New imidazo[1,2-b]pyrazoles as anticancer agents: synthesis, biological evaluation and structure activity relationship analysis

Redox-neutral zinc-catalyzed cascade [1,4]-H shift/annulation of diaziridines with donor-acceptor aziridines

The coupling of diaziridines with donor-acceptor aziridines (DAAs) has been achieved using Zn-catalysis to furnish imidazopyrazole-4,4-dicarboxylates via [1,4]-hydride shift. The use of Zn-catalysis, [1,4]-hydride shift, natural product modification and a late-stage molecular docking study are important practical features.

Imidazole-pyridine hybrids as potent anti-cancer agents

In the current investigation, fifteen novel imidazole-pyridine-based molecules were synthesized and tested against cell lines of the lung (H1299) and colon (HCT116) adenocarcinomas by proliferation assay. The results demonstrated that compounds 5a, 5d, 5e, and 5f were the most active (IC₅₀<30 µM). Based on recent literature and the current results, the glycogen synthase kinase-3β (GSK-3β) protein was investigated in-silico as a possible target. The molecular docking and QSAR revealed an excellent binding affinity of the selected imidazole-pyridine compounds to GSK-3β. Notably, GSK-3β protein levels were significantly upregulated in hepatocellular liver carcinoma (LIHCs) tissues and negatively affected patient prognosis. Consequently, the compounds were evaluated on liver cancer cell lines (HepG2, HUH-7, and PLC/PRF/5) by the MTT assay, and 5d showed the highest antitumor activity. This study offers new compounds with interesting biological activity on GSK-3β as a target, exhibiting a potential therapeutic impact for hepatocellular carcinoma patients.

Formulation, Optimization and Evaluation of Cytarabine-Loaded Iron Oxide Nanoparticles: From In Vitro to In Vivo Evaluation of Anticancer Activity

Innovative drug delivery systems based on iron oxide nanoparticles (INPs) has generated a lot of interest worldwide and have prime biomedical benefits in anticancer therapy. There are still issues reported regarding the stability, absorption, and toxicity of iron oxide nanoparticles (INPs) when administered due to its rapid surface oxidation and agglomeration with blood proteins. To solve this problem, we have synthesized trehalose-coated stabilized iron oxide nanoparticles (TINPs) by a co-precipitation technique. The surface coating of INPs with trehalose helps to improve the stability, prevents protein binding, and increase absorption uptake inside the body. Developed TINPs was then loaded with anticancer drug cytarabine by chemical crosslinking encapsulation method using suitable solvent. Engineered cytarabine-loaded trehalose-coated stabilized iron oxide nanoparticles (CY-TINPs) were optimized for particle size, zeta potential (-13.03 mV), and solid-state characterization such as differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and transmission electron microscope (TEM) studies. The particle size of 50 nm was achieved for developed CY-TINPs. The developed CY-TINPs was further evaluated for in vitro cell line investigations which confirmed potential cytotoxic activity. Developed CY-TINPs show remarkable enhancement in in vivo pharmacokinetic parameters C_max as 425.26 ± 2.11 and AUC_0-72 as 11,546.64 ± 139.82 as compared to pure drug. Compared to traditional drug delivery, the CY-TINPs formulation can effectively delay release, improve bioavailability, and boost cytotoxic activity against tumors.

Recent Advancement in Drug Design and Discovery of Pyrazole Biomolecules as Cancer and Inflammation Therapeutics

Pyrazole, an important pharmacophore and a privileged scaffold of immense significance, is a five-membered heterocyclic moiety with an extensive therapeutic profile, viz., anti-inflammatory, anti-microbial, anti-anxiety, anticancer, analgesic, antipyretic, etc. Due to the expansion of pyrazolecent red pharmacological molecules at a quicker pace, there is an urgent need to put emphasis on recent literature with hitherto available information to recognize the status of this scaffold for pharmaceutical research. The reported potential pyrazole-containing compounds are highlighted in the manuscript for the treatment of cancer and inflammation, and the results are mentioned in % inhibition of inflammation, % growth inhibition, IC₅₀, etc. Pyrazole is an important heterocyclic moiety with a strong pharmacological profile, which may act as an important pharmacophore for the drug discovery process. In the struggle to cultivate suitable anti-inflammatory and anticancer agents, chemists have now focused on pyrazole biomolecules. This review conceals the recent expansion of pyrazole biomolecules as anti-inflammatory and anticancer agents with an aim to provide better correlation among different research going around the world.

Selective functionalization of the 1H-imidazo[1,2-b]pyrazole scaffold. A new potential non-classical isostere of indole and a precursor of push-pull dyes

We report the selective functionalization of the 1H-imidazo[1,2-b]pyrazole scaffold using a Br/Mg-exchange, as well as regioselective magnesiations and zincations with TMP-bases (TMP = 2,2,6,6-tetramethylpiperidyl), followed by trapping reactions with various electrophiles. In addition, we report a fragmentation of the pyrazole ring, giving access to push-pull dyes with a proaromatic (1,3-dihydro-2H-imidazol-2-ylidene)malononitrile core. These functionalization methods were used in the synthesis of an isostere of the indolyl drug pruvanserin. Comparative assays between the original drug and the isostere showed that a substitution of the indole ring with a 1H-imidazo[1,2-b]pyrazole results in a significantly improved solubility in aqueous media.

Inhibition of Caco-2 and MCF-7 cancer cells using chalcones: synthesis, biological evaluation and computational study

Cancer is the second death cause worldwide, with breast and colon cancer among the most prevalent types. Traditional treatment strategies have several side effects that inspire the development of novel anticancer agents derived from natural sources, like chalcone derivatives. For this investigation, twenty-three chalcones (4a-w) were synthesized and evaluated as antiproliferative agents against MCF-7 and Caco-2 cells, finding three and two compounds with similar or higher antiproliferative activity than daunorubicin, while only two chalcones showed better selectivity indexes than daunorubicin on MCF-7. From these results, we developed good-performance QSAR models (r > 0.850, q²>0.650), finding several structural features that could modify chalcone activity and selectivity. According to these models, chalcones 4w and 4t have high potency and selectivity against Caco-2 and MCF-7, respectively, which make them attractive candidates for hit-to-lead development of ROS-independent pro apoptotic agents.

Pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amines as Potential Cytotoxic Agents against Human Neuroblastoma

We report herein the evaluation of various pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amines as potential cytotoxic agents. These molecules were obtained by developing the multicomponent Groebke-Blackburn-Bienaymé reaction to yield various pyrido[2',1':2,3]imidazo[4,5-c]quinolines which are isosteres of ellipticine whose biological activities are well established. To evaluate the anticancer potential of these pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amine derivatives in the human neuroblastoma cell line, the cytotoxicity was examined using the WST-1 assay after 72 h drug exposure. A clonogenic assay was used to assess the ability of treated cells to proliferate and form colonies. Protein expressions (Bax, bcl-2, cleaved caspase-3, cleaved PARP-1) were analyzed using Western blotting. The colony number decrease in cells was 50.54%, 37.88% and 27.12% following exposure to compounds 2d, 2g and 4b respectively at 10 μM. We also show that treating the neuroblastoma cell line with these compounds resulted in a significant alteration in caspase-3 and PARP-1 cleavage.

Recent Progress on Anticancer Agents Incorporating Pyrazole Scaffold

The search of new anticancer agents is considered as a dynamic field of medicinal chemistry. In recent years, the synthesis of compounds with anticancer potential has increased and a large number of structurally varied compounds displaying potent anticancer activities have been published. Pyrazole is an important biologically active scaffold that possessed nearly all types of biological activities. The aim of this review is to collate literature work reported by researchers to provide an overview on in vivo and in vitro anticancer activities of pyrazole based derivatives among the diverse biological activities displayed by them and also presents recent efforts made on this heterocyclic moiety regarding anticancer activities. This review has been driven from the increasing number of publications, on this issue, which have been reported in the literature since the ending of the 20th century (from 1995-to date).

An Insight into the Synthesis and SAR of 2,4-Thiazolidinediones (2,4-TZD) as Multifunctional Scaffold: A Review

2,4-Thiazolidinedione (2,4-TZD) is a versatile pharmacophore, a privileged scaffold, and a remarkable sulphur-containing heterocyclic compound with diverse pharmacological activities. The multifarious biological activities, due to different mechanisms of action, low cost, and easy availability of 2,4-TZD impressed medicinal chemists to integrate this moiety to develop various lead compounds with diverse therapeutic actions. This resulted in the swift development in the last decade for generating different new potential molecules bearing 2,4-TZD. In this review, the authors attempt to shape and present the latest investigations (2012 onwards) going on in generating promising 2,4-TZD containing lead compounds. The data has been collected and analyzed to develop the structure-activity relationship (SAR). The SAR and active pharmacophores of various leads accountable for antidiabetic, anticancer, antimicrobial, and antioxidant activities have also been illustrated. This review also highlighted some of the important chemical synthetic routes for the preparation of various 2,4-TZD derivatives. This review will definitely serve as a useful source of structural information to medicinal chemists and may be utilized for the strategic design of potent 2,4-TZD derivatives in the future.

Synthesis and Crystal Structures of 4,5-Dihydroimidazo[1,5-b]pyrazol-6-ones

The synthesis of previously unattainable 2,5-disubstituted 4,5-dihydroimidazo[1,5-b]pyrazol-6-ones has been developed. Electrochemical reductions of readily available 2,2,2-trichloroethylideneacetophenones were followed by reaction with hydrazine, leading to 3-aryl-5-dichloromethyl-2-pyrazolines. These were treated with isocyanates to obtain the corresponding aminocarbonyl derivatives, which were found to be able to form an otherwise almost inaccessible imidazo[1,5-b]pyrazole ring system via a one-step reaction involving internal condensation followed by hydrogen chloride elimination and aromatization. The molecular­ structures of 2-(4-methylphenyl)-5-tosyl-4,5-dihydro­imidazo[1,5-b]pyrazol-6-one, 5-dichloromethyl-N-(4-chlorophenyl)-4,5-dihydro-3-p-tolylpyrazole-1-carboxamide, and 5-(4-bromophenyl)-2-p-tolyl-4,5-dihydroimidazo[1,5-b]pyrazol-6-one were determined by X-ray crystallographic analysis.

Predictions of Drug-Protein Interactions and Study of Magnetically Assisted Release Dynamics of 5-Fluorouracil from Soya Protein-Coated Iron Oxide Core-Shell Nanoparticles

In silico studies were performed using 5-fluorouracil (5-FU) to explore the efficacy of template docking and facilitate designing of drug nanocarrier systems. The binding of human uridine phosphorylase (huPP1) with 5-FU was found to show the following interactions: (1) hydrogen bonds were alleviated by a network of GLN217 and ARG219, (2) hydrophobic interactions were shown by PHE213, THR141, LEU272, and ILE281 (3) positive electrostatic interactions were shown by PHE213, THR141, LEU272, SER142, GLU248, and GLY143. As an experimental supplementation and validation to the adopted computational approach, 5- FU-loaded soya protein-coated iron oxide (SPCIO) core-shell nanoparticles were prepared following microemulsion and co-precipitation techniques and subsequently characterized by FTIR, particle size and zeta potential studies, TEM, XRD, and DSC techniques. Whereas the FTIR spectra confirm the presence of the soya protein and drug 5-FU in the nanoparticles, the zeta potential was found to be suppressed due to the loading of 5-FU. The XRD study confirmed the crystalline nature of the drug-loaded nanoparticles. TEM analysis suggested that the nanoparticles have sizes up to 200 nm and the morphology and size remain almost the same even after loading of the drug 5-FU onto nanoparticles. The soya protein-coated iron oxide nanoparticles demonstrated zero cytotoxicity against fibroblast cells. The controlled release of 5-FU was studied in vitro, and the effects of pH, chemical composition of nanoparticles, extent of drug loading, and simulated biofluids on the controlled release of 5-FU were studied. The swelling of nanoparticles and release of 5-FU were found to increase with increasing strength of the externally applied magnetic field.

Novel phthalimide based analogues: design, synthesis, biological evaluation, and molecular docking studies

Pyrazolylphthalimide derivative 4 was synthesized and reacted with different reagents to afford the target compounds imidazopyrazoles 5-7, pyrazolopyrimidines 9, 12, 14 and pyrazolotriazines 16, 17 containing phthalimide moiety. The prepared compounds were established by different spectral data and elemental analyses. Additionally, all synthesized derivatives were screened for their antibacterial activity against four types of Gram + ve and Gram-ve strains, and for antifungal activity against two fungi micro-organisms by well diffusion method. Moreover, the antiproliferative activity was tested for all compounds against human liver (HepG-2) cell line in comparison with the reference vinblastine. Moreover, drug-likeness and toxicity risk parameters of the newly synthesized compounds were calculated using in silico studies. The data from structure-actvity relationship (SAR) analysis suggested that phthalimide derivative bearing 3-aminopyrazolone moiety, 4 illustrated the best antimicrobial and antitumor activities and might be considered as a lead for further optimization. To investigate the mechanism of the antimicrobial and anticancer activities, enzymatic assay and molecular docking studies were carried out on E. coli topoisomerase II DNA gyrase B and VEGFR-2 enzymes.

Development of Novel and Efficient Processes for the Synthesis of 5-Amino and 5-Iminoimidazo[1,2-a]imidazoles via Three-Component Reaction Catalyzed by Zirconium(IV) Chloride

General and efficient approaches for the synthesis of new 5-amino and 5-iminoimidazo[1,2-a]imidazoles were developed through a three-component reaction of 1-unsubstituted 2-aminoimidazoles with various aldehydes and isocyanides mediated by zirconium(IV) chloride. The protocols were established considering the reactivity of the starting substrate, which varies depending on the presence of a substituent on the 2-aminoimidazole moiety. A library of new N-fused ring systems with wide structural diversification, novel synthetic, and potential pharmacological interest was obtained in moderate to good yields.

[Design and synthesis of imidazo-fused heterocycles derivatives and their anti-tumor activity against breast cancer in mice]

OBJECTIVE

To synthesize compounds based on imidazo-fused heterocycles and evaluate their anti-tumor activity against breast cancer.

METHODS

The compounds 1a-1e, 2a and 2b were synthesized by aerobic copper-catalyzed halocyclization of methyl N-heteroaromatics with aliphatic amines; 3a and 3b were generated by sonogashira reaction and Suzuki reaction, respectively; the compounds 4a-4c were obtained by Buchwald-Hartwig reaction of the corresponding amines and 1e. The effects of these compounds against breast cancer cells and their nephrotoxicity were determined using MTT assay. Annexin VFITC/PI apoptosis detection kit was used to assess the apoptosis-inducing effects of these compounds in breast cancer cells. With normal saline as the control, the safety and anti-tumor activity of the compound 2a (daily dose of 10 mg/kg for 14 days) was tested in a mouse model bearing human breast cancer xenografts.

RESULTS

The compounds 2a, 4a, 4b and 4c all showed obvious anti-tumor activities. Among these compounds, 2a showed the most potent anti-tumor effect against breast cancer cells with an IC₅₀ of 9.77 ± 2.32 μmol/L, similar to that of cisplatin (IC₅₀=8.96 ± 2.35 μmol/L); 2a also showed a slightly lower nephrotoxicity than cisplatin, and their CC₅₀ was 10.79±0.87 μmol/L and 8.45±0.68 μmol/L, respectively. 2a obviously promoted apoptosis of breast cancer cells in vitro and caused a moderate suppression of the breast cancer growth in the tumor-bearing mouse models without producing serious adverse effects.

CONCLUSIONS

Four compounds synthesized based on imidazo-fused heterocycles have anti-tumor activities against breast cancer. The compound 2a is capable of dose-dependently promoting apoptosis of breast cancer cells in vitro and has a good safety and a moderate efficacy for suppressing tumor growth in mouse models bearing human breast cancer xenografts.

Revealing quinquennial anticancer journey of morpholine: A SAR based review

Morpholine, a six-membered heterocycle containing one nitrogen and one oxygen atom, is a moiety of great significance. It forms an important intermediate in many industrial and organic syntheses. Morpholine containing drugs are of high therapeutic value. Its wide array of pharmacological activity includes anti-diabetic, anti-emetic, growth stimulant, anti-depressant, bronchodilator and anticancer. Multi-drug resistance in cancer cases have emerged in the last few years and have led to the failure of many chemotherapeutic drugs. Newer treatment methods and drugs are being developed to overcome this problem. Target based drug discovery is an effective method to develop novel anticancer drugs. To develop newer drugs, previously reported work needs to be studied. Keeping this in mind, last five year's literature on morpholine used as anticancer agents has been reviewed and summarized in the paper herein.

Pyrazole and imidazo[1,2-b]pyrazole Derivatives as New Potential Antituberculosis Agents

Background:

We screened a large library of differently decorated imidazo-pyrazole and pyrazole derivatives as possible new antitubercular agents and this preliminary screening showed that many compounds are able to totally inhibit Mycobacterium growth (>90 %). Among the most active compounds, we selected some new possible hits based on their similarities and, at the same time, on their novelty with respect to the pipeline drugs. </P><P> Methods: In order to increase the potency and obtain more information about structure-activity relationship (SAR), we designed and synthesized three new series of compounds (2a–e, 3a–e, and 4a–l).

Conclusion:

Performed tests confirmed that both new pyrazoles and imidazo-pyrazoles could represent a new starting point to obtain more potent compounds and further work is now underway to identify the protein targets of this new class of anti-TB agents.

The Newly Synthesized Pyrazole Derivative 5-(1-(3 Fluorophenyl)-1H-Pyrazol-4-yl)-2H-Tetrazole Reduces Blood Pressure of Spontaneously Hypertensive Rats via NO/cGMO Pathway

The search for new antihypertensive drugs has grown in recent years because of high rate of morbidity among hypertensive patients and several side effects that are associated with the first-line medications. The current study sought to investigate the antihypertensive effect of a newly synthesized pyrazole derivative known as 5-(1-(3 fluorophenyl)-1H-pyrazol-4-yl)-2H-tetrazole (LQFM-21). Spontaneously hypertensive rats (SHR) were used to evaluate the effect of LQFM-21 on mean arterial pressure (MAP), heart rate (HR), renal vascular conductance (RVC), arterial vascular conductance (AVC), baroreflex sensitivity (BRS) index, and vascular reactivity. Acute intravenous (iv) administration of LQFM-21 (0.05, 0.1, 0.2, and 0.4 mg kg^-1) reduced MAP and HR, and increased RVC and AVC. Chronic oral administration of LQFM-21 (15 mg kg^-1) for 15 days reduced MAP without altering BRS. The blockade of muscarinic receptors and nitric oxide synthase by intravenous infusion of atropine and L-NAME, respectively, attenuated cardiovascular effects of LQFM-21. In addition, ex vivo experiments showed that LQFM-21 induced an endothelium-dependent relaxation in isolated aortic rings from SHR. This effect was blocked by guanylyl cyclase inhibitor (ODQ) and L-NAME. These findings suggest the involvement of muscarinic receptor and NO/cGMP pathway in the antihypertensive and vasodilator effects of LQFM-21.

Synthesis of novel series of 7,7′-(substituted methylene)bis-imidazo[1,2-b]pyrazoles via an acid catalyzed one-pot three-component reaction

An efficient and rapid synthesis of new series of N-alkyl-2-aryl-5H-imidazo[1,2-b]pyrazoles has been achieved in high yields through a three-component reaction of 3-amino-4-substituted pyrazoles, aromatic aldehydes and isocyanides mediated by acid catalysts.

Synergistic effect of pyrazoles derivatives and doxorubicin in claudin-low breast cancer subtype

BACKGROUND

Breast cancer is a global public health problem. For some subtypes, such as Claudin-low, the prognosis is poorer and the treatment is still a challenge. Pyrazoles are an important class of heterocyclic compounds and are promising anticancer agents based on their chemical properties. The present study was aimed not only at testing pyrazoles previously prepared by our research group in two breast cancer cell lines characterized by intermediated response to conventional chemotherapy but also at analyzing the possible synergistic effect of these pyrazoles associated with doxorubicin.

METHODS

Four 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H pyrazoles were tested for the first time in MCF-7 and MDA-MB-231 culture cells. The pyrazoles with best results in cytotoxicity were used in combination with doxorubicin and compared with this drug alone as standard. The synergic effect was analyzed using Combination Index method. In addition, cell death and apoptosis assays were carried out.

RESULTS

Two pyrazoles with cytotoxic effect in MCF-7 and especially in MDA-MB-231 were identified. This activity was markedly higher in pyrazoles containing bromine and chlorine substituents. The combination of these pyrazoles with doxorubicin had a significant synergic effect in both cells tested and mainly in MDA-MB-231. These data were confirmed with apoptosis and cell death analysis.

CONCLUSIONS

The synergic effect observed with combination of these pyrazoles and doxorubicin deserves special attention in Claudin-low breast cancer subtype. This should be explored in order to improve treatment results and minimize side effects.

3-[(3,5-Dimethyl-1H-pyrazol-1-yl)methyl]-4-(4-methylphenyl)-4,5-dihydro-1H-1,2,4-triazole-5-thione

With the pyrazolyl andp-tolyl groups lying to one side of the plane through the linking 1,2,4-triazole-5-thione residue [forming dihedral angles of 87.05 (8) and 81.41 (7)°, respectively], the title molecule, C15H17N5S, adopts a `pincer' conformation stabilized in part by two intramolecular C—H...π(ring) interactions. A three-dimensional network structure is generated by a combination of intermolecular N—H...N and C—H...S hydrogen bonds, as well as C—H...π(ring) interactions.

Small hybrid heteroaromatics: resourceful biological tools in cancer research

Nowadays, hybrid drugs containing two or more covalently linked known potential pharmacophores are designed to simultaneously modulate multiple targets of multifactorial diseases to overcome the side effects associated with a single drug.

A new synthetic approach to the imidazo[1,5-a]imidazole-2-one scaffold and effective functionalization through Suzuki–Miyaura cross coupling reactions

A pathway to new 7-bromo-1-(4-methoxybenzyl)-5-methyl-imidazo[1,5-a]imidazole-2-one was reported. The synthetic potential of this scaffold was demonstrated by displacing bromine by Suzuki–Miyaura cross-coupling reactions.

Synthesis, in vitro and in vivo anticancer activity of novel 1-(4-imino-1-substituted-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl)urea derivatives

A series of pyrazolo[3,4-d]pyrimidine and urea hybrids have been designed, synthesized and evaluated for their anticancer activity in vitro and in vivo cancer models.

Novel conformationally constrained pyrazole derivatives as potential anti-cancer agents

The synthesis of 17 novel conformationally constrained pyrazole derivatives is reported herein, along with the assessment of their anti-proliferative and anti-angiogenic activities. The evaluation of their inhibitory effect on cell proliferation against HepG2, HeLa, and MCF-7 cells revealed the pyrrolo[2,3-g]indazole 23 as a potent inhibitor of cell growth with IC50 values of 5 μm. Additionally, the inhibition of vascular endothelial growth factor by pyrazoles 20 and 23 (30 % and 35 %, respectively) in HeLa supernatant cells was evidenced. These findings highlight the usefulness of these compounds as potential scaffolds for the design and development of novel anti-cancer agents with pronounced anti-angiogenic activity.

Meglumine catalyzed one-pot, three-component combinatorial synthesis of pyrazoles bearing a coumarin unit

Meglumine has been found to be an efficient catalyst for the synthesis of pyrazolylcoumarins by one-pot three-component reaction of salicylaldehyde, 4-hydroxy-6-methyl-2H-pyran-2-one, and hydrazine.