Synthesis and biological evaluation of podophyllotoxin congeners as tubulin polymerization inhibitors

A series of new podophyllotoxin derivatives containing structural modifications at C-7, C-8, and C-9 were synthesized and evaluated for their cytotoxic activity against three human cancer cell lines. All the synthesized compounds showed significant growth inhibition with GI₅₀ values in micromolar levels while some of the compounds were several times more potent against MCF-7 and HeLa cell lines than MIAPACA cell line. Three compounds (12a, 12d and 12e) emerged as potent compounds with broad spectrum of cytotoxic activity against all the tested cell lines with GI₅₀ values in the range of 0.01–2.1 μM. These compounds induce microtubule depolymerization and arrests cells at the G2/M phase of the cell cycle. Moreover, compounds 12d and 12e disrupted microtubule network and accumulated tubulin in the soluble fraction in a similar manner to their parent podophyllotoxin scaffold. In addition, structure activity relationship studies within the series were also discussed. Molecular docking studies of these compounds into the colchicine-binding site of tubulin, revealed possible mode of inhibition by these compounds.     

Synthesis,molecular docking and biological evaluation of some benzimidazole derivatives as potent pancreatic lipase inhibitors

In this study, a new series of benzimidazole and bisbenzimidazole derivatives were prepared via the reaction of iminoester hydrochlorides and o-phenylenediamines and then screened for their lipase inhibition properties. Among the synthesized molecules, compounds 7a, 8a and 8c showed the best inhibitory effect against lipase enzyme with IC₅₀ values of 1.72 ± 0.12 µM, 1.92 ± 0.28 and 0.98 ± 0.07 µM, respectively. Moreover, molecular modeling studies were performed in order to understand to the inhibitory activity of the molecules. Binding poses of the studied compounds were determined at the target sites using induced fit docking (IFD) algorithms.     

Synthesis,biological evaluation and molecular docking studies of trans-indole-3-acrylamide derivatives,a new class of tubulin polymerization inhibitors

In this study, we synthesized a series of trans-indole-3-acrylamide derivatives (3a–k) and investigated their activity for inhibition of cell proliferation against five human cancer cell lines (HeLa, MCF7, MDA-MB-231, Raji and HL-60) by MTT assay. Compound 3e showed significant antiproliferative activity against both the Raji and HL-60 cell lines with IC₅₀ values of 9.5 and 5.1 μM, respectively. Compound 3e also exhibited moderate inhibitory activity on tubulin polymerization (IC₅₀ = 17 μM). Flow cytometric analysis of cultured cells treated with 3e also demonstrated that the compound caused cell cycle arrest at the G2/M phase in HL-60 and HeLa cells. Moreover, 3e, the most active compound, caused an apoptotic cell death through the activation of caspase-3. Docking simulations suggested that 3e binds to the colchicine site of tubulin.     

Synthesis and biological evaluation of Schizandrin derivatives as tubulin polymerization inhibitors

A series of oxime ester-derivatives were prepared by utilizing the schizandrin (1), a major compound isolated from Schisandra grandiflora, which is deployed in different traditional system of medicine. The in vitro antiproliferative activities of the synthesized compounds were assessed against a selected panel of human cancer cell lines (A549, RKO P3, DU145 and Hela) and normal cell (HEK293). Several of these derivatives were found more potent in comparison to parent compound, schizandrin (1). Particularly, 4a and 4b demonstrated potent activity against DU-145 and RKOP3 cell lines with IC₅₀ values of 3.42 µM and 3.35 µM respectively. To characterize the molecular mechanisms involved in antitumoral activity, these two compounds, 4a and 4b were selected for further studies. Cell cycle analysis revealed that both the compounds were able to induce apoptosis and cell cycle arrest at G₀/G₁ phase. To know the extent of apoptosis in DU145 and RKOP3 cell lines, Annexin V-FITC were performed. Moreover, the tubulin polymerization assay indicated that 4a and 4b exhibits potent inhibitory effect on the tubulin assembly. Molecular docking studies and competitive binding assay also indicated that 4a and 4b effectively bind at the colchicine binding site of the tubulin.     

Synthesis,anticancer activity and molecular docking studies on 1,2-diarylbenzimidazole analogues as anti-tubulin agents

Twenty-four 1,2-diarylbenzimidazole derivatives were designed, synthesized and biologically evaluated. It turned out that most of them were potential anticancer drugs. Among them, compound c24 showed the highest anti-tumor activity (GI₅₀ = 0.71–2.41 μM against HeLa, HepG2, A549 and MCF-7 cells), and low toxicity to normal cells (CC₅₀ > 100 μM against L02 cells). In the microtubule binding assay, c24 showed the most potent inhibition of microtubule polymerization (IC₅₀ = 8.47 μM). The binding ability of compound c24 to tubulin crystal was verified by molecular docking simulation experiment. Further studies on HepG2 and HeLa cells showed that compound c24 could cause mitotic arrest of tumor cells to G2/M phase then inducing apoptosis. To sum up, compound c24 is a promising microtubule assembly inhibitor.     

Synthesis,cytotoxic evaluation and molecular docking study of 2-alkylthio-4-(2,3,4-trimethoxyphenyl)-5-aryl-thiazoles as tubulin polymerization inhibitors

A series of cis-restricted 2-alkylthio-4-(2,3,4-trimethoxyphenyl)-5-aryl-thiazole analogues of combretastatin A-4 were synthesized and investigated for inhibition of cell proliferation against three cancer cell lines, HT-29, MCF-7, and AGS, and a normal mouse fibroblastic cell line, NIH-3T3, using an MTT assay. The biological study showed that 2-(methylthio) substituted compounds showed little cytotoxic activity against the four cell lines. In contrast, the presence of the 2-(benzylthio) group on the thiazole ring resulted in a significant improvement in cytotoxic activity relative to the 2-(methylthio) substituted derivatives. Furthermore, the inhibition of tubulin polymerization by some potent compounds was evaluated. All the compounds studied were moderate tubulin polymerization inhibitors. The flow cytometry analysis confirmed that the synthesized compounds led to cell cycle arrest at the G₂/M phase. Docking simulation was performed to insert these compounds into the crystal structure of tubulin at the colchicine binding site to determine a probable binding model.     

Synthesis,biological evaluation and molecular modeling study of pyrazole derivatives as selective COX-2 inhibitors and anti-inflammatory agents

A novel series of pyrazole derivatives were synthesized and evaluated in vivo for their anti-inflammatory activity in carrageenan-induced rat paw edema model. Among all compounds, 5a, and 5b showed comparable anti-inflammatory activity to Nimesulide, the standard drug taken for the studies. In silico (docking) studies were carried out to investigate the theoretical binding mode of the compounds to target the cyclooxygenase (COX-2) using Autodock 4.2.     

A simple and efficient synthesis of novel inhibitors of alpha-glucosidase based on benzimidazole skeleton and molecular docking studies

A novel series of benzimidazole derivatives were prepared starting from o-phenylenediamine and 4-nitro-o-phenylenediamine with iminoester hydrochlorides. Acidic proton in benzimidazole was exchanged with ethyl bromoacetate, then ethyl ester group was transformed into hydrazide group. Cyclization using CS₂/KOH leads to the corresponding 1,3,4-oxadiazole derivative, which was treated with phenyl isothiocyanate resulted in carbothioamide group, respectively. As the target compounds, triazole derivative was obtained under basic condition and thiadiazole derivative was obtained under acidic condition from cyclization of carbothioamide group. Most reactions were conducted using both the microwave and conventional methods to compare yields and reaction times. All compounds obtained in this study were investigated for α-glucosidase inhibitor activity. Compounds 6a, 8a, 4b, 5b, 6b and 7b were potent inhibitors with IC₅₀ values ranging from 10.49 to 158.2 μM. This has described a new class of α-glucosidase inhibitors. Molecular docking studies were done for all compounds to identify important binding modes responsible for inhibition activity of α-glucosidase.     

Synthesis,molecular properties prediction and biological evaluation of indole-vinyl sulfone derivatives as novel tubulin polymerization inhibitors targeting the colchicine binding site

Twenty-two novel indole-vinyl sulfone derivatives were designed, synthesized and evaluated as tubulin polymerization inhibitors. The physicochemical and drug-likeness properties of all target compounds were predicted by Osiris calculations. All compounds were evaluated for their antiproliferative activities, among them, compound 7f exhibited the most potent activity against a panel of cancer cell lines, which was 2–7 folds more potent than our previously reported compound 4. Especially, 7f displayed about 8-fold improvement of selective index as compared with compound 4, indicating that 7f might have lower toxicity. Besides, 7f inhibited the microtubule polymerization by binding to the colchicine site of tubulin. Further investigations showed that compound 7f effectively disrupted microtubule network, caused cell cycle arrest at G2/M phase and induced cell apoptosis in K562 cells. Moreover, 7f reduced the cell migration and disrupted capillary-like tube formation in HUVEC cells. Importantly, the in vivo anti-tumor activity of 7f was validated in H22 liver cancer xenograft mouse model without apparent toxicity, suggesting that 7f is a promising anti-tubulin agent for cancer therapy.     

Design,synthesis and molecular docking of novel diarylcyclohexenone and diarylindazole derivatives as tubulin polymerization inhibitors

New target compounds were designed as inhibitors of tubulin polymerization relying on using two types of ring B models (cyclohexenone and indazole) to replace the central ring in colchicine. Different functional groups (R¹) were attached to manipulate their physicochemical properties and/or their biological activity. The designed compounds were assessed for their antitumor activity on HCT-116 and MCF-7 cancer cell lines. Compounds 4b, 5e and 5f exhibited comparable or higher potency than colchicine against colon HCT-116 and MCF-7 tumor cells. The mechanism of the antitumor activity was investigated through evaluating the tubulin inhibition potential of the active compounds. Compounds 4b, 5e and 5f showed percentage inhibition of tubulin in both cell line homogenates ranging from 79.72% to 89.31%. Cell cycle analysis of compounds 4b, 5e and 5f revealed cell cycle arrest at G₂/M phase. Molecular docking revealed the binding mode of these new compounds into the colchicine binding site of tubulin.     

Synthesis of stable benzimidazole derivatives bearing pyrazole as anticancer and EGFR receptor inhibitors

A new series of benzimidazole linked pyrazole derivatives were synthesized by cyclocondensation reaction through one-pot multicomponent reaction in absolute ethanol. All the synthesized compounds were tested for their in vitro anticancer activities on five human cancer cell lines including MCF-7, HaCaT, MDA-MB231, A549 and HepG2. EGFR receptor inhibitory activities were carried out for all the compounds. Majority of the compounds showed potent antiproliferative activity against the tested cancer cell lines. Compound 5a showed the most effective activity against the lungs cancer cell lines (IC₅₀ = 2.2 µM) and EGFR binding (IC₅₀ = 0.97 µM) affinity as compared to other members of the series. Compound 5a inhibited growth of A549 cancer cells by inducing a strong G₂/M phase arrest. In addition, same compound inhibited growth of A549 cancer cells by inducing apoptosis. In molecular docking studies compound 5a was bound to the active pocket of the EGFR (PDB 1M17) with five key hydrogen bonds and two π-π interaction with binding energies ΔG = −34.581 Kcal/mol.     

Design,synthesis and biological evaluation of novel indole-based oxalamide and aminoacetamide derivatives as tubulin polymerization inhibitors

A series of novel indole-based oxalamide and aminoacetamide derivatives were designed, synthesized, and evaluated for antiproliferative activities. Preliminary results revealed that compound 8g exhibited significant antiproliferative effect against PC-3, HeLa and HCT-116 cell lines. Flow cytometric analysis of the cell cycle demonstrated the compound 8g induced the cell cycle arrest at G2/M phase in HeLa cell lines. Immunocytochemistry revealed loss of intact microtubule structure in cells treated with 8g and inhibition of tubulin polymerization. Additionally, molecular docking analysis suggested that 8g formed stable interactions in the colchicine-binding site of tubulin. These preliminary results demonstrated that a new class of novel indole-based oxalamide and aminoacetamide derivatives described in the investigation could be developed as potential scaffolds to new anticancer agents.     

Synthesis,biological evaluation and molecular docking analysis of novel benzopyrimidinone derivatives as potential anti-tyrosinase agents

2-substitued-benzopyrimidinones 2 were synthesized in high to excellent yields in a single step via condensation of 2-aminobenzamide 1 with some aryl-aldehydes in the presence of iodine. Cyclocondensation reaction of hydrazides 3 which were obtained in two steps from benzopyrimidinones 2, with some electrophilic species such as 2,4-pentandione, 2,5-hexandione, 1-phenylbutan-1,3-dione and cyclic anyhdrides provided the new compounds 4a–c, 5a–c, 6a–c, 7a–c, 8a–c and 9a–c. The synthesized compounds were characterized by spectroscopic means. They were also evaluated for their anti-tyrosinase potential. The structure-activity relationship (SAR) was discussed on the basis of the molecular docking analysis.     

Design,synthesis and biological evaluation of novel 5-phenyl-1H-pyrazole derivatives as potential BRAFV600E inhibitors

A series of novel 5-phenyl-1H-pyrazole derivatives (5a–5u) containing niacinamide moiety were synthesized and evaluated for biological activity as potential BRAF^V600E inhibitors. Among them, compound 5h exhibited the most potent inhibitory activity with an IC₅₀ value of 0.33 μM for BRAF^V600E. Antiproliferative assay results indicated that compound 5h has better antiproliferative activity against WM266.4 and A375 in vitro with IC₅₀ value of 2.63 and 3.16 μM, respectively, being comparable with the positive control vemurafenib. Molecular docking of 5h into the BRAF^V600E active site was performed to determine the probable binding mode. Furthermore, molecular docking and 3D QSAR study by means of DS 3.5 (Discovery Studio 3.5, Accelrys, Co. Ltd) explored the binding modes and the structure and activity relationship (SAR) of these derivatives.     

Synthesis,biological activities,and docking studies of d-pantolactone derivatives as novel FAS inhibitors

A novel series of fatty acid synthase (FAS) inhibitors with D-(−)-pantolactone moiety and potential utility for the treatment of obesity were designed, synthesized and characterized, in which the structure of compound 3k was further confirmed by single X-ray diffraction. The mouse FAS inhibitory activity of synthesized compounds was evaluated. Major synthesized compounds (except 3g, 3i, 3k, 3l, and 3n) exhibited moderate FAS inhibitory properties with IC₅₀ values in the range of 13.68 ± 1.52–33.19 ± 1.39 μM, reference inhibitor C75 has IC₅₀ value of 13.86 ± 2.79 μM. Eight compounds (3c, 3d, 3e, 3f, 3j, 3m, 3q and 3r) also displayed inhibitory effect on lipid accumulation in human HepG2 cells. Additionally, the molecular docking study revealed that compound 3m having good inhibition activity against FAS and lipid accumulation also showed promising binding affinities with hFAS, while its binding model with hFAS (PDB ID: 4PIV) was different from that of reference compound C75.     

Synthesis,biological evaluation and molecular docking of novel pyrazole derivatives as potent carbonic anhydrase and acetylcholinesterase inhibitors

A series of substituted pyrazole compounds (1–8 and 9a, b) were synthesized and their structure was characterized by IR, NMR, and Mass analysis. These obtained novel pyrazole derivatives (1–8 and 9a, b) were emerged as effective inhibitors of the cytosolic carbonic anhydrase I and II isoforms (hCA I and II) and acetylcholinesterase (AChE) enzymes with K_i values in the range of 1.03 ± 0.23–22.65 ± 5.36 µM for hCA I, 1.82 ± 0.30–27.94 ± 4.74 µM for hCA II, and 48.94 ± 9.63–116.05 ± 14.95 µM for AChE, respectively. Docking studies were performed for the most active compounds, 2 and 5, and binding mode between the compounds and the receptors were determined.     

Synthesis,biological evaluation,and molecular docking studies of novel 1,3,4-oxadiazole derivatives possessing benzotriazole moiety as FAK inhibitors with anticancer activity

1,3,4-Oxadiazole derivatives have drawn continuing interest over the years because of their varied biological activities. In order to search for novel anticancer agents, we designed and synthesized a series of new 1,3,4-oxadiazole derivatives containing benzotriazole moiety as potential focal adhesion kinase (FAK) inhibitors. All the synthesized compounds were firstly reported. Among the compounds, compound 4 shows the most potent inhibitory activity against MCF-7 and HT29 cell lines with IC₅₀ values of 5.68 μg/ml and 10.21 μg/ml, respectively. Besides, all the compounds were assayed for FAK inhibitory activity using the TRAP–PCR–ELISA assay. The results showed compound 4 exhibited the most potent FAK inhibitory activity with IC₅₀ values of 1.2 ± 0.3 μM. Docking simulation by positioning compound 4 into the FAK structure active site was performed to explore the possible binding mode. Apoptosis which was analyzed by flow cytometry, demonstrated that compound 4 induced apoptosis against MCF-7 cells. Therefore, compound 4 may be a potential anticancer agent against MCF-7 cancer cell.     

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,biological activities,and molecular docking studies of 2-mercaptobenzimidazole based derivatives

A new series of N-acylhydrazone derivatives of 2-mercaptobenzimidazole (2-MBI) has been synthesized through S-alkylation with 1-bromotetradecane and N-alkylation with ethyl-2-chloroacetate. The resulting ester was synthetically modified through hydrazine hydrate to acyl hydrazide which was condensed with aromatic aldehydes to afford the title N-acylhydrazones (4-17). Chemical structures of the newly synthesized compounds have been confirmed through mass, FT-IR and ¹HNMR techniques. In vitro free radical scavenging and α-glucosidase inhibition activities of the compounds were investigated with reference to the standard ascorbic acid and acarbose, respectively. Amongst the target compounds, 13 showed the highest inhibition in DPPH scavenging assay (IC₅₀ = 131.50 µM) and α-glucosidase inhibition potential (IC₅₀ = 352 µg/ml). We extended our investigations to explore the mechanism of enzyme inhibition and conducted docking analysis by using Molecular Operating Environment (MOE 2016.08). A homology model for α-glucosidase was constructed and validated using Ramachandran plot. Docking studies were also carried out on human intestinal α-glucosidases. In view of the importance of the nucleus involved, the synthesized compounds might find extensive medicinal applications as reported in the literature.     

Synthesis,biological evaluation and molecular docking studies of benzyloxyacetohydroxamic acids as LpxC inhibitors

The inhibition of the UDP-3-O-[(R)-3-hydroxymyristoyl]-N-acetylglucosamine deacetylase (LpxC) represents a promising strategy to combat infections caused by multidrug-resistant Gram-negative bacteria. In order to elucidate the functional groups being important for the inhibition of LpxC, the structure of our previously reported hydroxamic acid 4 should be systematically varied. Therefore, a series of benzyloxyacetohydroxamic acids was prepared, of which the diphenylacetylene derivatives 28 (K_i = 95 nM) and 21 (K_i = 66 nM) were the most potent inhibitors of Escherichia coli LpxC. These compounds could be synthesized in a stereoselective manner employing a Sharpless asymmetric dihydroxylation and a Sonogashira coupling in the key steps. The obtained structure–activity relationships could be rationalized by molecular docking studies.