Synthesis of 7-chloro-2,3-dihydro-2-[1-(pyridinyl)alkyl]-pyridazino[4,5-b]quinoline-1,4,10(5H)-triones as NMDA glycine-site antagonists

Several members of the 7-chloro-2,3-dihydro-2-[1-(pyridinyl)alkyl]-pyridazino[4,5-b]quinoline-1,4,10(5H)-triones (2) have been identified as being potent and selective NMDA glycine-site antagonists. Increasing size of the alkyl substituent on the alpha-carbon led to a progressive decrease in binding affinity. Some of these analogues possess improved drug-like properties such as cellular permeability, solubility and oral absorption.     

5-(2-amino-pyrimidin-4-yl)-1H-pyrrole and 2-(2-amino-pyrimidin-4-yl)-1,5,6,7-tetrahydro-pyrrolo[3,2-c]pyridin-4-one derivatives as new classes of selective and orally available Polo-like kinase 1 inhibitors

The discovery and characterization of two new chemical classes of potent and selective Polo-like kinase 1 (PLK1) inhibitors is reported. For the most interesting compounds, we discuss the biological activities, crystal structures and preliminary pharmacokinetic parameters. The more advanced compounds inhibit PLK1 in the enzymatic assay at the nM level and exhibit good activity in cell proliferation on A2780 cells. Furthermore, these compounds showed high levels of selectivity on a panel of unrelated kinases, as well as against PLK2 and PLK3 isoforms. Additionally, the compounds show acceptable oral bioavailability in mice making these inhibitors suitable candidates for further in vivo activity studies.     

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.     

Discovery of 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) as a potent,selective and orally efficacious cannabinoid-1 receptor antagonist

Structure–activity relationship studies in a series of diarylpyrazolyl thiadiazoles identified cannabinoid-1 receptor antagonists with excellent potency and selectivity. Based on its exceptional in vivo efficacy in animal models and its favorable pharmacokinetic and toxicological profiles, 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) was selected as a preclinical candidate for the treatment of obesity.     

Identification of a novel 1'-[5-((3,5-dichlorobenzoyl)methylamino)-3-(3,4-dichlorophenyl)-4-(methoxyimino)pentyl]-2-oxo-(1,4'-bipiperidine) as a dual NK(1)/NK(2) antagonist

A novel series of dual NK(1)/NK(2) receptor antagonists, based on the 2-oxo-(1,4'-bipiperidine) template, has been prepared. Compound 10R is a potent dual NK(1)/NK(2) antagonist and demonstrates excellent in vivo activity and good oral plasma levels in the dog.     

Prodrugs of the cancer cell selective anti-cancer agent (Z)-2-(1H-indol-3-yl)-3-(isoquinolin-5-yl)acrylonitrile (A131) are orally efficacious in a mouse model of resistant colon cancer

A131 (1) possesses a unique cancer cell selective dual mechanism of action where cancer cells are killed but normal cells only undergo growth arrest and are able to regrow after removal of 1. SAR studies of 1 indicate that only the specific structure of 1 elicits the full pharmacological effect. However, application of 1 in mouse models of cancer has been hampered by its low solubility and stability when given orally. In this work we describe the study of various prodrugs based on modification of the indole nitrogen. A range of acyl analogues were prepared as prodrugs which were shown to undergo degradation to the parent drug in plasma. A preferred prodrug fully elicited the pharmacological effects of 1 in cells and led to high aqueous solubility suitable for oral administration. In a mouse model of paclitaxel-resistant colon cancer, compound 10, as a TFA salt, showed 76% tumor growth inhibition when administered at an oral dose of 80?mg/kg twice a day.     

Discovery of 1-(4-((3-(4-methylpiperazin-1-yl)propyl)amino)benzyl)-5-(trifluoromethyl)pyridin-2(1H)-one,an orally active multi-target agent for the treatment of diabetic nephropathy

Oxidative stress, inflammation and fibrosis can cause irreversible damage on cell structure and function of kidney and are key pathological factors in Diabetic Nephropathy (DN). Therefore, multi-target agents are urgently need for the clinical treatment of DN. Using Pirfenidone as a lead compound and based on the previous research, two novel series (5-trifluoromethyl)-2(1H)-pyridone analogs were designed and synthesized. SAR of (5-trifluoromethyl)-2(1H)-pyridone derivatives containing nitrogen heterocyclic ring have been established for in vitro potency. In addition, compound 8, a novel agent that act on multiple targets of anti-DN with IC₅₀ of 90 μM in NIH3T3 cell lines, t_1/2 of 4.89 ± 1.33 h in male rats and LD₅₀ > 2000 mg/kg in mice, has been advanced to preclinical studies as an oral treatment for DN.     

2-(2-[3-(pyridin-3-yloxy)phenyl]-2H-tetrazol-5-yl) pyridine: a highly potent, orally active, metabotropic glutamate subtype 5 (mGlu5) receptor antagonist

Structure-activity relationship studies on 3-(5-pyridin-2-yl-2H-tetrazol-2-yl)benzonitrile 2 led to the discovery of 2-(2-[3-(pyridin-3-yloxy)phenyl]-2H-tetrazol-5-yl)pyridine (10)-a highly potent and selective mGlu5 receptor antagonist with good brain penetration and in vivo receptor occupancy in rat and cross-species oral bioavailability.     

The discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazolo-[1 ,5-a]-pyrimidine: a corticotropin-releasing factor (hCRF1) antagonist

Structure activity relationship studies led to the discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazo lo-[1,5-a]-pyrimidine 11-31 (DMP904), whose pharmacological profile strongly supports the hypothesis that hCRF1 antagonists may be potent anxiolytic drugs. Compound 11-31 (hCRF1 Ki = 1.0+/-0.2 nM (n = 8)) was a potent antagonist of hCRF1-coupled adenylate cyclase activity in HEK293 cells (IC50= 10.0+/-0.01 nM versus 10 nM r/hCRF, n = 8); alpha-helical CRF(9-41) had weaker potency (IC50 = 286+/-63 nM, n = 3). Analogue 11-31 had good oral activity in the rat situational anxiety test; the minimum effective dose for 11-31 was 0.3 mg/kg (po). Maximal efficacy (approximately 57% reduction in latency time in the dark compartment) was observed at this dose. Chlordiazepoxide caused a 72% reduction in latency at 20 mg/kg (po). The literature compound 1 (CP154526-1, 30 mg/kg (po)) was inactive in this test. Compound 11-31 did not inhibit open-field locomotor activity at 10, 30, and 100 mg/kg (po) in rats. In beagle dogs, this compound (5 mg/kg, iv, po) afforded good plasma levels. The key iv pharmacokinetic parameters were t1/2, CL and Vd,ss values equal to 46.4+/-7.6 h. 0.49+/-0.08 L/kg/h and 23.0+/-4.2 L/kg, respectively. After oral dosing, the mean Cmax, Tmax t1/2 and bioavailability values were equal to 1260+/-290 nM, 0.75+/-0.25 h. 45.1+/-10.2 h and 33.1%, respectively. The overall rat behavioral profile of this compound suggests that it may be an anxiolytic drug with a low motor side effect liability.     

2-(1H-Imidazol-4-yl)ethanamine and 2-(1H-pyrazol-1-yl)ethanamine side chain variants of the IGF-1R inhibitor BMS-536924

A series of IGF-1R inhibitors is disclosed, wherein the (m-chlorophenyl)ethanol side chain of BMS-536924 (1) is replaced with a series of 2-(1H-imidazol-4-yl)ethanamine and 2-(1H-pyrazol-1-yl)ethanamine side chains. Some analogs show improved IGF-1R potency and oral exposure. Analogs from both series, 16a and 17f, show in vivo activity comparable to 1 in our constitutively activated IGF-1R Sal tumor model. This may be the due to the improved protein binding in human and mouse serum for imidazole 16a and the excellent oral exposure of pyrazole 17f.     

Antifertility effect of busulfan and DL-6-(N-2-pipecolinomethyl)-5-hydroxy-indane maleate (PMHI) in coyotes (Canis Latrans )

Antifertility effects of busulfan were evaluated using adult coyotes. In addition, antifertility effects of PMHI were evaluated in adult males. Adult males and females were alloted randomly to the following treatments: (1) untreated control, (2) a single oral dose of 3 mg busulfan/kg of body weight (BW) or (3) two oral doses of 3 mg busulfan/kg BW given nine days apart. The untreated males were used as controls in both experiments. Additional male coyotes were allotted randomly to PMHI treatments as follows: (1) a single oral dose of 2 mg PMHI/kg BW, or (2) two oral doses of 1 mg PMHI/kg BW given seven days apart. Blood samples were taken from females and serum analyzed for progesterone by radioimmunoassay. Males were hemicastrated (left testicle) 30 days after onset of treatment. The right testicle was removed 30 days later. Testes and epididymides were fixed in 10% buffered formalin and prepared for histologic examination. For females developing corpus luteum (CL), the maximum peak progesterone concentration for those given two doses of busulfan was less (P<0.05) than that for untreated controls and single-dose females (16.9, 22.4 and 26.3 ng/ml, respectively). The double treatment of busulfan prevented more females (4 of 10) from developing CL (P<0.08) than controls (0 of 7) or single-dose females (1 of 9). None of the busulfan-treated male coyotes had histologic evidence of spermatogenesis 60 days after the onset of treatment. The oral dose or doses of PMHI did not result in complete degeneration of seminiferous tubules. Busulfan given orally did not cause any adverse reactions, but orally administered PMHI often induced vomiting within 18 min after treatment. We conclude that busulfan is capable of affecting male and female reproductive parameters, but PMHI appears to have little effect on spermatogenesis in coyotes when given orally in a single- or a double-dose.     

Discovery of (1R,2R)-N-(4-(6-isopropylpyridin-2-yl)-3-(2-methyl-2H-indazol-5-yl)isothiazol-5-yl)-2-methylcyclopropanecarboxamide,a potent and orally efficacious mGlu5 receptor negative allosteric modulator

A novel series of selective negative allosteric modulators (NAMs) for metabotropic glutamate receptor 5 (mGlu5) was discovered from an isothiazole scaffold. One compound of this series, (1R,2R)-N-(4-(6-isopropylpyridin-2-yl)-3-(2-methyl-2H-indazol-5-yl)isothiazol-5-yl)-2-methylcyclopropanecarboxamide (24), demonstrated satisfactory pharmacokinetic properties and, following oral dosing in rats, produced dose-dependent and long-lasting mGlu5 receptor occupancy. Consistent with the hypothesis that blockade of mGlu5 receptors will produce analgesic effects in mammals, compound 24 produced a dose-dependent reduction in paw licking responses in the formalin model of persistent pain.     

Interactions of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas with dopamine D2 and 5-hydroxytryptamine 5HT(1A) receptors

It is suggested that the ratio of dopamine D(2) to 5-hydroxytryptamine 5-HT(1A) activity is an important parameter that determines the efficiency of antipsychotic drugs. Here we present the synthesis of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas and their structure-activity relationship studies on dopamine D(2) and 5-hydrohytryptamine 5-HT(1A) receptors. It was shown that ligand selectivity and affinity strongly depends on their topology and the presence of a pyridyl group in the head of molecules. Molecular modeling studies using homology modeling and docking simulation revealed a rational explanation for the ligand behavior. The observed binding modes and receptor-ligand interactions provided us with a clue for optimizing the optimal selectivity towards 5-HT(1A) receptors.     

Evaluation of 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (FIAU) as an ex vivo bacterial detection agent

The nucleoside analogue, 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (FIAU) is a substrate for thymidine kinase (TK), which is commonly expressed in bacteria. It is currently being investigated in clinical studies as an in vivo bacterial infection detection agent. In developing countries where imaging facilities are not readily available, deploying such technology can be a big hurdle. However, a portable ex vivo system might provide a good alternative. In an in vitro system, [¹²⁵I]-FIAU incubated with bacteria is phosphorylated by TK, and is trapped within the bacteria, which can be detected by radioscintography. The suitability of this agent to be utilized as part of an ex vivo bacterial detection system was evaluated. In the first part of this report, the optimization of the incubation and detection condition using E. coli as a test case is described. Samples were incubated in a growth promoting medium containing the label, then after filtering and washing, the amount of radioactivity trapped on the filter was quantitated by a scintillation counter. As a proof of concept demonstration, blinded urine samples from urinary tract infection (UTI) patients and normal donors were tested in the FIAU system. Of the 13 UTI positive and 15 normal urine samples tested, there were 2 false negatives and 1 false positive, respectively. Potential explanations for the false positive and negatives as well as the commercialization possibility of this system will be discussed.     

Design,synthesis and biological activity of novel non-amidine factor Xa inhibitors. Part 1: P(1) structure-activity relationships of the substituted 1-(2-Naphthyl)-1H-pyrazole-5-carboxylamides

Based on DuPont Pharmaceuticals' monobenzamidine lead structure SN429, we have designed the biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides as a novel series of non-basic factor Xa inhibitors. We have discovered that the displacement of the benzamidine moiety with substituted 2-naphthyl structures not only results in highly potent factor Xa inhibitors, but also significantly increases their enzyme specificity and oral bioavailability.     

5-(3-Cyclopentyl-2-thioxo-2,3-dihydro-1H-benzimidazol-5-yl)-1-methyl-1H-pyrrole-2-carbonitrile: A novel, highly potent, selective, and orally active non-steroidal progesterone receptor agonist

We have recently discovered 5-(3-cyclopentyl-2-thioxo-2,3-dihydro-1H-benzimidazol-5-yl)-1-methyl-1H-pyrrole-2-carbonitrile (14) as a potent, selective, and orally active non-steroidal progesterone receptor (PR) agonist. Compound 14 and its analog 13 possessed sub-nanomolar in vitro potency (EC(50) 0.1-0.5nM) in the T47D alkaline phosphatase assay, similar to that of the steroidal PR agonist medroxyprogesterone acetate (MPA). In contrast to MPA, 14 was highly selective (>500-fold) for the PR over both glucocorticoid and androgen receptors. In the rat uterine decidualization and complement component C3 models, 14 had oral ED(50) values of 0.02 and 0.003mg/kg, respectively, and was from 6- to 20-fold more potent than MPA. In the monkey ovulation inhibition model, compound 14 was also highly efficacious and potent with an oral ED(100) of 0.03mg/kg.     

A dinuclear europium(III) complex with thenoyltrifluoroacetonato and 1-(2-pyridylzao)-2-naphtholato ligands and its optical properties

Dinuclear lanthanide complexes of the general for Ln₂(TTA)₄(PAN)₂ (Ln = Eu, Gd, Tb, Yb; TTA and monodeprotonated thenoyltrifluoroacetone and PAN 1-(2-pyridylazo)-2-naphthol, respectively) were prepared and structurally characterized. These novel complexes, representing the first examples of crystallographically characterized lanthanide-PAN complexes, each feature a dinuclear core with the metal atoms bridged by the phenolato O atoms of the chelating-bridging PAN ligands. Electronic spectroscopic and photoluminescence studies were carried out for the Eu(III) complex, and the results are consistent with ligand-mediated energy transfer and ligand-sensitized luminescence characteristic of Eu(III). The Eu(III) complex doped into a polymeric film was shown to effectively limit a nanosecond 523-nm laser pulse, and the limiting effect is rationalized in terms of reverse saturable absorption due to the strong absorption of the metal’s excited triplet states that are populated by intersystem crossing.     

Potent inhibitory effects of the 5'-triphosphates of (E)-5-(2-bromovinyl)-2'-deoxyuridine and (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil on DNA polymerase gamma

(E)-5-(2-Bromovinyl)-2'-deoxyuridine 5'-triphosphate (BrVdUTP) and (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil 5'-triphosphate (BrVarafUTP), which are known as specific inhibitors of herpes simplex viral (type 1 and 2) DNA polymerase, were found to be strong inhibitors of DNA polymerase gamma from human KB and murine myeloma cells. In fact BrVdUTP and BrVarafUTP were found to be stronger inhibitors of DNA polymerase gamma than of other DNA polymerases having viral (herpes simplex virus or retrovirus) origin or cellular (eukaryotic alpha and beta, or prokaryotic) origin. The mode of inhibition of DNA polymerase gamma by BrVdUTP and BrVarafUTP was competitive with respect to dTTP, the normal substrate. Whereas BrVdUTP was an efficient substrate for DNA polymerase gamma and other DNA polymerases that were examined, BrVarafUTP failed to serve as a substrate for DNA synthesis. Ki values for BrVdUTP (40 nM) and BrVarafUTP (7 nM) with DNA polymerase gamma, as determined with (rA)n.(dT) as the template.primer, were much smaller than the Km values for dTTP (0.16 microM and 0.71 microM for murine and human DNA polymerase gamma, respectively). Thus, the affinity of BrVdUTP or BrVarafUTP for DNA polymerase gamma was much stronger than that of dTTP.     

3-(4-Piperidinyl)- and 3-(8-aza-bicyclo[3.2.1]oct-3-yl)-2-phenyl-1H-indoles as bioavailable h5-HT2A antagonists

A series of 3-(4-piperidinyl)- and 3-(8-aza-bicyclo[3.2.l]oct-3-yl)-2-phenyl-1H-indoles have been prepared and evaluated as ligands for the h5-HT_2A receptor. 3-(8-Phenethyl-8-aza-bicyclo[3.2.l]oct-3-yI)-2-phenyl-1H-indole is a high-affinity (1.2 nM), selective (>800 fold over h5-HT_2C and hD₂ receptors) antagonist at the h5-HT_2A receptor with oral bioavailability in rats.     

Novel and potent inhibitors of stearoyl-CoA desaturase-1. Part II: Identification of 4-ethylamino-3-(2-hydroxyethoxy)-N-[5-(3-trifluoromethylbenzyl)thiazol-2-yl]benzamide and its biological evaluation

The continuing investigation of SAR studies of 3-(2-hydroxyethoxy)-N-(5-benzylthiazol-2-yl)-benzamides as stearoyl-CoA desaturase-1 (SCD-1) inhibitors is reported. Our prior hit-to-lead effort resulted in the identification of 1a as a potent and orally efficacious SCD-1 inhibitor. Further optimization of the structural motif resulted in the identification of 4-ethylamino-3-(2-hydroxyethoxy)-N-[5-(3-trifluoromethylbenzyl)thiazol-2-yl]benzamide (37c) with sub nano molar IC₅₀ in both murine and human SCD-1 inhibitory assays. This compound demonstrated a dose-dependent decrease in the plasma desaturation index in C57BL/6J mice on a non-fat diet after 7 days of oral administration.