2-Anilinoquinoline based arylamides as broad spectrum anticancer agents with B-RAFV600E/C-RAF kinase inhibitory effects: Design, synthesis, in vitro cell-based and oncogenic kinase assessments

Design, synthesis, and evaluation of 1,4-benzodioxane-hydrazone derivatives as potential therapeutics for skin cancer: In silico, in vitro, and in vivo studies

In the pursuit of novel chemotherapeutic agents for skin cancer, we synthesized a series of 1,4-benzodioxane-hydrazone derivatives (7a-l) using the Wolff-Kishner reaction. These compounds were initially screened against the NCI-60 oncological cell lines in a one-dose assay at 10 μM. Among them, compound 7e emerged as a potent inhibitor of cancer cell growth across 56 cell lines, with an average GI50 of 6.92 μM. Notably, it exhibited enhanced efficacy in melanoma cell lines, including MDA-MB-435, M14, SK-MEL-2, and UACC-62, with GI50 values of 0.20, 0.46, 0.57, and 0.27 μM, respectively. Apoptosis assay and cell cycle analysis studies revealed that compound 7e induced apoptosis and caused S-phase arrest in MDA-MB-435 cells. Furthermore, an in vitro enzyme inhibition assay against mTOR kinase yielded an IC50 of 5.47 μM, while molecular docking studies of compound 7e (docking score: -8.105 kcal/mol) supported its binding affinity. Compound 7e adhered to Lipinski's rule of five and displayed favourable ADMET properties. In vivo studies demonstrated its safety and efficacy in ameliorating skin cancer in a mice model when administered intraperitoneally at 20 mg/kg. Structure-activity relationships were established through in vitro, in vivo, molecular docking, and molecular dynamics analysis. Collectively, these findings highlight 1,4-benzodioxane-hydrazone derivatives as promising scaffold for the development of novel chemotherapeutic agents for skin cancer.

Discovery of novel 4-trifluoromethyl-2-anilinoquinoline derivatives as potential anti-cancer agents targeting SGK1

Given the critical necessity for the development of more potent anti-cancer drugs, a series of novel compounds incorporating trifluoromethyl groups within the privileged 2-anilinoquinoline scaffold was designed, synthesized, and subjected to biological evaluation through a pharmacophore hybridization strategy. Upon evaluating the in vitro anti-cancer characteristics of the target compounds, it became clear that compound 8b, which contains a (4-(piperazin-1-yl)phenyl)amino substitution at the 2-position of the quinoline skeleton, displayed superior efficacy against four cancer cell lines by inducing apoptosis and cell cycle arrest. Following research conducted in a PC3 xenograft mouse model, it was found that compound 8b exhibited significant anti-cancer efficacy while demonstrating minimal toxicity. Additionally, the analysis of a 217-kinase panel pinpointed SGK1 as a potential target for this compound class with anti-cancer capabilities. This finding was further verified through molecular docking analysis and cellular thermal shift assays. To conclude, our results emphasize that compound 8b can be used as a lead compound for the development of anti-cancer drugs that target SGK1.

New 5, 6, 7, 8-Tetrahydro-Isoquinolines Bearing 2-Nitrophenyl Group Targeting RET Enzyme: Synthesis, Anticancer Activity, Apoptotic Induction and Cell Cycle Arrest

In this work, we synthesized new 5, 6, 7, 8-tetrahydroisoquinolines and 6, 7, 8, 9-tetrahydrothieno[2, 3-c]isoquinolines derivatives, and the structures of these new compounds were confirmed with different spectroscopic techniques. Furthermore, the anticancer activities of these compounds were assessed against eight tumor cell lines and one normal human skin fibroblast cell line (HSF). Subsequently, IC50 values of the synthesized compounds were determined for two specific cancer cell lines. Compound 3 exhibited the most potent antiproliferative activity against the HEPG2 cell line, whereas compound 9c demonstrated superior efficacy against the HCT116 cell line. Moreover, the mechanism of action for compound 3 on HEPG2 cells using flow cytometry and Annexin V-FITC apoptosis analysis was studied. Compound 3 caused cell cycle arrest at the G2/M with a 50-fold increase in apoptosis of the HEPG2 cell line. Finally, a molecular docking study was conducted to assess the inhibitory potential of compounds 3 and 7 against the RET enzyme. Results indicated that compounds 3 and 7 bind to the RET enzyme with binding energies of -5.2 and -5.6 kcal/mol, respectively. Although these values suggest inhibitory activity, they are less potent than the standard inhibitor, alectinib, which exhibits a binding energy of -7.2 kcal/mol.

Emodin, a Potent Anthraquinone Mitigates MPTP-Induced Parkinsons' Disease Pathology by Regulating Nrf2 and Its Downstream Targets: In Silico and In Vivo Approach

Parkinson's disease (PD) is marked by neurodegeneration that follows the destruction of dopaminergic neurons, mainly localized to the substantia nigra. It results in debilitating motor as well as non-motor symptoms. The current study investigated the neuroprotective potential of emodin, a naturally occurring anthraquinone derivative, in a well-established model of PD in mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The key focus is the Nrf2 signaling pathway, the major defense mechanism of the cells against oxidative damage and neuroinflammation, both exacerbated in the pathology of PD. Using molecular docking, the binding affinity of emodin to Nrf2 was predicted, revealing strong interactions that suggest emodin's potential to activate Nrf2. Subsequently, in vivo experiments were conducted where MPTP-induced PD mice were treated with emodin, and additional groups received Nrf2 modulators: dimethyl fumarate (DMF) as an agonist and all-trans retinoic acid (ATRA) as an antagonist. Emodin treatment led to a significant upregulation of Nrf2 expression, a reduction in oxidative stress markers such as malondialdehyde, and notable improvements in motor and cognitive behavior. DMF co-administration enhanced emodin's neuroprotective effects, whereas ATRA diminished them, highlighting the central role of Nrf2. These findings suggest that emodin effectively targets PD pathology via the Nrf2 pathway.

Discovery of novel naphthalene-based diarylamides as pan-Raf kinase inhibitors with promising anti-melanoma activity: rational design, synthesis, in vitro and in silico screening

Raf kinase enzymes are often dysregulated in melanoma. While sorafenib demonstrates strong activity against wild-type B-Raf, it fails to effectively inhibit the mutated form of B-Raf. In this study, sorafenib served as a lead compound for the development of new derivatives designed to enhance inhibitory activity across multiple Raf isoforms (pan-Raf inhibitors). Novel naphthalene-based diarylamide derivatives were subsequently designed, synthesized, and evaluated for their biological activity against various Raf kinase isoforms and the melanoma A375 cell line. Among these, compound 9a, containing a difluoromethoxy group, demonstrated strong inhibitory activity across B-RafWT, B-RafV600E, and c-Raf. Additionally, it induced G2/M phase arrest and triggered dose-dependent apoptosis, effectively suppressing both cell proliferation and survival. Compound 9a also exhibited high selectivity for Raf isoforms with minimal off-target effects, underscoring its specificity and therapeutic potential for Raf-driven malignancies.

An overview of RAF kinases and their inhibitors (2019-2023)

Protein kinases (PKs) including RAF, perform a principal role in regulating countless cellular events such as cell growth, differentiation, and angiogenesis. Overexpression and mutation of RAF kinases are significant contributors to the development and spread of cancer. Therefore, RAF kinase inhibitors show promising outcomes as anti-cancer small molecules by suppressing the expression of RAF protein, blocking RAS/RAF interaction, or inhibiting RAF enzymes. Currently, there are insufficient reports about approving drugs with minimal degree of toxicity. Therefore, it is an urgent need to develop new RAF kinase inhibitors correlated with increased anticancer activity and lower cytotoxicity. This review outlines reported RAF kinase inhibitors for cancer treatment in patents and literature from 2019 to 2023. It highlights the available inhibitors by shedding light on their chemical structures, biochemical profiles, and current status. Additionally, we highlighted the hinge region-binding moiety of the reported compounds by showing the hydrogen bond patterns of representative inhibitors with the hinge region for each class. In recent years, RAF kinase inhibitors have gained considerable attention in cancer research and drug development due to their potential to be studied under clinical trials and their demonstration of various degrees of efficacy and safety profiles across different cancer types. However, addressing challenges related to drug resistance and safety represents a major avenue for the optimization and enhancement of RAF kinase inhibitors. Strategies to overcome such obstacles were discussed such as developing novel pan-RAF inhibitors, RAF dimer inhibitors, and combination treatments.

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.

Overcoming the imatinib-resistant BCR-ABL mutants with new ureidobenzothiazole chemotypes endowed with potent and broad-spectrum anticancer activity

The design of kinase inhibitors targeting the oncogenic kinase BCR-ABL constitutes a promising paradigm for treating chronic myeloid leukaemia (CML). Nevertheless, the efficacy of imatinib, the first FDA-approved targeted therapy for CML, is curbed by the emergence of resistance. Herein, we report the identification of the 2-methoxyphenyl ureidobenzothiazole AK-HW-90 (2b) as a potent pan-BCR-ABL inhibitor against imatinib-resistant mutants, particularly T315I. A concise array of six compounds 2a-f was designed based on our previously reported benzothiazole lead AKE-5l to improve its BCR-ABL^T315I inhibitory activity. Replacing the 6-oxypicolinamide moiety of AKE-5l with o-methoxyphenyl and changing the propyl spacer with phenyl afforded 2a and AK-HW-90 (2b) with IC₅₀ values of 2.0 and 0.65 nM against BCR-ABL^T315I, respectively. AK-HW-90 showed superior anticancer potency to imatinib against multiple cancer cells (NCI), including leukaemia K-562. The obtained outcomes offer AK-HW-90 as a promising candidate for the treatment of CML and other types of cancer.

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.

Discovery of New Quinolone-Based Diarylamides as Potent B-RAFV600E/C-RAF Kinase Inhibitors Endowed with Promising In Vitro Anticancer Activity

The emergence of cancer resistance to targeted therapy represents a significant challenge in cancer treatment. Therefore, identifying new anticancer candidates, particularly those addressing oncogenic mutants, is an urgent medical demand. A campaign of structural modifications has been conducted to further optimize our previously reported 2-anilinoquinoline-diarylamides conjugate VII as a B-RAFV600E/C-RAF inhibitor. Considering the incorporation of a methylene bridge between the terminal phenyl and cyclic diamine, focused quinoline-based arylamides have been tailored, synthesized, and biologically evaluated. Among them, the 5/6-hydroxyquinolines 17b and 18a stood out as the most potent members, with IC₅₀ values of 0.128 µM, 0.114 µM against B-RAF^V600E, and 0.0653 µM, 0.0676 µM against C-RAF. Most importantly, 17b elicited remarkable inhibitory potency against the clinically resistant B-RAF^V600K mutant with an IC₅₀ value of 0.0616 µM. The putative binding mode of 17b and 18a were studied by molecular docking and molecular dynamics (MD). Moreover, the antiproliferative activity of all target compounds has been examined over a panel of NCI-60 human cancer cell lines. In agreement with cell-free assays, the designed compounds exerted superior anticancer impact over the lead quinoline VII against all cell lines at a 10 µM dose. Notably, both 17b and 18b showed highly potent antiproliferative activity against melanoma cell lines with growth percent under -90% (SK-MEL-29, SK-MEL-5, and UACC-62) at a single dose, while 17b maintained potency with GI₅₀ values of 1.60-1.89 µM against melanoma cell lines. Taken together, 17b, a promising B-RAF^V600E/V600K and C-RAF kinase inhibitor, may serve as a valuable candidate in the arsenal of anticancer chemotherapeutics.

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.

New 1,2,3-triazole linked ciprofloxacin-chalcones induce DNA damage by inhibiting human topoisomerase I& II and tubulin polymerization

A series of novel 1,2,3-triazole-linked ciprofloxacin-chalcones 4a-j were synthesised as potential anticancer agents. Hybrids 4a-j exhibited remarkable anti-proliferative activity against colon cancer cells. Compounds 4a-j displayed IC₅₀s ranged from 2.53-8.67 µM, 8.67-62.47 µM, and 4.19-24.37 µM for HCT116, HT29, and Caco-2 cells; respectively, whereas the doxorubicin, showed IC₅₀ values of 1.22, 0.88, and 4.15 µM. Compounds 4a, 4b, 4e, 4i, and 4j were the most potent against HCT116 with IC₅₀ values of 3.57, 4.81, 4.32, 4.87, and 2.53 µM, respectively, compared to doxorubicin (IC₅₀ = 1.22 µM). Also, hybrids 4a, 4b, 4e, 4i, and 4j exhibited remarkable inhibitory activities against topoisomerase I, II, and tubulin polymerisation. They increased the protein expression level of γH2AX, indicating DNA damage, and arrested HCT116 in G2/M phase, possibly through the ATR/CHK1/Cdc25C pathway. Thus, the novel ciprofloxacin hybrids could be exploited as potential leads for further investigation as novel anticancer medicines to fight colorectal carcinoma.

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.