Design,synthesis and biological evaluation of anti-pancreatic cancer activity of plinabulin derivatives based on the co-crystal structure

Based on the co-crystal structures of tubulin with plinabulin and Compound 1 (a derivative of plinabulin), a total of 18 novel plinabulin derivatives were designed and synthesized. Their biological activities were evaluated against human pancreatic cancer BxPC-3 cell lines. Two novel Compounds 13d and 13e exhibited potent activities with IC₅₀ at 1.56 and 1.72?nM, respectively. The tubulin polymerization assay indicated that these derivatives could inhibit microtubule polymerization. Furthermore, the interaction between tubulin and these compounds were elucidated by molecular docking. The binding modes of Compounds 13d and 13e were similar to the co-crystal structure of Compound 1. H-π interaction was observed between the aromatic hydrogen of thiophene moiety with Phe20, which could enhance their binding affinities.     

Structure-based design and synthesis of novel furan-diketopiperazine-type derivatives as potent microtubule inhibitors for treating cancer

Plinabulin, a synthetic analog of the marine natural product “diketopiperazine phenylahistin,” displayed depolymerization effects on microtubules and targeted the colchicine site, which has been moved into phase III clinical trials for the treatment of non-small cell lung cancer (NSCLC) and the prevention of chemotherapy-induced neutropenia (CIN). To develop more potent anti-microtubule and cytotoxic derivatives, the co-crystal complexes of plinabulin derivatives were summarized and analyzed. We performed further modifications of the tert-butyl moiety or C-ring of imidazole-type derivatives to build a library of molecules through the introduction of different groups for novel skeletons. Our structure–activity relationship study indicated that compounds 17o (IC₅₀ = 14.0 nM, NCI-H460) and 17p (IC₅₀ = 2.9 nM, NCI-H460) with furan groups exhibited potent cytotoxic activities at the nanomolar level against various human cancer cell lines. In particular, the 5-methyl or methoxymethyl substituent of furan group could replace the alkyl group of imidazole at the 5-position to maintain cytotoxic activity, contradicting previous reports that the tert-butyl moiety at the 5-position of imidazole was essential for the activity of such compounds. Immunofluorescence assay indicated that compounds 17o and 17p could efficiently inhibit microtubule polymerization. Overall, the novel furan-diketopiperazine-type derivatives could be considered as a potential scaffold for the development of anti-cancer drugs.     

New benzimidazole-2-urea derivates as tubulin inhibitors

Emerging drug resistance and other drawbacks limit tubulin inhibitors’ therapeutic applications and developing novel tubulin inhibitors still attracts intensive efforts. We describe the discovery and structure–activity relationship study of a series of benzimidazole-2-urea derivatives as novel β tubulin inhibitors. The representative compound 6o potently suppressed the proliferation of a panel of human cancer cells (NCI-H460, Colo205, K562, A431, HepG2, Hela, MDA-MB-435S) with IC₅₀ values of 0.040, 0.050, 0.006, 0.026, 1.774, 0.452 and 0.052 μM, respectively. Compound 6o obviously inhibited NCI-H460 spindles formation and induced cell cycle arrest at G2/M phase at 0.10 μM. Computational study suggested that 6o interacts with β tubulin in a novel binding mode. Our results suggested that benzimidazole-2-urea derivatives might be promising tubulin inhibitors with novel binding mode for further development.     

Design,synthesis, and biological evaluation of 4-phenoxyquinoline derivatives as potent c-Met kinase inhibitor

A series of novel 4-phenoxyquinoline derivatives containing 3-oxo-3,4-dihydro-quinoxaline moiety were synthesized and evaluated for their antiproliferative activity against five human cancer cell lines (A549, H460, HT-29, MKN-45 and U87MG) in vitro. Most of the tested compounds exhibited more potent inhibitory activities than the positive control foretinib. Compound 1b, 1s and 1t were further examined for their inhibitory activity against c-Met kinase. The most promising compound 1s (with c-Met IC₅₀ value of 1.42 nM) showed remarkable cytotoxicity against A549, H460, HT-29, MKN45 and U87MG cell lines with IC₅₀ values of 0.39 μM, 0.18 μM, 0.38 μM, 0.81 μM, respectively. Their preliminary structure-activity relationships (SARs) study indicated that the replacement of the aromatic ring with the cyclohexane improved their antiproliferative activity.     

Discovery and optimization of 3,4,5-trimethoxyphenyl substituted triazolylthioacetamides as potent tubulin polymerization inhibitors

Based on our previous research, three series of new triazolylthioacetamides possessing 3,4,5-trimethoxyphenyl moiety were synthesized, and evaluated for antiproliferative activities and inhibition of tubulin polymerization. The most promising compounds 8b and 8j demonstrated more significant antiproliferative activities against MCF-7, HeLa, and HT-29 cell lines than our lead compound 6. Moreover, analogues 8f, 8j, and 8o manifested more potent antiproliferative activities against HeLa cell line with IC₅₀ values of 0.04, 0.05 and 0.16?μM, respectively, representing 100-, 82-, and 25-fold improvements of the activity compared to compound 6. Furthermore, the representative compound, 8j, was found to induce significant cell cycle arrest at the G₂/M phase in HeLa cell lines via a concentration-dependent manner. Meanwhile, compound 8b exhibited the most potent tubulin polymerization inhibitory activity with an IC₅₀ value of 5.9?μM, which was almost as active as that of CA-4 (IC₅₀?=?4.2?μM). Additionally, molecular docking analysis suggested that 8b formed stable interactions in the colchicine-binding site of tubulin.     

Modification of imidazothiazole derivatives gives promising activity in B-Raf kinase enzyme inhibition; synthesis,in vitro studies and molecular docking

B-Raf mutation was identified as a key target in cancer treatment. Based on structural features of dabrafenib (potent FDA approved B-Raf inhibitor), the design of new NH₂-based imidazothiazole derivatives was carried out affording new highly potent derivatives of imidazothiazole-based scaffold with amino substitution on the terminal phenyl ring as well as side chain with sulfonamide group and terminal substituted phenyl ring. In vitro enzyme assay was investigated against V600E B-Raf kinase. Compounds 10l, 10n and 10o showed higher inhibitory activities (IC₅₀ = 1.20, 4.31 and 6.21 nM, respectively). In vitro cytotoxicity evaluation was assessed against NCI-60 cell lines. Most of tested derivatives showed cytotoxic activities against melanoma cell line. Compound 10k exhibited most potent activity (IC₅₀ = 2.68 µM). Molecular docking study revealed that the new designed derivatives preserved the same binding mode of dabrafenib with V600E B-Raf active site. It was investigated that the new modification in the synthesized derivatives (substituted with NH₂) had a significant inhibitory activity towards V600E B-Raf. This core scaffold is considered a key compound for further structural and molecular optimization.     

Design,synthesis and biological evaluation of novel spiro-pentacylamides as acetyl-CoA carboxylase inhibitors

Acetyl-CoA carboxylase (ACC) catalyzes the rate-determining step in de novo lipogenesis and plays an important role in the regulation of fatty acid oxidation. Therefore, ACC inhibition offers a promising option for intervention in nonalcoholic fatty liver disease (NAFLD), type 2 diabetes (T2DM) and cancer. In this paper, a series of spiropentacylamide derivatives were synthesized and evaluated for their ACC1/2 inhibitory activities and anti-proliferation effects on A549, H1975, HCT116, SW620 and Caco-2 cell lines in vitro. Compound 6o displayed potent ACC1/2 inhibitory activity (ACC1 IC₅₀?=?0.527?μM, ACC2 IC₅₀?=?0.397?μM) and the most potent anti-proliferation activities against A549, H1975, HCT116, SW620 and Caco-2 cell lines, with IC₅₀ values of 1.92?μM, 0.38?μM, 1.22?μM, 2.05?μM and 5.42?μM respectively. Further molecular docking studies revealed that compound 6o maintained hydrogen bonds between the two carbonyls and protein backbone NHs (Glu-B2026 and Gly-B1958). These results indicate that compound 6o is a promising ACC1/2 inhibitor for the potent treatment of cancer.     

Novel quinoline-3-carboxamides (Part 2): Design,optimization and synthesis of quinoline based scaffold as EGFR inhibitors with potent anticancer activity

EGFR has a key role in cell growth. Its mutation and overexpression share in epithelial malignancies and tumor growth. Quinazoline and quinoline derivatives are common anticancer intracellular inhibitors of EGFR kinase, and their optimization is an important issue for development of potent targeted anticancer agents. Based on these facts, different strategies were used for optimizing our reported quinoline-3-carboxamide compound III (EGFR IC₅₀ = 5.283 µM and MCF-7 IC₅₀ = 3.46 µM) through different molecular modeling techniques. The optimized compounds were synthesized and subjected to EGFR binding assay and accordingly some more potent inhibitors were obtained. The most potent quinoline-3-carboxamides were the furan derivative 5o; thiophene derivative 6b; and benzyloxy derivative 10 showing EGFR IC₅₀ values 2.61, 0.49 and 1.73 μM, respectively. Furthermore, the anticancer activity of compounds eliciting potent EGFR inhibition (5o, 5p, 6b, 8a, 8b, and 10) was evaluated against MCF-7 cell line where they exhibited IC₅₀ values 3.355, 3.647, 5.069, 3.617, 0.839 and 10.85 μM, respectively. Compound 6b was selected as lead structure for further optimization hoping to produce more potent EGFR inhibitors.     

Discovery of thiazolidin-4-one urea analogues as novel multikinase inhibitors that potently inhibit FLT3 and VEGFR2

A series of novel thiazolidine-4-one urea analogues were designed, synthesized and biologically evaluated. The structure-activity relationship (SAR) at several positions of the scaffolds was investigated and its binding mode was analyzed by molecular modeling studies. Compound 17b proved to be the most potent one, and IC₅₀ values against A549 and HT-29 cancer cell lines were 0.65?μM and 0.11?μM, respectively. The results of kinase profile demonstrated that compound 17b is a multikinase inhibitor that potently inhibits FLT3 (IC₅₀?=?8.6?nM) and VEGFR2 (IC₅₀?=?18.7?nM). The results of real-time live-cell imaging indicated that compound 17b showed excellent cytotoxicity and anti-proliferative activity against HT-29 cancer cells in a time- and dose-dependent manner, which was significantly potent than that of Cabozantinib. In addition, in vitro antitumor activity was associated with inducing cancer cell apoptosis and suppression of cancer cell migration.     

Synthesis,biological evaluation and molecular docking studies of aminochalcone derivatives as potential anticancer agents by targeting tubulin colchicine binding site

A series of aminochalcone derivatives have been synthesized, characterized by HRMS, ¹H NMR and ¹³C NMR and evaluated for their antiproliferative activity against HepG2 and HCT116 human cancer cell lines. The most of new synthesized compounds displayed moderate to potent antiproliferative activity against test cancer cell lines. Among the derivatives, compound 4 displayed potent inhibitory activity with IC₅₀ values ranged from 0.018 to 5.33 μM against all tested cancer cell lines including drug resistant HCT-8/T. Furthermore, this compound showed low cytotoxicity on normal human cell lines (LO2). The in vitro tubulin polymerization assay showed that compound 4 inhibited tubulin assembly in a concentration-dependent manner with IC₅₀ value of 7.1 μM, when compared to standard colchicine (IC₅₀ = 9.0 μM). Further biological evaluations revealed that compound 4 was able to arrest the cell cycle in G2/M phase. Molecular docking study demonstrated the interaction of compound 4 at the colchicine binding site of tubulin. All the results indicated that compound 4 is a promising inhibitor of tubulin polymerization for the treatment of cancer.     

Design,synthesis and molecular modeling of new 4-phenylcoumarin derivatives as tubulin polymerization inhibitors targeting MCF-7 breast cancer cells

A new set of 4-phenylcoumarin derivatives was designed and synthesized aiming to introduce new tubulin polymerization inhibitors as anti-breast cancer candidates. All the target compounds were evaluated for their cytotoxic effects against MCF-7 cell line, where compounds 2f, 3a, 3b, 3f, 7a and 7b, showed higher cytotoxic effect (IC₅₀?=?4.3–21.2?μg/mL) than the reference drug doxorubicin (IC₅₀?=?26.1?μg/mL), additionally, compounds 1 and 6b exhibited the same potency as doxorubicin (IC₅₀?=?25.2 and 28.0?μg/mL, respectively). The thiazolidinone derivatives 3a, 3b and 3f with potent and selective anticancer effects towards MCF-7 cells (IC₅₀?=?11.1, 16.7 and 21.2?μg/mL) were further assessed for tubulin polymerization inhibition effects which showed that the three compounds were potent tubulin polymerization suppressors with IC₅₀ values of 9.37, 2.89 and 6.13?μM, respectively, compared to the reference drug colchicine (IC₅₀?=?6.93?μM). The mechanistic effects on cell cycle progression and induction of apoptosis in MCF-7 cells were determined for compound 3a due to its potent and selective cytotoxic effects in addition to its promising tubulin polymerization inhibition potency. The results revealed that compound 3a induced cell cycle cessation at G2/M phase and accumulation of cells in pre-G1 phase and prevented its mitotic cycle, in addition to its activation of caspase-7 mediating apoptosis of MCF-7 cells. Molecular modeling studies for compounds 3a, 3b and 3f were carried out on tubulin crystallography, the results indicated that the compounds showed binding mode similar to the co-crystalized ligand; colchicine. Moreover, pharmacophore constructed models and docking studies revealed that thiazolidinone, acetamide and coumarin moieties are crucial for the activity. Molecular dynamics (MD) studies were carried out for the three compounds over 100?ps. MD results of compound 3a showed that it reached the stable state after 30?ps which was in agreement with the calculated potential and kinetic energy of compound 3a.     

Design,synthesis and biological evaluation of a series of pyrano chalcone derivatives containing indole moiety as novel anti-tubulin agents

A new series of pyrano chalcone derivatives containing indole moiety (3–42, 49a–49r) were synthesized and evaluated for their antiproliferative activities. Among all the compounds, compound 49b with a propionyloxy group at the 4-position of the left phenyl ring and N-methyl-5-indoly on the right ring displayed the most potent cytotoxic activity against all tested cancer cell lines including multidrug resistant phenotype, which inhibits cancer cell growth with IC₅₀ values ranging from 0.22 to 1.80 μM. Furthermore, 49b significantly induced cell cycle arrest in G2/M phase and inhibited the polymerization of tubulin. Molecular docking analysis demonstrated the interaction of 49b at the colchicine binding site of tubulin. In experiments in vivo, 49b exerted potent anticancer activity in HepG2 human liver carcinoma in BALB/c nude mice. These results indicated these compounds are promising inhibitors of tubulin polymerization for the potential treatment of cancer.     

Synthesis,biological evaluation and molecular modeling of 1,3,4-thiadiazol-2-amide derivatives as novel antitubulin agents

A series of 1,3,4-thiadiazol-2-amide derivatives (6a–w) were designed and synthesized as potential inhibitors of tubulin polymerization and as anticancer agents. The in vitro anticancer activities of these compounds were evaluated against three cancer cell lines by the MTT method. Among all the designed compounds, compound 6f exhibited the most potent anticancer activity against A549, MCF-7 and HepG2 cancer cell lines with IC₅₀ values of 0.03 μM, 0.06 μM and 0.05 μM, respectively. Compound 6f also exhibited significant tubulin polymerization inhibitory activity (IC₅₀ = 1.73 μM), which was superior to the positive control. The obtained results, along with a 3D-QSAR study and molecular docking that were used for investigating the probable binding mode, could provide an important basis for further optimization of compound 6f as a novel anticancer agent.     

Synthesis and biological evaluation of novel 4,7-dihydroxycoumarin derivatives as anticancer agents

A series of novel 4,7-dihydroxycoumarin based acryloylcyanohydrazone derivatives were synthesized and evaluated for antiproliferative activity against four different cancer cell lines (A549, HeLa, SKNSH, and MCF7). Most of the compounds displayed potent cytotoxicity with IC₅₀ values ranging from 3.42 to 31.28 µM against all the tested cancer cell lines. The most active compound, 8h was evaluated for pharmacological mechanistic studies on cell cycle progression and tubulin polymerization inhibition assay. The results revealed that the compound 8h induced the cell cycle arrest at G2/M phase and inhibited tubulin polymerization with IC₅₀ = 6.19 µM. Experimental data of the tubulin polymerization inhibition assay was validated by molecular docking technique and the results exhibited strong hydrogen bonding interactions with amino acids (ASN-101, TYR-224, ASN-228, LYS-254) of tubulin.     

Design,synthesis and biological evaluation of millepachine derivatives as a new class of tubulin polymerization inhibitors

A series of novel tubulin polymerization inhibitors (9a–9p) have been synthesized and evaluated for their in vitro and in vivo biological activities. Among these compounds, 9e displayed strong antiproliferative activity against several tumor cell lines (IC₅₀ = 0.15–0.62 μM). Compound 9e was also shown to arrest cells in the G2/M phase of the cell cycle and inhibit the polymerization of tubulin. Molecular docking studies suggested that 9e binds into the colchicine binding site of tubulin. In xenograft experiments, 9e exerted more potent anticancer effect than anticancer drug taxol against the H460 Human lung carcinoma in BALB/c nude mice. In summary, these findings suggest that 9e is a promising new antimitotic compound for the potential treatment of cancer.     

Potent dual EGFR/Her4 tyrosine kinase inhibitors containing novel (1,2-dithiolan-4-yl)acetamides

Modifications at C₆ and C₇ positions of 3-cyanoquinolines 6 and 7 led to potent inhibitors of the ErbB family of kinases particularly against EGFR^WT and Her4 enzymes in the radioisotope filter binding assay. The lead (4, SAB402) displayed potent dual biochemical activities with EGFR^WT/Her4 IC₅₀ ratio of 80 due to its potent inhibition of Her4 activity (IC₅₀ 0.03 nM), however, the selectivity towards activating mutations (EGFR^L858R, EGFR^ex19del) was decreased. Inhibitor 4 also exhibited excellent growth inhibition in seven different cancer types and reduced cell viability in female NMRI nude mice in the intraperitoneally implanted hollow fibers which have been loaded with MOLT-4 (leukemia) and NCI-H460 (NSCLC) cells in a statistically significant manner.     

Novel benzotriazole N-acylarylhydrazone hybrids: Design,synthesis, anticancer activity,effects on cell cycle profile,caspase-3 mediated apoptosis and FAK inhibition

A series of novel benzotriazole N-acylarylhydrazone hybrids was synthesized according fragment-based design strategy. All the synthesized compounds were evaluated for their anticancer activity against 60 human tumor cell lines by NCI (USA). Five compounds: 3d, 3e, 3f, 3o and 3q exhibited significant to potent anticancer activity at low concentrations. Compound 3q showed the most prominent broad-spectrum anticancer activity against 34 tumor cell lines, with mean growth inhibition percent of 45.80%. It exerted the highest potency against colon HT-29 cell line, with cell growth inhibition 86.86%. All leukemia cell lines were highly sensitive to compound 3q. Additionally, compound 3q demonstrated lethal activity to MDA-MB-435 belonging melanoma. Compound 3e exhibited the highest anticancer activity against leukemic CCRF-CEM and HL-60(TB) cell lines, with cell growth inhibition 86.69% and 86.42%, respectively. Moreover, it exerted marked potency against ovarian OVCAR-3 cancer cell line, with cell growth inhibition 78.24%. Four compounds: 3d, 3e, 3f and 3q were further studied through determination of IC₅₀ values against the most sensitive cancer cell lines. The four compounds exhibited highly potent anticancer activity against ovarian cancer OVCAR-3 and leukemia HL-60 (TB) cell lines, with IC₅₀ values in nano-molar range between 25 and 130 nM. They showed 18–2.3 folds more potent anticancer activity than doxorubicin. The most prominent compound was 3e, (IC₅₀ values 29 and 25 nM against OVCAR-3 and HL-60 (TB) cell lines, respectively), representing 10 and 18 folds more potency than doxorubicin. The anti-proliferative activity of these four compounds appeared to correlate well with their ability to inhibit FAK at nano-molar range between 44.6 and 80.75 nM. Compound 3e was a potent, inhibitor of FAK and Pyk2 activity with IC₅₀ values of 44.6 and 70.19 nM, respectively. It was 1.6 fold less potent for Pyk2 than FAK. Additionally, it displayed inhibition in cell based assay measuring phosphorylated-FAK (IC₅₀ = 32.72 nM). Inhibition of FAK enzyme led to a significant increase in the level of active caspase-3, compared to control (11.35 folds), accumulation of cells in pre-G1 phase and annexin-V and propidium iodide staining in addition to cell cycle arrest at G2/M phase indicating that cell death proceeded through an apoptotic mechanism.     

Synthesis,molecular modeling and biological evaluation of N-benzylidene-2-((5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl)thio)acetohydrazide derivatives as potential anticancer agents

A series of new 1,3,4-oxadiazole derivatives (6a–6x) containing pyridine and acylhydrazone moieties were synthesized and developed as potential telomerase inhibitors. The bioassay tests demonstrated that compounds 6n, 6o, 6q, 6s and 6t exhibited significant broad-spectrum anticancer activity with IC₅₀ range from 0.76 to 9.59 μM against the four cancer cell lines (HEPG2, MCF7, SW1116 and BGC823). Moreover, all the title compounds were assayed for telomerase inhibition using the TRAP-PCR-ELISA assay. Compound 6s showed the highest anticancer activity with IC₅₀ of 0.76–1.54 μM against the tested cancer cell lines and exhibited the most potent telomerase inhibitory activity with IC₅₀ of 1.18 ± 0.14 μM. The docking simulation was carried out to investigate a possible binding mode of compound 6s into the active site of telomerase (pdb. 3DU6) while the QSAR model was built to check the previous work as well as to introduce new directions.     

Design,semisynthesis and potent cytotoxic activity of novel 10-fluorocamptothecin derivatives

Fluorination is a well-known strategy for improving the bioavailability of bioactive molecules in the lead optimization phase of drug discovery projects. In an attempt to improve the antitumor activity of camptothecins (CPTs), novel 10-fluoro-CPT derivatives were designed, synthesized and evaluated for cytotoxicity against five human cancer cell lines (A-549, MDA-MB-231, KB, KB-VIN and MCF-7). All of the derivatives showed more potent in vitro cytotoxic activity than the clinical CPT-derived drug irinotecan against the tumor cell lines tested, and most of them showed comparable or superior potency to topotecan. Remarkably, compounds 16b (IC₅₀, 67.0 nM) and 19b (IC₅₀, 99.2 nM) displayed the highest cytotoxicity against the multidrug-resistant (MDR) KB-VIN cell line and merit further development as preclinical drug candidates for treating cancer, including MDR phenotype. Our study suggested that incorporation of a fluorine atom into position 10 of CPT is an effective method for discovering new potent CPT derivatives.     

Discovery of adamantane based highly potent HDAC inhibitors

Herein, we report the development of highly potent HDAC inhibitors for the treatment of cancer. A series of adamantane and nor-adamantane based HDAC inhibitors were designed, synthesized and screened for the inhibitory activity of HDAC. A number of compounds exhibited GI₅₀ of 10-100 nM in human HCT116, NCI-H460 and U251 cancer cells, in vitro. Compound 32 displays efficacy in human tumour animal xenograft model.