A novel series of 4-methyl substituted pyrazole derivatives as potent glucagon receptor antagonists: Design,synthesis and evaluation of biological activities

A novel series of 4-methyl substituted pyrazole derivatives were designed, synthesized and biologically evaluated as potent glucagon receptor (GCGR) antagonists. In this study, compounds 9q, 9r, 19d and 19e showed high GCGR binding (IC₅₀?=?0.09?μM, 0.06?μM, 0.07?μM and 0.08?μM, respectively) and cyclic-adenosine monophosphate (cAMP) activities (IC₅₀?=?0.22?μM, 0.26?μM, 0.44?μM and 0.46?μM, respectively) in cell-based assays. Most importantly, the docking experiment demonstrated that compound 9r formed extensive hydrophobic interactions with the receptor binding pocket, making it justifiable to further investigate the potential of becoming a GCGR antagonist.     

Amine-free melanin-concentrating hormone receptor 1 antagonists: Novel 1-(1H-benzimidazol-6-yl)pyridin-2(1H)-one derivatives and design to avoid CYP3A4 time-dependent inhibition

Melanin-concentrating hormone (MCH) is an attractive target for antiobesity agents, and numerous drug discovery programs are dedicated to finding small-molecule MCH receptor 1 (MCHR1) antagonists. We recently reported novel pyridine-2(1H)-ones as aliphatic amine-free MCHR1 antagonists that structurally featured an imidazo[1,2-a]pyridine-based bicyclic motif. To investigate imidazopyridine variants with lower basicity and less potential to inhibit cytochrome P450 3A4 (CYP3A4), we designed pyridine-2(1H)-ones bearing various less basic bicyclic motifs. Among these, a lead compound 6a bearing a 1H-benzimidazole motif showed comparable binding affinity to MCHR1 to the corresponding imidazopyridine derivative 1. Optimization of 6a afforded a series of potent thiophene derivatives (6q–u); however, most of these were found to cause time-dependent inhibition (TDI) of CYP3A4. As bioactivation of thiophenes to form sulfoxide or epoxide species was considered to be a major cause of CYP3A4 TDI, we introduced electron withdrawing groups on the thiophene and found that a CF₃ group on the ring or a Cl adjacent to the sulfur atom helped prevent CYP3A4 TDI. Consequently, 4-[(5-chlorothiophen-2-yl)methoxy]-1-(2-cyclopropyl-1-methyl-1H-benzimidazol-6-yl)pyridin-2(1H)-one (6s) was identified as a potent MCHR1 antagonist without the risk of CYP3A4 TDI, which exhibited a promising safety profile including low CYP3A4 inhibition and exerted significant antiobesity effects in diet-induced obese F344 rats.     

Design and synthesis of 1-(1-benzothiophen-7-yl)-1H-pyrazole,a novel series of G protein-coupled receptor 52 (GPR52) agonists

G-protein-coupled receptor 52 (GPR52) is classified as an orphan Gs-coupled G-protein-coupled receptor. GPR52 cancels dopamine D2 receptor signaling and activates dopamine D1/N-methyl-d-aspartate receptors via intracellular cAMP accumulation. Therefore, GPR52 agonists are expected to alleviate symptoms of psychotic disorders. A novel series of 1-(benzothiophen-7-yl)-1H-pyrazole as GPR52 agonists was designed and synthesized based on compound 1b. Compound 1b has been reported by our group as the first orally active GPR52 agonist, but high lipophilicity and poor aqueous solubility still remained as issues for candidate selection. To resolve these issues, replacement of the benzene ring at the 7-positon of compound 1b with heterocylic rings, such as pyrazole and pyridine, was greatly expected to reduce lipophilicity to levels for which calculated logD values were lower than that of compound 1b. While evaluating the pyrazole derivatives, introduction of a methyl substituent at the 3-position of the pyrazole ring led to increased GPR52 agonistic activity. Moreover, additional methyl substituent at the 5-position of the pyrazole and further introduction of hydroxy group to lower logD led to significant improvement of solubility while maintaining the activity. As a result, we identified 3-methyl-5-hydroxymethyl-1H-pyrazole derivative 17 (GPR52 EC₅₀?=?21?nM, E_max?=?103%, logD?=?2.21, Solubility at pH 6.8?=?21?μg/mL) with potent GPR52 agonistic activity and good solubility compared to compound 1b. Furthermore, this compound 17 dose-dependently suppressed methamphetamine-induced hyperlocomotion in mice.     

Synthesis and biological activity of a series of tetrasubstituted-imidazoles as P2X7 antagonists

A series of analogues of the pyrazole lead 1 were synthesized in which the heterocyclic core was replaced with an imidazole. A number of potent antagonists were identified and structure–activity relationships (SAR) were investigated both with respect to activity at the P2X₇ receptor and in vitro metabolic stability. Compound 10 was identified as a potent P2X₇ antagonist with reduced in vitro metabolism and high solubility.     

Synthesis and biological evaluation of pyrazole derivatives containing thiourea skeleton as anticancer agents

Two series of pyrazole derivatives designing for potential EGFR kinase inhibitors have been discovered. Some of them exhibited significant EGFR inhibitory activity. Compound 3-(3,4-dimethylphenyl)-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide (C5) displayed the most potent EGFR inhibitory activity with IC₅₀ of 0.07 μM, which was comparable to the positive control erlotinib. Docking simulation was performed to position compound C5 into the EGFR active site to determine the probable binding model. Antiproliferative assay results indicating that some of the pyrazole derivatives own high antiproliferative activity against MCF-7. Compound C5 showed significant antiproliferative activity against MCF-7 with IC₅₀ of 0.08 μM. Therefore, compound C5 with potent inhibitory activity in tumor growth inhibition would be a potential anticancer agent.     

Antagonists to sex pheromones of the American cockroach

• 1.1. Considering the structures of periplanones A (1) and B (2) (sex pheromones of the American cockroach), derivatives of germacrene D (3) were prepared in order to find antagonists to the pheromones.
• 2.2. A new sex pheromone mimic (7) was found in the derivatives. Among pheromonally inactive derivatives, compounds 5 and 6 were found as a specific antagonist of 1 and a non-specific antagonist of 1 and 2, respectively.
• 3.3. In the DS-EAG experiment, 5 was revealed to participate specifically in the periplanone A receptor and to inhibit further participation of 1 in the receptor.

     

Discovery of 6-[5-(4-fluorophenyl)-3-methyl-pyrazol-4-yl]-benzoxazin-3-one derivatives as novel selective nonsteroidal mineralocorticoid receptor antagonists

In the course of our study on selective nonsteroidal mineralocorticoid receptor (MR) antagonists, a series of novel benzoxazine derivatives possessing an azole ring as the core scaffold was designed for the purpose of attenuating the partial agonistic activity of the previously reported dihydropyrrol-2-one derivatives. Screening of alternative azole rings identified 1,3-dimethyl pyrazole 6a as a lead compound with reduced partial agonistic activity. Subsequent replacement of the 1-methyl group of the pyrazole ring with larger lipophilic side chains or polar side chains targeting Arg817 and Gln776 increased MR binding activity while maintaining the agonistic response at the lower level. Among these compounds, 6-[1-(2,2-difluoro-3-hydroxypropyl)-5-(4-fluorophenyl)-3-methyl-1H-pyrazol-4-yl]-2H-1,4-benzoxazin-3(4H)-one (37a) showed highly potent in vitro activity, high selectivity versus other steroid hormone receptors, and good pharmacokinetic profiles. Oral administration of 37a in deoxycorticosterone acetate-salt hypertensive rats showed a significant blood pressure-lowering effect with no signs of antiandrogenic effects.     

Synthesis and fungicidal activity of novel pyrazole derivatives containing 5-Phenyl-2-Furan

Pyrazole constitutes an important heterocyclic family covering a broad range of synthetic as well as natural products that exhibit numerous chemical, biological, agrochemical and pharmacological properties. In order to explore compounds with good fungicidal activity, a series of new pyrazole derivatives containing 5-phenyl-2-furan were designed and synthesized. In vitro and in vivo fungicidal activities were evaluated and the compound ethyl-1-(5-phenylfuran-2-carbonyl)-5-propyl-1H-pyrazole-3-carboxylate (I8) displayed significant fungicidal activity against various fungi, especially against P. infestans. The structures of the novel pyrazole derivatives were confirmed by ¹H NMR, ¹³C NMR, MS, elemental analysis and X-ray single crystal diffraction. Further study showed that compound I8 might act on the synthesis of cell walls from morphological and ultrastructural studies by SEM and TEM. The results also revealed that compound I8 could block the nutritional transportation leading to cells senescence and death. These results suggested that the novel pyrazole derivatives proved to be promising lead compounds.     

Thiazolidinedione derivatives as PTP1B inhibitors with antihyperglycemic and antiobesity effects

Benzylidene-2,4-thiazolidinedione derivatives with substitutions on the phenyl ring at the ortho or para positions of the thiazolidinedione (TZD) group were synthesized as PTP1B inhibitors with IC₅₀ values in a low micromolar range. Compound 3e, the lowest, bore an IC₅₀ of 5.0 μM. In vivo efficacy of 3e as an antiobesity and hypoglycemic agent was evaluated in a mouse model system. Significant improvement of glucose tolerance was observed. This compound also significantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol and NEFA. Compound 3e was also found to activate peroxisome proliferator-activated receptors (PPARs) indicating multiple mechanisms of action.     

The identification of nonpeptide neurotensin receptor partial agonists from the potent antagonist SR48692 using a calcium mobilization assay

In a search for nonpeptide agonists for the neurotensin receptor (NTR1), we replaced the adamantyl amino acid moiety found in the antagonist SR48692 (1a) with leucine and related α-alkylamino acids found in peptide agonists. When tested in a calcium mobilization assay, we found that both d- and l-leucine confer partial agonist activity to the pyrazole scaffold with the l-enantiomer (3a) providing a significantly greater response. A brief SAR survey demonstrated that the observed agonist activity was resilient to changes made to the dimethoxyaryl ring in 3a. The resulting compounds were less potent relative to 3a but showed greater agonist responses. The partial agonist activity was extinguished when the chloroquinoline ring was replaced with naphthalene. Thus, while l-leucine appears to possess a powerful agonist directing affect for the NTR1 receptor, its presence alone in the molecular architecture is not sufficient to insure agonist behavior.     

Disulfide linked pyrazole derivatives inhibit phagocytosis of opsonized blood cells

Immune thrombocytopenia (ITP) is caused by production of an autoantibody to autologous platelets. ITP can be treated either by reducing platelet destruction or by increasing platelet production. Fcγ receptor mediated phagocytosis of the opsonized blood cells is a well-accepted mechanism for the underlying pathogenesis of ITP and inhibition of this phagocytosis process with small molecules is a potential strategy for the development of drugs against ITP. A broad screen indicated that 4-methyl-1-phenyl-pyrazole derivative (1) could inhibit the phagocytosis of opsonized blood cells with weak potency. We reveal here the discovery of the polysulfide products, synthesis of various 1-phenyl-pyrazole derivatives, and the biological evaluation of pyrazole derivatives as inhibitors of phagocytosis for potential use as therapeutics for ITP. Substitution at C4 of the pyrazole moiety in the disulfide-bridged dimers influenced the potency in the increasing order of 10 ? 11 ? 16 < 19 < 20. A novel scaffold, 20 with an IC₅₀ of 100 nM inhibiting opsonized blood cell phagocytosis was identified as a potential candidate for further studies. Confirmation of the disulfide bridge additionally provides clues for the non-thiol or non-disulfide bridge carrying ligands targeting ITP and other similar disorders.     

Identification of novel azaindazole CCR1 antagonist clinical candidates

Exploring various cyclization strategies, using a submicromolar pyrazole HTS screening hit 6 as a starting point, a novel indazole based CCR1 antagonist core was discovered. This report presents the design and SAR of CCR1 indazole and azaindazole antagonists leading to the identification of three development compounds, including 19e that was advanced to early clinical trials.     

Pyrazole[3,4-d]pyridazine derivatives: Molecular docking and explore of acetylcholinesterase and carbonic anhydrase enzymes inhibitors as anticholinergics potentials

Recently, the pyridazine nucleus has been widely studied in the field of particular and new medicinal factors as drugs acting on the cardiovascular system. Additionally, a number of thienopyridazines have been claimed to possess interacting biological macromolecules and pharmacological activities such as NAD(P)H oxidase inhibitor, anticancer, and identified as a novel allosteric modulator of the adenosine A1 receptor. The literature survey demonstrates that coumarin, 1,2-pyrazole benzothiazole, and 1,3- thiazole scaffolds are the most versatile class of molecules. In this study, a series of substituted pyrazole[3,4-d]pyridazine derivatives (2a–n) were prepared, and their structures were characterized by Mass analysis, NMR, and FT-IR. These obtained pyrazole[3,4-d]pyridazine compounds were very good inhibitors of the carbonic anhydrase (hCA I and II) isoenzymes and acetylcholinesterase (AChE) with K_i values in the range of 9.03 ± 3.81–55.42 ± 14.77 nM for hCA I, 18.04 ± 4.55–66.24 ± 19.21 nM for hCA II, and 394.77 ± 68.13–952.93 ± 182.72 nM for AChE, respectively. The possible inhibition mechanism of the best-posed pyrazole[3,4-d]pyridazine and pyrazole-3-carboxylic acid derivatives and their interaction with catalytic active pocket residues were determined based on the calculations.     

Antiobesity and emetic effects of a short-length peptide YY analog and its PEGylated and alkylated derivatives

Neuropeptide Y2 receptor (Y2R) agonism is an important anorectic signal and a target of antiobesity drug discovery. Recently, we synthesized a short-length Y2R agonist, PYY-1119 (4-imidazolecarbonyl-[d-Hyp²⁴,Iva²⁵,Pya(4)²⁶,Cha^27,36,γMeLeu²⁸,Lys³⁰,Aib³¹]PYY(23–36), 1) as an antiobesity drug candidate. Compound 1 induced marked body weight loss in diet-induced obese (DIO) mice; however, 1 also induced severe vomiting in dogs at a lower dose than the minimum effective dose administered to DIO mice. The rapid absorption of 1 after subcutaneous administration caused the severe vomiting. Polyethylene glycol (PEG)- and alkyl-modified derivatives of 1 were synthesized to develop Y2R agonists with improved pharmacokinetic profiles, i.e., lower maximum plasma concentration (C_max) and longer time at maximum concentration (T_max). Compounds 5 and 10, modified with 20?kDa PEG at the N-terminus and eicosanedioic acid at the Lys³⁰ side chain of 1, respectively, showed high Y2R binding affinity and induced significant body weight reduction upon once-daily administration to DIO mice. Compounds 5 and 10, with their relatively low C_max and long T_max, partially attenuated emesis in dogs compared with 1. These results indicate that optimization of pharmacokinetic properties of Y2R agonists is an effective strategy to alleviate emesis induced by Y2R agonism.     

Identification of novel 3,5-diarylpyrazoline derivatives containing salicylamide moiety as potential anti-melanoma agents

There is an accumulating body of experimental evidences validating oncogenic BRAF^V600E as a therapeutic target and offering opportunities for anti-melanoma drug development. Encouraged by the positive results of pyrazole derivatives as BRAF^V600E inhibitors, we sought to design diverse novel potential BRAF^V600E inhibitors as antitumor agents based on pyrazole skeleton. In silico and in vitro screening of our designed pyrazole derivatives has identified Hit 1 as BRAF^V600E inhibitor. Based on its structure and through further structure modification, compound 25, which exhibited the most potent inhibitory activity with an IC₅₀ value of 0.16 μM for BRAF^V600E and GI₅₀ value of 0.24 μM for mutant BRAF-dependent melanoma cells, was obtained. The 3D-QSAR models and the molecular docking simulation were introduced to analyze the structure–activity relationship.     

1-Methyl-1H-pyrrole-2-carbonitrile containing tetrahydronaphthalene derivatives as non-steroidal progesterone receptor antagonists

Non-steroidal 1-methyl-1H-pyrrole-2-carbonitrile containing tetrahydronaphthalenes and acyclic derivatives were evaluated as novel series of progesterone receptor (PR) antagonists using the T47D cell alkaline phosphatase assay. Moderate to potent PR antagonists were achieved with these scaffolds. Several compounds (e.g., 15 and 20) demonstrated low nanomolar PR antagonist potency and good selectivity versus other steroid receptors.     

Design and synthesis of novel androgen receptor antagonists via molecular modeling

Several androgen receptor (AR) antagonists are clinically prescribed to treat prostate cancer. Unfortunately, many patients become resistant to the existing AR antagonists. To overcome this, a novel AR antagonist candidate called DIMN was discovered by our research group in 2013. In order to develop compounds with improved potency, we designed novel DIMN derivatives based on a docking study and substituted carbons with heteroatom moieties. Encouraging in vitro results for compounds 1b, 1c, 1e, 3c, and 4c proved that the new design was successful. Among the newly synthesized compounds, 1e exhibited the strongest inhibitory effect on LNCaP cell growth (IC₅₀ = 0.35 μM) and also acted as a competitive AR antagonist with selectivity over the estrogen receptor (ER) and the glucocorticoid receptor (GR). A docking study of compound 1e fully supported these biological results. Compound 1e is considered to be a novel, potent and AR-specific antagonist for treating prostate cancer. Thus, our study successfully applied molecular modeling and bioisosteric replacement for hit optimization. The methods here provide a guide for future development of drug candidates through structure-based drug discovery and chemical modifications.     

Design,synthesis, modeling studies and biological screening of novel pyrazole derivatives as potential analgesic and anti-inflammatory agents

Reported herein are the design, synthesis, and pharmacologic evaluation of novel pyrazole and pyrazoline derivatives. The study presents the effect of lengthening of carbon chain in different pyrazole derivatives bearing various amine moieties. Combination of pyrazoline ring with either pyrazole or quinoline rings (Floctafenine derivatives) through synthesis of chalcones and their cyclization into pyrazolines was involved. The structures of target compounds were confirmed by elemental analysis and spectral data. All the newly synthesized compounds were investigated for their anti-inflammatory and analgesic activities compared to Indomethacin as a reference drug. Docking and molecular modeling study was initiated to validate the attained pharmacological data and provide understandable evidence for the observed anti-inflammatory behavior of the most potent compounds 14b, 15b and 22 through their various interactions with the active site of COX-2 isozyme. Protein Data Bank (PDB) file of COX II enzyme with the code 4Z0L and its co-crystallized ligand Indomethacin were used for this purpose. The binding affinity was evaluated via comparing the scoring energy (S) and amino acid interactions of novel compounds with Indomethacin.     

Essential structure of orexin 1 receptor antagonist YNT-707, Part II: Drastic effect of the 14-hydroxy group on the orexin 1 receptor antagonistic activity

The 14-dehydration- and 14-H derivatives of the orexin 1 receptor (OX₁R) antagonist YNT-707 (2) were synthesized. The obtained derivatives showed higher affinities for OX₁R than the corresponding 14-hydroxy derivatives. The conformational analysis suggested that the 17-sulfonamide groups in the derivatives without the 14-hydroxy group have a greater tendency to be oriented toward the upper side of the D-ring compared with the 14-hydroxy derivatives. Additionally, the 14-dehydration-derivative with 6α-amide side chain showed significantly higher affinity than the 14-hydroxy derivative, while the corresponding 14-H derivative showed only slightly higher affinity. Thus, the 14-hydroxy group strongly affects the affinity of the antagonist for the OX₁R.     

Discovery of novel indazole derivatives as dual angiotensin II antagonists and partial PPARγ agonists

Identification of indazole derivatives acting as dual angiotensin II type 1 (AT₁) receptor antagonists and partial peroxisome proliferator-activated receptor-γ (PPARγ) agonists is described.Starting from Telmisartan, we previously described that indole derivatives were very potent partial PPARγ agonists with loss of AT₁ receptor antagonist activity.Design, synthesis and evaluation of new central scaffolds led us to the discovery of pyrrazolopyridine then indazole derivatives provided novel series possessing the desired dual activity.Among the new compounds, 38 was identified as a potent AT₁ receptor antagonist (IC₅₀ = 0.006 μM) and partial PPARγ agonist (EC₅₀ = 0.25 μM, 40% max) with good oral bioavailability in rat.The dual pharmacology of compound 38 was demonstrated in two preclinical models of hypertension (SHR) and insulin resistance (Zucker fa/fa rat).