Anticancer properties of N-alkyl-2, 4-diphenylimidazo [1, 2-a] quinoxalin-1-amine derivatives; kinase inhibitors

Structure activity correlation revealed that the quinoxaline ring is a satisfactory backbone for anticancer activity and a specific functional group at position 1 and 2 can improve the activity. In this basis, besides quinoxaline, imidazoles as potential anticancer agents were used as a supplementary agents for cancer treatment.In this paper, a new series of N-alkyl-2, 4-diphenylimidazo [1, 2-a] quinoxalin-1-amine derivatives were synthesized in a simple and efficient step. The products are fully characterized by 1H NMR, ¹³C NMR, FT-IR, HRMS, and CHN elemental analysis. Several starting materials with different functionalities have been used for the synthesis of the final products with high isolated yields. The biological activities of the synthesized compounds were evaluated in kinase inhibition and cytotoxic activity in several cancerous cell lines. All compounds (6) were evaluated for inhibition of the cell proliferation using 4 cancerous cell lines. Five of the more active compounds were studied for determination of IC50_%. Compounds 6(32–34) showed good activity on some of cancerous cell lines.The results showed that compound 6–32 has the highest biological activity (IC₅₀% 9.77 for K562 cell line). An IC₅₀% value of 15.84 µM was observed for 6–34. Furthermore 6–34 exhibited inhibition of ABL1 and c-Src kinases with an IC50% value of 5.25 µM and 3.94 µM respectively. Docking simulation was performed to position active synthesized compounds 6–32, 6–33, and 6–34 over the ABL1 active site in two different wild-type (DFG-in and DFG-out motif conformer) and T315I mutant to determine the probable binding orientation, conformation and mode of interaction. According to docking study, the docked location in wild type forms is similar and can be found near the P-loop region while in the case of T315I mutant form, the compounds have a distinct docked location which is close to the αC helix and activation loop. Also, it concluded the role of R₁ substituent on phenyl ring produced higher interaction energy. Additionally, the detailed inter-molecular energy and types of non-bonding interaction of these compounds over the wild-type and mutant form of ABL1.     

Biological evaluation and SAR analysis of novel covalent inhibitors against fructose-1,6-bisphosphatase

Fructose-1,6-bisphosphatase (FBPase) is an attractive target for affecting the GNG pathway. In our previous study, the C128 site of FBPase has been identified as a new allosteric site, where several nitrovinyl compounds can bind to inhibit FBPase activity. Herein, a series of nitrostyrene derivatives were further synthesized, and their inhibitory activities against FBPase were investigated in vitro. Most of the prepared nitrostyrene compounds exhibit potent FBPase inhibition (IC₅₀ < 10 μM). Specifically, when the substituents of F, Cl, OCH₃, CF₃, OH, COOH, or 2-nitrovinyl were installed at the R₂ (meta-) position of the benzene ring, the FBPase inhibitory activities of the resulting compounds increased 4.5–55 folds compared to those compounds with the same groups at the R₁ (para-) position. In addition, the preferred substituents at the R₃ position were Cl or Br, thus compound HS36 exhibited the most potent inhibitory activity (IC₅₀ = 0.15 μM). The molecular docking and site-directed mutation suggest that C128 and N125 are essential for the binding of HS36 and FBPase, which is consistent with the C128-N125-S123 allosteric inhibition mechanism. The reaction enthalpy calculations show that the order of the reactions of compounds with thiol groups at the R₃ position is Cl > H > CH₃. CoMSIA analysis is consistent with our proposed binding mode. The effect of compounds HS12 and HS36 on glucose production in primary mouse hepatocytes were further evaluated, showing that the inhibition was 71% and 41% at 100 μM, respectively.     

Synthesis,anti-thymidine phosphorylase activity and molecular docking of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones

In our lead finding program, a series of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones and their 5-thio-alkyl derivatives were designed and synthesized which contained different substituents at ortho-position of 2-phenyl ring attached to the fused ring structure. The preliminary pharmacological evaluation demonstrated that the synthesized compounds exhibited a varying degree of inhibitory activity towards thymidine phosphorylase (TP), comparable to reference compound, 7-Deazaxanthine (7-DX, 2) (IC₅₀ value = 42.63 μM). The study also inferred that the ortho-substituted group at the phenyl ring and 5-thio-alkyl moiety imparted steric hindrance effects in the binding site of the enzyme, leading to a reduced inhibitory response. In addition, compound 3a was identified as a mixed-type inhibitor of TP. Moreover, computational docking study was performed to illustrate the important structural information on the plausible ligand-enzyme binding interactions.     

Exploring the molecular determinants of substrate-selective inhibition of cyclooxygenase-2 by lumiracoxib

Lumiracoxib is a substrate-selective inhibitor of endocannabinoid oxygenation by cyclooxygenase-2 (COX-2). We assayed a series of lumiracoxib derivatives to identify the structural determinants of substrate-selective inhibition. The hydrogen-bonding potential of the substituents at the ortho positions of the aniline ring dictated the potency and substrate selectivity of the inhibitors. The presence of a 5′-methyl group on the phenylacetic acid ring increased the potency of molecules with a single ortho substituent. Des-fluorolumiracoxib (2) was the most potent and selective inhibitor of endocannabinoid oxygenation. The positioning of critical substituents in the binding site was identified from a 2.35 Å crystal structure of lumiracoxib bound to COX-2.     

Design,synthesis and biological evaluation of (E)-2-(2-arylhydrazinyl)quinoxalines,a promising and potent new class of anticancer agents

A series of forty-seven quinoxaline derivatives, 2-(XYZC₆H₂CHN–NH)-quinoxalines, 1, have been synthesized and evaluated for their activity against four cancer cell lines: potent cytotoxicities were found (IC₅₀ ranging from 0.316 to 15.749 μM). The structure–activity relationship (SAR) analysis indicated that the number, the positions and the type of substituents attached to the aromatic ring are critical for biological activity. The activities do not depend on the electronic effects of the substituents nor on the lypophilicities of the molecules. A common feature of active compounds is an ortho-hydroxy group in the phenyl ring. A potential role of these ortho-hydroxy derivatives is as N,N,O-tridentate ligands complexing with a vital metal, such as iron, and thereby preventing proliferation of cells. The most active compound was (1: X,Y = 2,3-(OH)₂, Z = H), which displayed a potent cytotoxicity comparable to that of the reference drug doxorubicin.     

Novel synthetic 2-amino-10-(3,5-dimethoxy)benzyl-9(10H)-acridinone derivatives as potent DNA-binding antiproliferative agents

A series of novel 9(10H)-acridinone derivatives with terminal amino substituents at C2 position on the acridinone ring were synthesized and studied for their antiproliferative activity and underlying mechanisms. These compounds demonstrated promising cytotoxicity to leukemia cells CCRF-CEM, displaying IC₅₀ values in the low micromolar range. Structure–activity relationships (SAR) indicated that the compound 6d bearing a pyrrolidine substituent and 8a with a methyl ammonium side chain displayed higher cytotoxicity to CCRF-CEM cells and also solid tumor cells A549, HepG2, and MCF7. Furthermore, the compounds 6d and 8a had strong binding activity to calf thymus DNA (ct DNA), as detected by UV absorption and fluorescence quenching assays, but limited inhibitory activity to human topoisomerase 1 (topo 1). Taken together, this study discovered a series of new synthetic 9(10H)-acridinone derivatives with potent DNA binding and anticancer activity.     

Thioether-bridged arylalkyl-linked N-phenylpyrazole derivatives: Design,synthesis, insecticidal activities,structure-activity relationship and molecular-modeling studies

Owing to thioether diverse physicochemical properties by non-covalent interactions with bio-macromolecules, thioether derivatives containing heterocyclic moiety are known for their interesting insecticidal bioactivities and attracting considerable attention as neuroactive insecticides. Here we synthesis a series of novel thioether bridged N-phenylpyrazole derivatives incorporating various (hetero)aromatic substituents into 4-position of the pyrazole ring. Structure-activity relationship (SAR) studies resulted in compounds 6d and 7d with the most potent insecticidal activity among the series containing various substituted benzene substituents (LC₅₀?=?13.70–25.47?μg/g). Further optimization to increase the lipophilicity and charge density of aromatic substituents of compounds 6d and 7d resulted in compounds 12d, 14d and 16d with sulfur-containing heterocycle substituents possessing good insecticidal activity against Musca domestica L. among the series (LC₅₀?=?0.67–1.30?μg/g). The thioether bridge N-phenylpyrazole derivatives, which exhibit different length of the spacer arm introduced between N-phenylpyrazole moiety and the (hetero)aromatic substituents, were also prepared and evaluated. By contrast, the insecticidal activities of compounds containing the short thioether bridge, 1,2-bis((hetero)aromatic thio) ethane, are higher than that containing the long thioether bridge, 1,3-bis((hetero)aromatic thio) propane. The results of molecular docking and pharmacophore analyses indicated A299, T303, and L306 of a subunit were essential to form non-covalent interactions contacts with the ligands. Specially, the sulfur-containing heterocycle substituent derivatives 12d and 14d as the sterically favored areas could form the important hydrophobic interactions with the deeper residue P295.     

New imidazoquinoxaline derivatives: Synthesis,biological evaluation on melanoma,effect on tubulin polymerization and structure–activity relationships

Microtubules are considered as important targets of anticancer therapy. EAPB0503 and its structural imidazo[1,2-a]quinoxaline derivatives are major microtubule-interfering agents with potent anticancer activity. In this study, the synthesis of several new derivatives of EAPB0503 is described, and the anticancer efficacy of 13 novel derivatives on A375 human melanoma cell line is reported. All new compounds show significant antiproliferative activity with IC₅₀ in the range of 0.077–122 μM against human melanoma cell line (A375). Direct inhibition of tubulin polymerization assay in vitro is also assessed. Results show that compounds 6b, 6e, 6g, and EAPB0503 highly inhibit tubulin polymerization with percentages of inhibition of 99%, 98%, 90%, and 84% respectively. Structure–activity relationship studies within the series are also discussed in line with molecular docking studies into the colchicine-binding site of tubulin.     

Design,synthesis, and evaluation of 2-piperidone derivatives for the inhibition of β-amyloid aggregation and inflammation mediated neurotoxicity

A series of novel multipotent 2-piperidone derivatives were designed, synthesized and biologically evaluated as chemical agents for the treatment of Alzheimer’s disease (AD). The results showed that most of the target compounds displayed significant potency to inhibit Aβ_1–42 self-aggregation. Among them, compound 7q exhibited the best inhibition of Aβ_1–42 self-aggregation (59.11% at 20 μM) in a concentration-dependent manner. Additionally, the compounds 6b, 7p and 7q as representatives were found to present anti-inflammation properties in lipopolysaccharide (LPS)-induced microglial BV-2 cells. They could effectively suppress the production of pro-inflammatory cytokines such as TNF-α, IL-1β and IL-6. Meanwhile, compound 7q could prevent the neuronal cell SH-SY5Y death by LPS-stimulated microglia cell activation mediated neurotoxicity. The molecular modeling studies demonstrated that compounds matched the pharmacophore well and had good predicted physicochemical properties and estimated IC₅₀ values. Moreover, compound 7q exerted a good binding to the active site of myeloid differentiation factor 88 (MyD88) through the docking analysis and could interfere with its homodimerization or heterodimerization. Consequently, these compounds emerged as promising candidates for further development of novel multifunctional agents for AD treatment.     

Design,parallel synthesis,and crystal structures of biphenyl antithrombotics as selective inhibitors of tissue factor FVIIa complex. Part 1: Exploration of S2 pocket pharmacophores

Factor VIIa (FVIIa), a serine protease enzyme, coupled with tissue factor (TF) plays an important role in a number of thrombosis-related disorders. Inhibition of TF·FVIIa occurs early in the coagulation cascade and might provide some safety advantages over other related enzymes. We report here a novel series of substituted biphenyl derivatives that are highly potent and selective TF·FVIIa inhibitors. Parallel synthesis coupled with structure-based drug design allowed us to explore the S2 pocket of the enzyme active site. A number of compounds with IC₅₀ value of <10 nM were synthesized. The X-ray crystal structures of some of these compounds complexed with TF·FVIIa were determined and results were applied to design the next round of inhibitors. All the potent inhibitors were tested for inhibition against a panel of related enzymes and selectivity of 17,600 over thrombin, 450 over trypsin, 685 over FXa, and 76 over plasmin was achieved. Two groups, vinyl 36b and 2-furan 36ab, were identified as the optimum binding substituents on the phenyl ring in the S2 pocket. Compounds with these two substituents are the most potent compounds in this series with good selectivity over related serine proteases. These compounds will be further explored for structure–activity relationship.     

Synthesis,molecular docking and anti-inflammatory screening of novel quinoline incorporated pyrazole derivatives using the Pfitzinger reaction II

In continuation of our study of novel quinolines with anti-inflammatory activity using the Pfitzinger reaction, several new quinoline derivatives were synthesized and tested for their anti-inflammatory and ulcerogenic effect. A docking study on the COX-2 binding pocket was carried out for the target compounds to rationalize the possible selectivity of them against COX-2 enzyme. The most active compounds (5a, 8a and 11a) were found to be superior to celecoxib. Compound 11a demonstrated the highest anti-inflammatory activity as well as the best binding profiles into the COX-2 binding site. Moreover, compounds 9c, 9e, 10a and 11a were devoid of ulcerogenic activity.     

Novel thioureido-benzenesulfonamide derivatives with enaminone linker as potent anticancer,radiosensitizers and VEGFR2 inhibitors

In this study, novel series of thioureido-benzenesulfonamide derivatives bearing an enaminone linker either meta or para oriented and having terminal linear or substituted aromatic or heteroaromatic ring system 5–16a,b were designed and synthesized based on the general pharmacophoric features of type II VEGFR2 inhibitors. Evaluation of the synthesized compounds against HEPG2 hepatocellular carcinoma cells in vitro identified compounds 5b, 6b and 10–13b as most active anticancer agents with IC₅₀ equal to 0.12, 0.29, 0.58, 0.44, 0.42 and 0.66?µM, respectively. These compounds were evaluated for their ability to in vitro inhibit VEGFR2 kinase enzyme. The results demonstrated highly potent dose-related VEGFR2 inhibition with IC₅₀ values in nanomolar range (33, 57, 210, 37, 37 and 220?nM, respectively). The radiosensitizing ability of the most promising compounds was studied which showed an increase in the cell killing effect of radiation after combination with the synthesized compounds which revealed lowered IC₅₀ by nearly 50%. Molecular docking for the most potent compounds was performed to predict their possible binding mode within VEGFR2 active site and they showed binding affinity in a similar way to sorafenib.     

Quinazolinone-based rhodanine-3-acetic acids as potent aldose reductase inhibitors: Synthesis,functional evaluation and molecular modeling study

A series of quinazolinone-based rhodanine-3-acetic acids was synthesized and tested for in vitro aldose reductase inhibitory activity. All the target compounds displayed nanomolar activity against the target enzyme. Compounds 3a, 3b, and 3e exhibited almost 3-fold higher activity as compared to the only marketed reference drug epalrestat. Structure-activity relationship studies indicated that bulky substituents at the 3-phenyl ring of the quinazolinone moiety are generally not tolerated in the active site of the enzyme. Insertion of a methoxy group on the central benzylidene ring was found to have a variable effect on ALR-2 activity depending on the nature of peripheral quinazolinone ring substituents. Removal of the acetic acid moiety led to inactive or weakly active target compounds. Docking and molecular dynamic simulations of the most active rhodanine-3-acetic acid derivatives were also carried out, to provide the basis for further structure-guided design of novel inhibitors.     

Potential antimicrobial agents from triazole-functionalized 2H-benzo[b][1,4]oxazin-3(4H)-ones

A series of substituted triazole functionalized 2H-benzo[b][1,4]oxazin-3(4H)-ones were synthesized by employing click chemistry and further characterized based on ¹H NMR, ¹³C NMR, IR and mass spectral studies. All the synthesized derivatives were screened for their in vitro antimicrobial activities. Further, molecular docking studies were accomplished to explore the binding interactions between 1,2,3-triazol-4-yl-2H-benzo[b][1,4]oxazin-3(4H)-one and the active site of Staphylococcus aureus (CrtM) dehydrosqualene synthase (PDB ID: 2ZCS). These docking studies revealed that the synthesized derivatives showed high binding energies and strong H-bond interactions with the dehydrosqualene synthase validating the observed antimicrobial activity data. Based on antimicrobial activity and docking studies, the compounds 9c, 9d and 9e were identified as promising antimicrobial leads.     

A novel templates of piperazinyl-1,2-dihydroquinoline-3-carboxylates: Synthesis,anti-microbial evaluation and molecular docking studies

A series of piperazinyl-1,2-dihydroquinoline carboxylates were synthesized by the reaction of ethyl 4-chloro-1-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylates with various piperazines and their structures were confirmed by ¹H NMR, ¹³C NMR, IR and mass spectral analysis. All the synthesized compounds were screened for their in vitro antimicrobial activities. Further, the in silico molecular docking studies of the active compounds was performed to explore the binding interactions between piperazinyl-1,2-dihydroquinoline carboxylate derivatives and the active site of the Staphylococcus aureus (CrtM) dehydrosqualene synthase (PDB ID: 2ZCQ). The docking studies revealed that the synthesized derivatives showed high binding energies and strong H-bond interactions with the dehydrosqualene synthase validating the observed antimicrobial activity data. Based on antimicrobial activity and docking studies, the compounds 9b and 10c were identified as promising antimicrobial lead molecules. This study might provide insights to identify new drug candidates that target the S. aureus virulence factor, dehydrosqualene synthase.     

Synthesis and biological evaluation of novel 2-amino-3-aroyl-4-neopentyl-5-substituted thiophene derivatives as allosteric enhancers of the A1 adenosine receptor

2-Amino-3-benzoyl thiophenes have been widely reported to act as allosteric enhancers at the A₁ adenosine receptor. Their activity can be increased considerably by appropriate substitutions at the 4- and 5-positions of the thiophene ring. Substituent size at the thiophene C-4 position seemed to be a factor closely related to activity, with the 4-neopentyl (2,2-dimethylpropyl) substitution showing the greatest enhanced activity. A wide series of 2-amino-3-aroyl-4-neopentylthiophene derivatives with general structure 3, characterized by the presence of different substituents (bromine, aryl and heteroaryl) at the 5-position of the thiophene ring, have been identified as potent AEs at the A₁AR. With only one exception, all of the synthesized compounds proved to be superior to the reference compound PD 81,723 in a functional assay. Derivatives 3p, 3u, 3am, 3ap and 3ar were the most active compounds in binding (saturation and competition) and functional cAMP studies, being able to potentiate agonist [³H]CCPA binding to the A₁ receptor.     

Design,synthesis and molecular docking of novel pyrazolo[1,5-a][1,3,5]triazine derivatives as CDK2 inhibitors

Cyclin Dependent Kinases CDKs unpredictable activity has been accounted for a wide assortment of human malignancies, so it might be conceivable to design pharmacologically relevant ligands that go about as specific and potent inhibitors of CDK2 action. In this respect, a series of novel pyrazolo[1,5-a][1,3,5]triazine derivatives were designed, synthesized and evaluated for CDK2 enzyme inhibitory and anticancer activity. Compounds 9f and 10c showed best CDK2 inhibition among the newly synthesized compounds, with percent inhibition at 82.38%, and 81.96% against CDK2 and IC₅₀ of 1.85 and 2.09 µM, respectively. Additionally, the newly synthesized compounds were tested for their antiproliferative activity against 60 NCI cell lines. Molecular docking revealed the binding mode of these new compounds into the roscovitine binding site of CDK2 enzyme (PDB code: 3ddq). Conclusively, pyrazolotriazine derivatives represent a talented starting point for further study as anticancer drug.     

Synthesis of 2-,4,-6-, and/or 7-substituted quinoline derivatives as human dihydroorotate dehydrogenase (hDHODH) inhibitors and anticancer agents: 3D QSAR-assisted design

Following our research for human dihydroorotate dehydrogenase (hDHODH) inhibitors as anticancer agents, herein we describe 3D QSAR-based design, synthesis and in vitro screening of 2-,4,-6-, and/or 7-substituted quinoline derivatives as hDHODH inhibitors and anticancer agents. We have designed 2-,4,-6-, and/or 7-substituted quinoline derivatives and predicted their hDHODH inhibitory activity based on 3D QSAR study on 45 substituted quinoline derivatives as hDHODH inhibitors, and also predicted toxicity. Designed compounds were docked into the binding site of hDHODH. Designed compounds which showed good predictive activity, no toxicity, and good docking score were selected for the synthesis, and in vitro screening as hDHODH inhibitors in an enzyme inhibition assay, and anticancer agents in MTT assay against cancer cell lines (HT-29 and MDA-MB-231). Synthesized compounds 7 and 14 demonstrated IC₅₀ value of 1.56?µM and 1.22?µM, against hDHODH, respectively, and these are our lead compounds for the development of new hDHODH inhibitors and anticancer agents.     

Synthesis,molecular docking study and in vitro thymidine phosphorylase inhibitory potential of oxadiazole derivatives

We have synthesized oxadiazole derivatives (1–16), characterized by ¹H NMR, ¹³C NMR and HREI-MS and screened for thymidine phosphorylase inhibitory potential. All derivatives display varied degree of thymidine phosphorylase inhibition in the range of 1.10 ± 0.05 to 49.60 ± 1.30 μM when compared with the standard inhibitor 7-Deazaxanthine having an IC₅₀ value 38.68 ± 1.12 μM. Structure activity relationships (SAR) has been established for all compounds to explore the role of substitution and nature of functional group attached to the phenyl ring which applies imperious effect on thymidine phosphorylase activity. Molecular docking study was performed to understand the binding interaction of the most active derivatives with enzyme active site.