Design, synthesis, and biological evaluation of novel pyridine-bridged analogues of combretastatin-A4 as anticancer agents

Copper-Catalyzed Four-Component Domino Cyclization for the Synthesis of 2-Methylpyridines

A convenient protocol for synthesis of unsymmetrical 2-methylpyridines from acetyl ketones, ammonium salts and tertiary amines is described. The construction of two C-C bonds and two C-N bonds via [2 + 2 + 1 + 1] four-component domino cyclization reaction is achieved using Cu(OTf) as catalyst in one pot. This cyclization reaction shows good selectivity and produces multisubstituted 2-methylpyridine derivatives in good yields with various functional groups.

The Structure-Antiproliferative Activity Relationship of Pyridine Derivatives

Pyridine, a compound with a heterocyclic structure, is a key player in medicinal chemistry and drug design. It is widely used as a framework for the design of biologically active molecules and is the second most common heterocycle in FDA-approved drugs. Pyridine is known for its diverse biological activity, including antituberculosis, antitumor, anticoagulant, antiviral, antimalarial, antileishmania, anti-inflammatory, anti-Alzheimer's, antitrypanosomal, antimalarial, vasodilatory, antioxidant, antimicrobial, and antiproliferative effects. This review, spanning from 2022 to 2012, involved the meticulous identification of pyridine derivatives with antiproliferative activity, as indicated by their minimum inhibitory concentration values (IC50) against various cancerous cell lines. The aim was to determine the most favorable structural characteristics for their antiproliferative activity. Using computer programs, we constructed and calculated the molecular descriptors and analyzed the electrostatic potential maps of the selected pyridine derivatives. The study found that the presence and positions of the -OMe, -OH, -C=O, and NH2 groups in the pyridine derivatives enhanced their antiproliferative activity over the cancerous cellular lines studied. Conversely, pyridine derivatives with halogen atoms or bulky groups in their structures exhibited lower antiproliferative activity.

Structure-based approaches for the design of 6-aryl-1-(3,4,5-trimethoxyphenyl)-1H-benzo[d][1,2,3]triazoles as tubulin polymerization inhibitors

The colchicine binding site on tubulin has been widely acknowledged as an attractive target for anticancer drug exploitation. Here, we reported the structural optimization of the lead compound 4, which was proved in our previous work as a colchicine binding site inhibitor (CBSI). Based on docking researches for the active binding conformation of compound 4, a series of novel 6-aryl-1-(3,4,5-trimethoxyphenyl)-1H-benzo[d][1,2,3]triazole derivatives (9a-9x) were developed by replacing a CH group in the 1H-benzo[d]imidazole skeleton of compound 4 with a nitrogen atom as a hydrogen bond acceptor. Among them, compound 9a showed the strongest antiproliferative activity with IC50 values ranging from 14 to 45 nM against three human cancer cell lines (MCF-7, SGC-7901 and A549), lower than that of compound 4. Mechanistic studies indicated that compound 9a could inhibit tubulin polymerization, destroy the microtubule skeleton, block the cell cycle in G2/M phase, induce cancer cell apoptosis, prevent cancer cell migration and colony formation. Moreover, compound 9a significantly inhibited tumor growth in vivo without observable toxicity in the mice 4T1 xenograft tumor model. In conclusion, this report shows a successful case of the structure-based design approach of a potent tubulin polymerization inhibitor for cancer treatment.

Design, synthesis and mechanistic study of new dual targeting HDAC/tubulin inhibitors

Aim: The purpose of this work is to create and synthesize a new class of chemicals: 3-cyano-2-substituted pyridine compounds with expected multitarget inhibition of histone deacetylase (HDAC) and tubulin. Materials & methods: The target compounds (3a-c, 4a-c and 5a-c) were synthesized utilizing 6-(4-methoxyphenyl)-2-oxo-4-(3,4,5-trimethoxyphenyl)-3-cyanopyridine, with various linkers and zinc-binding groups (ZBGs). Results: Most of the tested compounds showed promising growth inhibition, and hydroxamic acid-containing hybrids possessed higher HDAC inhibition than other ZBGs. Compound 4b possessed the highest potency; however, it showed the most tubulin polymerization inhibition. Docking studies displayed good binding into HDAC1 and six pockets and tubulin polymerization protein. Conclusion: Compound 4b could be considered a good antitumor candidate to go further into in vivo and clinical studies.

PM534, an Optimized Target-Protein Interaction Strategy through the Colchicine Site of Tubulin

Targeting microtubules is the most effective wide-spectrum pharmacological strategy in antitumoral chemotherapy, and current research focuses on reducing main drawbacks: neurotoxicity and resistance. PM534 is a novel synthetic compound derived from the Structure-Activity-Relationship study on the natural molecule PM742, isolated from the sponge of the order Lithistida, family Theonellidae, genus Discodermia (du Bocage 1869). PM534 targets the entire colchicine binding domain of tubulin, covering four of the five centers of the pharmacophore model. Its nanomolar affinity and high retention time modulate a strikingly high antitumor activity that efficiently overrides two resistance mechanisms in cells (detoxification pumps and tubulin βIII isotype overexpression). Furthermore, PM534 induces significant inhibition of tumor growth in mouse xenograft models of human non-small cell lung cancer. Our results present PM534, a highly effective new compound in the preclinical evaluation that is currently in its first human Phase I clinical trial.

Exploring the therapeutic potential of focal adhesion kinase inhibition in overcoming chemoresistance in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is among the leading causes of cancer-related deaths worldwide. Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase often overexpressed in PDAC. FAK has been linked to cell migration, survival, proliferation, angiogenesis and adhesion. This review first highlights the chemoresistant nature of PDAC. Second, the role of FAK in PDAC cancer progression and resistance is carefully described. Additionally, it discusses recent developments of FAK inhibitors as valuable drugs in the treatment of PDAC, with a focus on diamine-substituted-2,4-pyrimidine-based compounds, which represent the most potent class of FAK inhibitors in clinical trials for the treatment of PDAC disease. To conclude, relevant computational studies performed on FAK inhibitors are reported to highlight the key structural features required for interaction with the protein, with the aim of optimizing this novel targeted therapy.

Clickable bisreactive small gold nanoclusters for preparing multifunctionalized nanomaterials: application to photouncaging of an anticancer molecule

In this study, we successfully synthesized a small-sized gold nanocluster (2 nm) coated with homogeneous tripeptides bearing azido and amino groups that enable facile multifunctionalizations. Using sodium phenoxide to reduce tetrachloroauric(iii) acid in the presence of the cysteine-containing tripeptide, we efficiently prepared the gold nanoclusters without damaging the azido group. We then utilized this clickable bisreactive nanocluster as a versatile platform for synthesizing multifunctionalized gold nanomaterials. The resulting nanoclusters were conjugated with an anticancer compound connected to an indolizine moiety for photoinduced uncaging, a photodynamic therapy agent acting as a photosensitizer for uncaging, and a cyclic RGD peptide. The cytotoxicity of the multifunctionalized gold nanoclusters was demonstrated through red light irradiation of human lung cancer-derived A549 cells treated with the synthesized nanomaterials. The significant cytotoxicity exhibited by the cells underscores the potential utility of this method in advanced cancer therapies.

Synthesis and Selective Anticancer Activity Evaluation of 2-phenylacrylonitrile Derivatives as Tubulin Inhibitors

OBJECTIVE

This study aimed at synthesizing 13 series of novel derivatives with 2-phenylacrylonitrile, evaluating antitumor activity both in vivo and in vitro, and obtaining novel tubulin inhibitors.

METHOD

The 13 series of 2-phenylacrylonitrile derivatives were synthesized by Knoevenagel condensation and the anti-proliferative activities were determined by MTT assay. The cell cycle and apoptosis were analyzed by flow cytometer. Quantitative cell migration was performed using 24-well Boyden chambers. The proteins were detected by western blotting. in vitro kinetics of microtubule assembly was measured using ELISA kit for Human β-tubulin (TUBB). Molecular docking was done by Discovery Studio (DS) 2017 Client online tool.

RESULTS

Among the derivatives, compound 1g2a possessed strong inhibitory activity against HCT116 (IC50 = 5.9 nM) and BEL-7402 (IC50 = 7.8 nM) cells. Compound 1g2a exhibited better selective antiproliferative activities and specificities than all the positive control drugs, including taxol. Compound 1g2a inhibited proliferation of HCT116 and BEL-7402 cells by arresting them in the G2/M phase of the cell cycle, inhibited the migration of HCT116 and BEL-7402 cells and the formation of cell colonies. Compound 1g2a showed excellent tubulin polymerization inhibitory activity on HCT116 and BEL-7402 cells. The results of molecular docking analyses showed that 1g2a may inhibit tubulin to exert anticancer effects.

CONCLUSION

Compound 1g2a shows outstanding antitumor activity both in vivo and in vitro and has the potential to be further developed into a highly effective antitumor agent with little toxicity to normal tissues.

Experimental Design of D-α-tocopherol polyethylene glycol 1000 succinate Stabilized Bile Salt Based Nano-vesicles for Improved Cytotoxicity and Bioavailability of Colchicine Binding Site Inhibitor Candidates: In Vitro, In silico, and Pharmacokinetic Studies

Nowadays, conventional anticancer therapy suffers many pitfalls, including drastic side effects and limited therapeutic efficacy resulting from diminished oral bioavailability. So, in an attempt to enhance their poor solubility and oral bioavailability along with the cytotoxic activity, the developed lead compounds (C1 and C2) were loaded in D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) modified vesicles adopting thin film hydration technique. The formulations of the aforementioned candidates (F1 and F2, respectively) were elected as the optimum formula with desirability values of 0.701 and 0.618, respectively. Furthermore, an outstanding enhancement in the drug's cytotoxic activity against different cancer cell lines (MCF-7, HepG-2, MDA-MB-321, A375, and MGC-803) after being included in the nano-TPGS-modified optimum formula was noticed relative to the unformulated compounds. The formula F1 showed the best cytotoxic activities against HepG-2 with an IC₅₀ = 3 µM. Furthermore, regarding MCF-7, F1 was shown to be the most potent and protective among all the tested formulations with an IC₅₀ = 6 µM. Besides, F1 exerted the best caspase 3/7 activity stimulation (around a 5-folds increase) compared to control in the MCF-7 cell line. Notably, it was disclosedthat both C1 and C2 induced cell cycle arrest at the resting S growth phase. Moreover, C1 and C2 decreased tubulin concentrations by approximately 2-folds and 6-folds, respectively. Meanwhile, the conducted molecular docking studies ensure the eligible binding affinities of the assessed compounds. Besides, MD simulations were performed for 1000 ns to confirm the docking results and study the exact behavior of the target candidates (C1 and C2) toward the CBS.

Lignin-Based Catalysts for C-C Bond-Forming Reactions

Carbon-carbon (C-C) bond formation is the key reaction in organic synthesis to construct the carbon framework of organic molecules. The continuous shift of science and technology toward eco-friendly and sustainable resources and processes has stimulated the development of catalytic processes for C-C bond formation based on the use of renewable resources. In this context, and among other biopolymer-based materials, lignin has attracted scientific attention in the field of catalysis during the last decade, either through its acid form or as a support for metal ions and metal nanoparticles that drive the catalytic activity. Its heterogeneous nature, as well as its facile preparation and low cost, provide competitive advantages over other homogeneous catalysts. In this review, we have summarized a variety of C-C formation reactions, such as condensations, Michael additions of indoles, and Pd-mediated cross-coupling reactions that were successfully carried out in the presence of lignin-based catalysts. These examples also involve the successful recovery and reuse of the catalyst after the reaction.

Nitrogen Containing Heterocycles as Anticancer Agents: A Medicinal Chemistry Perspective

Cancer is one of the major healthcare challenges across the globe. Several anticancer drugs are available on the market but they either lack specificity or have poor safety, severe side effects, and suffer from resistance. So, there is a dire need to develop safer and target-specific anticancer drugs. More than 85% of all physiologically active pharmaceuticals are heterocycles or contain at least one heteroatom. Nitrogen heterocycles constituting the most common heterocyclic framework. In this study, we have compiled the FDA approved heterocyclic drugs with nitrogen atoms and their pharmacological properties. Moreover, we have reported nitrogen containing heterocycles, including pyrimidine, quinolone, carbazole, pyridine, imidazole, benzimidazole, triazole, β-lactam, indole, pyrazole, quinazoline, quinoxaline, isatin, pyrrolo-benzodiazepines, and pyrido[2,3-d]pyrimidines, which are used in the treatment of different types of cancer, concurrently covering the biochemical mechanisms of action and cellular targets.

Synthesis and bioactive evaluation of N-((1-methyl-1H-indol-3-yl)methyl)-N-(3,4,5-trimethoxyphenyl)acetamide derivatives as agents for inhibiting tubulin polymerization

Based on the inhibitory effect of CA-4 analogues and indoles on tubulin polymerization, we designed and synthesized a series of N-((1-methyl-1H-indol-3-yl)methyl)-2-(1H-pyrazol-1-yl or triazolyl)-N-(3,4,5-trimethoxyphenyl)acetamides. All the synthesized compounds were evaluated for their in vitro antiproliferative activities against HeLa, MCF-7 and HT-29 cancer cell lines, and some of the target compounds demonstrated effective activities towards the three tumour cell lines. Among them, compound 7d exhibited the most potent activities against HeLa (IC50 = 0.52 μM), MCF-7 (IC50 = 0.34 μM) and HT-29 (IC50 = 0.86 μM). Mechanistic studies revealed that compound 7d induced cell apoptosis in a dose-dependent manner, arrested the cells in the G2/M phase and inhibited polymerization of tubulin via a consistent way with colchicine. Therefore, 7d is a potential agent for the further development of tubulin polymerization inhibitors.

Synthesis of Palladium-Catalysed C-C Bond Forming 5-Chloro Quinolines via Suzuki-Miyaura Coupling; Anti-Pancreatic Cancer Screening on PANC-1 Cell Lines

Pancreatic cancer is the most severe among other cancers due to its late detection and less chance of survivability. Heterocycles are proven ring systems in the treatment of various cancers and this is due to the presence of two biodynamic molecules combined, which have a greater synergistic efficacy in many anticancer drugs. Quinoline and pyridine ring systems are brought together to obtain greater potency and this is achieved by coupling both using Pd-catalyst, and in the present investigation, Suzuki-Miyaura coupling (SMC) reactions are adopted to generate potent molecular entities. Pancreatic cancer is difficult to treat due to overexpression of the VEGFR2 protein. VEGFR2 is targeted to design the molecules of quinoline-coupled pyridine moieties and is docked to evaluate the protein-ligand interaction at the binding site. The binding affinity of conjugates revealed the potency and capability of ligands to inhibit the VEGFR2 pathway. The in-silico ADMET properties determined their inherent pharmacokinetic feasibility. The synthesized conjugates have been evaluated by MTT assay against the human pancreatic cancer cell lines (PANC-1). Among the series, compounds 5d, 5e, and 5h exhibited a greater inhibitory activity against the cell lines with an IC₅₀ value of 82.32±1.38, 54.74±1.18 and 80.35±1.68 μM. In the present exploration, 5e exhibited greater inhibitory activity and it could be a promising lead for the development of new chemotherapeutics against pancreatic cancer.

Exploring the Gallic and Cinnamic Acids Chimeric Derivatives as Anticancer Agents over HeLa Cell Line: An in silico and in vitro Study

Cervical cancer is one of the most aggressive and important cancer types in the female population, due to its low survival rate. Actually, the search for new bioactive compounds, like gallic and cinnamic acid, is one of the most employed options to finding a treatment. In the present study, 134 phenolic compounds with cytotoxic activity over HeLa cell line were used to generate a descriptive ( R 2 ${{R}^{2}}$ =0.76) and predictive ( Q 2 ${{Q}^{2}}$ =0.69 and Q e x t 2 ${{Q}_{{\rm e}{\rm x}{\rm t}}^{2}}$ =0.62) QSAR model. Structural, electronic, steric, and hydrophobic features are represented as different molecular descriptors in our QSAR model. From this model, nine gallate-cinnamate ester derivatives (N1-N9) were designed and synthesized. Furthermore, in vitro cytotoxic activity was evaluated against HeLa and non-tumorigenic cells. Derivatives N6, N5, N1, and N9 were the most active molecules with IC_50ExpHeLa values from 7.26 to 11.95 μM. Finally, the binding of the synthesized compounds to the colchicine binding site on tubulin was evaluated by molecular docking as a possible action mechanism. N1, N5 and N6 can be considered as templates for the design of new cervical anticancer compounds.

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.

Design and synthesis of new trimethoxylphenyl-linked combretastatin analogues loaded on diamond nanoparticles as a panel for ameliorated solubility and antiproliferative activity

A new series of vinyl amide-, imidazolone-, and triazinone-linked combretastatin A-4 analogues have been designed and synthesised. These compounds have been evaluated for their cytotoxic activity against MDA-MB-231 breast cancer cells. The triazinone-linked combretastatin analogues (6 and 12) exhibited the most potent cytotoxic activity, in sub-micromolar concentration compared with combretastatin A-4 as a reference standard. The results of β-tubulin polymerisation inhibition assay appear to correlate well with the ability to inhibit β-tubulin polymerisation. Additionally, these compounds were subjected to biological assays relating to cell cycle aspects and apoptosis induction. In addition, the most potent compound 6 was loaded on PEG-PCL modified diamond nanoparticles (PEG-PCL-NDs) and F4 was picked as the optimum formula. F4 exhibited enhanced solubility and release over the drug suspension. In the comparative cytotoxic activity, PEG-PCL modified F4 was capable of diminishing the IC50 by around 2.89 times for nude F4, while by 3.48 times relative to non-formulated compound 6.

Design, synthesis and biological evaluation of novel diarylpyridine derivatives as tubulin polymerisation inhibitors

A set of novel diarylpyridines as anti-tubulin agents were designed, synthesised using a rigid pyridine as a linker to fix the cis-orientation of ring-A and ring-B. All of the target compounds were evaluated for their in vitro antiproliferative activities. Among them, 10t showed remarkable antiproliferative activities against three cancer cell lines (HeLa, MCF-7 and SGC-7901) in sub-micromolar concentrations. Consistent with its potent antiproliferative activity, 10t also displayed potent anti-tubulin activity. Cellular mechanism investigation elucidated 10t disrupted the cellular microtubule structure, arrested cell cycle at G2/M phase and induces apoptosis. Molecular modelling studies showed that 10t could bind to the colchicine binding site on microtubules. These results provide motivation and further guidance for the development of new CA-4 analogues.

[5]-Helistatins: Tubulin-Binding Helicenes with Antimitotic Activity

Helicenes are high interest synthetic targets with unique conjugated helical structures that have found important technological applications. Despite this interest, helicenes have had limited impact in chemical biology. Herein, we disclose a first-in-class antimitotic helicene, helistatin 1 (HA-1), where the helicene scaffold acts as a structural mimic of colchicine, a known antimitotic drug. The synthesis proceeds via sequential Pd-catalyzed coupling reactions and a π-Lewis acid cycloisomerization mediated by PtCl2. HA-1 was found to block microtubule polymerization in both cell-free and live cell assays. Not only does this demonstrate the feasibility of using helicenes as bioactive scaffolds against protein targets, but also suggests wider potential for the use of helicenes as isosteres of biaryls or cis-stilbenes-themselves common drug and natural product scaffolds. Overall, this study further supports future opportunities for helicenes for a range of chemical biological applications.

Discovery of polymethoxyphenyl-pyridines bearing amino side chains as tubulin colchicine-binding site inhibitors

Nineteen TH03 analogues were designed and synthesized as tubulin colchicine-binding site inhibitors with potent antiproliferative activities. Among these compounds, 3,5-dimethoxyphenylpyridines 8j bearing a 4-methoxybenzyl aniline side-chain displayed the best antiproliferative activities against glioma (U87MG and U251). In addition, the trimethoxyphenylpyridine 8o bearing a 4-methyl-N-methyl aniline side-chain showed the best antiproliferative activities against colon carcinoma and lung cancer with the lowest IC₅₀ value (0.09 µM < IC₅₀ < 0.86 µM). Compared with CA-4, Compounds 8j and 8o displayed lower cytotoxicities toward normal cells but higher antiproliferative activities against RKO (IC₅₀ = 0.15 µM and 0.09 µM respectively), NCI-H1299 (IC₅₀ = 0.73 µM and 0.14 µM respectively), and A549 cells (IC₅₀ = 0.86 µM and 0.37 µM respectively). Further investigations revealed that 8o shows higher tubulin polymerization inhibitory activity (IC₅₀ = 3.1 ± 0.5 µM) than colchicine (IC₅₀ = 8.6 ± 0.2 µM), and induced cell cycle arrest at the G2/M phase and cellular apoptosis through disrupting the microtubule network.

Recent Advances in Synthesis of Multiply Arylated/Alkylated Pyridines

Multiply aryl/alkyl-substituted pyridines are some of the untapped synthetic targets because of the challenge in regioselectively introducing less polar aryl/alkyl groups at the desired positions in the pyridine framework. Interestingly, the importance of this family of compounds has increased annually, particularly in biological and materials engineering applications. The syntheses of such pyridines have been extensively reported, but there is a lack of comprehensive review articles. Hence, this review discusses recent advances by grouping reaction patterns that generally deliver tri-, tetra-, and penta-aryl/alkyl pyridines.

Synthesis and characterization of novel combretastatin analogues of 1,1-diaryl vinyl sulfones, with antiproliferative potential via in-silico and in-vitro studies

Novel 1,1-diaryl vinyl-sulfones analogues of combretastatin CA-4 were synthesized via Suzuki-Miyaura coupling method and screened for in-vitro antiproliferative activity against four human cancer cell lines: MDA-MB 231(breast cancer), HeLa (cervical cancer), A549 (lung cancer), and IMR-32 (neuroblast cancer), along with a normal cell line HEK-293 (human embryonic kidney cell) by employing 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. The compounds synthesised had better cytotoxicity against the A549 and IMR-32 cell lines compared to HeLa and MDA-MB-231 cell lines. The synthesized compounds also showed significant activity on MDA-MB-231 cancer cell line with IC₅₀ of 9.85-23.94 µM, and on HeLa cancer cell line with IC₅₀ of 8.39-11.70 µM relative to doxorubicin having IC₅₀ values 0.89 and 1.68 µM respectively for MDA-MB-231 and HeLa cell lines. All the synthesized compounds were not toxic to the growth of normal cells, HEK-293. They appear to have a higher binding affinity for the target protein, tubulin, PDB ID = 5LYJ (beta chain), relative to the reference compounds, CA4 (- 7.1 kcal/mol) and doxorubicin (- 7.2 kcal/mol) except for 4E, 4M, 4N and 4O. The high binding affinity for beta-tubulin did not translate into enhanced cytotoxicity but the compounds (4G, 4I, 4J, 4M, 4N, and 4R, all having halogen substituents) that have a higher cell permeability (as predicted in-silico) demonstrated an optimum cytotoxicity against the tested cell lines in an almost uniform manner for all tested cell lines. The in-silico study provided insight into the role that cell permeability plays in enhancing the cytotoxicity of this class of compounds and as potential antiproliferative agents.

Recent Trends in Tubulin-Binding Combretastatin A-4 Analogs for Anticancer Drug Development

Although significant progress over several decades has been evidenced in cancer therapy, there still remains a need for the development of novel and effective therapeutic strategies to treat several relapsed and intractable cancers. In this regard, tubulin protein has become one of the efficient and major targets for anticancer drug discovery. Considering the antimitotic ability, several tubulin inhibitors have been developed to act against various cancers. Among various tubulin inhibitors available, combretastatin-A4 (CA-4), a naturally occurring lead molecule, offers exceptional cytotoxicity (including the drug-resistant cell lines) and antivascular effects. Although CA-4 offers exceptional therapeutic efficacy, several new advancements have been proposed, such as the structural modification via A and B rings, as well as cis-olefinic bridging, which provide highly efficient analogs with improved tubulin-binding efficiency to meet the anticancer drug development requirements. This review systematically emphasizes the recent trends and latest developments in the anticancer drug design & discovery, using CA-4 analogs as the tubulin inhibiting agents, highlighting their structure-activity relationships (SAR) and resultant pharmacological efficacies.

Recent Advances in the Development of Pyrazolopyridines as Anticancer Agents

Cancer, especially malignant tumor, is a serious threat to people's life and health. It is recognized as an enormous challenge in the 21st century. Continuous efforts are needed to overcome this problem. Pyrazolopyridine nucleus, similar in structure to purine, shows a variety of biological activities, which is mainly attributed to the antagonistic nature towards the natural purines in many biological processes. This has aroused enormous attention for many researchers. At present, a large number of new chemical entities containing pyrazolopyridine nucleus have been found as anticancer agents. In this review we summarize novel pyrazolopyridine-containing derivatives with biological activities. Furthermore, we outline the relationships between the structures of variously modified pyrazolopyridines and their anticancer activity.

Design, synthesis and bioevaluation of 2,7-diaryl-pyrazolo[1,5-a]pyrimidines as tubulin polymerization inhibitors

Two series of 2,7-diaryl-pyrazolo[1,5-a]pyrimidines as tubulin polymerization inhibitors were designed to restrict bioactive configuration of (E,Z)-vinylogous CA-4. All of the target compounds were synthesized and then evaluated for their in vitro antiproliferative activities against three cancer cell lines (MCF-7, SGC-7901 and A549). Among them, 6d exhibited the most potent antiproliferative activity against the MCF-7 with IC₅₀ value of 0.047 μM. Moreover, 6d significantly inhibited tubulin polymerization, disrupted microtubule networks, arrested cell cycle at G2/M phase, induced apoptosis and hindered cancer cell migration. Colchicine competition assay and molecular docking studies suggested that 6d could interact with tubulin by binding to the colchicine site.

Endogenous reactive oxygen species burst induced and spatiotemporally controlled multiple drug release by traceable nanoparticles for enhancing antitumor efficacy

Reactive oxygen species (ROS) are not only used as a therapeutic reagent in chemodynamic therapy (CDT), to stimulate the release of antineoplastic drugs, they can also be used to achieve a combined effect of CDT and chemotherapy to enhance anticancer effects. Herein, we synthesized a pH-responsive prodrug (PEG2k-NH-N-DOX), ROS-responsive prodrug (PEG2k-S-S-CPT-ROS), organic CDT agents (TPP-PEG2k-LND, TPP-PEG2k-TOS), and T1-enhanced magnetic resonance imaging contrast agents (Gd-DTPA-N16-16), and used them to encapsulate combrestatinA4 (CA4) to prepare traceable pH/ROS dual-responsive multifunctional nanoparticles (TLDCAG NPs) with endogenous ROS burst and spatiotemporally controlled multiple drug release ability. Firstly, TLDCAG NPs were accumulated in the tumor cell microenvironment via an enhanced permeability and retention (EPR) effect. Secondly, CA4 was released and specifically destroyed angiogenesis to facilitate the interaction between the tumor and the remaining TLDCG NPs. After accumulating in tumor cells, the TLDCG NPs could be destroyed under acidic conditions to quickly release doxorubicin (DOX), TPP-PEG2k-LND, and TPP-PEG2k-TOS. Thirdly, TPP-PEG2k-LND and TPP-PEG2k-TOS quickly targeted mitochondria, induced endogenous ROS bursts, reduced the mitochondrial membrane potential, and induced tumor cell apoptosis. Endogenous ROS can not only be used as a therapeutic reagent for CDT, but also can cut off the thioketal bond in PEG2k-S-S-CPT-ROS and release camptothecin (CPT). Finally, TLDCAG NPs were traced by magnetic resonance imaging (MRI). Furthermore, in vitro and vivo results indicate that the TLDCAG NPs have vigorous antitumor activity and negligible systemic toxicity. Therefore, the TLDCAG NPs provide an efficient strategy for enhancing antitumor efficacy.

β-Carboline-based molecular hybrids as anticancer agents: a brief sketch

Cancer is a huge burden on the healthcare system and is foremost cause of mortality across the globe. Among various therapeutic strategies, chemotherapy plays an enormous role in overcoming the challenges of treating cancer, especially in late stage detection. However, limitations such as extreme side/adverse effects and drug resistance associated with available drugs have impelled the development of novel chemotherapeutic agents. In this regard, we have reviewed the development of β-carboline-based chemotherapeutic agents reported in last five years. The review mainly emphasizes on the molecular hybrids of β-carbolines with various pharmacophores, their synthetic strategies, and in vitro anticancer evaluation. In addition, the mechanisms of action, in silico studies, structural influence on the potency and selectivity among diverse cancer cell lines have been critically presented. The review updates readers on the diverse molecular hybrids prepared and the governing structural features of high potential molecules that can help in the future development of novel cytotoxic agents.

A traceable, GSH/pH dual-responsive nanoparticles with spatiotemporally controlled multiple drugs release ability to enhance antitumor efficacy

Constructing highly efficient and multifunctional nanoparticles to overcome the multiple challenges of targeted drug delivery is a new strategy urgently needed in tumor therapy. Here, we synthesized pH-responsive prodrug (PEG_2K-NH-N-DOX), GSH-responsive prodrug (PEG_2K-S-S-CPT), folate-receptor targeting polymers (FA-PEG_2K-L8, FA-PEG_2K-TOS) and T1-enhanced magnetic resonance imaging contrast agents (Gd-DTPA-N16-16), used to encapsulate combrestatinA4 (CA4) to prepare multifunctional nanoparticles (FTDCAG NPs). Unlike other nanoparticles, FTDCAG NPs contains three drugs with the ability to control the release in time and space, which can maximize the effectiveness of precise cancer chemotherapy. We first confirmed that specific binding between FTDCAG NPs and overexpressed folate-receptor cells by flow cytometry and confocal laser scanning microscopy. We then investigated the spatiotemporally controlled release ability of FTDCAG NPs loaded with doxorubicin (DOX), CA4 and camptothecin (CPT). Relative to pH = 7.4, the release efficiency of CA4 in the pH = 6.5 increased by 63.4 %. The first released CA4 is able to destroy the angiogenesis and help tumor cells to be exposed to the remaining FTDCG NPs. After being internalized into the tumor cells, FTDCG NPs is disassembled and the CPT and DOX were released due to the increase of intracellular GSH concentration and the decrease of pH value. Besides, the relaxation time of FTDCAG NPs is 3.86 times that of clinical Gd-DTPA, and the in vitro and vivo T1-weighted imaging is brighter, which can be used to trace the nanoparticles by MRI. Therefore, FTDCAG NPs provide an efficient strategy for the design of multifunctional drug delivery systems for enhancing antitumor efficacy.

Discovery of novel indole-1,2,4-triazole derivatives as tubulin polymerization inhibitors

A series of novel indole-1,2,4-triazole derivatives have been designed, synthesized, and evaluated as potential tubulin polymerization inhibitors. The top hit 12, bearing the 3,4,5-trimethoxyphenyl moiety, exhibited substantial anti-proliferative activity against HepG2, HeLa, MCF-7, and A549 cells in vitro with IC₅₀ values of 0.23 ± 0.08 μM, 0.15 ± 0.18 μM, 0.38 ± 0.12 μM, and 0.30 ± 0.13 μM, respectively. It also inhibited tubulin polymerization with the IC₅₀ value of 2.1 ± 0.12 μM, which was comparable with that of the positive controls. Furthermore, compound 12 regulated the expression of cell cycle-related proteins (Cyclin B1, Cdc25c, and Cdc2) and apoptosis-related proteins (Bcl-2, Bcl-x, and Mcl-1). Mechanistically, compound 12 could arrest cell cycle at the G2/M phase, thus induce an increase of apoptotic cell death. In addition, molecular docking hinted the possible interaction mode of compound 12 into the colchicine binding site of tubulin heterodimers. According to the applications of microtubule-targeting agents in both direct and synergistic cancer therapies, we hope this work might be of significance for future researches.

In vivo and in vitro anti-inflammatory, antipyretic and ulcerogenic activities of pyridone and chromenopyridone derivatives, physicochemical and pharmacokinetic studies

Throughout this study, we present the victorious synthesis of a novel class of 2(1H)-pyridone molecules, bearing a 4-hydroxyphenyl moiety through a one-pot reaction of 2-cyano-N-(4-hydroxyphenyl)acetamide with cyanoacetamide, acetylacetone or ethyl acetoacetate, and their corresponding aldehydes. In addition, the chromene moiety was introduced into the pyridine skeleton through the cyclization of the cyanoacetamide 2 with salicylaldehyde, followed by treatment with malononitrile, ethyl cyanoacetate, and cyanoacetamide, in order to improve their biological behaviour. Due to their anti-inflammatory, ulcerogenic, and antipyretic characters, the target molecules have undergone in-vitro and in-vivo examination, that display promising results. Moreover, in order to predict the physicochemical and ADME traits of all synthesized compounds and standard reference drugs, paracetamol and phenylbutazone, the in-silico prediction methodology was provided.

Combretastatin A-4 sulfur-containing heterocyclic derivatives: Synthesis, antiproliferative activities and molecular docking studies

Combretastatin A-4 inspired heterocyclic derivatives were synthesized and evaluated for their biological activities on tubulin polymerization and cell proliferation. Among the 19 described sulfur-containing compounds, derivatives (Z)-4h and (Z)-4j exhibited interesting in cellulo tubulin polymerization inhibition and antiproliferative activities with IC₅₀ values for six different cell lines between 8 and 27 nM. Furthermore, in silico docking studies within the colchicine/CA-4 binding site of tubulin were carried out to understand the interactions of our products with the protein target. The effects on the cell cycle of follicular lymphoma cells were also investigated at 1-10 nM concentrations showing that apoptotic processes occurred.

A novel series of benzothiazepine derivatives as tubulin polymerization inhibitors with anti-tumor potency

In this work, a series of diaryl benzo[b][1,4]thiazepine derivatives D1-D36 were synthesized and screened as tubulin polymerization inhibitors with anti-tumor potency. They were designed by introducing the seven-member ring benzothiazepine as the linker for CA-4 modification for the first time. Among them, the hit compound D8 showed potential on inhibiting the growth of several cancer cell lines (IC₅₀ values: 1.48 μM for HeLa, 1.47 μM for MCF-7, 1.52 μM for HT29 and 1.94 μM for A549), being comparable with the positive controls Colchicine and CA-4P. The calculated IC₅₀ value of D8 as an tubulin polymerization inhibitor was 1.20 μM. The results of the flow cytometry assay revealed that D8 could induce the mitotic catastrophe and the death of living cancer cells. D8 also indicated the anti-vascular activity. The possible binding pattern was implied by docking simulation, inferring the possibility of introducing interactions with the nearby tubulin chain. Since the novel structural trial has been conducted with preliminary discussion, this work might stimulate new ideas in further modification of tubulin-related anti-cancer agents and therapeutic approaches.

Design, synthesis, docking study and anticancer evaluation of new trimethoxyphenyl pyridine derivatives as tubulin inhibitors and apoptosis inducers

Microtubules have become an appealing target for anticancer drug development including mainly colchicine binding site inhibitors (CBSIs). A new series of novel trimethoxypyridine derivatives were designed and synthesized as tubulin targeting agents. In vitro anti-proliferative activities of the tested compounds compared to colchicine against hepatocellular carcinoma (HepG-2), colorectal carcinoma (HCT-116), and breast cancer (MCF-7) was carried out. Most of compounds showed significant cytotoxic activities. Compounds Vb, Vc, Vf, Vj and VI showed superior anti-proliferative activities to colchicine. Where compound VI showed IC₅₀ values of 4.83, 3.25 and 6.11 μM compared to colchicine (7.40, 9.32, 10.41 μM) against HCT 116, HepG-2 and MCF-7, respectively. The enzymatic activity against tubulin enzyme was carried out for the compounds that showed high anti-proliferative activity. Also, compound VI exhibited the highest tubulin polymerization inhibitory effect with an IC₅₀ value of 8.92 nM compared to colchicine (IC₅₀ value = 9.85 nM). Compounds Vb, Vc, Vf, Vj, & VIIIb showed promising activities with IC₅₀ values of 22.41, 17.64, 20.39, 10.75, 31.86 nM, respectively. Cell cycle and apoptosis test for compound VI against HepG-2 cells, indicated that compound VI can arrest cell cycle at G2/M phase, and can cause apoptosis at pre-G1 phase, with high apoptotic effect 18.53%. Molecular docking studies of the designed compounds confirmed the essential hydrogen bonding with CYS241 beside the hydrophobic interaction at the binding site compared to reference compounds which assisted in the prediction of the structure requirements for the detected antitumor activity.

Interaction of compounds VI (IC₅₀ = 8.92 nM) (A) and Vj (IC₅₀ = 10.75 nM) (B) with key amino acids of CBS.

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

A waste biomass, sodium lignosulfonate, was treated with sodium 2-formylbenzenesulfonate, and the phenylaldehyde condensation product was then used as a robust supporting material to immobilize a copper species. The so-obtained catalyst was characterized by many physicochemical methods including FTIR, EA, FSEM, FTEM, XPS, and TG. This catalyst exhibited excellent catalytic activity in the synthesis of nitrogen-containing heterocycles such as tricyclic indoles bearing 3,4-fused seven-membered rings, 2‑arylpyridines, aminonaphthalenes and 3-phenylisoquinolines. In addition, this catalyst showed to be recyclable and could be reused several times without significant loss in activity during the course of the reaction process.

Cyclic bridged analogs of isoCA-4: Design, synthesis and biological evaluation

In this work, a series of cyclic bridged analogs of isocombretastatin A-4 (isoCA-4) with phenyl or pyridine linkers were designed and synthesized. The synthesis of the desired analogs was performed by the formation of nitro-vinyl intermediates, followed by a Cadogan cyclization. Structure activity relationship (SAR) study demonstrates the critical role of the combination of quinaldine as ring A, pyridine as the linker, and indole as ring B in the same molecule, for the cytotoxic activity. Among all tested compounds, compound 42 showed the highest antiproliferative activity against a panel of cancer cell lines with average IC50 values of 5.6 nM. Also, compound 42 showed high antiproliferative activity against the MDR1-overexpressing K562R cell line; thus, it was 1.5- and 12-fold more active than the reference compounds, isoCA-4 and CA-4, respectively. Moreover, 42 displayed a strong antiproliferative activity against the colon-carcinoma cells (HT-29), which are resistant to combretastatin A-4 and isoCA-4, and it was found to be 8000-fold more active than natural CA-4. Compound 42 also effectively inhibited tubulin polymerization both in vitro and in cells, and induced cell cycle arrest in G2/M phase. Next, we demonstrated that compound 42 dose-dependently caused caspase-induced apoptosis of K562 cells through mitochondrial dysfunction. Finally, we evaluated the effect of compound 42 in human no cancer cells compared to the reference compound. We demonstrated that 42 was 73 times less cytotoxic than isoCA-4 in quiescent peripheral blood lymphocytes (PBLs). In summary, these results suggest that compound 42 represents a promising tubulin inhibitor worthy of further investigation.

Synthesis, Biological Evaluation, and Molecular Docking of Arylpyridines as Antiproliferative Agent Targeting Tubulin

Mimicking different pharmacophoric units into one scaffold is a promising structural modification tool to design new drugs with enhanced biological properties. To continue our research on the tubulin inhibitors, the synthesis and biological evaluation of arylpyridine derivatives (9-29) are described herein. Among these compounds, 6-arylpyridines (13-23) bearing benzo[d]imidazole side chains at the 2-position of pyridine ring displayed selective antiproliferative activities against HT-29 cells. More interestingly, 2-trimethoxyphenylpyridines 25, 27, and 29 bearing benzo[d]imidazole and benzo[d]oxazole side chains displayed more broad-spectrum antitumor activities against all tested cancer cell lines. 29 bearing a 6-methoxybenzo[d]oxazole group exhibited comparable activities against A549 and U251 cells to combretastatin A-4 (CA-4) and lower cytotoxicities than CA-4 and 5-Fu. Further investigations revealed 29 displays strong tubulin polymerization inhibitory activity (IC₅₀ = 2.1 μM) and effectively binds at the colchicine binding site and arrests the cell cycle of A549 in the G2/M phase by disrupting the microtubules network.

Highly Selective Room-Temperature Suzuki-Miyaura Coupling of Bromo-2-sulfonyloxypyridines for Unsymmetrical Diarylpyridines

A new and mild synthetic approach has been developed for the synthesis of pharmaceutically important unsymmetrical diarylpyridines via chemoselective Suzuki-Miyaura coupling reactions of bromo-2-sulfonyloxypyridines. Most reactions allow for facile access to aryl-2-sulfonyloxypyridines at room temperature in yields of 5-99% with excellent chemoselectivity in the presence of Pd(OAc)₂ (2.0 mol %) and Ad₂BnP (2.4 mol %). The second arylation of the remaining tosyl or triflyl group in the monoarylpyridine derivatives obtained was successfully accomplished for the synthesis of unsymmetrical 2,3-, 2,4-, 2,5-, and 2,6-diarylpyridine derivatives. Furthermore, a one-pot synthesis of unsymmetrical diarylpyridines starting from bromo-2-sulfonyloxypyridine was accomplished to demonstrate the practical convenience. Finally, with this method, an antibacterial agent, a topoisomerase inhibitor, and etoricoxib, a nonsteroidal anti-inflammatory drug, were successfully synthesized from the corresponding bromo-2-hydroxypyridines in overall yields of 80, 86, and 49%, respectively.

Discovery of a chiral fluorinated azetidin-2-one as a tubulin polymerisation inhibitor with potent antitumour efficacy

Inhibition of tubulin polymerisation with small molecules has been clinically validated as a promising therapy for multiple solid tumours. Herein, a series of chiral azetidin-2-ones were asymmetrically synthesised and biologically evaluated for antitumour activities. Among them, a chiral fluorinated azetidin-2-one, 18, was found to exhibit the most potent activities against five cancer cell lines, including a drug-resistant cell line, with IC₅₀ values ranging from 1.0 to 3.6 nM. Further mechanistic studies revealed that the compound 18 worked by disrupting tubulin polymerisation, blocking the cell cycle in the G₂/M phase, inducing cellular apoptosis, and suppressing angiogenesis. Additionally, 18 exhibited higher human-microsomal metabolic stability and aqueous solubility compared to those of combretastatin A-4. Finally, 18 was also found to effectively inhibit tumour growth in a xenograft mice model with low toxicity and thus might be a promising lead for further clinical development.

Synthesis and biological evaluation of novel pyrazolo[3,4-b]pyridines as cis-restricted combretastatin A-4 analogues

Twenty-six novel pyrazolo[3,4-b]pyridine-bridged analogues of combretastatin A-4 possessing 3,4,5-trimethoxylphenyl groups, were synthesized and evaluated for their antiproliferative and tubulin polymerization inhibitory activities. Preliminary biological evaluation demonstrated that some of the target compounds displayed significant antiproliferative effectagainst four different cell lines including MCF-7, MDA-MB-231, HeLa and Kyse150. The most active analogue 6n was found to induce HeLa cells arrest in the G2/M phase in a dose-dependent manner. Molecular modeling studies indicated that derivative 6n most likely occupies the colchicine site of tubulin. The initial results suggest that the 3,4,5-trimethoxyphenyl substituted pyrazolo[3,4-b]pyridine could serve as a promising scaffold for development of potent tubulin inhibitors as anticancer agents.

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.

Development Of Novel Liposome-Encapsulated Combretastatin A4 Acylated Derivatives: Prodrug Approach For Improving Antitumor Efficacy

Purpose

The objective of the present study was to develop a liposomal drug delivery system based on combretastatin A4 (CA4) prodrugs modified with varying alkyl chains and investigate the in vitro drug conversion from prodrug and in vivo antitumor effect.

Methods

The prodrug of CA4 was synthesized with stearyl chloride (18-carbon chain), palmitoyl chloride (16-carbon chain), myristoyl chloride (14-carbon chain), decanoyl chloride (10-carbon chain), and hexanoyl chloride (6-carbon chain) at the 3′-position of the CA4. Subsequently, it was encapsulated with liposomes through the thin-film evaporation method. Furthermore, the characteristics of prodrug-liposome were evaluated using in vitro drug release, conversion, and cytotoxicity assays, as well as in vivo pharmacokinetic, antitumor, and biodistribution studies.

Results

The liposome system with loaded CA4 derivatives was successfully developed with nano-size and electronegative particles. The rate of in vitro drug release and conversion was reduced as the fatty acid carbon chain lengthened. On the contrary, in vivo antitumor effects were improved with the enlargement of the fatty acid carbon chain. The results of the in vivo pharmacokinetic and tissue distribution studies indicated that the reduced rate of CA4 release with a long carbon chain could prolong the circulation time and increase the drug concentration in the tumor tissue.

Conclusion

These results suggested that the release or hydrolysis of the parent drug from the prodrug was closely related with the in vitro and in vivo properties. The slow drug release of CA4 modified with longer acyl chain could prolong the circulation time and increase the concentration of the drug in the tumor tissue. These effects play a critical role in increasing the antitumor efficacy.

Novel [1,2,4]triazolo[1,5-a]pyrimidine derivatives as potent antitubulin agents: Design, multicomponent synthesis and antiproliferative activities

As restricted CA-4 analogues, a novel series of [1,2,4]triazolo[1,5-a]pyrimidines possessing 3,4,5-trimethoxylphenyl groups has been achieved successfully via an efficient one-pot three-component reaction of 3-(3,4,5-trimethoxyphenyl)-1H-1,2,4-triazol-5-amine, 1,3-dicarbonyl compounds and aldehydes. Initial biological evaluation demonstrated some of target compounds displayed potent antitumor activity in vitro against three cancer cell lines. Among them, the most highly active analogue 26 inhibited the growth of HeLa, and A549 cell lines with IC₅₀ values at 0.75, and 1.02 μM, respectively, indicating excellent selectivity over non-tumoural cell line HEK-293 (IC₅₀ = 29.94 μM) which suggested that the target compounds might possess a high safety index. Moreover, cell cycle analysis illustrated that the analogue 26 significantly induced HeLa cells arrest in G2/M phase, meanwhile the compound could dramatically affect cell morphology and microtubule networks. In addition, compound 28 exhibited potent anti-tubulin activity with IC₅₀ values of 9.90 μM, and molecular docking studies revealed the analogue occupied the colchicine-binding site of tubulin. These observations suggest that [1,2,4]triazolo[1,5-a]pyrimidines represent a new class of tubulin polymerization inhibitors and well worth further investigation aiming to generate potential anticancer agents.

3-Vinylazetidin-2-Ones: Synthesis, Antiproliferative and Tubulin Destabilizing Activity in MCF-7 and MDA-MB-231 Breast Cancer Cells

Microtubule-targeted drugs are essential chemotherapeutic agents for various types of cancer. A series of 3-vinyl-β-lactams (2-azetidinones) were designed, synthesized and evaluated as potential tubulin polymerization inhibitors, and for their antiproliferative effects in breast cancer cells. These compounds showed potent activity in MCF-7 breast cancer cells with an IC₅₀ value of 8 nM for compound 7s 4-[3-Hydroxy-4-methoxyphenyl]-1-(3,4,5-trimethoxyphenyl)-3-vinylazetidin-2-one) which was comparable to the activity of Combretastatin A-4. Compound 7s had minimal cytotoxicity against both non-tumorigenic HEK-293T cells and murine mammary epithelial cells. The compounds inhibited the polymerisation of tubulin in vitro with an 8.7-fold reduction in tubulin polymerization at 10 μM for compound 7s and were shown to interact at the colchicine-binding site on tubulin, resulting in significant G2/M phase cell cycle arrest. Immunofluorescence staining of MCF-7 cells confirmed that β-lactam 7s is targeting tubulin and resulted in mitotic catastrophe. A docking simulation indicated potential binding conformations for the 3-vinyl-β-lactam 7s in the colchicine domain of tubulin. These compounds are promising candidates for development as antiproiferative microtubule-disrupting agents.