Design, synthesis and biological evaluation of novel (E)-α-benzylsulfonyl chalcone derivatives as potential BRAF inhibitors

The vinyl sulfone motif as a structural unit for novel drug design and discovery

INTRODUCTION

Vinyl sulfones are a special sulfur-containing structural unit that have attracted considerable attention, owing to their important role in serving as key structural motifs of various biologically active compounds as well as serving as versatile building blocks for organic transformations. The synthetic strategy of vinyl sulfone derivatives has been substantially upgraded over the past 30 years, and the wide application of this functional group in drug design and discovery has been promoted.

AREA COVERED

In this review, the authors review the application of vinyl sulfones in drug discovery and select optimized compounds which might have significant impact or potential inspiration for drug design.

EXPERT OPINION

Vinyl sulfones have been reported to target various macromolecular targets via non-covalent or covalent interactions, including multiple kinases, tubulin, cysteine protease, transcription factor, and so on. Thus, it has been significantly applied as a privileged scaffold in the design of anticancer, anti-infective, anti-inflammatory, and neuroprotective agents. However, much work remains to be done to improve the drug-like properties, such as chemical and metabolic stability, ADME, and toxicity. Besides, the chemical space of vinyl sulfones needs to be expanded, including but not limited to the design of constrained endocyclic and exocyclic vinyl sulfones.

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.

Design, synthesis, and modelling study of new 1,2,3-triazole/chalcone hybrids with antiproliferative action as epidermal growth factor receptor inhibitors

A novel series of 1,2,3-triazole/chalcone hybrids 6a-n was designed and synthesized using a molecular hybridization approach to develop a new cytotoxic agent capable of targeting epidermal growth factor receptor (EGFR) and/or BRAF. The antiproliferative effect of the novel hybrids was investigated against four cancer cells using doxorubicin as a reference. Hybrids 6a, 6d, 6f-h, and 6n have the highest antiproliferative activity (IC₅₀ values 0.95-1.80 μM) compared to doxorubicin (IC₅₀ 1.14 μM). The most potent antiproliferative derivative, compound 6d, was also the most potent EGFR inhibitor with an IC₅₀ of 0.09 ± 0.05 μM, which is comparable to the reference Erlotinib (IC₅₀  = 0.05 ± 0.03 μM). 6d has modest BRAF inhibitory action with an IC₅₀ of 0.90 ± 0.10 μM. The findings were also related to molecular docking studies, which provided models of strong interactions with the EGFR-TK domain for the inhibitors. In cell cycle analysis, hybrid 6d caused a cell cycle arrest at the G1 transition phase.

Discovery of novel JAK2 and EGFR inhibitors from a series of thiazole-based chalcone derivatives

The Janus kinase (JAK) and epidermal growth factor receptor (EGFR) have been considered as potential targets for cancer therapy due to their role in regulating proliferation and survival of cancer cells. In the present study, the aromatic alkyl-amino analogs of thiazole-based chalcone were selected to experimentally and theoretically investigate their inhibitory activity against JAK2 and EGFR proteins as well as their anti-cancer effects on human cancer cell lines expressing JAK2 (TF1 and HEL) and EGFR (A549 and A431). In vitro cytotoxicity screening results demonstrated that the HEL erythroleukemia cell line was susceptible to compounds 11 and 12, whereas the A431 lung cancer cell line was vulnerable to compound 25. However, TF1 and A549 cells were not sensitive to our thiazole derivatives. From kinase inhibition assay results, compound 25 was found to be a dual inhibitor against JAK2 and EGFR, whereas compounds 11 and 12 selectively inhibited the JAK2 protein. According to the molecular docking analysis, compounds 11, 12 and 25 formed hydrogen bonds with the hinge region residues Lys857, Leu932 and Glu930 and hydrophobically came into contact with Leu983 at the catalytic site of JAK2, while compound 25 formed a hydrogen bond with Met769 at the hinge region, Lys721 near a glycine loop, and Asp831 at the activation loop of EGFR. Altogether, these potent thiazole derivatives, following Lipinski's rule of five, could likely be developed as a promising JAK2/EGFR targeted drug(s) for cancer therapy.

Systemic review on B-RafV600E mutation as potential therapeutic target for the treatment of cancer

Cancer is one of the major public catastrophes worldwide and as per WHO, cancer is the leading cause of death universally after CVS disorders accounting for 9.6 million deaths in 2018. WHO statistics revealed five dangerous types of cancer viz. lung, breast, colorectal, prostate and skin. In male, lung cancer causes highest death, while in female, breast cancer causes the most. Alteration in MAPK signalling pathway plays a significant role in majority of cancer cases. Raf protein is activated by phosphorylation via downstream regulation of the MAPK pathway. Raf composed of 3 subtypes, viz. A-Raf, B-Raf, and C-Raf. B-Raf kinase plays a significant role in healthy cell growth in the MAPK pathway and the problem associated with B-Raf mutation leads to the development of cancer and other diseases. The progression of mutant B-Raf (B-Raf^V600E) protein is higher in cancer as compare to other diseases. In 2002, B-Raf^V600E mutation was identified for the first time in the development of cancer. The frequency of B-Raf^V600E mutation is higher in melanoma, thyroid, colorectal and ovarian cancer. We have covered small molecule B-Raf^V600E inhibitors reported in various literatures; from 2002 to 2020 and also covered clinical trial data. To widen the scope of readers, we compiled details of small molecules, specifically inhibiting B-Raf^V600E mutant and showing anti-proliferative activity against various cancer cell lines along with in-vivo data. We believe that the information covered here will be important in signifying the potentials of B-Raf^V600E mutation and its inhibitors as potent anticancer agents.

Chalcone hybrids as potential anticancer agents: Current development, mechanism of action, and structure-activity relationship

The continuous emergency of drug-resistant cancers and the low specificity of anticancer agents have been the major challenges in the control and treatment of cancer, making an urgent need to develop novel anticancer agents with high efficacy. Chalcones, precursors of flavonoids and isoflavonoids, exhibit structural heterogeneity and can act on various drug targets. Chalcones which demonstrated potential in vitro and in vivo activity against both drug-susceptible and drug-resistant cancers, are useful templates for the development of novel anticancer agents. Hybridization of chalcone moiety with other anticancer pharmacophores could provide the hybrids which have the potential to overcome drug resistance and improve the specificity, so it represents a promising strategy to develop novel anticancer agents. This review emphasizes the development, the mechanisms of action as well as structure-activity relationships of chalcone hybrids with potential therapeutic application for many cancers in recent 10 years.

Recent advances of analogues of curcumin for treatment of cancer

Curcumin (CU), an edible natural pigment from Curcuma Longa, has demonstrated extensive anti-tumor effect in vivo and in vitro. With the property of reversing drug resistance and low toxicity, CU has been considered to develop a new adjuvant chemotherapy protocol of cancer. However, the poor stability, solubility, in vivo bioavailability and weak activity of CU greatly limit its clinical application. Therefore, CU analogues have been extensively studied. Starting from the study of natural CU analogues, multiple approaches are being sought to obtain more stable, soluble and effective analogues of CU. This review focuses on the progress of these approaches to more potent CU analogues.

Crystal structure of 2,3-diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one 1-oxide

In the racemic title compound, C20H15NO2S, the planes of the two phenyl substituents form dihedral angles of 48.97 (15) and 69.26 (15)° with that of the fused benzene ring of the parent benzo-thia-zine ring, while the heterocyclic thia-zine ring exhibits a screw-boat pucker. The O atom on the S atom of the ring is pseudo-axial on the thia-zine ring and trans to the 2-phenyl group. In the crystal, mol-ecules are arranged in layers in the ac plane, the layers being linked across b through inter-molecular C-H⋯O hydrogen-bonding inter-actions.

Design, synthesis and cytotoxicity evaluation of novel (E)-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-1-(pyridin-3-yl)prop-2-en-1-ones as anticancer agents

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Molecular targeted approaches to cancer therapy and prevention using chalcones

There is an emerging paradigm shift in oncology that seeks to emphasize molecularly targeted approaches for cancer prevention and therapy. Chalcones (1,3-diphenyl-2-propen-1-ones), naturally-occurring compounds with widespread distribution in spices, tea, beer, fruits and vegetables, consist of open-chain flavonoids in which the two aromatic rings are joined by a three-carbon α, β-unsaturated carbonyl system. Due to their structural diversity, relative ease of chemical manipulation and reaction of α, β-unsaturated carbonyl moiety with cysteine residues in proteins, some lead chalcones from both natural products and synthesis have been identified in a variety of screening assays for modulating important pathways or molecular targets in cancers. These pathways and targets that are affected by chalcones include MDM2/p53, tubulin, proteasome, NF-kappa B, TRIAL/death receptors and mitochondria mediated apoptotic pathways, cell cycle, STAT3, AP-1, NRF2, AR, ER, PPAR-γ and β-catenin/Wnt. Compared to current cancer targeted therapeutic drugs, chalcones have the advantages of being inexpensive, easily available and less toxic; the ease of synthesis of chalcones from substituted benzaldehydes and acetophenones also makes them an attractive drug scaffold. Therefore, this review is focused on molecular targets of chalcones and their potential implications in cancer prevention and therapy.

Anti-cancer chalcones: Structural and molecular target perspectives

Chalcone or (E)-1,3-diphenyl-2-propene-1-one scaffold remained a fascination among researchers in the 21st century due to its simple chemistry, ease of synthesis and a wide variety of promising biological activities. Several natural and (semi) synthetic chalcones have shown anti-cancer activity due to their inhibitory potential against various targets namely ABCG2/P-gp/BCRP, 5α-reductase, aromatase, 17-β-hydroxysteroid dehydrogenase, HDAC/Situin-1, proteasome, VEGF, VEGFR-2 kinase, MMP-2/9, JAK/STAT signaling pathways, CDC25B, tubulin, cathepsin-K, topoisomerase-II, Wnt, NF-κB, B-Raf and mTOR etc. In this review, a comprehensive study on molecular targets/pathways involved in carcinogenesis, mechanism of actions (MOAs), structure activity relationships (SARs) and patents granted have been highlighted. With the knowledge of molecular targets, structural insights and SARs, this review may be helpful for (medicinal) chemists to design more potent, safe, selective and cost effective anti-cancer chalcones.

Design, synthesis and biological evaluation of novel 5-phenyl-1H-pyrazole derivatives as potential BRAF(V600E) inhibitors

A series of novel 5-phenyl-1H-pyrazole derivatives (5 a-5 u) containing niacinamide moiety were synthesized and evaluated for biological activity as potential BRAF(V600E) inhibitors. Among them, compound 5h exhibited the most potent inhibitory activity with an IC50 value of 0.33 μM for BRAF(V600E). Antiproliferative assay results indicated that compound 5h has better antiproliferative activity against WM266.4 and A375 in vitro with IC50 value of 2.63 and 3.16 μM, respectively, being comparable with the positive control vemurafenib. Molecular docking of 5h into the BRAF(V600E) active site was performed to determine the probable binding mode. Furthermore, molecular docking and 3D QSAR study by means of DS 3.5 (Discovery Studio 3.5, Accelrys, Co. Ltd) explored the binding modes and the structure and activity relationship (SAR) of these derivatives.

Antiobesity, antioxidant and cytotoxicity activities of newly synthesized chalcone derivatives and their metal complexes

Four sets of rationally designed chalcones were prepared for evaluation of their antiobesity, antioxidant and cytotoxicity activities. These sets include nine oleoyl chalcones as mimics of oleoyl estrone, three monohydroxy chalcones (chalcone ligands), Schiff base-derived chalcones and four copper as well as zinc complexes. Oleoyl chalcones 4d, 4e and particularly 6a as an isosteric isomer of oleoyl estrone, were as active as Orlistat on weight loss and related metabolic parameters using male SD rats in vivo. Chalcone ligands 10a-c and Schiff base-derived chalcones 11 and 14a,b were weakly antioxidants, while, the copper and zinc complexes 15a-d were good antioxidants with zinc chelates 15b,d being more active than their copper analogues 15a,cin vitro. Compounds 10c and 14a showed good cytotoxicity activities as Doxorubicin against PC3 cancer cell line in vitro, while, the copper complex 15c showed promising activity with IC₅₀ value of 5.95 μM. The estimated IC₅₀ value for Doxorubicin was 8.7 μM. Chalcones 14a,b are bifunctional probes for potential investigations in cancer diagnosis and radiotherapy by complexation with Gd(3+) or metal radioisotopes followed by posttranslation of Shiga toxin B-subunits that target globotriosyl ceramide expressing cancer cells.

Design, synthesis and biological evaluation of (1,3-diphenyl-1H-pyrazol-4-yl) methyl benzoate derivatives as potential BRAFV600E inhibitors

A series of (1,3-diphenyl-1H-pyrazol-4-yl) methyl benzoate derivatives (6a–10d) were designed and synthesized and evaluated as BRAF^V600 inhibitors. Among them, compound 10a showed the most potent inhibitory activity against A375, WM266.4 and BRAF^V600Ein vitro with IC₅₀ values of 1.36 μM, 0.94 μM and 0.11 μM, respectively.