Design, synthesis and bio-evaluation of novel 2-aryl-4-(3,4,5-trimethoxy-benzoyl)-5-substituted-1,2,3-triazoles as the tubulin polymerization inhibitors

Innovative medicinal chemistry strategies for enhancing drug solubility

Drug candidates with poor solubility have been recognized as the cause of many drug development failures, owing to the fact that low solubility is unfavorable for physicochemical, pharmacokinetic (PK) and pharmacodynamic (PD) properties. Given the imperative role of solubility during drug development, we herein summarize various strategies for solubility optimizations from a medicinal chemistry perspective, including introduction of polar group, salt formation, structural simplification, disruption of molecular planarity and symmetry, optimizations on the solvent exposed region as well as prodrug design. In addition, methods for solubility assessment and prediction are reviewed. Besides, we have deeply discussed the strategies for solubility improvement. This paper is expected to be beneficial for the development of drug-like molecules with good solubility.

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.

Discovery of novel arylamide derivatives containing piperazine moiety as inhibitors of tubulin polymerisation with potent liver cancer inhibitory activity

In this work, a series of novel arylamide derivatives containing piperazine moiety were designed and synthesised as tubulin polymerisation inhibitors. Among 25 target compounds, compound 16f (MY-1121) exhibited low nanomolar IC50 values ranging from 0.089 to 0.238 μM against nine human cancer cells. Its inhibitory effects on liver cancer cells were particularly evident with IC50 values of 89.42 and 91.62 nM for SMMC-7721 and HuH-7 cells, respectively. Further mechanism studies demonstrated that compound 16f (MY-1121) could bind to the colchicine binding site of β-tubulin and directly act on β-tubulin, thus inhibiting tubulin polymerisation. Additionally, compound 16f (MY-1121) could inhibit colony forming ability, cause morphological changes, block cell cycle arrest at the G2 phase, induce cell apoptosis, and regulate the expression of cell cycle and cell apoptosis related proteins in liver cancer cells. Overall, the promising bioactivities of compound 16f (MY-1121) make the novel arylamide derivatives have the value for further development as tubulin polymerisation inhibitors with potent anticancer activities.

Preparation of novel acyl pyrazoles and triazoles by means of oxidative functionalization reactions

Novel acyl pyrazoles and acyl triazoles have been prepared by means of the oxidative amidation of aldehydes in the presence of the requisite azole. Yields range from modest to good in both cases, and some limitations of the substrate scope have been discovered. Acyl pyrazoles were prepared by treatment of a mixture of aldehyde and pyrazole with an oxoammonium salt bearing the nitrate anion. In the case of acyl triazoles, the oxidative functionalization was performed using sodium persulfate as a terminal oxidant in the presence of a catalytic quantity of a nitroxide.

A novel tubulin inhibitor, 6h, suppresses tumor-associated angiogenesis and shows potent antitumor activity against non-small cell lung cancers

Tumor angiogenesis is closely associated with the metastasis and progression of non-small cell lung cancer (NSCLC), a highly vascularized solid tumor. However, novel therapeutics are lacking for the treatment of this cancer. Here, we developed a series of 2-aryl-4-(3,4,5-trimethoxy-benzoyl)-5-substituted-1,2,3-triazol analogs (6a-6x) as tubulin colchicine-binding site inhibitors, aiming to find a novel promising drug candidate for NSCLC treatment. We first identified 2-(2-fluorophenyl)-3-(3,4,5-trimethoxybenzoyl)-5-(3-hydroxyazetidin-1-yl)-2H-1,2,3-triazole (6h) as a hit compound, which inhibited angiogenesis induced by NSCLC cells both in vivo and in vitro. In addition, our data showed that 6h could tightly bind to the colchicine-binding site of tubulin and inhibit tubulin polymerization. We also found that 6h could effectively induce G2/M cell cycle arrest of A549 and H460 cells, inhibit cell proliferation, and induce apoptosis. Furthermore, we showed 6h had the potential to inhibit the migration and invasion of NSCLC cells, two basic characteristics of tumor metastasis. Finally, we found 6h could effectively inhibit tumor progression in A549 xenograft mouse models with minimal toxicity. Taken together, these findings provide strong evidence for the development of 6h as a promising microtubule colchicine-binding site inhibitor for NSCLC treatment.

Design, synthesis and evaluation of novel bis-substituted aromatic amide dithiocarbamate derivatives as colchicine site tubulin polymerization inhibitors with potent anticancer activities

As the continuation of our work on the development of tubulin inhibitors with potential anticancer activities, novel bis-substituted aromatic amide dithiocarbamate derivatives were designed by contacting bis-substituted aryl scaffolds (potential anti-tubulin fragments) with N-containing heterocycles (potential anti-tubulin fragments) in one hybrid using the anticancer dithioformate unit as the linker. The antiproliferative activity against three digestive tract tumor cells was evaluated and preliminary structure activity relationships were summarized. Among these compounds, compound 20q exhibited most potent antiproliferative activity against MGC-803, HCT-116, Kyse30 and Kyse450 cells with IC₅₀ values of 0.084, 0.227, 0.069 and 0.078 μM, respectively. In further studies, compound 20q was identified as a novel tubulin inhibitor targeting the colchicine binding site. Compound 20q could inhibit the microtubule assembly and disrupt cytoskeleton in Kyse30 and Kyse450 cells. The results of molecular docking suggested that compound 20q could tightly bind into the colchicine binding site of tubulin by hydrogen bonds and hydrophobic interactions. Compound 20q dose-dependently inhibited the cell growth and colony formation, effectively arrested cells at the G2/M phase and induce mitochondrial apoptosis in Kyse30 and Kyse450 cells. In addition, Compound 20q could regulate the expression of G2/M phase and mitochondrial apoptosis related proteins. Collectively, compound 20q was here reported as a novel tubulin inhibitor with potential anticancer activities.

W436, a novel SMART derivative, exhibits anti-hepatocarcinoma activity by inducing apoptosis and G2/M cell cycle arrest in vitro and in vivo and induces protective autophagy

Hepatocellular carcinoma (HCC) is considered one of the most common primary liver cancers and the second leading cause of cancer-associated mortality around the world annually. Therefore, it is urgent to develop novel drugs for HCC therapy. We synthesized a novel 4-substituted-methoxybenzoyl-aryl-thiazole (SMART) analog, (5-(4-aminopiperidin-1-yl)-2-phenyl-2H-1,2,3-triazol-4-yl) (3,4,5-trimethoxyphenyl) methanone (W436), with higher solubility, stability, and antitumor activity than SMART against HCC cells in vivo. The purpose of this study was to investigate the mechanisms by which W436 inhibited cell growth in HCC cells. We observed that W436 inhibited the proliferation of HepG2 and Hep3B cells in a dose-dependent manner. Importantly, the anticancer activity of W436 against HCC cells was even higher than that of SMART in vivo. In addition, the antiproliferative effects of W436 on HCC cells were associated with G2/M cell cycle arrest and apoptosis via the activation of reactive oxygen species-mediated mitochondrial apoptotic pathway. W436 also induced protective autophagy by inhibiting the protein kinase B/mammalian target of rapamycin pathway. At the same time, W436 treatment inhibited the cell adhesion and invasion as well as the process of epithelial-to-mesenchymal transition Taken together, our results showed that W436 had the promising potential for the therapeutic treatment of HCC with improved solubility, stability, and bioavailability.

Design, synthesis and biological evaluation of indole-based [1,2,4]triazolo[4,3-a] pyridine derivatives as novel microtubule polymerization inhibitors

A series of indole-based [1,2,4]triazolo [4,3-a]pyridine derivatives was designed and synthesized as novel microtubulin polymerization inhibitors by using a conformational restriction strategy. These compounds exhibited moderate to potent anti-proliferative activities against a panel of cancer cell lines (HeLa, A549, MCF-7 and HCT116). Among them, compound 12d featuring a N-methyl-5-indolyl substituent at the C-6 position of the [1,2,4]triazolo [4,3-a]pyridine core exhibited the highest antiproliferative activity with the IC₅₀ values ranging from 15 to 69 nM, and remarkable inhibitory effect on tubulin polymerization with an IC₅₀ value of 1.64 μM. Mechanistic studies revealed that compound 12d induced cellular apoptosis and cell cycle arrest at the G₂/M phase in a dose-dependent fashion. Moreover, compound 12d significantly suppressed wound closure and disturbed microtubule networks.

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.

Design, synthesis and biological evaluation of novel imidazole-chalcone derivatives as potential anticancer agents and tubulin polymerization inhibitors

Novel imidazole-chalcone derivatives were designed and synthesized as tubulin polymerization inhibitors and anticancer agents. The antiproliferative activity of the imidazole-chalcone was assessed on some human cancer cell lines including A549 (adenocarcinoma human alveolar basal epithelial cells), MCF-7 (human breast cancer cells), MCF-7/MX (mitoxantrone resistant human breast cancer cells), and HEPG2 (human hepatocellular carcinoma cells). Generally, the imidazole-chalcone derivatives exhibited more cytotoxicity on A549 cancer cells in comparison to the other three cell lines, among them compounds 9j' and 9g showed significant cytotoxicity with IC₅₀ values ranging from 7.05 to 63.43 μM against all the four human cancer cells. The flow cytometry analysis of A549 cancer cells treated with 9g and 9j' displayed that these compounds induced cell cycle arrest at the G2/M phase at low concentrations and increased the number of apoptotic cells (cells in subG1 phase) at higher concentrations. They have also inhibited tubulin polymerization similar to combretastatin A-4 (CA-4). Annexin V binding staining assay in A549 cancer cells revealed that compound 9j' induced apoptosis (early and late). Finally, molecular docking studies of 9j' into the colchicine-binding site of tubulin presented the probable interactions of these compounds with tubulin.

Discovery and development of novel pyrimidine and pyrazolo/thieno-fused pyrimidine derivatives as potent and orally active inducible nitric oxide synthase dimerization inhibitor with efficacy for arthritis

In order to discover and develop drug-like anti-inflammatory agents against arthritis, based on "Hit" we found earlier and to overcome drawbacks of toxicity, twelve series of total 89 novel pyrimidine, pyrazolo[4,3-d]pyrimidine and thieno[3,2-d]pyrimidine derivatives were designed, synthesized and screened for their anti-inflammatory activity against NO and toxicity for normal liver cells (LO2). Relationships of balance toxicity and activity have been summarized through multi-steps, and title compounds 22o, 22l were found to show lower toxicity (against LO2: IC₅₀ = 2934, 2301 μM, respectively) and potent effect against NO release (IR = 98.3, 97.67%, at 10 μM, respectively). Furthermore, compound 22o showed potent iNOS inhibitory activity with value of IC₅₀ is 0.96 μM and could interfere stability and formation of the active dimeric iNOS. It's anti-inflammatory activity in vivo was assessed by AIA rat model. Furthermore, the results of metabolic stability, CYP, PK study in vivo, acute toxicity study and subacute toxicity assessment indicated this compound had good drug-like properties for treatment.

Design, synthesis and evaluation of antiproliferative and antitubulin activities of 5-methyl-4-aryl-3-(4-arylpiperazine-1-carbonyl)-4H-1,2,4-triazoles

A series of novel 5-methyl-4-aryl-3-(4-arylpiperazine-1-carbonyl)-4H-1,2,4-triazoles possessing 1,2,4-triazole as the hydrogen-bond acceptor were designed, synthesized and evaluated for their antiproliferative and tubulin polymerization inhibitory activities. Some of them exhibited moderate activities in vitro against the three cancer cell lines including SGC-7901, A549 and HeLa. Compound 6e exhibited the highest potency against the three cancer cell lines. Moreover, the tubulin polymerization experiments indicated that compound 6e could inhibit the tubulin polymerization. Immunofluorescence study and cell cycle analysis clearly revealed compound 6e could disrupt intracellular microtubule organization, arrest cell cycle at the G2/M phase. In addition, molecular docking analysis demonstrated the interaction of compound 6e at the colchicine-binding site of tubulin. These preliminary results suggested that compound 6e is a new colchicine binding site inhibitor and worthy of further investigation.