Structure-Activity Relationship Studies of β-Lactam-azide Analogues as Orally Active Antitumor Agents Targeting the Tubulin Colchicine Site

Growth inhibition and toxicity assessments of cis-3,4-diaryl-α-methylene-γ-butyrolactams in cultured human renal cancer cells and zebrafish embryos

This study aimed to compare and evaluate the growth inhibition effects of eight previously synthesized compounds, cis-3,4-diaryl-α-methylene-γ-butyrolactams (compounds 1-8), on two human renal carcinoma cell (RCC) lines: CRL-1932 (rapid growth) and HTB-44 (slow growth). MTT assays and flow cytometry were conducted, revealing that compounds 5 and 6 had the potential to induce cell death in the slow-growing RCC cells (HTB-44), while compound 8 demonstrated effectiveness in both RCC lines (HTB-44 and CRL-1932). Additionally, a non-transformed HEK293 cell line and a transgenic zebrafish with a green fluorescent kidney Tg(wt1b:egfp) were used to assess the toxicities of compounds 5, 6, and 8. The findings suggested that compound 8 was relatively non-toxic compared to the others. Western blot analysis indicated that compounds 5, 6, and 8 may interact with the P53/mTOR pathways. Based on these results, we concluded that compound 8 exhibits RCC growth inhibition properties and has lower toxicity, making it a candidate for further investigation in mammalian models.

Tubulin/HDAC dual-target inhibitors: Insights from design strategies, SARs, and therapeutic potential

Microtubules, one of the cytoskeletons in eukaryotic cells, maintain the proper operation of several cellular functions. Additionally, they are regulated by the acetylation of HDAC6 and SIRT2 which affects microtubule dynamics. Given the fact that tubulin and HDAC inhibitors play a synergistic effect in the treatment of many cancers, the development of tubulin/HDAC dual-target inhibitors is conducive to addressing multiple limitations including drug resistance, dose toxicity, and unpredictable pharmacokinetic properties. At present, tubulin/HDAC dual-target inhibitors have been obtained in three main ways: uncleavable linked pharmacophores, cleavable linked pharmacophores, and modification of single-target drugs. Their therapeutic efficacy has been verified in vivo and in vitro assays. In this article, we reviewed the research progress of tubulin/HDAC dual inhibitors from design strategies, SARs, and biological activities, which may provide help for the discovery of novel tubulin/HDAC dual inhibitors.

Unraveling the Anti-Cancer Mechanisms of Antibiotics: Current Insights, Controversies, and Future Perspectives

Cancer persists as a significant global health challenge, claiming millions of lives annually despite remarkable strides in therapeutic innovation. Challenges such as drug resistance, toxicity, and suboptimal efficacy underscore the need for novel treatment paradigms. In this context, the repurposing of antibiotics as anti-cancer agents has emerged as an attractive prospect for investigation. Diverse classes of antibiotics have exhibited promising anti-cancer properties in both in vitro and in vivo studies. These mechanisms include the induction of apoptosis and cell cycle arrest, generation of reactive oxygen species, and inhibition of key regulators of cell proliferation and migration. Additional effects involve the disruption of angiogenesis and modulation of pivotal processes such as inflammation, immune response, mitochondrial dynamics, ferroptosis, and autophagy. Furthermore, antibiotics have demonstrated the potential to enhance the efficacy of conventional modalities like chemotherapy and radiotherapy, while alleviating treatment-induced toxicities. Nevertheless, the integration of antibiotics into oncological applications remains contentious, with concerns centered on their disruption of gut microbiota, interference with immunotherapeutic strategies, contribution to microbial resistance, and potential association with tumorigenesis. This narrative review explores the mechanisms of antibiotics' anti-cancer activity, addresses controversies about their dual role in cancer biology, and envisions future perspectives that include the development of novel derivatives and innovative frameworks for their incorporation into cancer treatment paradigms.

Dual site reactivity of indole-3-Schiff bases with S/Se/Cl substituted ketenes for stereoselective C-4 substituted indole-β-lactams, biological evaluations, magic chloro effect and molecular docking studies

A convenient methodology for C-4 indole-β-lactam hybrids with chloro, sulphur and seleno substitutions through dual site reactivity of indole-3-Schiff bases towards ketenes has been developed. The reaction proceeded in a stereospecific manner with the exclusive formation of trans-β-lactams assigned with respect to C3-H and C4-H. The synthesized novel β-lactams have been characterized with the help of elemental analysis (CHNS) and spectroscopic techniques viz.1H NMR, 13C NMR, DEPT 135, HSQC and IR. The trans configuration was further estabilished based on X-ray crystallographic data. Examination of antibacterial properties unveiled that only derivatives 5a and 5b, featuring chloro substitution, exhibited potent activities, underscoring the emergence of the recently coined term "magic chloro effect". Molecular docking analysis provided additional support for the observed in vitro antibacterial activities of compounds 5a-b.

Azide-modified corrole phosphorus complexes for endoplasmic reticulum-targeted fluorescence bioimaging and effective cancer photodynamic therapy

Study on corrole photosensitizers (PSs) for photodynamic therapy (PDT) has made remarkable progress. Targeted delivery of PSs is of great significance for enhancing therapeutic efficiency, decreasing the dosage, and reducing systemic toxicity during PDT. The development of PSs that can be specifically delivered to the subcellular organelle is still an attractive and challenging work. Herein, we synthesize a series of azide-modified corrole phosphorus and gallium complex PSs, in which phosphorus corrole 2-P could not only precisely target the endoplasmic reticulum (ER) with a Pearson correlation coefficient (PCC) up to 0.92 but also possesses the highest singlet oxygen quantum yields (ΦΔ = 0.75). This renders it remarkable PDT activity at a very low dosage (IC50 = 23 nM) towards HepG2 tumor cell line while ablating solid tumors in vivo with excellent biosecurity. Furthermore, 2-P exhibits intense red fluorescence (ΦF = 0.25), outstanding photostability, and a large Stokes shift (190 nm), making it a promising fluorescent probe for ER. This study provides a clinically potential photosensitizer for cancer photodynamic therapy and a promising ER fluorescent probe for bioimaging.

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.

Discovery of dual tubulin-NEDDylation inhibitors with antiproliferative activity

Although various dual-target tubulin inhibitors have been designed and synthesised, no dual tubulin-NEDDylation inhibitors as antiproliferative agents were reported so far. In this work, a series of trimethoxyphenyl analogues as potential dual tubulin-NEDDylation inhibitors were synthesised and evaluated for their antiproliferative activity. Among them, compound C11 exhibited the most potent inhibitory activity with IC₅₀ values of 1.17, 2.48, and 1.47 μM against HepG2, PC3, and MCF7 cells, respectively. In addition, it displayed the potent inhibitory activity against tubulin with an IC₅₀ value of 2.40 μM and obviously inhibited tubulin polymerisation in HepG2 cells. Furthermore, C11 inhibited NEDDylation by a ATP-dependent manner. Molecular docking studies revealed that the methoxy group and dithiocarbamate group of C11 could form hydrogen bonds with residues of tubulin and E1 NEDD8-activating enzyme (NAE). These results suggested that compound C11 was a dual tubulin-NEDDylation inhibitor with antiproliferative activity.

Two Important Anticancer Mechanisms of Natural and Synthetic Chalcones

ATP-binding cassette subfamily G and tubulin pharmacological mechanisms decrease the effectiveness of anticancer drugs by modulating drug absorption and by creating tubulin assembly through polymerization. A series of natural and synthetic chalcones have been reported to have very good anticancer activity, with a half-maximal inhibitory concentration lower than 1 µM. By modulation, it is observed in case of the first mechanism that methoxy substituents on the aromatic cycle of acetophenone residue and substitution of phenyl nucleus by a heterocycle and by methoxy or hydroxyl groups have a positive impact. To inhibit tubulin, compounds bind to colchicine binding site. Presence of methoxy groups, amino groups or heterocyclic substituents increase activity.

Synthesis, Characterization, and Biological Evaluation of Some Novel Pyrazolo[5,1-b]thiazole Derivatives as Potential Antimicrobial and Anticancer Agents

The pharmacological activities of thiazole and pyrazole moieties as antimicrobial and anticancer agents have been thoroughly described in many literature reviews. In this study, a convenient synthesis of novel pyrazolo[5,1-b]thiazole-based heterocycles was carried out. The synthesized compounds were characterized by IR, ¹H and ¹³C NMR spectroscopy and mass spectrometry. Some selected examples were screened and evaluated for their antimicrobial and anticancer activities and showed promising results. These products could serve as leading compounds in the future design of new drug molecules.

Tubulin Inhibitors: A Chemoinformatic Analysis Using Cell-Based Data

Inhibiting the tubulin-microtubules (Tub-Mts) system is a classic and rational approach for treating different types of cancers. A large amount of data on inhibitors in the clinic supports Tub-Mts as a validated target. However, most of the inhibitors reported thus far have been developed around common chemical scaffolds covering a narrow region of the chemical space with limited innovation. This manuscript aims to discuss the first activity landscape and scaffold content analysis of an assembled and curated cell-based database of 851 Tub-Mts inhibitors with reported activity against five cancer cell lines and the Tub-Mts system. The structure-bioactivity relationships of the Tub-Mts system inhibitors were further explored using constellations plots. This recently developed methodology enables the rapid but quantitative assessment of analog series enriched with active compounds. The constellations plots identified promising analog series with high average biological activity that could be the starting points of new and more potent Tub-Mts inhibitors.

Novel piperidine derivatives as colchicine binding site inhibitors induce apoptosis and inhibit epithelial-mesenchymal transition against prostate cancer PC3 cells

Tubulin polymerisation inhibitors that target colchicine binding site were powerful anticancer agents. Although along the years many colchicine binding site inhibitors (CBSIs) have been reported, few piperidine derivatives were identified as CBSIs. In this regard, we focussed efforts on the piperidine as a promising chemotype to develop potent CBSIs. Herein, novel piperidine derivatives were synthesised and evaluated for their antiproliferative activities. Among them, compound 17a displayed powerful anticancer activity with the IC₅₀ value of 0.81 µM against PC3 cells, which was significantly better than 5-fluorouracil. It could inhibit tubulin polymerisation binding at the colchicine site and inhibit the tumour growth in vitro and in vivo. Further biological studies depicted that 17a suppressed the colony formation, induced apoptosis, and inhibited epithelial-mesenchymal transition against PC3 cells. These results revealed that compound 17a is a promising colchicine binding site inhibitor for the treatment of cancer and it is worthy of further exploitation.

Tubulin Inhibitors Binding to Colchicine-Site: A Review from 2015 to 2019

Due to the three domains of the colchicine-site which is conducive to the combination with small molecule compounds, colchicine-site on the tubulin has become a common target for antitumor drug development, and accordingly, a large number of tubulin inhibitors binding to the colchicine-site have been reported and evaluated over the past years. In this study, tubulin inhibitors targeting the colchicine-site and their application as antitumor agents were reviewed based on the literature from 2015 to 2019. Tubulin inhibitors were classified into ten categories according to the structural features, including colchicine derivatives, CA-4 analogs, chalcone analogs, coumarin analogs, indole hybrids, quinoline and quinazoline analogs, lignan and podophyllotoxin derivatives, phenothiazine analogs, N-heterocycle hybrids and others. Most of them displayed potent antitumor activity, including antiproliferative effects against Multi-Drug-Resistant (MDR) cell lines and antivascular properties, both in vitro and in vivo. In this review, the design, synthesis and the analysis of the structure-activity relationship of tubulin inhibitors targeting the colchicine-site were described in detail. In addition, multi-target inhibitors, anti-MDR compounds, and inhibitors bearing antitumor activity in vivo are further listed in tables to present a clear picture of potent tubulin inhibitors, which could be beneficial for medicinal chemistry researchers.

Progress of tubulin polymerization activity detection methods

Tubulin, an important target in tumor therapy, is one of the hotspots in the field of antineoplastic drugs in recent years, and it is of great significance to design and screen new inhibitors for this target. Natural products and chemical synthetic drugs are the main sources of tubulin inhibitors. However, due to the variety of compound structure types, it has always been difficult for researchers to screen out polymerization inhibitors with simple operation, high efficiency and low cost. A large number of articles have reported the screening methods of tubulin inhibitors and their biological activity. In this article, the biological activity detection methods of tubulin polymerization inhibitors are reviewed. Thus, it provides a theoretical basis for the further study of tubulin polymerization inhibitors and the selection of methods for tubulin inhibitors.

Discovery of novel indole derivatives that inhibit NEDDylation and MAPK pathways against gastric cancer MGC803 cells

A series of novel indole derivatives were synthesized and evaluated for their antiproliferative activity against three selected cancer cell lines (MGC803, EC-109 and PC-3). Among these analogues, 2-(5-methoxy-1H-indol-1-yl)-N-(4-methoxybenzyl)-N-(3,4,5-trimethoxyphenyl)acetamide (V7) showed the best inhibitory activity against MGC803 cells with an IC₅₀ value of 1.59 μM. Cellular mechanisms elucidated that V7 inhibited colony formation, induced apoptosis and arrested cell cycle at G2/M phase. Importantly, indole analogue V7 inhibited NEDDylation pathway and MAPK pathway against MGC803 cells.

Antiproliferative benzothiazoles incorporating a trimethoxyphenyl scaffold as novel colchicine site tubulin polymerisation inhibitors

Tubulin polymerisation inhibitors exhibited an important role in the treatment of patients with prostate cancer. Herein, we reported the medicinal chemistry efforts leading to a new series of benzothiazoles by a bioisosterism approach. Biological testing revealed that compound 12a could significantly inhibit in vitro tubulin polymerisation of a concentration dependent manner, with an IC₅₀ value of 2.87 μM. Immunofluorescence and EBI competition assay investigated that compound 12a effectively inhibited tubulin polymerisation and directly bound to the colchicine-binding site of β-tubulin in PC3 cells. Docking analysis showed that 12a formed hydrogen bonds with residues Tyr357, Ala247 and Val353 of tubulin. Importantly, it displayed the promising antiproliferative ability against C42B, LNCAP, 22RV1 and PC3 cells with IC₅₀ values of 2.81 μM, 4.31 μM, 2.13 μM and 2.04 μM, respectively. In summary, compound 12a was a novel colchicine site tubulin polymerisation inhibitor with potential to treat prostate cancer.

Azetidin-2-ones: structures of anti-mitotic compounds based on the 1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one core

A series of related substituted 1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-ones have been characterized: 3-(4-fluoro-phen-yl)-4-(4-meth-oxy-phen-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one, C25H24FNO5 (1), 3-(furan-2-yl)-4-(4-meth-oxy-phen-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one, C23H23NO6 (2), 4-(4-meth-oxyphen-yl)-3-(naphthalen-1-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one, C29H27NO5 (3), 3-(3,4-di-meth-oxy-phen-yl)-4-(4-meth-oxy-phen-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one, C27H29NO7 (4) and 4,4-bis-(4-meth-oxy-phen-yl)-3-phenyl-1-(3,4,5-tri-meth-oxy-phen-yl)azetidin-2-one, C32H31NO6 (5). All of the compounds are racemic. The lactam and 3,4,5-tri-meth-oxy-phenyl rings are approximately co-planar and the orientation of the lactam and the 4-meth-oxy-phenyl substituent is approximately orthogonal. The chiral centres, although eclipsed by geometry, have torsion angles ranging from -7.27 to 13.08° for the 3 position, and -8.69 to 13.76° for the 4 position of the β-lactam. The structures display intra-molecular C-H⋯O bonding between the 3,4,5-tri-meth-oxy-phenyl ring and the lactam ketone. Further C-H⋯O inter-actions are observed and form either an opposing meth-oxy 'buckle' to join two mol-ecules together or a cyclic dimer.

Discovery of tertiary amide derivatives incorporating benzothiazole moiety as anti-gastric cancer agents in vitro via inhibiting tubulin polymerization and activating the Hippo signaling pathway

On the basis and continuation of our previous studies on anti-tubulin and anti-gastric cancer agents, novel tertiary amide derivatives incorporating benzothiazole moiety were synthesized and the antiproliferative activity was studied in vitro. Preliminary structure activity relationships (SARs) were explored according to the in vitro antiproliferative activity results. Some of compounds could significantly inhibit the proliferation of three cancer cells (HCT-116, MGC-803 and PC-3 cells) and compound F10 exhibited excellent antiproliferative activity against HCT-116 cells (IC₅₀ = 0.182 μM), MGC-803 cells (IC₅₀ = 0.035 μM), PC-3 cells(IC₅₀ = 2.11 μM) and SGC-7901 cells (IC₅₀ = 0.049 μM). Compound F10 effectively inhibited tubulin polymerization (IC₅₀ = 1.9 μM) and bound to colchicine binding site of tubulin. Molecular docking results suggested compound F10 could bind tightly into the colchicine binding site of β-tubulin. Moreover, compound F10 could regulate the Hippo/YAP signaling pathway. Compound F10 activated Hippo signaling pathway from its very beginning MST1/2, as the result of Hippo cascade activation YAP were inhibited. And then it led to a decrease of c-Myc and Bcl-2 expression. Further molecular experiments showed that compound F10 arrested at G2/M phase, inhibited cell colony formatting and induced extrinsic and intrinsic apoptosis in MGC-803 and SGC-7901 cells. Collectively, compound F10 was the first to be reported as a new anticancer agent in vitro via inhibiting tubulin polymerization and activating the Hippo signaling pathway.

β-Lactams as promising anticancer agents: Molecular hybrids, structure activity relationships and potential targets

β-Lactam, commonly referred as azetidin-2-one, is a multifunctional building block for synthesizing β-amino ketones, γ-amino alcohols, and other compounds. Besides its well known antibiotic activity, this ring system exhibits a wide range of activities, attracting the attention of researchers. However, the structurally diverse β-lactam analogues as anticancer agents and their different molecular targets are poorly discussed. The purpose of this review is 3-fold: (1) to explore the molecular hybridization approach to design β-lactams hybrids as anticancer agents; (2) the structure activity relationship of the most active anticancer β-lactams and (3) to summarize their antitumor mechanisms.

β-Lactams with antiproliferative and antiapoptotic activity in breast and chemoresistant colon cancer cells

A series of novel 1,4-diaryl-2-azetidinone analogues of combretastatin A-4 (CA-4) have been designed, synthesised and evaluated in vitro for antiproliferative activity, antiapoptotic activity and inhibition of tubulin polymerisation. Glucuronidation of CA-4 by uridine 5-diphosphoglucuronosyl transferase enzymes (UGTs) has been identified as a mechanism of resistance in cancer cells. Potential sites of ring B glucuronate conjugation are removed by replacing the B ring meta-hydroxy substituent of selected series of β-lactams with alternative substituents e.g. F, Cl, Br, I, CH₃. The 3-phenyl-β-lactam 11 and 3-hydroxy-β-lactam 46 demonstrate improved activity over CA-4 in CA-4 resistant HT-29 colon cancer cells (IC₅₀ = 9 nM and 3 nM respectively compared with IC₅₀ = 4.16 μM for CA-4), while retaining potency in MCF-7 breast cancer cells (IC₅₀ = 17 nM and 22 nM respectively compared with IC₅₀ = for 4 nM for CA-4). Compound 46 binds at the colchicine site of tubulin, and strongly inhibits tubulin assembly at micromolar concentrations comparable to CA-4. In addition, compound 46 induced mitotic arrest at low concentration in both cell lines MCF-7 and HT-29 together with downregulation of expression of antiapoptotic proteins Mcl-1, Bcl-2 and survivin in MCF-7 cells. These novel antiproliferative and antiapoptotic β-lactams are potentially useful scaffolds in the development of tubulin-targeting agents for the treatment of breast cancers and chemoresistant colon cancers.

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.

Novel tertiary sulfonamide derivatives containing benzimidazole moiety as potent anti-gastric cancer agents: Design, synthesis and SAR studies

With the expectation to find out new anti-gastric cancer agents with high efficacy and selectivity, a series of novel tertiary sulfonamide derivatives were synthesized and the anti-cancer activity was studied in three selected cancer cell lines (MGC-803, PC-3, MCF-7) in vitro. Some of the synthesized compounds could significantly inhibit the proliferation of these tested cancer cells and were more potent than the positive control (5-Fu). The structure-activity relationship of tertiary sulfonamide derivatives was explored in this report. Among the tested compounds, compound 13g containing benzimidazole moiety showed the best anti-proliferation activities against MGC-803 cells (IC₅₀ = 1.02 μM), HGC-27 cells (IC₅₀ = 1.61 μM), SGC-7901 (IC₅₀ = 2.30 μM) cells as well as the good selectivity between the cancer and normal cells. Cellular mechanism studies elucidated compound 13g inhibited the colony formation of gastric cancer cell lines. Meanwhile, compound 13g arrested cell cycle at G2/M phase and induced cell apoptosis. Mechanistically, compound 13g markedly decreased p-Akt and p-c-Raf expression, which revealed that compound 13g targeted gastric cancer cell lines via interfering with AKT/mTOR and RAS/Raf/MEK/ERK pathways. All the findings suggest that compound 13g might be a valuable lead compound for the anti-gastric cancer agents.

Discovery of indoline derivatives that inhibit esophageal squamous cell carcinoma growth by Noxa mediated apoptosis

A series of novel indoline derivatives were synthesized and evaluated for antiproliferative activity against four selected cancer cell lines (Hela, A549, HepG2 and KYSE30). Among them, compound 20 displayed the potent inhibition activity against esophageal cancer cells (Kyse30, Kyse450, Kyse510 and EC109). Cellular mechanism studies in esophageal squamous cell carcinoma (ESCC) cells elucidated compound 20 inhibited cell growths in vitro and in vivo, reduced colony formation, arrested cell cycle at M phase, and induced Noxa-dependent apoptosis in ESCC. Importantly, compound 20 was identified as a novel Noxa mediated apoptosis inducer. These results suggested that compound 20 might be a promising anticancer agent with potential for development of further clinical applications.

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.

Molecular diversity of trimethoxyphenyl-1,2,3-triazole hybrids as novel colchicine site tubulin polymerization inhibitors

Structurally diverse trimethoxyphenyl-1,2,3-triazole hybrids were designed, synthesized and evaluated for their antiproliferative activity against three cancer cell lines (PC3, MGC803 and HepG2). Among them, trimethoxyphenyl-1,2,3-triazole containing the coumarin fragement 19c displayed better antiproliferative activity results with IC50 values from 0.13 μM to 1.74 μM than anticancer drug colchicine. Compound 19c could inhibit MGC803 cell growth and colony formation, induce G2/M phase arrest by down expression of CDK1, and promote apoptosis by regulating DR5 and Bcl-2 family. Moreover, 19c strongly inhibited tubulin polymerization by interacting with the colchicine site.

Design, Antileishmanial Activity, and QSAR Studies of a Series of Piplartine Analogues

Piplartine is an alkamide found in different Piper species and possesses several biological activities, including antiparasitic properties. Thus, the aim of the present study was to evaluate a series of 32 synthetic piplartine analogues against the Leishmania amazonensis promastigote forms and establish the structure-activity relationship and 3D-QSAR of these compounds. The antileishmanial effect of the compounds was determined using the MTT method. Most compounds were found to be active against L. amazonensis. Among 32 assayed derivatives, compound (E)-(−)-bornyl 3-(3,4,5-trimethoxyphenyl)-acrylate exhibited the most potent antileishmanial activity (IC50 = 0.007 ± 0.008 μM, SI > 10), followed by benzyl 3,4,5-trimethoxybenzoate (IC50 = 0.025 ± 0.009 μM, SI > 3.205) and (E)-furfuryl 3-(3,4,5-trimethoxyphenyl)-acrylate (IC50 = 0.029 ± 0.007 μM, SI > 2.688). It was found that the rigid substituents contribute to increasing antiparasitic activity against L. amazonensis promastigotes. The presence of the unsaturated heterocyclic substituent in the phenylpropanoid chemical structure (furfuryl group) resulted in a bioactive derivative. Molecular simplification of benzyl 3,4,5-trimethoxybenzoate by omitting the spacer group contributed to the bioactivity of this compound. Furthermore, bornyl radical appears to be important for antileishmanial activity, since (E)-(−)-bornyl 3-(3,4,5-trimethoxyphenyl)-acrylate exhibited the most potent antileishmanial activity. These results show that some derivatives studied would be useful as prototype molecules for the planning of new derivatives with profile of antileishmanial drugs.

Bioactive heterocycles containing a 3,4,5-trimethoxyphenyl fragment exerting potent antiproliferative activity through microtubule destabilization

Novel bioactive heterocycles containing a 3,4,5-trimethoxyphenyl fragment as antiproliferative agents by targeting tubulin were synthesized and their preliminary structure activity relationships (SARs) were explored. Among all these chemical agents, 2-(Benzo[d]oxazol-2-ylthio)-N-(4-methoxybenzyl)-N-(3,4,5-trimethoxyphenyl)acetamide (4d) exhibited the potent antiproliferative activity against MGC-803 cells with an IC₅₀ value of 0.45 μM by induction of G2/M pahse arrest and cell apoptosis. In addition, 4d could change the membrane potential (ΔΨ) of the mitochondria against MGC-803 cells. Importantly, 4d acted as a novel tubulin polymerization inhibitor binding to colchicine site with an IC₅₀ value of 3.35 μM.

Design, synthesis and antiproliferative evaluation of novel sulfanilamide-1,2,3-triazole derivatives as tubulin polymerization inhibitors

Microtubule as an important target in the cancer therapy was used to design novel tubulin polymerization inhibitors. Sulfanilamide-1,2,3-triazole hybrids were designed by a molecular hybridization strategy and their antiproliferative activity against three selected cancer cell lines (BGC-823, MGC-803 and SGC-7901) were evaluated. All sulfanilamide-1,2,3-triazole hybrids displayed potent inhibitory activity against all cell lines. In particular, compound 10b showed the most excellent inhibitory effect against MGC-803 cells, with an IC₅₀ value of 0.4 μM. Cellular mechanism studies elucidated that 10b induced apoptosis by decreasing the expression level of Bcl-2 and Parp and increasing the expression level of BAX. 10b inhibited the epithelial-mesenchymal transition process by up-regulating E-cadherin and down-regulating N-cadherin. Furthermore, the tubulin polymerization inhibitory activity in vitro of 10b was 2.4 μM. In vivo anticancer assay, 10b effectively inhibited MGC-803 xenograft tumor growth without causing significant loss of body weight. These sulfanilamide-1,2,3-triazole hybrids as potent tubulin polymerization inhibitors might be used as promising candidates for cancer therapy.