Design, synthesis, and biological evaluation of novel imidazole derivatives possessing terminal sulphonamides as potential BRAFV600Einhibitors

An insight into recent developments in imidazole based heterocyclic compounds as anticancer agents: Synthesis, SARs, and mechanism of actions

Among all non-communicable diseases, cancer is ranked as the second most common cause of death and is rising constantly. While cancer treatments mainly include radiation therapy, chemotherapy, and surgery; chemotherapy is considered the most commonly employed and effective treatment. Most of the chemotherapeutic agents are azoles based compounds and imidazole is one such insightful azole. The anticancer properties of imidazole-based compounds have been thoroughly explored in recent years and all monosubstituted, disubstituted, trisubstituted, and tetrasubstituted imidazoles have been explored for their anticancer activities. Along with these compounds, other imidazole-based compounds like 1,3-dihydro-2H-imidazole-2-thiones, imidazolones, and poly imidazole compounds have also been explored for their anticancer activities. The activities of these compounds are heavily influenced by their structural resemblance to combretastatin 4A and ABI (2-aryl-4-benzoyl-imidazole). The lead compounds were highly active on breast, gastric, colon, ovarian, cervical, bone marrow, melanoma, prostate, lung, leukemic, neuroblastoma, liver, Ehrlich, melanoma, and pancreatic cancers. The targets of these leads like tubulin, heme oxygenases, VEGF, tyrosine kinases, EGFR, and others have also been explored. The exploration of the anticancer potential of substituted imidazole compounds is the main topic of this review including synthesis, SAR, and mechanism.

An updated literature on BRAF inhibitors (2018-2023)

BRAF is the most common serine-threonine protein kinase and regulates signal transduction from RAS to MEK inside the cell. The BRAF is a highly active isoform of RAF kinase. BRAF has two domains such as regulatory and kinase domains. The BRAF inhibitors bind in the c-terminus of the kinase domain and inhibit the downstream pathways. The mutation occurs mainly in the A-loop of the kinase domain. The mutation occurs due to a conversion of valine to glutamate/lysine/arginine/aspartic acid at 600th position. Among the diverse mutations, BRAFV600E is the most common and responsible for numerous cancer such as melanoma, colorectal, ovarian, and thyroid cancer. Due to mutations in RAC1, loss of PTEN, NF1, CCND1, USP28-FBW7 complex, COT overexpression, and CCND1 amplification, the BRAF kinase enzyme developed resistance over the commercially available BRAF inhibitors. There is still unmute urgence for the development of BRAF inhibitors to overcome the persistent limitation such as resistance, mutation, and adverse effects of drugs. In the current study, we described the structure, activation, downstream signaling pathway, and mutation of BRAF. Our group also provided a detailed review of BRAF inhibitors from the last five years (2018-2023) highlighting the structure-activity relationship, mechanistic study, and molecular docking studies. We hope that the current analysis will be a useful resource for researchers and provide chemists a glimpse into the future as design and development of more effective and secure BRAF kinase inhibitors.

Recent development of azole-sulfonamide hybrids with the anticancer potential

Cancer exhibits heterogeneity that enables adaptability and remains grand challenges for effective treatment. Chemotherapy is a validated and critically important strategy for the treatment of cancer, but the emergence of multidrug resistance which may lead to recurrence of disease or even death is a major hurdle for successful chemotherapy. Azoles and sulfonamides are important anticancer pharmacophores, and azole-sulfonamide hybrids have the potential to simultaneously act on dual/multiple targets in cancer cells, holding great promise to overcome drug resistance. This review outlines the current scenario of azole-sulfonamide hybrids with the anticancer potential, and the structure-activity relationships as well as mechanisms of action are also discussed, covering articles published from 2020 onward.

2-Thioxo-3,4-dihydropyrimidine and thiourea endowed with sulfonamide moieties as dual EGFRT790M and VEGFR-2 inhibitors: Design, synthesis, docking, and anticancer evaluations

The effectiveness of a new series of thiopyrimidine and thiourea containing sulfonamides moieties was tested on HCT-116, MCF-7, HepG2, and A549. HepG2 cell line was the one that all the new derivatives affected the most. The greatest potent compounds against the four HepG2, HCT116, MCF-7, and A549 cell lines were 8f and 8g with IC50  = 4.13, 6.64, 5.74, 6.85 µM and 4.09, 4.36, 4.22, 7.25 µM correspondingly. Compound 8g exhibited higher activity than sorafenib against HCT116 and MCF-7 but exhibited lower activity against HepG2 and A549. Moreover, compounds 8f and 8g exhibited higher activities than erlotinib on HepG2, HCT116, and MCF-7 but demonstrated lower activity on A549. The most potent cytotoxic derivatives 6f, 6g, 8c, 8d, 8e, 8f, and 8g were examined on normal VERO cell lines. Our derivatives have low toxicity on VERO cells with IC50 values ranging from 32.05 to 53.15 μM. Additionally, all compounds were assessed for dual VEGFR-2 and EGFRT790M inhibition effects. Compounds 8f and 8g were the most potent derivatives inhibited VEGFR-2 at IC50 value of 0.88 and 0.90 µM, correspondingly. As well, derivatives 8f and 8g could inhibit EGFRT790M demonstrating strongest effects with IC50  = 0.32 and 0.33 µM sequentially. Additionally, the greatest active derivatives ADMET profile was evaluated in relationship with sorafenib and erlotinib as reference agents. The data attained from docking were greatly related to that achieved from the biological testing.

Anti-inflammatory effect of 3-fluorophenyl pyrimidinylimidazo[2,1-b]thiazole derivatives as p38α inhibitors

In the present work, the anti-inflammatory effect of 30 compounds containing 3-fluorophenyl pyrimidinylimidazo[2,1-b]thiazole was investigated. All final target compounds showed significant Inhibitory effect on p38α. P38α is considered one of the key kinases in the inflammatory process due to its regulatory effect on pro-inflammatory mediators. The final target compounds divided into four group based on the type of terminal moiety (amide and sulfonamide) and the linker between pyrimidine ring and terminal moiety (ethyl and propyl). Most compounds with terminal sulfonamide moiety and propyl linker between the sulfonamide and pyrimidine ring were the most potent among all synthesized final target compounds with sub-micromolar IC50s. Compound 24g (with p-Cl benzene sulfonamide and propyl linker) exhibited the highest activity over P38α with IC50 0.68 µM. All final target compounds were tested for their ability to inhibit nitric oxide release and prostaglandin E2 production. Compounds having amide terminal moiety with ethyl linker showed higher inhibitory activity for nitric oxide release and compound 21d exhibited the highest activity for nitric oxide release with IC50 1.21 µM. Compounds with terminal sulfonamide moiety and propyl linker showed the highest activity for inhibiting PGE2 production and compounds 24i and 24g had the lowest IC50s with value 0.87 and 0.89 µM, respectively. Compounds 21d, 22d and 24g were tested for their ability to inhibit over expression of iNOS, COX1, and COX2. In addition the ability of compounds 21d, 22d and 24g to inhibit inflammatory cytokines were determined. Finally molecular docking of the three compounds were performed on P38α crystal structure to expect their mode of binding.

In-vitro anticancer evaluation of newly designed and characterized tri/tetra-substituted imidazole congeners- maternal embryonic leucine zipper kinase inhibitors: Molecular docking and MD simulation approaches

Our cascading attempt to develop new potent molecules now involves designing a series of imidazole derivatives and synthesizing two sets of 2,4,5- tri-substituted (4a-4d) and 1,2,4,5-tetra-substituted (6a-6d) imidazole by the principle of Debus-Radziszewski multicomponent synthesis reaction. The structures of the obtained compounds were confirmed by 1H/13C NMR, FT-IR, elemental analysis, purity and the retention time was analyzed by HPLC. Based upon the binding affinity in the molecular docking studies, we have synthesized different imidazole derivatives from which compound 6c have been found to show more anti-proliferative activity by inducing apoptosis at a higher rate than the other compounds corroborating the in-silico prediction. The structure and crystallinity of compound 4d have been confirmed by single XRD analysis. The synthesized molecules were screened for their in vitro anti-cancer properties in triple negative breast cancer cell line (MDA-MB-231), pancreatic cancer cell lines (MIA PaCa-2) and oral squamous cell carcinoma cell line (H357) and results indicated that all the compounds inhibited the cell proliferation in a concentration-dependent manner at different time points. The compounds 4b and 6d were found to be effective against the S. aureus bacterial strain whereas only compound 4d fairly inhibited the fungal strain of T. rubrum with a MIC 12.5 μg/mL. Molecular docking study reveals good interaction of the synthesized compounds with known target MELK involved in oncogenesis having high binding profiles. The lead compound 6c was further analyzed by the detailed molecular dynamics study to establish the stability of the ligand-enzyme complex.

Challenges and Opportunities in the Crusade of BRAF Inhibitors: From 2002 to 2022

Serine/threonine-protein kinase B-Raf (BRAF; RAF = rapidly accelerated fibrosarcoma) plays an important role in the mitogen-activated protein kinase (MAPK) signaling cascade. Somatic mutations in the BRAF gene were first discovered in 2002 by Davies et al., which was a major breakthrough in cancer research. Subsequently, three different classes of BRAF mutants have been discovered. This class includes class I monomeric mutants (BRAFV600), class II BRAF homodimer mutants (non-V600), and class III BRAF heterodimers (non-V600). Cancers caused by these include melanoma, thyroid cancer, ovarian cancer, colorectal cancer, nonsmall cell lung cancer, and others. In this study, we have highlighted the major binding pockets in BRAF protein, their active and inactive conformations with inhibitors, and BRAF dimerization and its importance in paradoxical activation and BRAF mutation. We have discussed the first-, second-, and third-generation drugs approved by the Food and Drug Administration and drugs under clinical trials with all four different binding approaches with DFG-IN/OUT and αC-IN/OUT for BRAF protein. We have investigated particular aspects and difficulties with all three generations of inhibitors. Finally, this study has also covered recent developments in synthetic BRAF inhibitors (from their discovery in 2002 to 2022), their unique properties, and importance in inhibiting BRAF mutants.

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.

Anticancer activity and QSAR study of sulfur-containing thiourea and sulfonamide derivatives

Sulfur-containing compounds are considered as attractive pharmacophores for discovery of new drugs regarding their versatile properties to interact with various biological targets. Quantitative structure-activity relationship (QSAR) modeling is one of well-recognized in silico tools for successful drug discovery. In this work, a set of 38 sulfur-containing derivatives (Types I–VI) were evaluated for their in vitro anticancer activities against 6 cancer cell lines. In vitro findings indicated that compound 13 was the most potent cytotoxic agent toward HuCCA-1 cell line (IC₅₀ = 14.47 μM). Compound 14 exhibited the most potent activities against 3 investigated cell lines (i.e., HepG2, A549, and MDA-MB-231: IC₅₀ range = 1.50–16.67 μM). Compound 10 showed the best activity for MOLT-3 (IC₅₀ = 1.20 μM) whereas compound 22 was noted for T47D (IC₅₀ = 7.10 μM). Subsequently, six QSAR models were built using multiple linear regression (MLR) algorithm. All constructed QSAR models provided reliable predictive performance (training sets: R_tr range = 0.8301–0.9636 and RMSE_tr = 0.0666–0.2680; leave-one-out cross validation sets: R_CV range = 0.7628–0.9290 and RMSE_CV = 0.0926–0.3188). From QSAR modeling, chemical properties such as mass, polarizability, electronegativity, van der Waals volume, octanol-water partition coefficient, as well as frequency/presence of C–N, F–F, and N–N bonds in the molecule are essential key predictors for anticancer activities of the compounds. In summary, a series of promising fluoro-thiourea derivatives (10, 13, 14, 22) were suggested as potential molecules for future development as anticancer agents. Key structure-activity knowledge obtained from the QSAR modeling was suggested to be advantageous for suggesting the effective rational design of the related sulfur-containing anticancer compounds with improved bioactivities and properties.

New Potential Agents for Malignant Melanoma Treatment-Most Recent Studies 2020-2022

Malignant melanoma (MM) is the most lethal skin cancer. Despite a 4% reduction in mortality over the past few years, an increasing number of new diagnosed cases appear each year. Long-term therapy and the development of resistance to the drugs used drive the search for more and more new agents with anti-melanoma activity. This review focuses on the most recent synthesized anti-melanoma agents from 2020-2022. For selected agents, apart from the analysis of biological activity, the structure-activity relationship (SAR) is also discussed. To the best of our knowledge, the following literature review delivers the latest achievements in the field of new anti-melanoma agents.

The crystal structure of 1-methyl-2-nitroimidazole, C4H5N3O2

C4H5N3O2, monoclinic, P21/c (no. 14), a = 4.0668(13) Å, b = 11.198(4) Å, c = 6.137(2) Å, β = 97.033(11)°, V = 277.40(16) Å3, Z = 2, R gt (F) = 0.0444, wR ref (F 2) = 0.1048, T = 170.00 K.

Recent development of imidazole derivatives as potential anticancer agents

Cancer, one of the key health problems globally, is a group of related diseases that share a number of characteristics primarily the uncontrolled growth and invasive to surrounding tissues. Chemotherapy is one of the ways for the treatment of cancer which uses one or more anticancer agents as per chemotherapy regimen. Limitations of most anticancer drugs due to a variety of reasons such as serious side effects, drug resistance, lack of sensitivity and efficacy etc. generate the necessity towards the designing of novel anticancer lead molecules. In this regard, the synthesis of biologically active heterocyclic molecules is an appealing research area. Among heterocyclic compounds, nitrogen containing heterocyclic molecules has fascinated tremendous consideration due to broad range of pharmaceutical activity. Imidazoles, extensively present in natural products as well as synthetic molecules, have two nitrogen atoms, and are five membered heterocyclic rings. Because of their countless physiological and pharmacological characteristics, medicinal chemists are enthused to design and synthesize new imidazole derivatives with improved pharmacodynamic and pharmacokinetic properties. The aim of this present chapter is to discuss the synthesis, chemistry, pharmacological activity, and scope of imidazole-based molecules in anticancer drug development. Finally, we have discussed the current challenges and future perspectives of imidazole-based derivatives in anticancer drug development.

Structural optimization of 4-(imidazol-5-yl)pyridine derivatives affords broad-spectrum anticancer agents with selective B-RAFV600E/p38α kinase inhibitory activity: Synthesis, in vitro assays and in silico study

In the current article, we introduce design of a new series of 4-(imidazol-5-yl)pyridines with improved anticancer activity and selective B-RAF^V600E/p38α kinase inhibitory activity. Based on a previous work, a group of structural modifications were applied affording the new potential antiproliferative agents. Towards extensive biological assessment of the target compounds, an in vitro anticancer assay was conducted over NCI 60-cancer cell lines panel representing blood, lung, colon, CNS, skin, ovary, renal, prostate, and breast cancers. Compounds 7c, 7d, 8b, 9b, 9c, 10c, 10d, and 11b exhibited the highest potency among the tested compounds and demonstrated sub-micromolar or one-digit micromolar GI₅₀ values against the majority of the employed cell lines. Compound 10c emerged as the most potent agent with nano-molar activity over most of the cells and incredible activity against melanoma (MDA-MB-435) cell line (GI₅₀ 70 nM). It is much more potent than sorafenib, the clinically used anticancer drug, against almost all the NCI-60 cell lines. Further cell-based mechanistic assays showed that compound 10c induced cell cycle arrest and promoted apoptosis in K562, MCF-7 and HT29 cancer cell lines. In addition, compound 10c induced autophagy in the three cancer cell lines. Kinase profiling of 10c showed its inhibitory effects and selectivity towards B-RAF^V600E and p38α kinases with IC₅₀ values of 1.84 and 0.726 µM, respectively. Docking of compound 10c disclosed its high affinity in the kinases pockets. Compound 10c represent a promising anticancer agent, that could be optimized in order to improve its kinase activity aiming at developing potential anticancer agents. The conformational stability of compound 10c in the active site of B-RAF^V600E and p38α kinases was studied by applying molecular dynamic simulation of the compound in the two kinases for 600 ns in comparison to the native ligands.

Exploration of Benzenesulfonamide-Bearing Imidazole Derivatives Activity in Triple-Negative Breast Cancer and Melanoma 2D and 3D Cell Cultures

Heterocyclic compounds are one of the main groups of organic compounds possessing wide range of applications in various areas of science and their derivatives are present in many bioactive structures. They display a wide variety of biological activities. Recently, more and more attention has been focused to such heterocyclic compounds as azoles. In this work, we have synthesized a series of new imidazole derivatives incorporating a benzenesulfonamide moiety in their structure, which then were evaluated for their cytotoxicity against human triple-negative breast cancer MDA-MB-231 and human malignant melanoma IGR39 cell lines by MTT assay. Benzenesulfonamide-bearing imidazole derivatives containing 4-chloro and 3,4-dichlorosubstituents in benzene ring, and 2-ethylthio and 3-ethyl groups in imidazole ring have been determined as the most active compounds. Half-maximal effective concentration (EC50) of the most cytotoxic compound was 27.8 ± 2.8 µM against IGR39 cell line and 20.5 ± 3.6 µM against MDA-MB-231 cell line. Compounds reduced cell colony formation of both cell lines and inhibited the growth and viability of IGR39 cell spheroids more efficiently compared to triple-negative breast cancer spheroids.

Imidazole as a Promising Medicinal Scaffold: Current Status and Future Direction

Various imidazole-containing compounds have been tested for their medical usefulness in clinical trials for several disease conditions. The rapid expansion of imidazole-based medicinal chemistry suggests the promising and potential therapeutic values of imidazole-derived compounds for treating incurable diseases. Imidazole core scaffold contains three carbon atoms, and two nitrogen with electronic-rich characteristics that are responsible for readily binding with a variety of enzymes, proteins, and receptors compared to the other heterocyclic rings. Herein, we provide a thorough overview of the current research status of imidazole-based compounds with a wide variety of biological activities including anti-cancer, anti-microbial, anti-inflammatory and their potential mechanisms including topoisomerase IIR catalytic inhibition, focal adhesion kinase (FAK) inhibition, c-MYC G-quadruplex DNA stabilization, and aurora kinase inhibition. Additionally, a great interest was reported in the discovery of novel imidazole compounds with anti-microbial properties that break DNA double-strand helix and inhibit protein kinase. Moreover, anti-inflammatory mechanisms of imidazole derivatives include inhibition of COX-2 enzyme, inhibit neutrophils degranulation, and generation of reactive oxygen species. This systemic review helps to design and discover more potent and efficacious imidazole compounds based on the reported derivatives, their ADME profiles, and bioavailability scores that together aid to advance this class of compounds.

5-Aryl-1-Arylideneamino-1H-Imidazole-2(3H)-Thiones: Synthesis and In Vitro Anticancer Evaluation

A novel series of N-1 arylidene amino imidazole-2-thiones were synthesized, identified using IR, ¹H-NMR, and ¹³C-NMR spectral data. Cytotoxic effect of the prepared compounds was carried out utilizing three cancer cell lines; MCF-7 breast cancer, HepG2 liver cancer, and HCT-116 colon cancer cell lines. Imidazole derivative 5 was the most potent of all against three cell lines. DNA flow cytometric analysis showed that, imidazoles 4d and 5 exhibit pre-G1 apoptosis and cell cycle arrest at G2/M phase. The results of the VEGFR-2 and B-Raf kinase inhibition assay revealed that compounds 4d and 5 displayed good inhibitory activity compared with reference drug erlotinib.

Design, synthesis, biological evaluation, and docking studies of novel (imidazol-5-yl)pyrimidine-based derivatives as dual BRAFV600E/p38α inhibitors

The synergistic effect of dual inhibition of serine/threonine protein kinases that are involved in the same signalling pathway of the diseases can exert superior biological benefits for treatment of these diseases. In the present work, a new series of (imidazol-5-yl)pyrimidine was designed and synthesized as dual inhibitors of BRAF^V600E and p38α kinases which are considered as key regulators in mitogen-activated protein kinase (MAPK) signalling pathway. The target compounds were evaluated for dual kinase inhibitory activity. The tested compounds exhibited nanomolar scale IC₅₀ values against BRAF^V600E and low to sub-micromolar IC₅₀ range against p38α. Compound 20h was identified as the most potent dual BRAF^V600E/p38α inhibitor with IC₅₀ values of 2.49 and 85 nM, respectively. Further deep investigation revealed that compound 20h possesses inhibitory activity of TNF-α production in lipopolysaccharide-induced RAW 264.7 macrophages with IC₅₀ value of 96.3 nM. Additionally, the target compounds efficiently frustrated the proliferation of LOX-IMVI melanoma cell line. Compound 20h showed a satisfactory antiproliferative activity with IC₅₀ value of 13 μM, while, compound 18f exhibited the highest cytotoxicity potency with IC₅₀ value of 0.9 μM. Compound 18f is 11.11-fold more selective toward LOX-IMVI melanoma cells than IOSE-80PC normal cells. The newly reported compounds represent therapeutically promising candidates for further development of BRAF^V600E/p38α inhibitors in an attempt to overcome the acquired resistance of BRAF mutant melanoma.