Indole molecules as inhibitors of tubulin polymerization: potential new anticancer agents

Recent report on indoles as a privileged anti-viral scaffold in drug discovery

In recent years, viral infections such as COVID-19, Zika virus, Nipah virus, Ebola, Influenza, Monkeypox, and Dengue have substantially impacted global health. These outbreaks have led to heightened global health initiatives and collaborative efforts to address and mitigate these significant threats effectively. Thus, developing antiviral treatments and research in this field has become highly important. Heterocycles, particularly indole motifs, have been a valuable resource in drug discovery, as they can be used as treatments or inspire the synthesis of new potent candidates. Indole-containing drugs, such as enfuvirtide (T-20), arbidol, and delavirdine, have demonstrated significant efficacy in treating viral diseases. This review aims to comprehensively assess the latest research and developments in novel indoles as potential scaffolds for antiviral activity. We have compiled detailed information about indoles as potential antivirals by conducting a thorough literature survey from the past ten years. The review includes discussions on synthetic protocols, inhibitory concentrations, SAR study, and computational study. This review shall identify new antiviral indoles that may help to combat new viral threats in the future.

Pharmacological Evaluation of Bioisosterically Replaced and Triazole- Tethered Derivatives for Anticancer Therapy

Cancer has been the cause of the highest number of deaths in the human population despite the development and advancement in treatment therapies. The toxicity, drug resistance, and side effects of the current medicaments and therapies have left the void for more research and development. One of the possibilities to fill this void is by incorporating Triazole moieties within existing anticancer pharmacophores to develop new hybrid drugs with less toxicity and more potency. The placement of nitrogen in the triazole ring has endowed its characterization of being integrated with anticancer pharmacophores via bioisosteric replacement, click chemistry and organocatalyzed approaches. This review paper emphasizes the discussions from articles published from the early 2000s to the current 2020s about the triazole-based derivatives used in anticancer therapy, elaborating more on their chemical structures, target receptors or enzymes, mechanism of action, structure-activity relationships, different triazole-derived hybrid drugs under clinical and nonclinical trials, and recent advancements toward developing more potent and less toxic anticancer agents.

Ti-based MOFs with acetic acid pendings as an efficient catalyst in the preparation of new spiropyrans with biological moieties

The strategy of designing heterogeneous porous catalysts by a post-modification method is a smart strategy to increase the catalytic power of desired catalysts. Accordingly, in this report, metal-organic frameworks based on titanium with acetic acid pending were designed and synthesized via post-modification method. The structure of the target catalyst has been investigated using different techniques such as FT-IR, XRD, SEM, EDX, Mapping, and N2 adsorption/desorption (BET/the BJH) the correctness of its formation has been proven. The catalytic application of Ti-based MOFs functionalized with acetic acid was evaluated in the preparation of new spiropyrans, and the obtained results show that the catalytic performance is improved by this modification. The strategy of designing heterogeneous porous catalysts through post-modification methods presents a sophisticated approach to enhancing the catalytic efficacy of desired catalysts. In this context, our study focuses on the synthesis and characterization of metal-organic frameworks (MOFs) based on titanium, functionalized with acetic acid pendants, using a post-modification method. Various characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), mapping, and N2 adsorption/desorption (BET/BJH), were employed to investigate the structure and composition of the synthesized catalyst. These techniques collectively confirmed the successful formation and structural integrity of the target catalyst. The structure of the synthesized products was confirmed by melting point, 1H-NMR and 13C-NMR and FT-IR techniques. Examining the general process of catalyst synthesis and its catalytic application shows that the mentioned modification is very useful for catalytic purposes. The presented catalyst was used in synthesis of a wide range of biologically active spiropyrans with good yields. The simultaneous presence of several biologically active cores in the synthesized products will highlight the biological properties of these compounds. The present study offers a promising insight into the rational design, synthesis, and application of task-specific porous catalysts, particularly in the context of synthesizing biologically active candidate molecules.

Development of Benzimidazole-Substituted Spirocyclopropyl Oxindole Derivatives as Cytotoxic Agents: Tubulin Polymerization Inhibition and Apoptosis Inducing Studies

A series of spirocyclopropyl oxindoles with benzimidazole substitutions was synthesized and tested for their cytotoxicity against selected human cancer cells. Most of the molecules exhibited significant antiproliferative activity with compound 12 p being the most potent. It exhibited significant cytotoxicity against MCF-7 breast cancer cells (IC50 value 3.14±0.50 μM), evidenced by the decrease in viable cells and increased apoptotic features during phase contrast microscopy, such as AO/EB, DAPI and DCFDA staining studies. Compound 12 p also inhibited cell migration in wound healing assay. Anticancer potential of 12 p was proved by the inhibition of tubulin polymerization with IC50 of 5.64±0.15 μM. These results imply the potential of benzimidazole substituted spirocyclopropyl oxindoles, notably 12 p, as cytotoxic agent for the treatment of breast cancer.

K2CO3-mediated annulation of 1,3-acetonedicarboxylates with 2-fluoro-1-nitroarenes: synthesis of indoles

The K2CO3-mediated one-pot reaction of 1,3-acetonedicarboxylates with 2 equiv. of substituted 2-fluoro-1-nitrobenzenes has been developed to synthesize various 2,3-dicarboxylate indoles via a tandem annulation pathway. In the effective reaction, one carbon-carbon double bond, one carbon-carbon single bond and one carbon-nitrogen single bond are formed under open-vessel conditions. DFT calculations are used to rationalize the plausible mechanisms.

Design, synthesis, and anticancer evaluation of 1-benzo[1,3]dioxol-5-yl-3-N-fused heteroaryl indoles

A series of 1-benzo[1,3]dioxol-5-yl-indoles bearing 3-N-fused heteroaryl moieties have been designed based on literature reports of the activity of indoles against various cancer cell lines, synthesized via a Pd-catalyzed C-N cross-coupling, and evaluated for their anticancer activity against prostate (LNCaP), pancreatic (MIA PaCa-2), and acute lymphoblastic leukemia (CCRF-CEM) cancer cell lines. A detailed structure-activity relationship study culminated in the identification of 3-N-benzo[1,2,5]oxadiazole 17 and 3-N-2-methylquinoline 20, whose IC50 values ranged from 328 to 644 nM against CCRF-CEM and MIA PaCa-2. Further mechanistic studies revealed that 20 caused cell cycle arrest at the S phase and induced apoptosis in CCRF-CEM cancer cells. These 1-benzo[1,3]dioxol-5-yl-3-N-fused heteroaryl indoles may serve as a template for further optimization to afford more active analogs and develop a comprehensive understanding of the structure-activity relationships of indole anticancer molecules.

Novel cyanochalcones as potential anticancer agents: apoptosis, cell cycle arrest, DNA binding, and molecular docking studies

In the light of anticancer drug discovery and development, a new series of cyanochalcones incorporating indole moiety (5a-g) were efficiently synthesized and characterized by different spectral analysis. MTT assay was used to evaluate the antiproliferative activity of the synthesized compounds towards different cancer cells (Hela, MDA-MB-231, A375, and A549) in parallel with normal cells (HSF). Trimethoxy and diethoxy-containing derivatives (5d and 5e) displayed the most selective cytotoxic activities against cervical Hela cells with IC50 values of 8.29 and 11.82 µM, respectively, with great safety pattern toward normal HSF cells (Selectivity index: 21.3 and 13.9, respectively). Therefore, 5d and 5e were chosen to study their effects on apoptosis, cell cycle arrest, and migration of Hela cells using flow cytometric analysis and wound healing assay. They induced apoptosis and cell cycle arrest at the S phase and impaired migration of HeLa cells. Regarding their effects on the expression profile of crucial genes related to the potential anticancer activities, 5d and 5e remarkably upregulated caspase 3 and Beclin1 and downregulated cyclin A1, CDK2, CDH2, MMP9, and HIF1A using qRT-PCR and ELISA techniques. UV-Vis spectral measurement demonstrated the ability of 5d and 5e to bind CT-DNA efficiently with Kb values of 3.7 × 105 and 1 × 105 M-1, respectively. Moreover, in silico molecular docking was performed to assess the binding affinities of the compounds toward the active sites of Bcl2, CDK2, and DNA. Therefore, cyanochalcones 5d and 5e might be promising anticancer agents and could offer a scientific basis for intensive research into cancer chemotherapy.

Nitro-Enabled Atroposelective Dynamic Kinetic Resolution of 2-Arylindoles by Phase-Transfer Catalysis

This study presents the atroposelective alkylation of 2-arylindoles catalyzed by a substituted cinchonium salt as a phase-transfer catalyst. Under the optimized reaction conditions, various substrates are employed to yield products with high enantioselectivity. The presence of an ortho-nitro group at the aromatic ring is essential for high atroposelectivity, because it facilitates favorable interactions between the catalyst and substrate. The origin of the enantioselectivity reveals favorable π-π interactions for both enantiomers and unfavorable steric strains for undesired enantiomers.

Latest developments in coumarin-based anticancer agents: mechanism of action and structure-activity relationship studies

Many researchers around the world are working on the development of novel anticancer drugs with different mechanisms of action. In this case, coumarin is a highly promising pharmacophore for the development of novel anticancer drugs. Besides, the hybridization of this moiety with other anticancer pharmacophores has emerged as a potent breakthrough in the treatment of cancer to decrease its side effects and increase its efficiency. This review aims to provide a comprehensive overview of the recent development of coumarin derivatives and their application as novel anticancer drugs. Herein, we highlight and describe the largest number of research works reported in this field from 2015 to August 2023, along with their mechanisms of action and structure-activity relationship studies, making this review different from the other review articles published on this topic to date.

Indole-Based Compounds as Potential Drug Candidates for SARS-CoV-2

The COVID-19 pandemic has posed a significant threat to society in recent times, endangering human health, life, and economic well-being. The disease quickly spreads due to the highly infectious SARS-CoV-2 virus, which has undergone numerous mutations. Despite intense research efforts by the scientific community since its emergence in 2019, no effective therapeutics have been discovered yet. While some repurposed drugs have been used to control the global outbreak and save lives, none have proven universally effective, particularly for severely infected patients. Although the spread of the disease is generally under control, anti-SARS-CoV-2 agents are still needed to combat current and future infections. This study reviews some of the most promising repurposed drugs containing indolyl heterocycle, which is an essential scaffold of many alkaloids with diverse bio-properties in various biological fields. The study also discusses natural and synthetic indole-containing compounds with anti-SARS-CoV-2 properties and computer-aided drug design (in silico studies) for optimizing anti-SARS-CoV-2 hits/leads.

All-round catalytic and atroposelective strategy via dynamic kinetic resolution for N-/2-/3-arylindoles

As the complexity of organic molecules utilized by mankind increases, the phenomenon of atropisomerism is more frequently encountered. While a variety of well-established methods enable the control of a stereogenic center, a catalytic method for controlling a stereogenic axis in one substrate is typically unavailable for controlling axial chirality in other substrates with a similar structure. Herein, we report o-amidobiaryl as a flexible platform for chiral phosphoric acid-catalyzed atroposelective dynamic kinetic resolution. To demonstrate our strategy, three distinct types of arylindoles were utilized and reacted intermolecularly with ketomalonate in the presence of chiral phosphoric acid. An investigation of 46 substrates having an aromatic ring in different positions yields the desired products with excellent enantioselectivities. Computational investigation into the origin of enantioselectivity highlights the importance of the NH group. Given the biological significance of indoles, antiproliferative effects have been investigated; our scaffold exhibits good efficacy in this regard.

Natural and Synthetic Chalcones: Potential Impact on Breast Cancer

Chalcones are small molecules, naturally found in fruits and vegetables, and exhibit diverse pharmacological activities. They also possess anticancer activity against different tumors. They can be converted into numerous derivatives by modifying hydrogen moieties, enabling the exploration of their diverse anticancer potentials. The main aims are to provide valuable insights into the recent progress made in utilizing chalcones and their derivatives as agents against breast cancer while delivering their underlying molecular mechanisms of action. This review presents anticancer molecular mechanisms and signaling pathways modulated by chalcones. Furthermore, it helps in the understating of the precise mechanisms of action and specific molecular targets of chalcones and their synthetic derivatives for breast cancer treatment.

Synthesis and photobiological applications of naphthalimide-benzothiazole conjugates: cytotoxicity and topoisomerase IIα inhibition

Conjugates of naphthalimide, benzothiazole, and indole moieties are synthesized that show excellent cytotoxicity against A549 (lung), MCF7 (breast), and HeLa (cervix) cancer cell lines with IC₅₀ values in the range of 0.14–8.59 μM. Compounds 12 and 13 substituted with ethanolamine and propargyl groups reveal potent cytotoxicity towards A549 cancer cells with IC₅₀ values of 140 and 310 nM, respectively. These compounds are further evaluated as potent inhibitors of human type IIα topoisomerase. These conjugates also reveal strong interaction towards human serum albumin (HSA) with binding constant values of 1.75 × 10⁵ M⁻¹ and 1.88 × 10⁵ M⁻¹, respectively, and formation of the stable complex at ground state with static quenching. Docking studies also confirm the effective interactions between conjugates and topoisomerase.

Conjugates of naphthalimide, benzothiazole, and indole moieties are synthesized that show excellent cytotoxicity against A549 (lung), MCF7 (breast), and HeLa (cervix) cancer cell lines with IC₅₀ values in the range of 0.14–8.59 μM.

Synthesis of novel indole-isoxazole hybrids and evaluation of their cytotoxic activities on hepatocellular carcinoma cell lines

BACKGROUND

Liver cancer is predicted to be the sixth most diagnosed cancer globally and fourth leading cause of cancer deaths. In this study, a series of indole-3-isoxazole-5-carboxamide derivatives were designed, synthesized, and evaluated for their anticancer activities. The chemical structures of these of final compounds and intermediates were characterized by using IR, HRMS, 1H-NMR and 13C-NMR spectroscopy and element analysis.

RESULTS

The cytotoxic activity was performed against Huh7, MCF7 and HCT116 cancer cell lines using sulforhodamine B assay. Some compounds showed potent anticancer activities and three of them were chosen for further evaluation on liver cancer cell lines based on SRB assay and real-time cell growth tracking analysis. Compounds were shown to cause arrest in the G0/G1 phase in Huh7 cells and caused a significant decrease in CDK4 levels. A good correlation was obtained between the theoretical predictions of bioavailability using Molinspiration calculation, Lipinski's rule of five, and experimental verification. These investigations reveal that indole-isoxazole hybrid system have the potential for the development of novel anticancer agents.

CONCLUSIONS

This study has provided data that will form the basis of further studies that aim to optimize both the design and synthesis of novel compounds that have higher anticancer activities.

Construction of poly-N-heterocyclic scaffolds via the controlled reactivity of Cu-allenylidene intermediates

Controlling the sequence of the three consecutive reactive carbon centres of Cu-allenylidene remains a challenge. One of the impressive achievements in this area is the Cu-catalyzed annulation of 4-ethynyl benzoxazinanones, which are transformed into zwitterionic Cu-stabilized allenylidenes that are trapped by interceptors to provide the annulation products. In principle, the reaction proceeds via a preferential γ-attack, while annulation reactions via an α- or β-attack are infrequent. Herein, we describe a method for controlling the annulation mode, by the manipulation of a CF₃ or CH₃ substituent, to make it proceed via either a γ-attack or an α- or β-attack. The annulation of CF₃-substituted substrates with sulfamate-imines furnished densely functionalized N-heterocycles with excellent enantioselectivity via a cascade of an internal β-attack and an external α-attack. CH₃-variants were transformed into different heterocycles that possess a spiral skeleton, via a cascade of an internal β-attack and a hydride α-migration followed by a Diels-Alder reaction.

Box-copper catalyzed cascade asymmetric amidation for chiral exo-methylene aminoindoline derivatives

Enantioselective copper-catalyzed cascade inter- and intramolecular amidation was achieved between ethynyl benzoxazinanones and α-halohydroxamates in the presence of an indapybox ligand. The one-pot cascade transformation was triggered by the attack of hydroxamates to dipolar copper-allenylidene intermediates, followed by a nucleophilic annulation reaction. Thus, a series of exo-methylene 3-aminoindoline derivatives were obtained in good yields with high enantioselectivities under mild reaction conditions.

Synthesis of indole derivatives as prevalent moieties present in selected alkaloids

Indoles are a significant heterocyclic system in natural products and drugs. They are important types of molecules and natural products and play a main role in cell biology. The application of indole derivatives as biologically active compounds for the treatment of cancer cells, microbes, and different types of disorders in the human body has attracted increasing attention in recent years. Indoles, both natural and synthetic, show various biologically vital properties. Owing to the importance of this significant ring system, the investigation of novel methods of synthesis have attracted the attention of the chemical community. In this review, we aim to highlight the construction of indoles as a moiety in selected alkaloids.

Catalytic System-Controlled Divergent Reaction Strategies for the Construction of Diversified Spiropyrazolone Skeletons from Pyrazolidinones and Diazopyrazolones

A catalytic system-controlled divergent reaction strategy was here reported to construct four types of intriguing spiroheterocyclic skeletons from simple and readily available starting materials via a precise chemical bond activation/[n+1] annulation cascade. The tetraazaspiroheterocyclic and trizazspiroheterocyclic scaffolds could be independently constructed by a selective N-N bond activation/[n+1] annulation cascade, a C(sp² )-H activation/[4+1] annulation and a novel tandem C(sp² )-H/C(sp³ )-H bond activation/[4+1] annulation strategy, along with a broad scope of substrates, moderate to excellent yields and valuable transformations. More importantly, in these transformations, we are the first time to capture a N-N bond activation and a C(sp³ )-H bond activation of pyrazolidinones under different catalytic system.

Chalcone Derivatives: Role in Anticancer Therapy

Chalcones (1,3-diaryl-2-propen-1-ones) are precursors for flavonoids and isoflavonoids, which are common simple chemical scaffolds found in many naturally occurring compounds. Many chalcone derivatives were also prepared due to their convenient synthesis. Chalcones as weandhetic analogues have attracted much interest due to their broad biological activities with clinical potentials against various diseases, particularly for antitumor activity. The chalcone family has demonstrated potential in vitro and in vivo activity against cancers via multiple mechanisms, including cell cycle disruption, autophagy regulation, apoptosis induction, and immunomodulatory and inflammatory mediators. It represents a promising strategy to develop chalcones as novel anticancer agents. In addition, the combination of chalcones and other therapies is expected to be an effective way to improve anticancer therapeutic efficacy. However, despite the encouraging results for their response to cancers observed in clinical studies, a full description of toxicity is required for their clinical use as safe drugs for the treatment of cancer. In this review, we will summarize the recent advances of the chalcone family as potential anticancer agents and the mechanisms of action. Besides, future applications and scope of the chalcone family toward the treatment and prevention of cancer are brought out.

Cyclic Dipeptide: A Privileged Molecular Scaffold to Derive Structural Diversity and Functional Utility

Cyclic dipeptides (CDPs) are the simplest form of cyclic peptides with a wide range of applications from therapeutics to biomaterials. CDP is a versatile molecular platform endowed with unique properties such as conformational rigidity, intermolecular interactions, structural diversification through chemical synthesis, bioavailability and biocompatibility. A variety of natural products with the CDP core exhibit anticancer, antifungal, antibacterial, and antiviral activities. The inherent bioactivities have inspired the development of synthetic analogues as drug candidates and drug delivery systems. CDP plays a crucial role as conformation and molecular assembly directing core in the design of molecular receptors, peptidomimetics and fabrication of functional material architectures. In recent years, CDP has rapidly become a privileged scaffold for the design of advanced drug candidates, drug delivery agents, bioimaging, and biomaterials to mitigate numerous disease conditions. This review describes the structural diversification and multifarious biomedical applications of the CDP scaffold, discusses challenges, and provides future directions for the emerging field.

Hybridization of Imidazole with Various Heterocycles in Targeting Cancer: A Decade's Work

Cancer is the world‘s biggest global health concern. The prevalence and mortality rates of cancer remain high despite significant progress in cancer therapy. The search for more effective, as well as less toxic treatment methods for cancer, is at the focus of current studies. Approximately 24.6 million people are suffering from cancer across the world as per the world health organization (WHO). In the year 2020, approximately 10 million deaths were reported due to cancer which has emerged as the second leading cause of mortality across the globe. Anticancer medicines have played a pivotal role in the medication of different types of cancers; however, they are associated with several side effects and relevance of drug resistance which evoke an immediate need for designing of new anticancer agents with multitargeted effect. Imidazole is a heterocyclic compound privileged with considerable anticancer activities and some imidazole derivatives have already got approval to treat cancer. Many hybrid molecules are available that play an important role in the treatment of cancer like chalcone, pyrazole, purine, triazine etc., and their pharmacophore provide the anticancer drug with low drug resistance and high efficacy, with low chances of toxicity and side effects. This review provides various approaches for the drug development of new safe and efficient antitumor agents imidazole hybrids with other heterocyclic moieties. An attempt has been made to advancement of the anticancer potential of the derivatives and hybrids of imidazole having intact or condensed imidazole moiety in the last decade along with the structure‐activity relationship studies, and mechanism of action.

Structural Investigations of Aroylindole Derivatives through 3D-QSAR and Multiple Pharmacophore Modeling for the Search of Novel Colchicines Inhibitor

Background :

The ligand and structure based integrated strategies are being repeatedly and effectively employed for the precise search and design of novel ligands against various disease targets. Aroylindole derivative has a similar structural analogy as Combretastatin A-4, and exhibited potent anticancer activity on several cancer cell lines.

Objective:

To identify structural features of aroylindole derivatives through 3D-QSAR and multiple pharmacophore modelling for the search of novel colchicines inhibitor via virtual screening.

Method:

The present study utilizes ligand and structure based methodology for the establishment of structure activity correlation among trimethoxyaroylindole derivatives and the search of novel colchicines inhibitor via virtual screening. The 3D-QSAR studies were performed using Phase module and provided details of relationship between structure and biological activity. A single ligand based pharmacophore model was generated from Phase on compound 3 and compound 29 and three energetically optimized structure based pharmacophore models were generated from epharmacophore for co-crystallized ligand, compound 3 and compound 29 with protein PBD ID 1SA0, 5EYP and 5LYJ. These pharmacophoric features containing hit-like compounds were collected from commercially available ZINC database and screened using virtual screening workflow.

Results and Discussion:

The 3D-QSAR model studies with good PLSs statistics for factor four was characterized by the best prediction coefficient Q2 (0.8122), regression R2 (0.9405), SD (0.2581), F (102.7), P (1.56e-015), RMSE (0.402), Stability (0.5411) and Pearson-r (0.9397). The generated epharmacophores have GH scores over 0.5 and AUAC ≥ 0.7 indicated that all the pharmacophores were suitable for pharmacophore-based virtual screening. The virtual screened compounds ZINC12323179, ZINC01642724, and ZINC14238006 have showed similar structural alignment as co-crystallized ligand and showed the hydrogen bonding of ligand with ASN101, SER178, THR179, VAL238, CYS241 amino acid of protein.

Conclusion:

The study illustrates that the ligand and structure based pharmacophoric approach is beneficial for identification of structurally diverse hits, having better binding affinity on colchicines binding site as novel anticancer agents.

Recent advances in research of colchicine binding site inhibitors and their interaction modes with tubulin

Microtubules have been a concerning target of cancer chemotherapeutics for decades, and several tubulin-targeted agents, such as paclitaxel, vincristine and vinorelbine, have been approved. The colchicine binding site is one of the primary targets on microtubules and possesses advantages compared with other tubulin-targeted agents, such as inhibitors of tumor vessels and overcoming P-glycoprotein overexpression-mediated multidrug resistance. This study reviews and summarizes colchicine binding site inhibitors reported in recent years with structural studies via the crystal structures of complexes or computer simulations to discover new lead compounds. We are attempting to resolve the challenge of colchicine site agent research.

Indolyl-α-keto-1,3,4-oxadiazoles: Synthesis, anti-cell proliferation activity, and inhibition of tubulin polymerization

A series of novel indolyl-α-keto-1,3,4-oxadiazole derivatives have been synthesized by employing molecular iodine-mediated oxidative cyclization of acylhydrazones. In vitro anti cell proliferation activity of these derivatives against various cancer cells lines such as human lymphoblast (U937), leukemia (Jurkat & SB) and human breast (BT474) was investigated. Among the synthesized indolyl-α-keto-1,3,4-oxadiazoles 19a-p, only one compound (19e) exhibited significant antiproliferative activity against a panel of cell lines. The compound 19e with 3,4,5-trimethoxyphenyl motif, endowed strong cytotoxicity against U937, Jurkat, BT474 and SB cancer cells with IC₅₀ values of 7.1, 3.1, 4.1, and 0.8 µM, respectively. Molecular docking studies suggested a potential binding mode for 19e in the colchicine binding site of tubulin. When tested for in vitro tubulin polymerizaton, 19e inhibited tubulin polymezations (IC₅₀ = 10.66 µM) and induced apoptosis through caspase 3/7 activation. Further, the derivative 19e did not cause necrosis when measured using lactate dehydrogenase assay.

Discovery of novel N-benzylbenzamide derivatives as tubulin polymerization inhibitors with potent antitumor activities

A series of novel N-benzylbenzamide derivatives were designed and synthesized as tubulin polymerization inhibitors. Among fifty-one target compounds, compound 20b exhibited significant antiproliferative activities with IC₅₀ values ranging from 12 to 27 nM against several cancer cell lines, and possessed good plasma stability and satisfactory physicochemical properties. Mechanism studies demonstrated that 20b bound to the colchicine binding site and displayed potent anti-vascular activity. Notably, the corresponding disodium phosphate 20b-P exhibited an excellent safety profile with the LD₅₀ value of 599.7 mg/kg (i.v. injection), meanwhile, it significantly inhibited tumor growth and decreased microvessel density in liver cancer cell H22 allograft mouse model without obvious toxicity. Collectively, 20b and 20b-P are novel promising anti-tubulin agents with more druggable properties and deserve to be further investigated for cancer therapy.

Arenesulfonyl indole: new precursor for diversification of C-3 functionalized indoles

Arenesulfonyl indoles, bearing a good leaving group, are effective precursors for vinylogous imine intermediates which are generated in situ under basic conditions. This intermediate can readily react with other nucleophilic reagents to obtain C-3 substituted indole derivatives. In the last few years, a plethora of exciting synthetic applications of this substrate have been exploited. The stability of arylsulfonyl-containing substrates, mild reaction conditions, and the large variety of nucleophiles involved in these procedures are the key to their success in organic synthesis.

Pyrazoline Hybrids as Promising Anticancer Agents: An Up-to-Date Overview

Pyrazolines are five-membered heterocycles possessing two adjacent nitrogens. They have attracted significant attention from organic and medicinal chemists due to their potent biological activities and the numerous possibilities for structural diversification. In the last decade, they have been intensively studied as targets for potential anticancer therapeutics, producing a steady yearly rise in the number of published research articles. Many pyrazoline derivatives have shown remarkable cytotoxic activities in the form of heterocyclic or non-heterocyclic based hybrids, such as with coumarins, triazoles, and steroids. The enormous amount of related literature in the last 5 years prompted us to collect all these published data from screening against cancer cell lines, or protein targets like EGFR and structure activity relationship studies. Therefore, in the present review, a comprehensive account of the compounds containing the pyrazoline nucleus will be provided. The chemical groups and the structural modifications responsible for the activity will be highlighted. Moreover, emphasis will be given on recent examples from the literature and on the work of research groups that have played a key role in the development of this field.

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.

Blue LED Mediated Intramolecular C-H Functionalization and Cyclopropanation of Tryptamines: Synthesis of Azepino[4, 5-b]indoles and Natural Product Inspired Polycyclic Indoles

We report a novel blue LED mediated intramolecular C-H functionalization of tryptamine derivatives to generate azepino[4, 5-b]indoles (4) in moderate to good yields. By altering the substitution at the tryptamine nitrogen, intramolecular cyclopropanation is achieved in high yields under the same reactions condition to provide natural product inspired polycyclic indoles (6), which are further transformed to spiropiperidino (5 and 8) indoles in decent yields. The mechanism of formation of the compounds was investigated through DFT studies.

Synthesis and Evaluation of Antimicrobial Activities of Novel N-Substituted Indole Derivatives

Indole motifs are one of the most significant scaffolds in the discovery of new drugs. We have described a synthesis of new N-substituted indole derivatives (1-3), and their in vitro antimicrobial activities were investigated. The synthesis of titled compounds has been demonstrated by utilizing commercially available starting materials. The antibacterial and antifungal activities were performed using new strains of bacteria Staphylococcus aureus, Escherichia coli, and Candida albicans using the disc diffusion method. Notably, the compound 4-(1-(2-(1H-indol-1-yl) ethoxy) pentyl)-N,N-dimethyl aniline (1) was found to be most potent than the other analogues (2 and 3), which has shown higher inhibition than the standard drug chloramphenicol.

Colchicine-Binding Site Inhibitors from Chemistry to Clinic: A Review

It is over 50 years since the discovery of microtubules, and they have become one of the most important drug targets for anti-cancer therapies. Microtubules are predominantly composed of the protein tubulin, which contains a number of different binding sites for small-molecule drugs. There is continued interest in drug development for compounds targeting the colchicine-binding site of tubulin, termed colchicine-binding site inhibitors (CBSIs). This review highlights CBSIs discovered through diverse sources: from natural compounds, rational design, serendipitously and via high-throughput screening. We provide an update on CBSIs reported in the past three years and discuss the clinical status of CBSIs. It is likely that efforts will continue to develop CBSIs for a diverse set of cancers, and this review provides a timely update on recent developments.

Rhodium(iii)-catalyzed C–H annulation of 2-acetyl-1-arylhydrazines with sulfoxonium ylides: synthesis of 2-arylindoles

An efficient Rh(iii)-catalyzed synthesis of 2-arylindole derivatives via intermolecular C–H annulation of arylhydrazines with sulfoxonium ylides was accomplished. A variety of 2-acetyl-1-arylhydrazines with sulfoxonium ylides were converted into 2-arylindoles in satisfactory yields. Excellent selectivity and good functional group tolerance of this transformation were also observed.

Rh(iii)-catalyzed intermolecular C–H annulation of arylhydrazines with sulfoxonium ylides for synthesis of 2-arylindole derivatives was well established.

1,2,3-Triazole-containing hybrids as potential anticancer agents: Current developments, action mechanisms and structure-activity relationships

Anticancer agents are critical for the cancer treatment, but side effects and the drug resistance associated with the currently used anticancer agents create an urgent need to explore novel drugs with low side effects and high efficacy. 1,2,3-Triazole is privileged building block in the discovery of new anticancer agents, and some of its derivatives have already been applied in clinics or under clinical trials for fighting against cancers. Hybrid molecules occupy an important position in cancer control, and hybridization of 1,2,3-triazole framework with other anticancer pharmacophores may provide valuable therapeutic intervention for the treatment of cancer, especially drug-resistant cancer. This review emphasizes the recent advances in 1,2,3-triazole-containing hybrids with anticancer potential, covering articles published between 2015 and 2019, and the structure-activity relationships, together with mechanisms of action are also discussed.

Structural insights into the design of indole derivatives as tubulin polymerization inhibitors

Microtubules are composed of αβ-tubulin heterodimers, and drugs that interfere with microtubule dynamics are used widely in cancer chemotherapy. Small synthetic molecules with an indole nucleus as a core structure have been identified as microtubule inhibitors and recognized as anticancer agents. However, structural information for the interactions between indole derivatives and tubulin is sparse. Here, we present the 2.55 Å crystal structure of tubulin in complex with the indole derivative D64131. We compare the binding modes of D64131, colchicine, and five other indole derivatives to tubulin. These results reveal the interactions between the indole derivatives and tubulin, explain previous results of structure-activity-relationship (SAR) studies and, thus, provide insights into the development of new indole derivatives targeting the colchicine binding site.

Coumarin-containing hybrids and their anticancer activities

Cancer is the second leading cause of death worldwide, and it results in around 9 million deaths annually. The anticancer agents play an intriguing role in the treatment of cancers, while the severe anticancer scenario and the emergence of drug-resistant especially multidrug-resistant cancers create a huge demand for novel anticancer drugs with different mechanisms of action. The coumarin scaffold is ubiquitous in nature and is a highly privileged motif for the development of novel drugs due to its biodiversity and versatility. Coumarin derivatives can exert diverse antiproliferative mechanisms, and some of them such as Irosustat are under clinical trials for the treatment of various cancers, revealing their potential as putative anticancer drugs. Hybridization of coumarin moiety with other anticancer pharmacophores is a promising strategy to reduce side effects, overcome the drug resistance, and may provide valuable therapeutic intervention for the treatment of cancers. Thus, coumarin-containing hybrids occupy an important position in the development of novel anticancer agents. This review aims to summarize the recent advances made towards the development of coumarin-containing hybrids as potential anticancer agents, covering articles published between 2015 and 2019, and the structure-activity relationship together with mechanisms of action are also discussed.