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

Design, synthesis, and bioevaluation of diarylpyrimidine derivatives as novel microtubule destabilizers

In this work, a series of new diarylpyrimidine derivatives as microtubule destabilizers were designed, synthesized, and evaluated for anticancer activities. Based on restriction configuration strategy, we introduced the pyrimidine moiety containing the hydrogen-bond acceptors as cis-olefin bond of CA-4 analogs to improve structural stability. Compounds 11a-t exerted antiproliferative activities against three human cancer cell lines (SGC-7901, HeLa, and MCF-7), due to tubulin polymerization inhibition, showing high selectivity toward cancer cells in comparison with non-tumoral HSF cells, as evidenced by MTT assays. In mechanistic investigations, compound 11s remarkably inhibited tubulin polymerization and disorganized microtubule in SGC-7901 cells by binding to tubulin. Moreover, 11s caused G2/M phase cell cycle arrest in SGC-7901 cells in a concentration-dependent manner. Furthermore, molecular modeling analysis revealed that 11s interacts with tubulin through binding to the colchicine site. In addition, the prediction of physicochemical properties disclosed that 11s conformed well to the Lipinski's rule of five. This work offered a fresh viewpoint for the discovery of new tubulin-targeting anticancer drugs.

The Chromenopyridine Scaffold: A Privileged Platform in Drug Design

The chromenopyridine scaffold represents an important class of heterocyclic compounds exhibiting a broad spectrum of biological properties. This review describes novel and efficient procedures for the synthesis of this scaffold. Herein, several methods were detailed and grouped according to their starting material (e.g., salicylaldehydes, chromones, chromanones and coumarins) and respective biological activity, when reported. This review highlights the potential of the reported synthetic strategies for preparing chromenopyridine derivatives with promising biological activity, paving the way for further developments in drug discovery.

Design, synthesis of combretastatin A-4 piperazine derivatives as potential antitumor agents by inhibiting tubulin polymerization and inducing autophagy in HCT116 cells

A series of combretastatin A-4 (CA-4) derivatives were designed and synthesized, which contain stilbene core structure with different linker, predominantly piperazine derivatives. These compounds were evaluated for their cytotoxic activities against four cancer cell lines, HCT116, A549, AGS, and SK-MES-1. Among them, compound 13 displayed the best effectiveness with IC50 values of 0.227 μM and 0.253 μM against HCT116 and A549 cells, respectively, showing low toxicity to normal cells. Mechanistic studies showed that 13 inhibited HCT116 proliferation via arresting cell cycle at the G2/M phase through disrupting the microtubule network and inducing autophagy in HCT116 cells by regulating the expression levels of autophagy-related proteins. In addition, 13 displayed antiproliferative activities against A549 cells through blocking the cell cycle and inducing A549 cells apoptosis. Because of the poor water solubility of 13, four carbohydrate conjugates were synthesized which exhibited better water solubility. Further investigations revealed that 13 showed positive effects in vivo anticancer study with HCT116 xenograft models. These data suggest that 13 could be served as a promising lead compound for further development of anti-colon carcinoma agent.

An update on the development on tubulin inhibitors for the treatment of solid tumors

INTRODUCTION

Microtubules play a vital role in cancer therapeutics. They are implicated in tumorigenesis, thus inhibiting tubulin polymerization in cancer cells, and have now become a significant target for anticancer drug development. A plethora of drug molecules has been crafted to influence microtubule dynamics and presently, numerous tubulin inhibitors are being investigated. This review discusses the recently developed inhibitors including natural products, and also examines the preclinical and clinical data of some potential molecules.

AREA COVERED

The current review article summarizes the development of tubulin inhibitors while detailing their specific binding sites. It also discusses the newly designed inhibitors that may be useful in the treatment of solid tumors.

EXPERT OPINION

Microtubules play a crucial role in cellular processes, especially in cancer therapy where inhibiting tubulin polymerization holds promise. Ongoing trials signify a commitment to revolutionizing cancer treatment and exploring targeted therapies. Challenges in microtubule modulation, like resistance and off-target effects, demand focused efforts, emphasizing combination therapies and personalized treatments. Beyond microtubules, promising avenues in cancer research include immunotherapy, genomic medicine, CRISPR gene editing, liquid biopsies, AI diagnostics, and stem cell therapy, showcasing a holistic approach for future advancements.

Discovery of novel 2-(trifluoromethyl)quinolin-4-amine derivatives as potent antitumor agents with microtubule polymerization inhibitory activity

In this work, a series of 2-(trifluoromethyl)quinolin-4-amine derivatives were designed and synthesized through structural optimization strategy as a microtubule-targeted agents (MTAs) and their cytotoxicity activity against PC3, K562 and HeLa cell lines were evaluated. The half maximal inhibitory concentration (IC50) of 5e, 5f, and 5o suggested that their potency of anti-proliferative activities against HeLa cell lines were better than the combretastatin A-4. Compound 5e showed the higher anti-proliferative activity against PC3, K562 and HeLa in vitro with IC50 values of 0.49 µM, 0.08 µM and 0.01 µM, respectively. Further mechanism study indicated that the representative compound 5e was new class of tubulin inhibitors by EBI competition assay and tubulin polymerization assays, it is similar to colchicine. Immunofluorescence staining revealed that compound 5e apparently disrupted tubulin network in HeLa cells, and compound 5e arrested HeLa cells at the G2/M phase and induced cells apoptosis in a dose-dependent manner. Molecular docking results illustrated that the hydrogen bonds of represented compounds reinforced the interactions in the pocket of colchicine binding site. Preliminary results suggested that 5e deserves further research as a promising tubulin inhibitor for the development of anticancer agents.

Design, synthesis and antiproliferative screening of newly synthesized acrylate derivatives as potential anticancer agents

A new series of acrylic acid and acrylate ester derivatives as modified analogs of tubulin polymerization inhibitors were designed and synthesized. The antiproliferative activity of the constructed molecules was investigated against MCF-7 breast carcinoma cells using CA-4 as positive molecule. Methyl acrylate ester 6e emerged as the most potent cytotoxic agent against MCF-7 cells, with an IC50 value of 2.57 ± 0.16 μM. Also, methyl acrylate ester molecule 6e showed good β-tubulin polymerization inhibition activity. Cellular cycle analysis showed that compound 6e can arrest MCF-7 cells at the G2/M phase. In addition, this compound produced a significant increase in apoptotic power as compared to control untreated MCF-7 cells. Furthermore, the effect of acrylate ester 6e on the gene expression levels of p53, Bax and Bcl-2 was investigated. This molecule increased the expression levels of both p53 and Bax, and decreased the gene expression level of Bcl-2 as compared to control untreated MCF-7 carcinoma cells.

A Review of the Recent Developments of Molecular Hybrids Targeting Tubulin Polymerization

Microtubules are cylindrical protein polymers formed from αβ-tubulin heterodimers in the cytoplasm of eukaryotic cells. Microtubule disturbance may cause cell cycle arrest in the G2/M phase, and anomalous mitotic spindles will form. Microtubules are an important target for cancer drug action because of their critical role in mitosis. Several microtubule-targeting agents with vast therapeutic advantages have been developed, but they often lead to multidrug resistance and adverse side effects. Thus, single-target therapy has drawbacks in the effective control of tubulin polymerization. Molecular hybridization, based on the amalgamation of two or more pharmacophores of bioactive conjugates to engender a single molecular structure with enhanced pharmacokinetics and biological activity, compared to their parent molecules, has recently become a promising approach in drug development. The practical application of combined active scaffolds targeting tubulin polymerization inhibitors has been corroborated in the past few years. Meanwhile, different designs and syntheses of novel anti-tubulin hybrids have been broadly studied, illustrated, and detailed in the literature. This review describes various molecular hybrids with their reported structural-activity relationships (SARs) where it is possible in an effort to generate efficacious tubulin polymerization inhibitors. The aim is to create a platform on which new active scaffolds can be modeled for improved tubulin polymerization inhibitory potency and hence, the development of new therapeutic agents against cancer.

An Expedient Approach to Pyrazolo[3,4-b]pyridine-3-carboxamides via Palladium-Catalyzed Aminocarbonylation

Pyrazolo[3,4-b]pyridine is a privileged scaffold found in many small drug molecules that possess a wide range of pharmacological properties. Efforts to further develop and exploit synthetic methodologies that permit the functionalization of this heterocyclic moiety warrant investigation. To this end, a series of novel 1,3-disubstituted pyrazolo[3,4-b]pyridine-3-carboxamide derivatives have been prepared by introducing the 3-carboxamide moiety using palladium-catalyzed aminocarbonylation methodology and employing CO gas generated ex situ using a two-chamber reactor (COware®). The functional group tolerance of this optimized aminocarbonylation protocol is highlighted through the synthesis of a range of diversely substituted C-3 carbox­amide pyrazolo[3,4-b]pyridines in excellent yields of up to 99%.

Discovery of novel quinoline-based analogues of combretastatin A-4 as tubulin polymerisation inhibitors with apoptosis inducing activity and potent anticancer effect

A new series of quinoline derivatives of combretastatin A-4 have been designed, synthesised and demonstrated as tubulin polymerisation inhibitors. These novel compounds showed significant antiproliferative activities, among them, 12c exhibited the most potent inhibitory activity against different cancer cell lines (MCF-7, HL-60, HCT-116 and HeLa) with IC50 ranging from 0.010 to 0.042 µM, and with selectivity profile against MCF-10A non-cancer cells. Further mechanistic studies suggest that 12c can inhibit tubulin polymerisation and cell migration, leading to G2/M phase arrest. Besides, 12c induces apoptosis via a mitochondrial-dependant apoptosis pathway and caused reactive oxygen stress generation in MCF-7 cells. These results provide guidance for further rational development of potent tubulin polymerisation inhibitors for the treatment of cancer.HighlightsA novel series of quinoline derivatives of combretastatin A-4 have been designed and synthesised.Compound 12c showed significant antiproliferative activities against different cancer cell lines.Compound 12c effectively inhibited tubulin polymerisation and competed with [3H] colchicine in binding to tubulin.Compound 12c arrested the cell cycle at G2/M phase, effectively inducing apoptosis and inhibition of cell migration.

Design, Synthesis, and Antipoliferative Activities of Novel Substituted Imidazole-Thione Linked Benzotriazole Derivatives

A new series of benzotriazole moiety bearing substituted imidazol-2-thiones at N1 has been designed, synthesized and evaluated for in vitro anticancer activity against the different cancer cell lines MCF-7(breast cancer), HL-60 (Human promyelocytic leukemia), and HCT-116 (colon cancer). Most of the benzotriazole analogues exhibited promising antiproliferative activity against tested cancer cell lines. Among all the synthesized compounds, BI9 showed potent activity against the cancer cell lines such as MCF-7, HL-60 and HCT-116 with IC50 3.57, 0.40 and 2.63 µM, respectively. Compound BI9 was taken up for elaborate biological studies and the HL-60 cells in the cell cycle were arrested in G2/M phase. Compound BI9 showed remarkable inhibition of tubulin polymerization with the colchicine binding site of tubulin. In addition, compound BI9 promoted apoptosis by regulating the expression of pro-apoptotic protein BAX and anti-apoptotic proteins Bcl-2. These results provide guidance for further rational development of potent tubulin polymerization inhibitors for the treatment of cancer.

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.

Pyridine moiety: An insight into recent advances in treatment of cancer

The incidence of cancer is increasing worldwide, affecting a vast majority of the human population. As new different anticancer agents are being developed now, the requirement is to deal somehow with them and evaluate their safety. Among them, pyridine based drugs are contributing a lot, as it is one of the imperative pharmacophores occurring synthetically as well as naturally in heterocyclic compounds, and having a wide range of therapeutic applications in the area of drug discovery, thereby offering many chances for further improvement in antitumor agents via acting onto numerous receptors of extreme prominence. Many pyridine derivatives have been reported to inhibit enzymes, receptors and many other targets for controlling and curing the global health issue of cancer. Nowadays, in combination with other moieties, researchers are focusing on the development of pyridine-based new derivatives for cancer treatment. Therefore, this review sheds light on the recent therapeutic expansions of pyridine together with its molecular docking, structure-activity-relationship, availability in the market, and a summary of recently patented and published research works that shall jointly help the scientists to produce effective drugs with the desired pharmacological activity.

Discovery of highly potent tubulin polymerization inhibitors: Design, synthesis, and structure-activity relationships of novel 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidines

By removing 5-methyl and 6-acetyl groups in our previously reported compound 3, we designed a series of novel 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidine derivatives as potential tubulin polymerization inhibitors. Among them, compound 5e displayed low nanomolar antiproliferative efficacy on HeLa cells which was 166-fold higher than the lead analogue 3. Interestingly, 5e displayed significant selectivity in inhibiting cancer cells over HEK-293 (normal human embryonic kidney cells). In addition, 5e dose-dependently arrested HeLa in G2/M phase through the alterations of the expression levels of p-cdc2 and cyclin B1, and caused HeLa cells apoptosis by regulation of expressions of cleaved PARP. Further evidence demonstrated that 5e effectively inhibited tubulin polymerization and was 3-fold more powerful than positive control CA-4. Moreover, molecular docking analysis indicated that 5e overlapped well with CA-4 in the colchicine-binding site. These studies demonstrated that 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidine skeleton might be used as the leading unit to develop novel tubulin polymerization inhibitors as potential anticancer agents.

Synthesis, biological evaluation, and structure-activity relationships of new tubulin polymerization inhibitors based on 5-amino-1,2,4-triazole scaffold

Based on our previous research, thirty new 5-amino-1H-1,2,4-triazoles possessing 3,4,5-trimethoxyphenyl moiety were synthesized, and evaluated for antiproliferative activities. Among them, compounds IIa, IIIh, and IIIm demonstrated significant antiproliferative activities against a panel of tumor cell lines, and the promising compound IIIm dose-dependently caused G2/M phase arrest in HeLa cells. Furthermore, analogue IIa exhibited the most potent tubulinpolymerization inhibitory activity with an IC₅₀ value of 9.4 μM, and molecular modeling studies revealed that IIa formed stable interactions in the colchicine-binding site of tubulin, suggesting that 5-amino-1H-1,2,4-triazole scaffold has potential for further investigation to develop novel tubulin polymerization inhibitors with anticancer activity.