New 2-arylpyrazolo[4,3-c]quinoline derivatives as potent and selective human A3 adenosine receptor antagonists

Development and Applications of Chimera Platforms for Tyrosine Phosphorylation

Chimeric small molecules that induce post-translational modification (PTM) on a target protein by bringing it into proximity to a PTM-inducing enzyme are furnishing novel modalities to perturb protein function. Despite recent advances, such molecules are unavailable for a critical PTM, tyrosine phosphorylation. Furthermore, the contemporary design paradigm of chimeric molecules, formed by joining a noninhibitory binder of the PTM-inducing enzyme with the binder of the target protein, prohibits the recruitment of most PTM-inducing enzymes as their noninhibitory binders are unavailable. Here, we report two platforms to generate phosphorylation-inducing chimeric small molecules (PHICS) for tyrosine phosphorylation. We generate PHICS from both noninhibitory binders (scantily available, platform 1) and kinase inhibitors (abundantly available, platform 2) using cysteine-based group transfer chemistry. PHICS triggered phosphorylation on tyrosine residues in diverse sequence contexts and target proteins (e.g., membrane-associated, cytosolic) and displayed multiple bioactivities, including the initiation of a growth receptor signaling cascade and the death of drug-resistant cancer cells. These studies provide an approach to induce biologically relevant PTM and lay the foundation for pharmacologic PTM editing (i.e., induction or removal) of target proteins using abundantly available inhibitors of PTM-inducing or -erasing enzymes.

Cu(II)-Mediated aerobic oxidative synthesis of 2-sulfonylated chromeno[4,3-c]pyrazol-4(2H)-ones

Herein, a concise and facial synthesis of 2-sulfonylated chromeno [4,3-c]pyrazol-4(2H)-ones and 2,5-dihydro-4H-pyrazolo[4,3-c]quinolin-4-ones via a Cu(II)-promoted aerobic oxidative cascade C–C/C–N bonds formations was described. The protocol has advantages of atom economy,...

Synthesis of pyrazoline fatty chain derivatives and its effects on melanoma cells

Skin cancer is the most common type of cancer in Brazil, representing 30% of all cases. Among these, melanoma represents only 3% of malignant neoplasms; however, it is the most serious and has a high capacity for metastasis. For this reason, it is extremely important to identify more efficient compounds and treatments that stop or decrease the proliferation of melanoma, even in its more advanced stages. This work reports the synthesis and biological evaluation of two homologous series of pyrazoline fatty chain derivatives as potent antitumoral agents in the melanoma B16F10 cell line. Cells were treated with pyrazoline fatty chain compounds (3, 30, 300, and 3000 μM) for 0, 24, 48, and 72 h. Decreased cell viability was observed when using most compounds at different concentrations and times. The structure-activity relationship (SAR) between antitumoral activity and the number of carbons and lipophilicity, as well as the oxygen-sulfur bioisosteric exchange, was evaluated. Among the tested derivatives, the lipophilic compounds 5-hydroxy-5-(trifluoromethyl)-3-undecyl-4,5-dihydro-1H-pyrazole-1-carboxamide (2d) and 5-hydroxy-5-(trifluoromethyl)-3-undecyl-4,5-dihydro-1H-pyrazole-1-thiocarboxamide (3d) showed the best results in the B16F10 cell line, as they produced the best cell viability decrease effects. The presence of fatty unbranched undecyl chain in the molecular structure appears to be important for its antimelanoma properties.

A3 Adenosine Receptors as Modulators of Inflammation: From Medicinal Chemistry to Therapy

The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics. The efficacy of nucleoside agonists may be suppressed to produce antagonists, by structural modification of the ribose moiety. Diverse classes of heterocycles have been discovered as selective A3 AR blockers, although with large species differences. Thus, as a result of intense basic research efforts, the outlook for development of A3 AR modulators for human therapeutics is encouraging. Two prototypical selective agonists, N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA; CF101) and 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; CF102), have progressed to advanced clinical trials. They were found safe and well tolerated in all preclinical and human clinical studies and showed promising results, particularly in psoriasis and RA, where the A3 AR is both a promising therapeutic target and a biologically predictive marker, suggesting a personalized medicine approach. Targeting the A3 AR may pave the way for safe and efficacious treatments for patient populations affected by inflammatory diseases, cancer, and other conditions.

Crystal structure of 1-(4-chlorophenyl)-6,8-diphenyl-1H-pyrazolo[4,3-c]quinoline, C28H18ClN3

C28H18ClN3, monoclinic, P21/c, (no. 14) a = 5.9519(2) Å, b = 8.0511(3) Å, c = 43.4071(14) Å, β = 90.001(2)°, V =2080.04(12) Å3, Z = 4, Rgt(F) = 0.066, wRref(F2) = 0.190, T = 173 K.

Biologically active perspective synthesis of heteroannulated 8-nitroquinolines with green chemistry approach

A new class of pyrazolo[4,3-c]quinoline (5a-i, 7a-b) and pyrano[3,2-c]quinoline (9a-i) derivatives were designed and synthesized in moderate to good yields by microwave conditions. To enhance the yield of pyrano[3,2-c]quinoline derivatives, multicomponent one-pot synthesis has been developed. The synthesized compounds were identified by spectral and elemental analyses. Compounds 9a and 9i showed good antibacterial activity against Gram-positive and Gram-negative bacterial strains. All of the new compounds exhibited weak to moderate antioxidant activity, compound 9d exerted significant antioxidant power. The cytotoxicity of these compounds were also evaluated against MCF-7 (breast) and A549 (Lung) cancer cell lines. Most of the compounds displayed moderate to good cytotoxic activity against these cell lines. Compound 9i was found to be significantly active in this assay and also induced cell death by apoptosis. Molecular docking studies were carried out using EGFR inhibitor in order to determine the molecular interactions.

The chemistry and biological activity of heterocycle-fused quinolinone derivatives: A review

Among all heterocycles, the heterocycle-fused quinolinone scaffold is one of the privileged structures in drug discovery as heterocycle-fused quinolinone derivatives exhibit various biological activities allowing them to act as anti-inflammatory, anticancer, antidiabetic, and antipsychotic agents. This wide spectrum of biological activity has attracted a great deal of attention in the field of medicinal chemistry. In this review, we provide a comprehensive description of the biological and pharmacological properties of various heterocycle-fused quinolinone scaffolds and discuss the synthetic methods of some of their derivatives.

Identification of trisubstituted-pyrazol carboxamide analogs as novel and potent antagonists of farnesoid X receptor

Farnesoid X receptor (FXR, NRIH4) plays a major role in the control of cholesterol metabolism. This suggests that antagonizing the transcriptional activity of FXR is a potential means to treat cholestasis and related metabolic disorders. Here we describe the synthesis, biological evaluation, and structure-activity relationship (SAR) studies of trisubstituted-pyrazol carboxamides as novel and potent FXR antagonists. One of these novel FXR antagonists, 4j has an IC50 of 7.5 nM in an FXR binding assay and 468.5 nM in a cell-based FXR antagonistic assay. Compound 4j has no detectable FXR agonistic activity or cytotoxicity. Notably, 4j is the most potent FXR antagonist identified to date; it has a promising in vitro profile and could serve as an excellent chemical tool to elucidate the biological function of FXR.

The A3 adenosine receptor as multifaceted therapeutic target: pharmacology, medicinal chemistry, and in silico approaches

Adenosine is an ubiquitous local modulator that regulates various physiological and pathological functions by stimulating four membrane receptors, namely A(1), A(2A), A(2B), and A(3). Among these G protein-coupled receptors, the A(3) subtype is found mainly in the lung, liver, heart, eyes, and brain in our body. It has been associated with cerebroprotection and cardioprotection, as well as modulation of cellular growth upon its selective activation. On the other hand, its inhibition by selective antagonists has been reported to be potentially useful in the treatment of pathological conditions including glaucoma, inflammatory diseases, and cancer. In this review, we focused on the pharmacology and the therapeutic implications of the human (h)A(3) adenosine receptor (AR), together with an overview on the progress of hA(3) AR agonists, antagonists, allosteric modulators, and radioligands, as well as on the recent advances pertaining to the computational approaches (e.g., quantitative structure-activity relationships, homology modeling, molecular docking, and molecular dynamics simulations) applied to the modeling of hA(3) AR and drug design. 

New 2-heterocyclyl-imidazo[2,1-i]purin-5-one derivatives as potent and selective human A3 adenosine receptor antagonists

A series of 4-allyl/benzyl-7,8-dihydro-8-methyl/ethyl-2-[(substituted)isoxazol/pyrazol-3/5-yl]-1H-imidazo[2,1-i]purin-5(4H)-ones has been synthesized and evaluated in radioligand binding assays to determine their affinities at the human A(1), A(2A), and A(3) adenosine receptors. Efficacy at the hA(2B) AR and antagonism of selected ligands at the hA(3) AR were also assessed through cAMP experiments. All of the synthesized molecules exhibited high affinity at the hA(3) AR (K(i) values ranging from 1.46 to 44.8 nM), as well as remarkable selectivity versus A(1), A(2A), and A(2B) AR subtypes. Compound (R)-4-allyl-8-ethyl-7,8-dihydro-2-(3-methoxy-1-methyl-1H-pyrazol-5-yl)-1H-imidazo[2,1-i]purin-5(4H)-one (R-33) was found to be the most potent and selective ligand of the series (K(i) hA(3) = 1.46 nM, K(i) hA(2A)/K(i) hA(3) > 3425; IC(50) hA(2B)/K(i) hA(3) > 3425; K(i) hA(1)/K(i) hA(3) = 1729). Molecular modeling studies were helpful in rationalizing the available structure-activity relationships along with the selectivity profiles of the new series of ligands.

Pyrazolo derivatives as potent adenosine receptor antagonists: an overview on the structure-activity relationships

In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A₁, A_2A, A_2B, and A₃) has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR) profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.

Pyrimidine derivatives as potent and selective A3 adenosine receptor antagonists

Two regioisomeric series of diaryl 2- or 4-amidopyrimidines have been synthesized and their adenosine receptor affinities were determined in radioligand binding assays at the four human adenosine receptors (hARs). Some of the ligands prepared herein exhibit remarkable affinities (K(i) < 10 nm) and, most noticeably, the absence of activity at the A(1), A(2A), and A(2B) receptors. The structural determinants that support the affinity and selectivity profiles of the series were highlighted through an integrated computational approach, combining a 3D-QSAR model built on the second generation of GRid INdependent Descriptors (GRIND2) with a novel homology model of the hA(3) receptor. The robustness of the computational model was subsequently evaluated by the design of new derivatives exploring the alkyl substituent of the exocyclic amide group. The synthesis and evaluation of the novel compounds validated the predictive power of the model, exhibiting excellent agreement between predicted and experimental activities.

Heterocyclic analogues of xanthone and xanthione. 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones and thiones: synthesis and NMR data

The synthesis of the title compounds is described. Reaction of 1-substituted 2-pyrazolin-5-ones with 5-chloro-1-phenyl-1H-pyrazole-4-carbonyl chloride or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbonyl chloride, respectively, using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-heteroaroylpyrazol-5-ols, which were cyclized into 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones by treatment with K₂CO₃/DMF. The latter were converted into the corresponding thiones upon reaction with Lawesson’s reagent. Detailed NMR spectroscopic investigations (¹H, ¹³C, ¹⁵N) of the ring systems and their precursors are presented.

Synthesis of novel pyrazole derivatives and evaluation of their antidepressant and anticonvulsant activities

Substituted carboxylic acid hydrazides 1a-d reacted with ethenetetracarbonitril 2 in dimethyl formamide with the formation of diacylhydrazines 4a-d and 5-amino-1-substituted pyrazole-3,3,4-tricarbonitriles 5a-d. On the other hand, 1a-d reacted with diethyl (E)-2,3-dicyanobutenedioate 3 to give oxadiazole derivatives 10a-d and pyrazolone derivatives 11a-d, respectively. The prepared compounds 4a-d, 5a-d and 11a-d were evaluated each for antidepressant activity using tail suspension behavioral despair test and anticonvulsant activity against PTZ induced seizures in mice. Compounds 4a and 4b induced markedly antidepressant activity compared to imipramine, and their activities as antidepressant nearly equal twice the activity of imipramine at 10 mg kg(-1) dose level. On the other hand, compounds 11b, 11a and 11d exhibited remarkable protective effect against clonic seizures induced by i.p. injection of PTZ at a dose level of 20 mg kg(-1). The results of anticonvulsant activity are nearly close to phenobarbital sodium at a dose level of 30 mg kg(-1) and more potent than phenytoin sodium at a dose level of 30 mg kg(-1).

Medicinal chemistry of the A3 adenosine receptor: agonists, antagonists, and receptor engineering

A(3) adenosine receptor (A(3)AR) ligands have been modified to optimize their interaction with the A(3)AR. Most of these modifications have been made to the N(6) and C2 positions of adenine as well as the ribose moiety, and using a combination of these substitutions leads to the most efficacious, selective, and potent ligands. A(3)AR agonists such as IB-MECA and Cl-IB-MECA are now advancing into Phase II clinical trials for treatments targeting diseases such as cancer, arthritis, and psoriasis. Also, a wide number of compounds exerting high potency and selectivity in antagonizing the human (h)A(3)AR have been discovered. These molecules are generally characterized by a notable structural diversity, taking into account that aromatic nitrogen-containing monocyclic (thiazoles and thiadiazoles), bicyclic (isoquinoline, quinozalines, (aza)adenines), tricyclic systems (pyrazoloquinolines, triazoloquinoxalines, pyrazolotriazolopyrimidines, triazolopurines, tricyclic xanthines) and nucleoside derivatives have been identified as potent and selective A(3)AR antagonists. Probably due to the "enigmatic" physiological role of A(3)AR, whose activation may produce opposite effects (for example, concerning tissue protection in inflammatory and cancer cells) and may produce effects that are species dependent, only a few molecules have reached preclinical investigation. Indeed, the most advanced A(3)AR antagonists remain in preclinical testing. Among the antagonists described above, compound OT-7999 is expected to enter clinical trials for the treatment of glaucoma, while several thiazole derivatives are in development as antiallergic, antiasthmatic and/or antiinflammatory drugs.

Tautomerism Phenomenon of Pyrazolo[3,4-b]quinoline: Spectroscopic and Quantum Mechanical Studies

Tautomerism of pyrazolo[3,4-b]quinoline (PQ) was studied using electronic absorption and emission spectroscopies in various polar and nonpolar solvents. The absorption spectra of the tautomers were modeled, and the respective bands were assigned using ab initio quantum mechanical calculations. Temperature-dependent absorption spectra showed the dynamic equilibrium of the two species, which were observed only in aliphatic solvents. The anomalous relative populations of the tautomers were explained by the stabilizing effect of the specific PQ-hydrocarbon interactions. Excited-state intramolecular proton transfer (ESIPT) was proposed to explain the measured fluorescence spectra. Hydrogen bonds that are formed in methanol and benzene were shown to strongly influence the nature of both the absorption and emission spectra.

Syntheses and anti-cancer activities of 2-[1-(indol-3-yl-/pyrimidin-5-yl-/pyridine-2-yl-/quinolin-2-yl)-but-3-enylamino]-2-phenyl-ethanols

Schiff bases prepared by the reactions of substituted amines with indole-/, pyrimidine-/, pyridine-/, and quinoline-aldehydes are made to undergo indium mediated allylation whereby a (substituted amine, allyl)methyl group has been introduced at C-3 of indole, C-5 of pyrimidine, and C-2 of pyridine and quinoline. Amongst the 16 compounds investigated for anti-cancer activities at 59 human tumor cell lines 3, 9-12, and 14 show appreciable activities. The structure-activity relationship studies point that the contribution of phenylglycinol moiety as a part of side chain at C-3 of indole and C-5 of pyrimidine seems to be crucial for exhibiting anti-cancer activities.