy in inhibiting plasma Lp-PLA2 in rabbits has been demonstrated with a variety of structural classes.

3-Anilino-4-arylmaleimides: potent and selective inhibitors of glycogen synthase kinase-3 (GSK-3).

Potent 3-anilino-4-arylmaleimide glycogen synthase kinase-3 (GSK-3) inhibitors have been prepared using automated array methodology. A number of these are highly selective, having little inhibitory potency against more than 20 other protein kinases.

The identification of a potent, water soluble inhibitor of lipoprotein-associated phospholipase A2.

Modification of the pyrimidone 5-substituent in a series of 1-((amidolinked)-alkyl)-pyrimidones, lipophilic inhibitors of lipoprotein-associated phospholipase A2, has given inhibitors of nanomolar potency and improved physicochemical properties. Compound 23 was identified as a potent, highly water soluble. CNS penetrant inhibitor suitable for intravenous administration.

Solid-phase synthesis of cyclic alkoxyketones, inhibitors of the cysteine protease cathepsin K.

Using solid-phase synthesis, a library of novel cyclic alkoxyketones has been constructed which show strong inhibitory activity against the cysteine protease, cathepsin K (EC 3.4.22.38).

Diastereoselective synthesis, activity and chiral stability of cyclic alkoxyketone inhibitors of cathepsin K.

The diastereoselective synthesis of a novel class of cathepsin K inhibitors together with their cathepsin K affinity and stability towards aqueous buffer is reported.

N-1 substituted pyrimidin-4-ones: novel, orally active inhibitors of lipoprotein-associated phospholipase A2.

From two related series of 2-(alkylthio)-pyrimidones, a novel series of 1-((amidolinked)-alkyl)-pyrimidones has been designed as nanomolar inhibitors of human lipoprotein-associated phospholipase A2. These compounds show greatly enhanced activity in isolated plasma. Selected derivatives such as compounds 51 and 52 are orally active with a good duration of action.

CCR2B receptor antagonists: conversion of a weak HTS hit to a potent lead compound.

A weak HTS hit at the CCR2B receptor has been converted into a potent antagonist by array SAR studies. Selectivity over the closely related CCR5 receptor is also achieved.

2-(Alkylthio)pyrimidin-4-ones as novel, reversible inhibitors of lipoprotein-associated phospholipase A2.

Starting from two weakly active hits from high throughput screening, a novel series of 2-(alkylthio)-pyrimidin-4-ones with high potency and selectivity for lipoprotein-associated phospholipase A2 has been designed. In contrast to previously known inhibitors, these have been shown to act by a non-covalent and substrate competitive mechanism.

The inhibition of human cytomegalovirus (hCMV) protease by hydroxylamine derivatives.

Aryl hydroxylamine derivatives have been synthesised that are some of the most potent inhibitors of hCMV protease prepared to date (IC50 14-60 nM). Mass spectrometry studies indicate that oxazinone derived hydroxylamines inhibit the enzyme by acylation of Ser132 whereas non-oxazinone derived hydroxylamines appear to inhibit via formation of a sulfinanilide at Cys138.

Lipoprotein-associated phospholipase A2, platelet-activating factor acetylhydrolase, generates two bioactive products during the oxidation of low-density lipoprotein: use of a novel inhibitor.

A novel and potent azetidinone inhibitor of the lipoprotein-associated phospholipase A2 (Lp-PLA2), i.e. platelet-activating factor acetylhydrolase, is described for the first time. This inhibitor, SB-222657 (Ki=40+/-3 nM, kobs/[I]=6. 6x10(5) M-1.s-1), is inactive against paraoxonase, is a poor inhibitor of lecithin:cholesterol acyltransferase and has been used to investigate the role of Lp-PLA2 in the oxidative modification of lipoproteins. Although pretreatment with SB-222657 did not affect the kinetics of low-density lipoprotein (LDL) oxidation by Cu2+ or an azo free-radical generator as determined by assay of lipid hydroperoxides (LOOHs), conjugated dienes and thiobarbituric acid-reacting substances, in both cases it inhibited the elevation in lysophosphatidylcholine content. Moreover, the significantly increased monocyte chemoattractant activity found in a non-esterified fatty acid fraction from LDL oxidized by Cu2+ was also prevented by pretreatment with SB-222657, with an IC50 value of 5.0+/-0.4 nM. The less potent diastereoisomer of SB-222657, SB-223777 (Ki=6.3+/-0.5 microM, kobs/[I]=1.6x10(4) M-1.s-1), was found to be significantly less active in both assays. Thus, in addition to generating lysophosphatidylcholine, a known biologically active lipid, these results demonstrate that Lp-PLA2 is capable of generating oxidized non-esterified fatty acid moieties that are also bioactive. These findings are consistent with our proposal that Lp-PLA2 has a predominantly pro-inflammatory role in atherogenesis. Finally, similar studies have demonstrated that a different situation exists during the oxidation of high-density lipoprotein, with enzyme(s) other than Lp-PLA2 apparently being responsible for generating lysophosphatidylcholine.

ATP-Citrate lyase as a target for hypolipidemic intervention. 2. Synthesis and evaluation of (3R,5S)-omega-substituted-3-carboxy-3, 5-dihydroxyalkanoic acids and their gamma-lactone prodrugs as inhibitors of the enzyme in vitro and in vivo.

A series of (3R,5S)-omega-substituted-3-carboxy-3, 5-dihydroxyalkanoic acids have been synthesized and evaluated as inhibitors of the recombinant human form of ATP-citrate lyase. The best of these have Ki's in the 200-1000 nM range. As the corresponding thermodynamically favored gamma-lactone prodrugs, a number of compounds are able to inhibit cholesterol and fatty acid synthesis in HepG2 cells and reduce plasma triglyceride levels in vivo. The best of these, compound 77, is able to induce clear hypocholesterolemic and hypotriglyceridaemic responses when administered orally to rat and dog. These results provide evidence to support the hypothesis that compounds which inhibit ATP-citrate lyase have the potential to be a novel class of hypolipidemic agent, which possess combined hypocholesterolemic and hypotriglyceridemic activities.

Properties of the reversible K(+)-competitive inhibitor of the gastric (H+/K+)-ATPase, SK&F 97574. I. In vitro activity.

SK&F 97574 (3-butyryl-4-(2-methylamino)-8-(2-hydroxyethoxy)quinoline), is a potent inhibitor of the (H+/K+)-ATPase in membrane vesicles isolated from porcine gastric mucosa. It inhibits (H+/K+)-ATPase activity in lyophilised vesicles in a kinetically competitive manner with respect to the activating cation, K+, with an inhibition constant (Ki) of 0.46 +/- 0.003 microM. Inhibition of (H+/K+)-ATPase activity is freely reversible. Binding of SK&F 97574 was shown to be mutually exclusive and the previously reported reversible (H+/K+)-ATPase inhibitors, SCH 28080 and MDPQ. Therefore, despite its structural dissimilarity, SK&F 97574 appears to bind to the same lumenal region of the (H+/K+)-ATPase identified as the binding site for these compounds. SK&F 97574 is a weak base (pKa = 6.86), and would therefore be expected to accumulate in the acidic compartment at the lumenal face of the parietal cell. In intact gastric vesicles (which have the lumenal face of the ATPase on the interior), SK&F 97574 inhibited ATP-dependent H(+)-transport with a similar potency to ATPase activity. SK&F 97574 is therefore relatively membrane permeable, and would be predicted to gain access readily to its site of action in vivo. The effect of pH on inhibition of H+/K(+)-ATPase activity by SK&F 97574 is consistent with its being active only in its protonated form. The selectivity of SK&F 97574 for the gastric (H+/K+)-ATPase was tested by examining its ability to inhibit a closely related p-class pump, the (Na+/K+)-ATPase from dog kidney. SK&F 97574 was found to have a 60-fold greater sensitivity for the former enzyme. The (Na+/K+)-ATPase was not inhibited in a K(+)-competitive manner by SK&F 97574, indicating an entirely different, probably nonspecific, mechanism.

Properties of the reversible, K(+)-competitive inhibitor of the gastric (H+/K+)-ATPase, SK&F 97574. II. Pharmacological properties.

SK&F 97574 [3-Butryl-4-(2-methylamino)-8-(2-hydroxyethoxy) quinoline] is a potent, reversible inhibitor of the gastric (H+/K+)-ATPase. In an anaesthetised lumen-perfused rat preparation, it inhibited pentagastrin-stimulated gastric acid secretion with intravenous and intraduodenal inhibitory ED50 values of 2.40 mumol/kg and 4.43 mumol/kg, respectively. In the conscious fistula rat model, doses of 10 mumol/kg IV and 25 mumol/kg PO produced mean peak inhibitions of basal acid output of 91% and 97%, respectively. In these experiments, the duration of action of SK&F 97574 was much shorter than that of the covalent (H+/K+)-ATPase inhibitor, omeprazole. In the conscious Heidenhain pouch dog, SK&F 97574 inhibited histamine-stimulated gastric acid secretion after both intravenous and oral administration with ED50 values of 0.49 mumol/kg and 0.89 mumol/kg, respectively. In this model, duration of action studies showed that significant residual inhibition of acid secretion remained 8 hours after intravenous dosing with SK&F 97574 (producing peak inhibition of 92%). However, 24 hours after oral dosing of SK&F 97574 (10 mumol/kg), no significant inhibition remained. These data indicate that the duration of action of SK&F 97574 is longer than that of the histamine H2 receptor antagonists such as cimetidine, but shorter than that of covalent (H+/K+)-inhibitors such as omeprazole. Overall, the pharmacological properties of SK&F 97574 suggest that it could be a potentially useful clinical treatment for acid-related diseases.

Reversible inhibitors of the gastric (H+/K+)-ATPase. 4. Identification of an inhibitor with an intermediate duration of action.

3-Acyl-4-(arylamino)quinolines were previously identified as gastric (H+/K+)-ATPase inhibitors, and clinical efficacy has been demonstrated for compound 3 (SK&F 96067). In the present study the further structure-activity relationship of this series is developed. Only a limited range of substituents are tolerated on the N-aryl ring or the 6- and 7-positions of the quinoline, and although hydroxylated derivatives were identified possessing markedly greater affinity for the enzyme, none of these proved to have adequate potency after oral dosing. In contrast, the 8-position of the quinoline ring proved suitable for a wide variety of substituents, allowing modification of physicochemical properties while retaining primary activity. This led to the identification of compound 4 (SK&F 97574), which combines good oral potency with a somewhat longer duration of action than 3 (though much shorter than covalent inhibitors such as omeprazole). This compound was selected for further development and evaluation in man.

Reversible inhibitors of the gastric (H+/K+)-ATPase. 5. Substituted 2,4-diaminoquinazolines and thienopyrimidines.

Quinazolines bearing a secondary 4-(arylamino) substituent demonstrate an SAR for inhibition of the gastric (H+/K+)-ATPase different from the previously described 3-acylquinolines, suggesting that, although these compounds are also K(+)-competitive, they probably bind to the enzyme in a different orientation. Compounds bearing a tertiary 4-(arylamino) substituent, however, in particular 4-(N-methylarylamino), appear to possess an SAR quite similar to the 3-acylquinolines. We show that this arises from the effect of the N-methylation, which is to orientate the 4-(arylamino) substituent syn to C5, analogous to the 3-acylquinolines. Compounds possessing both a 4-(N-methylarylamino) substituent and a 2-(arylamino) substituent proved to be very potent, K(+)-competitive inhibitors of K(+)-stimulated ATPase activity with Ki values down to 12 nM. Some compounds also proved to be effective inhibitors of stimulated acid secretion in both the rat and dog when dosed intravenously. However, although a number of these demonstrated activity after oral administration in the dog, the level and variability precluded further evaluation.

Structures of histamine H1-receptor antagonists derived from the cimetidine group of histamine H2-receptor antagonists.

The crystal and molecular structures of ten compounds with strong structural resemblances to the cimetidine group of histamine H2-receptor antagonists, but exhibiting selective H1-receptor antagonist activity, (1)-(7), or H1 and H2 activity (8)-(10), have been determined: (1) 2-[4-(5-Bromo-3-methyl-2-pyridyl)butylamino]-5- (6-methyl-3-pyridylmethyl)-4-pyrimidone trihydrobromide (temalastine), C21H27BrN5O3+.3Br-, M(r) = 685.09, triclinic, P1, a = 6.314 (2), b = 11.192 (2), c = 19.441 (5) A, alpha = 102.47 (2), beta = 92.77 (2), gamma = 103.28 (2) degrees, V = 1298.51 A3, Z = 2, Dx = 1.75 g cm-3, mu = 61.6 cm-1, F(000) = 672, R = 2.93% for 3208 independent reflexions. (2) 2-[4-(5-Bromo-3-methyl-2-pyridyl)butylamino]-4-pyrimidone, C14H19BrN4O2, M(r) = 355.23, monoclinic, I2/a, a = 16.359 (3), b = 10.469 (6), c = 18.339 (4) A, beta = 90.90 (2) degrees, V = 3140.49 A3, Z = 8, Dx = 1.503 g cm-3, mu = 26.0 cm-1, F(000) = 1176, R = 4.2% for 1872 independent reflexions. (3) 3-[4-(5-Bromo-3-methyl-2-pyridyl)butylamino]-4- amino-1,2,5-thiadiazole-1-oxide, C12H16BrN5OS, M(r) = 358.26, triclinic, P1, a = 14.295 (2), b = 12.447 (2), c = 9.917 (2) A, alpha = 95.77 (2), beta = 113.86 (2), gamma = 106.91 (1) degrees, V = 1495.18 A3, Z = 4, Dx = 1.59 g cm-3, mu = 50.96 cm-1, F(000) = 728, R = 5.98% for 5674 independent reflexions. (4) 3-[4-(5-Bromo-3-methyl-2-pyridyl)butylamino]-4- benzylamino-1,2,5-thiadiazole-1-oxide, C19H22BrN5OS, M(r) = 448.38, monoclinic, P2(1)/c, a = 36.293 (7), b = 4.826 (2), c = 11.528 (3) A, beta = 96.91 (2) degrees, V = 2004.27 A3, Z = 4, Dx = 1.49 g cm-3, mu = 39.2 cm-1, F(000) = 920, R = 12.1% for 1945 independent reflexions. (5) 2-[3-(N-Benzyl-N-2- pyridylamino)propylamino]-4-pyrimidone, C19H21N5O, M(r) = 335.4, orthorhombic, Pbna, a = 7.082 (1), b = 19.889 (3), c = 24.899 (3) A, V = 3507.16 A3, Z = 8, Dx = 1.27 g cm-3, mu = 6.24 cm-1, F(000) = 1424, R = 4.05% from 2470 independent reflexions. (6) 3-[3-(N-4-Fluorobenzyl-N-2- pyridylamino)propylamino]-4-ethylamino-1,2,5-thiadiazole-1-oxide, C19H23FN6OS, M(r) = 402.5, monoclinic, P2(1)/n, a = 6.686 (2), b = 14.717 (3), c = 20.850 (5) A, beta = 97.83 (2) degrees, V = 2032.47 A3, Z = 4, Dx = 1.32 g cm-3, mu = 16.41 cm-1, F(000) = 848, R = 8.5% from 2484 independent reflexions. (7) 5-(6-Methyl-3-pyridylmethyl)-2-[3-(5,6,7,8-tetrahydro-8- quinolyl)propylamino]-4-pyrimidone, C23H29N5O2, M(r) = 407.5, monoclinic, P2(1)/c, a = 14.966 (2), b = 16.075 (2), c = 9.1608 (9) A, beta = 99.158 (8) degrees, V = 2175.83 A3, Z = 4, Dx = 1.24 g cm-3, mu = 6.19 cm-1; F(000) = 872, R = 5.3% from 2784 independent reflexions. (8) 2-(4-Phenylbutylamino)-5-(3-pyridyl-methyl)-4-pyrimidone, C20H26N4O3, M(r) = 370.5, monoclinic, P2(1)/c, a = 8.040 (4), b = 21.279 (4), c = 11.404 (2) A, beta = 92.08 (5) degrees, V = 1949.68 A3, Z = 4, Dx = 1.26 g cm-3, mu = 0.93 cm-1, F(000) = 792, R = 4.05% from 3816 independent reflexions.(ABSTRACT TRUNCATED AT 400 WORDS)

Reversible inhibitors of the gastric (H+/K+)-ATPase. 3. 3-substituted-4-(phenylamino)quinolines.

Previously, gastric (H+/K+)-ATPase inhibitors such as 2 have been prepared as analogues of 1a on the presumption that the 3-carbethoxy substituent plays a key role in establishing the orientation of the 4-arylamino group. In this paper we explore further the contribution made to activity by the quinoline 3-substituent. We show that, for compounds bearing such a substituent, only a particular combination of properties provides high activity, both in vitro and as inhibitors of gastric acid secretion in vivo. The ability of the substituent to affect activity by restricting rotation about the Cquin-N bond through a combination of both a pi-electron withdrawal and hydrogen bonding is supported by the current study. However, high activity is only achieved if the effect of this group on the quinoline pK(a) is kept to a minimum. 3-Acyl substituents provide an optimum combination of electronic properties. From this series, compound 17c (SK&F 96067) was shown to be a potent inhibitor of histamine-stimulated gastric acid secretion after oral dosing in the Heidenhain pouch dog and was selected for further development and evaluation in man.

Reversible inhibitors of the gastric (H+/K+)-ATPase. 2. 1-Arylpyrrolo[3,2-c]quinolines: effect of the 4-substituent.

Further work on compounds 1 has identified the 4-position as a site where substantial modifications are tolerated, leading to analogues which are more potent and less toxic than those described previously. The best compound in the series is 13a (SK&F 96356), which is a potent inhibitor of gastric acid secretion in both the pentagastrin-stimulated rat and the histamine-stimulated dog. This compound shows reversible, K(+)-competitive binding to the enzyme. Because of its fluorescent properties, it is also proving useful in vitro as a probe of the structure and function of the (H+/K+)-ATPase.