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.     

Identification of MK-1925: A selective,orally active and brain-penetrable opioid receptor-like 1 (ORL1) antagonist

Structure–activity relationship studies directed toward improving the metabolic stability of compound 1 resulted in the identification of 3-[5-(3,5-difluorophenyl)-3-({[(1S,3R)-3-fluorocyclopentyl]amino}methyl)-4-methyl-1H-pyrazol-1-yl]propanenitrile 39 (MK-1925) as a selective, orally available and brain-penetrable opioid receptor-like 1 (ORL1) antagonist. The compound also showed in vivo efficacy after oral dosing. Therefore, compound 39 was selected to undergo further studies as a clinical candidate.     

Synthesis of novel tetrazole derivatives and evaluation of their antifungal activity

With the appearance of the antifungal resistance, novel antifungal agents need to be identified. In this context new 2,5-disubstituted tetrazole derivatives containing benzothiazole, benzoxazole or phenylsulfonyl moiety were synthesized by N-alkylation of aryltetrazole with 2-[(3-chloropropyl)sulfanyl]-1,3-benzothiazole or 2-[(3-chloropropyl)sulfanyl]-1,3-benzoxazole and Michael-type addition of aryltetrazole to phenyl vinyl sulfone. The chemical structures of the synthesized compounds were confirmed by means of ¹H NMR, ¹³C NMR, IR and HRMS spectral data. The compounds were tested against the moulds: Fusarium sambucinum, Fusarium oxysporum, Colletotrichum coccodes, Aspergillus niger, and the yeast Candida albicans. The results showed that among the moulds only C. coccodes was significantly sensitive to all the structures examined. All the tetrazole derivatives acted at the same level against C. albicans and demonstrated a high cell growth inhibition (97–99%) at the concentrations ranging from 16 to 0.0313 μg/mL. The mode of action of 2-({3-[5-(4-chlorophenyl)-2H-tetrazol-2-yl]propyl}sulfanyl)-1,3-benzoxazole (5c) and 2-({3-[5-(2-chlorophenyl)-2H-tetrazol-2-yl]propyl}sulfanyl)-1,3-benzoxazole (5d) was established by verifying fungal growth in the presence of osmotic protector-sorbitol. The effect of compound 5c or 5d combined with Fluconazole was determined using the checkerboard method. The calculated fractional inhibitory concentration index (FIC) indicated antagonism (FIC >1). Additionally, survival experiments with lepidopteran Galleria mellonella treated with compounds 5c and 5d were performed and demonstrated the lack of toxicity of these compounds.     

Optimization of oxadiazole derivatives with a spirocyclic cyclohexane structure as novel GPR119 agonists

We describe here a novel GPR119 agonist 24, which showed a potent and long-acting hypoglycemic effect in rats via oral dosing. For the discovery of 24, we chose compound 5, which possessed an oxadiazole linker, as a lead compound among our spirocyclic cyclohexane GPR119 agonist series, taking into account its lower plasma protein binding nature. 3,5-Difluoro and 4-methylsulfonylmethy groups on the left side phenyl group, and a gem-difluoro group on the right side of 24 are important for its agonist potency and metabolic stability, respectively.     

Design,synthesis, and biological evaluation of deuterated apalutamide with improved pharmacokinetic profiles

A series of deuterated apalutamide were designed and prepared. Compared to its prototype compound 18, deuterated analogues 19 and 21 showed obviously higher plasma concentrations and better PK parameters after oral administration in mice. In rats, N-trideuteromethyl compound 19 displayed 1.8-fold peak concentration (C_max), and nearly doubled its drug exposure in plasma (AUC_0–∞) compared to compound 18. Unsurprisingly, compounds 18 and 19 had similar affinity for AR in vitro. In summary, the deuteration strategy could obviously improve PK parameters of apalutamide.     

Photoreactive 111In-cyclodextrin inclusion complex: a new heterobifunctional reagent for antibody labeling

The compound of interest, N-5-azido-2-nitrobenzoylaminomethyl-¹¹¹In-acetylacetone-α-cyclodextrin (CD) (V) was synthesized by the selective tosylation of α-CD to form 6-tosyl-6-deoxy-CD, which was then reacted with NaN₃ to form 6-azido-6-deoxy-CD (II). This was followed by catalytic hydrogenation to yield III. Compound III and ¹¹¹In-acetylacetone were mixed to form an inclusion complex, which was then reacted with N-5-azido-2-nitrobenzoyloxysuccinimide to yield compound V. Anti-melanoma MAbTP41.2 was added to compound V, followed by immediate photoreactivation labeling by u.v. light at 320 nm. The final product VI was purified from a Sephadex G-50 column. ¹¹¹In-DTPA-MAbTP41.2 was also prepared as a control.Immunoreactivity via the cell-binding assay of VI was 87%, compared with 57% by the BADTPA method. Biodistribution in non-tumor rats yielded a liver concentration in %ID/g of 3.5, 1.7 and 1.0 for compound VI, compared to the 5.5, 5.2 and 3.1 for the BADTPA compound, at 4, 24 and 48 h post-injection, respectively.     

Design and synthesis of prostate cancer antigen-1 (PCA-1/ALKBH3) inhibitors as anti-prostate cancer drugs

A series of 1-aryl-3,4-substituted-1H-pyrazol-5-ol derivatives was synthesized and evaluated as prostate cancer antigen-1 (PCA-1/ALKBH3) inhibitors to obtain a novel anti-prostate cancer drug. After modifying 1-(1H-benzimidazol-2-yl)-3,4-dimethyl-1H-pyrazol-5-ol (1), a hit compound found during random screening using a recombinant PCA-1/ALKBH3, 1-(1H-5-methylbenzimidazol-2-yl)-4-benzyl-3-methyl-1H-pyrazol-5-ol (35, HUHS015), was obtained as a potent PCA-1/ALKBH3 inhibitor both in vitro and in vivo. The bioavailability (BA) of 35 was 7.2% in rats after oral administration. As expected, continuously administering 35 significantly suppressed the growth of DU145 cells, which are human hormone-independent prostate cancer cells, in a mouse xenograft model without untoward effects.     

Synthesis of VS-105: A novel and potent vitamin D receptor agonist with reduced hypercalcemic effects

We have synthesized a novel vitamin D receptor agonist VS-105 ((1R,3R)-5-((E)-2-((3αS,7αS)-1-((R)-1-((S)-3-hydroxy-2,3-dimethylbutoxy)ethyl)-7α-methyldihydro-1H-inden-4(2H,5H,6H,7H,7αH)-ylidene)ethylidene)-2-methylenecyclohexane-1,3-diol). Preparation of a-ring phenylphosphine oxide 11, followed by Wittig–Horner coupling of 11 with the protected 25-hydroxy Grundmann’s ketone 22 generated the precursor 12. Deprotection of the TBDMS groups of 12 produced the target compound VS-105. The biological profiles of VS-105 were evaluated using in vitro assays (VDR receptor binding, VDR reporter gene and HL-60 differentiation) in comparison to calcitriol (the endogenous hormone) or paricalcitol. Furthermore, the PTH suppressing potency and hypercalcemic side effects of VS-105 were evaluated in the 5/6 nephrectomized uremic rats in comparison to paricalcitol. Combining various changes at 20-epi, 22-oxa, 24-methyl, and 2-methylene yielded VS-105 that not only is highly potent in inducing functional responses in vitro, but also effectively suppresses PTH in a dose range that does not affect serum calcium in the 5/6 nephrectomized uremic rats.     

Discovery of pyridone-containing imidazolines as potent and selective inhibitors of neuropeptide Y Y5 receptor

A series of 2-pyridone-containing imidazoline derivatives was synthesized and evaluated as neuropeptide Y Y5 receptor antagonists. Optimization of the 2-pyridone structure on the 2-position of the imidazoline ring led to identification of 1-(difluoromethyl)-5-[(4S,5S)-4-(4-fluorophenyl)-4-(6-fluoropyridin-3-yl)-5-methyl-4,5-dihydro-1H-imidazol-2-yl]pyridin-2(1H)-one (7m). Compound 7m displayed statistically significant inhibition of food intake in an agonist-induced food intake model in SD rats and no adverse cardiovascular effects in anesthetized dogs. In addition, markedly higher brain penetrability and a lower plasma Occ90 value were observed in P-gp-deficient mdr1a (?/?) mice compared to mdr1a (+/+) mice after oral administration of 7m.     

Design,synthesis and molecular modeling of novel N-acylhydrazone derivatives as pyruvate dehydrogenase complex E1 inhibitors

As potential inhibitors of pyruvate dehydrogenase complex E1 (PDHc-E1), a series of 19 1-((4-amino-2-methylpyrimidin-5-yl)methyl)-5-methyl-N′-(substituent)benzylidene-1H-1,2,3-triazole-4-carbohydrazide 4 has been synthesized and tested for their PDHc-E1 inhibitory activity in vitro. Some of these compounds such as 4a, 4g, 4l, 4o, 4p, and 4q were demonstrated to be effective inhibitors by the bioassay of Escherichia coli PDHc-E1. SAR analysis indicated that the PDHc-E1 inhibitory activity could be further enhanced by optimizing the substituted groups in the parent compound. Molecular modeling study with compound 4o as a model was performed to evaluate docking. The results of modeling study suggested a probable inhibition mechanism.     

Discovery of novel arylpyrazole series as potent and selective opioid receptor-like 1 (ORL1) antagonists

The synthesis and biological evaluation of new potent opioid receptor-like 1 antagonists are presented. A structure–activity relationship (SAR) study of arylpyrazole lead compound 1 obtained from library screening identified compound 31, (1S,3R)-N-{[1-(3-chloropyridin-2-yl)-5-(5-fluoro-6-methylpyridin-3-yl)-4-methyl-1H-pyrazol-3-yl]methyl}-3-fluorocyclopentanamine, which exhibits high intrinsic potency and selectivity against other opioid receptors and hERG potassium channel.     

Structure activity relationship studies of 3-arylsulfonyl-pyrido[1,2-a]pyrimidin-4-imines as potent 5-HT6 antagonists

Comprehensive structure activity relationship (SAR) studies were conducted on a focused screening hit, 2-(methylthio)-3-(phenylsulfonyl)-4H-pyrido[1,2-a]pyrimidin-4-imine (1, IC₅₀: 4.0 nM), as 5-HT₆ selective antagonists. Activity was improved some 2–4 fold when small, electron-donating groups were added to the central core as observed in 19, 20 and 26. Molecular docking of key compounds in a homology model of the human 5-HT₆ receptor was used to rationalize our structure–activity relationship (SAR) findings. In pharmacokinetic experiments, compound 1 displayed good brain uptake in rats following intra-peritoneal administration, but limited oral bioavailability.     

Facile synthesis of SSR180575 and discovery of 7-chloro-N,N,5-trimethyl-4-oxo-3(6-[18F]fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide,a potent pyridazinoindole ligand for PET imaging of TSPO in cancer

A novel synthesis of the translocator protein (TSPO) ligand 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (SSR180575, 3) was achieved in four steps from commercially available starting materials. Focused structure–activity relationship development about the pyridazinoindole ring at the N3 position led to the discovery of 7-chloro-N,N,5-trimethyl-4-oxo-3(6-fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (14), a novel ligand of comparable affinity. Radiolabeling with fluorine-18 (¹⁸F) yielded 7-chloro-N,N,5-trimethyl-4-oxo-3(6-[¹⁸F]fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide ([¹⁸F]-14) in high radiochemical yield and specific activity. In vivo studies of [¹⁸F]-14 revealed this agent as a promising probe for molecular imaging of glioma.     

Discovery and preclinical profile of teneligliptin (3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine): A highly potent,selective, long-lasting and orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes

Dipeptidyl peptidase IV (DPP-4) inhibition is suitable mechanism for once daily oral dosing regimen because of its low risk of hypoglycemia. We explored linked bicyclic heteroarylpiperazines substituted at the γ-position of the proline structure in the course of the investigation of l-prolylthiazolidines. The efforts led to the discovery of a highly potent, selective, long-lasting and orally active DPP-4 inhibitor, 3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine (8g), which has a unique structure characterized by five consecutive rings. An X-ray co-crystal structure of 8g in DPP-4 demonstrated that the key interaction between the phenyl ring on the pyrazole and the S₂ extensive subsite of DPP-4 not only boosted potency, but also increased selectivity. Compound 8g, at 0.03 mg/kg or higher doses, significantly inhibited the increase of plasma glucose levels after an oral glucose load in Zucker fatty rats. Compound 8g (teneligliptin) has been approved for the treatment of type 2 diabetes in Japan.     

Design,synthesis and biological evaluation of novel pyrrole derivatives as potential ClpP1P2 inhibitor against Mycobacterium tuberculosis

In an effort to discover novel inhibitors of M. tuberculosis Caseinolytic proteases (ClpP1P2), a combination strategy of virtual high-throughput screening and in vitro assay was employed and a new pyrrole compound, 1-(2-chloro-6-fluorobenzyl)-2, 5-dimethyl-4-((phenethylamino)methyl)-1H-pyrrole-3-carboxylate was found to display inhibitory effects against H₃₇Ra with an MIC value of 77 µM. In order for discovery of more potent anti-tubercular agents that inhibit ClpP1P2 peptidase in M. tuberculosis, a series of pyrrole derivatives were designed and synthesized based on this hit compound. The synthesized compounds were evaluated for in vitro studies against ClpP1P2 peptidase and anti-tubercular activities were also evaluated. The most promising compounds 2-(4-bromophenyl)-N-((1-(2-chloro-6-fluorophenyl)-2, 5-dimethyl-1H- pyrrolyl)methyl)ethan-1-aminehydrochloride 7d, ethyl 4-(((4-bromophenethyl) amino) methyl)-2,5-dimethyl-1-phenyl-1H-pyrrole-3-carboxylate hydrochloride 13i, ethyl 1-(4-chlorophenyl)-4-(((2-fluorophenethyl)amino)methyl)-2-methyl-5-phenyl-1H-pyrrole-3-carboxylate hydrochloride 13n exhibited favorable anti-mycobacterial activity with MIC value at 5 µM against Mtb H₃₇Ra, respectively.     

Development of selective inhibitors for the treatment of rheumatoid arthritis: (R)-3-(3-(Methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)pyrrolidin-1-yl)-3-oxopropanenitrile as a JAK1-selective inhibitor

A series of 3(R)-aminopyrrolidine derivatives were designed and synthesized for JAK1-selective inhibitors through the modification of tofacitinib’s core structure, (3R,4R)-3-amino-4-methylpiperidine. From the new core structures, we selected (R)-N-methyl-N-(pyrrolidin-3-yl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine as a scaffold for further SAR studies. From biochemical enzyme assays and liver microsomal stability tests, (R)-3-(3-(methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)pyrrolidin-1-yl)-3-oxopropanenitrile (6) was chosen for further in vivo test through oral administration. Compound 6 showed improved selectivity for JAK1 compared to that of tofacitinib (IC₅₀ 11, 2.4?×?10², 2.8?×?10³, and 1.1?×?10²?nM for JAK1, JAK2, JAK3, and TYK2, respectively). In CIA and AIA model tests, compound 6 exhibited similar efficacy to tofacitinib citrate.     

Design,synthesis, and biological evaluation of a novel series of peripheral-selective noradrenaline reuptake inhibitors—Part 2

Peripherally selective inhibition of noradrenaline reuptake is a novel mechanism for the treatment of stress urinary incontinence to overcome adverse effects associated with central action. Herein, we describe our medicinal chemistry approach to discover peripheral-selective noradrenaline reuptake inhibitors to avert the risk of P-gp-mediated DDI at the blood–brain barrier. We observed that steric shielding of the hydrogen-bond acceptors and donors (HBA and HBD) of compound 1 reduced the multidrug resistance protein 1 (MDR1) efflux ratio; however, the resulting compound 6, a methoxyacetamide derivative, was mainly metabolized by CYP2D6 and CYP2C19 in the in vitro phenotyping study, implying the risk of PK variability based on the genetic polymorphism of the CYPs. Replacement of the hydrogen atom with a deuterium atom in a strategic, metabolically hot spot led to compound 13, which was mainly metabolized by CYP3A4. To our knowledge, this study represents the first report of the effect of deuterium replacement for a major metabolic enzyme. The compound 13, N-{[(6S,7R)-7-(4-chloro-3-fluorophenyl)-1,4-oxazepan-6-yl]methyl}-2-[(2H³)methyloxy]acetamide hydrochloride, which exhibited peripheral NET selective inhibition at tested doses in rats, increased urethral resistance in a dose-dependent manner.     

Synthesis of novel 1,2,3-triazole/isoxazole functionalized 2H-Chromene derivatives and their cytotoxic activity

A series of novel 2-(1,2,3-triazolylmethoxy) 5a–q and isoxazole tagged 6a–g 2H-Chromene derivatives were prepared starting from salicylaldehyde and ethyl-4,4,4-trifluoroacetoacetate via cyclization to form ethyl 2-hydroxy-2-(trifluoromethyl)-2H-Chromene-3-carboxylate 3. Compound 3 on reaction with propargyl bromide resulted compound 4 and was independently reacted with aryl/alkyl azides and aryl aldoximes obtained 2-(1,2,3-triazolylmethoxy) and isoxazole tagged 2H-Chromene derivatives 5a–q, 6a–i, respectively. Compounds 6 were further hydrolysed to acid derivatives 7a–g. All the products 5a–q, 6a–i, 7a–g were screened for cytotoxic activity against four human cancer cell lines and among all the compounds, 5f, 5g, 5l, 5q showed promising activity at <20 μM concentration.     

Discovery of N-{N-[(3-cyanobenzene) sulfonyl]-4(R)-(3,3-difluoropiperidin-1-yl)-(l)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl) amino]-(l)-phenylalanine (MK-0617), a highly potent and orally active VLA-4 antagonist

A series of prolyl-N-isonicotinoyl-(L)-4-aminophenylalanine derivatives substituted at the proline 4-position with cyclic amines was evaluated as VLA-4 antagonists. The ring size and presence or absence of fluorine affected potency and receptor occupancy. The analog with 3,3-difluoropiperidine at the proline 4-position (13) was the most potent compound and had very good duration of receptor occupancy in vitro. The ethyl ester prodrug of 13 demonstrated excellent receptor occupancy after oral dosing in rats.     

Synthesis and structure–activity relationships of phenothiazine carboxylic acids having pyrimidine-dione as novel histamine H1 antagonists

A series of phenothiazine carboxylic acid derivatives, having 6-amino-pyrimidine-2,4(1H,3H)-dione moiety via a appropriate linker, were synthesized and evaluated for their affinity toward human histamine H₁ receptor and Caco-2 cell permeability. Selected compounds were further evaluated for their oral anti-histaminic activity in mice and bioavailability in rats. Finally, promising compounds were examined for their anti-inflammatory potential in mice OVA-induced biphasic cutaneous reaction model. Among the compounds tested, phenothiazineacetic acid compound 27 showed both histamine H₁-receptor antagonistic activity and anti-inflammatory activity in vivo model.