Synthesis and biological evaluation of 4-quinazolinones as Rho kinase inhibitors

Rho kinase (ROCK) is an attractive therapeutic target for various diseases including glaucoma, hypertension, and spinal cord injury. Herein, we report the development of a series of ROCK-II inhibitors based on 4-quinazolinone and quinazoline scaffolds. SAR studies at three positions of the quinazoline core led to the identification of analogs with high potency against ROCK-II and good selectivity over protein kinase A (PKA).     

Synthesis, biological evaluation and molecular modelling studies on benzothiadiazine derivatives as PDE4 selective inhibitors

A series of 2,1,3- and 1,2,4-benzothiadiazine derivatives (BTDs) were synthesized and evaluated for their inhibitory activity versus enzymatic isoforms PDE3, PDE4 and PDE7. The compounds characterized by the 3,5-di-tert-butyl-4-hydroxybenzyl moiety at N1 position of 2,1,3-benzothiadiazine core (8, 13, 18), were found active and selective at micromolar level versus PDE4 and could be studied as new leads for the treatment of asthma and COPD (Chronic Obstructive Pulmonary Disease). The antioxidant activity evaluation on the same compounds highlighted 13 as the most significative. Molecular modelling studies gave further support to biological results and suggested targeted modifications so as to improve their potency.     

Molecular docking of 1H-pyrazole derivatives to receptor tyrosine kinase and protein kinase for screening potential inhibitors

Tyrosine kinase receptor and protein kinases drawn much attention for the scientific fraternity in drug discovery due to its important role in different cancer, cardiovascular diseases and other hyper-proliferative disorders. Docking studies of pyrazole derivatives with tyrosine kinase and different serine/threonine protein kinases were employed by using flexible ligand docking approach of AutoDock 4.2. Among the molecules tested for docking study, 2-(4-chlorophenyl)-5-(3-(4-chlorophenyl)-5-methyl-1- phenyl-1H-pyrazol-4-yl)-1,3,4-thiadiazole (1b), 2-(4-methoxyphenyl)-5-(3-(4-methoxyphenyl)-5-methyl-1-phenyl-1H-pyrazol-4-yl)- 1,3,4-thiadiazole (1d) and 2-(4-chlorophenyl)-5-(3-(4-chlorophenyl)-5-methyl-1-phenyl-1H-pyrazol-4-yl)-1,3,4-thiadiazole (2b) revealed minimum binding energy of -10.09, -8.57 and -10.35 kJ/mol with VEGFR-2 (2QU5), Aurora A (2W1G) and CDK2 (2VTO) protein targets, respectively. These proteins are representatives of plausible models of interactions with different anticancer agents. All the ligands were docked deeply within the binding pocket region of all the three proteins, showing reasonable hydrogen bonds. The docking study results showed that these pyrazole derivatives are potential inhibitor of all the three protein targets; and also all these docked compounds have good inhibition constant, vdW + Hbond + desolv energy with best RMSD value.     

Kinase inhibitions in pyrido[4,3-h] and [3,4-g]quinazolines: Synthesis,SAR and molecular modeling studies

New pyrido[3,4-g]quinazoline derivatives were prepared and evaluated for their inhibitory potency toward 5 protein kinases (CLK1, DYRK1A, GSK3, CDK5, CK1). A related pyrido[4,3-h]quinazoline scaffold with an angular structure was also synthesized and its potency against the same protein kinase panel was compared to the analogous pyrido[3,4-g]quinazoline. Best results were obtained for 10-nitropyrido[3,4-g]quinazoline 4 toward CLK1 with nanomolar activities.     

Synthesis and biological evaluation of quinoline derivatives as potential anti-prostate cancer agents and Pim-1 kinase inhibitors

In this work, a series of quinoline derivatives were designed and synthesized as antitumor agents. Most quinolines showed potent anti-proliferative activity against human prostatic cancer PC-3 cell line. Among which, 9d, 9f and 9g were the most effective compounds with GI₅₀ values of 2.60, 2.81 and 1.29 μM, respectively. Structure–activity relationship analysis indicated that the secondary amine linked quinoline and pyridine ring played an important role in the anti-proliferative effects. Mechanistic studies revealed that 9g was a potential Pim-1 kinase inhibitor with abilities of cell cycle arrest and apoptosis induction. Considering of the increased activity of Pim-1 in prostate cancer, such compounds have potential to be developed as anti-prostate cancer agents.     

Synthesis and evaluation of 7-azaindole derivatives bearing benzocycloalkanone motifs as protein kinase inhibitors

Protein kinases are important drug targets, especially in the area of oncology. This paper reports the synthesis and biological evaluation of new 7-azaindole derivatives bearing benzocycloalkanone motifs as potential protein kinase inhibitors. Four compounds 8g, 8h, 8i, and 8l were discovered to inhibit cyclin-dependent kinase 9 (CDK9/CyclinT) and/or Haspin kinase in the micromolar to nanomolar range. 8l was identified as the most potent Haspin inhibitor (IC₅₀ = 14 nM), while 8g and 8h acted as dual inhibitors of CDK9/CyclinT and Haspin. These novel compounds constitute a promising starting point for the discovery of dual protein kinase inhibitors that have potential to be developed as anticancer agents, since both CDK9/CyclinT and Haspin are considered to be drug targets in oncology.     

Synthesis,molecular modelling and biological evaluation of tetrasubstituted thiazoles towards cholinesterase enzymes and cytotoxicity studies

Alzheimer is a neurodegenerative disease and requires the development of new scaffold to treat it. In this regard, thiazoles derivative are playing their significant role. In the current research paper we have focused our attention for the development of tetrasubstituted thiazole (3a-h) derivatives using domino synthesis by mixing the thiourea as a precursor, with acetophenone in the presence of iodine and tosic acid in DMSO and refluxed for 12–22 h. The structures of the newly synthesized compounds were confirmed by FTIR, ¹H NMR, ¹³C NMR and EIMS analysis. Thiazole derivatives were analyzed for their biological significances against acetyl and butylcholinesterase enzymes and compound 3b and 3d were found more active against these enzyme, respectively. The mode of inhibition was determined for the potent compounds against both the enzymes. Moreover, the molecular docking studies were carried out to explore the interactive behavior of the compounds within the active pocket of enzymes. Furthermore, the derivatives (3a-h) were evaluated for their anticancer potential against HeLa cancer cell lines. Most potent inhibition was observed by compound 3b.     

Benzoflavones as cholesterol esterase inhibitors: Synthesis,biological evaluation and docking studies

A library of forty 7,8-benzoflavone derivatives was synthesized and evaluated for their inhibitory potential against cholesterol esterase (CEase). Among all the synthesized compounds seven benzoflavone derivatives (A-7, A-8, A-10, A-11, A-12, A-13, A-15) exhibited significant inhibition against CEase in in vitro enzymatic assay. Compound A-12 showed the most promising activity with IC₅₀ value of 0.78 nM against cholesterol esterase. Enzyme kinetic studies carried out for A-12, revealed its mixed-type inhibition approach. Molecular protein–ligand docking studies were also performed to figure out the key binding interactions of A-12 with the amino acid residues of the enzyme’s active site. The A-12 fits well at the catalytic site and is stabilized by hydrophobic interactions. It completely blocks the catalytic assembly of CEase and prevents it to participate in ester hydrolysis mechanism. The favorable binding conformation of A-12 suggests its prevailing role as CEase inhibitor.     

Synthesis and biological evaluation of substituted 6-alkynyl-4-anilinoquinazoline derivatives as potent EGFR inhibitors

A series of C-6 or C-3' alkynyl-substituted 4-anilinoquinazoline derivatives was prepared straightforwardly by a Sonogashira reaction of the corresponding bromo-substituted 4-anilinoquinazolines. Bioactive assay of these compounds for in vitro EGFR kinase inhibition demonstrated that the novel 6-hydroxypropynyl-4-anilinoquinazoline 5e was a very potent EGFR kinase inhibitor with an IC(50) of 14 nM.     

Synthesis and biological evaluation of trisubstituted imidazole derivatives as inhibitors of p38alpha mitogen-activated protein kinase

A series of trisubstituted imidazole derivatives containing a 4-fluorophenyl group, a pyrimidine ring, and a CN- or CONH₂-substituted benzyl moiety have been synthesized and evaluated for p38α MAP kinase inhibitory activity. Among them, compounds 22c, 27b, and 28b inhibited p38α MAP kinase with IC₅₀ values 27.6, 28, and 31 nM, respectively.     

Synthesis and biological evaluation of benzyl styrylsulfonyl derivatives as potent anticancer mitotic inhibitors

We herein report the synthesis, biological activity and structure activity relationship of derivatives of benzylstyrylsulfone, benzylstyrylsulfine and benzylsulfonyl-N-phenylacetamide. A lead compound 7 represents a new class of mitotic inhibitors that demonstrates potent anti-proliferative activity and selectively induces cancer cell apoptosis while sparing non-transformed lung fibroblast.     

Synthesis and biological evaluation of quinoxaline derivatives as specific c-Met kinase inhibitors

A series of novel quinoxaline derivatives were synthesized and evaluated for their inhibitory activity against c-Met kinase enzyme. Most of the tested compounds exhibited potent inhibitory activity. All the synthesized quinoxaline compounds were further examined against c-Met overexpressed human gastric cancer cell line (MKN-45), which showed good inhibitory activity. Among the synthesized compounds, compound 4 exhibited better tumor growth inhibition in the animal model study; we also confirmed its acceptable drug property and highly selective target activity.     

Synthesis,biological activity and molecular modeling studies on 1H-benzimidazole derivatives as acetylcholinesterase inhibitors

A series of N-{2-[4-(1H-benzimidazole-2-yl)phenoxy]ethyl}substituted amine derivatives were designed to assess cholinesterase inhibitor activities. Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitor activities were evaluated in vitro by using Ellman’s method. It was discovered that most of the compounds displayed AChE and/or BuChE inhibitor activity and few compounds were selective against AChE/BuChE. Compound 3c and 3e were the most active compounds in the series against eeAChE and hAChE, respectively. Molecular docking studies and molecular dynamics simulations were also carried out.     

Molecular docking studies and biological evaluation of 1,3,4-thiadiazole derivatives bearing Schiff base moieties as tyrosinase inhibitors

1,3,4-Thiadiazole derivatives bearing Schiff base moieties were designed, synthesized, and their tyrosinase inhibitory activities were evaluated. Some compounds displayed potent tyrosinase inhibitory activities, especially, 4-(((5-mercapto-1,3,4-thiadiazol-2-yl)-imino)methyl)-2-methoxy-phenol (14) exhibited superior inhibitory effect to the other compounds with an IC₅₀ value of 0.036 μM. The structure–activity relationships (SARs) were preliminarily discussed and docking studies showed compound 14 had strong binding affinity to mushroom tyrosinase. Hydroxy might be the active groups. The inhibition kinetics study revealed that compounds (13 and 14) inhibited tyrosinase by acting as uncompetitive inhibitors. The LD₅₀ value of the compound 14 was 5000 mg/kg.     

Synthesis and biological evaluation of pyrrolopyridazine derivatives as novel HER-2 tyrosine kinase inhibitors

A series of novel pyrrolopyridazine derivatives have been discovered to be HER-2 inhibitors. These compounds selectively inhibited HER-2 kinase activity at low nanomolar concentrations. Compound 7d was identified as a potent HER-2 inhibitor with an IC₅₀ of 4 nM.     

Synthesis and biological evaluation of Oblongifolin C derivatives as c-Met inhibitors

Oblongifolin C, one of the polyprenylated benzoylphloroglucinol natural products (PPAPs) isolated from the fruits of Garcinia yunnanensis Hu, was recently discovered to be a potent anti-tumor agent. A collection of 12 derivatives with modifications on the benzophenone moieties were synthesized and tested for c-Met kinase inhibition and cytotoxicity against the HepG2, Miapaca-2, HCC827, Hela, A549, AGS, and HT-29 cell lines in vitro. An oxidized derivative, 10, was found to possess strong inhibition and anti-migration properties in the HCC827 cell line and serves as a potential lead compound for the development of new anticancer drugs. In addition, structure–activity relationships (SAR) were also evaluated to provide key information for future anticancer drug development.     

Synthesis,modification and docking studies of 5-sulfonyl isatin derivatives as SARS-CoV 3C-like protease inhibitors

The Severe Acute Respiratory Syndrome (SARS) is a serious life-threatening and strikingly mortal respiratory illness caused by SARS-CoV. SARS-CoV which contains a chymotrypsin-like main protease analogous to that of the main picornavirus protease, 3CL^pro. 3CL^pro plays a pivotal role in the viral replication cycle and is a potential target for SARS inhibitor development. A series of isatin derivatives as possible SARS-CoV 3CL^pro inhibitors was designed, synthesized, and evaluated by in vitro protease assay using fluorogenic substrate peptide, in which several showed potent inhibition against the 3CL^pro. Structure–activity relationship was analyzed, and possible binding interaction modes were proposed by molecular docking studies. Among all compounds, 8k₁ showed most potent inhibitory activity against 3CL^pro (IC₅₀ = 1.04 μM). These results indicated that these inhibitors could be potentially developed into anti-SARS drugs.     

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.     

Synthesis and biological evaluation of pyrimidine derivatives as novel human Pin1 inhibitors

Pin1 (Protein interacting with NIMA1) is a cis–trans isomerase and promotes the amide bond rotation of phosphoSer/Thr-Pro motifs in its substrates. Inhibition of Pin1 might be a novel strategy for developing anticancer agents. Herein, a series of pyrimidine derivatives were synthesized and their Pin1 inhibitory activities were evaluated. Among them, four compounds (2a, 2f, 2h and 2l) displayed potent inhibitory activities against Pin1 with IC₅₀ values lower than 3?µM. This series of pyrimidine-based inhibitors presented time-dependent inhibition against Pin1. The structure–activity relationships on the 2-, 4- and 5-positions of the pyrimidine ring were analyzed in details, which would facilitate further exploration of new Pin1 inhibitors.     

Design and development of topoisomerase inhibitors using molecular modelling studies

Topoisomerase inhibitors are used as anticancer and antibacterial agents. A series of novel 2,4,6-tri-substituted pyridine derivatives reported as topoisomerase inhibitors were used for quantitative structure–activity relationship (QSAR) study. In order to understand the structural requirement of these topoisomerase inhibitors, a ligand-based pharmacophore and atom-based 3D-QSAR model have been developed. A five-point pharmacophore with one hydrophobic group (H4), four aromatic rings (R5, R6, R7 and R8) was obtained. The pharmacophore hypothesis yielded a 3D-QSAR model with good partial least-square (PLS) statistic results. The training set correlation is characterized by PLS factors (r² = 0.7892, SD = 0.2948, F = 49.9, P = 1.379). The test set correlation is characterized by PLS factors (q² = 0.7776, root mean squared error = 0.2764, Pearson R = 0.8926). The docking study revealed the binding orientations of these inhibitors at active site amino acid residues of topoisomerases enzyme. The results of pharmacophore hypothesis and 3D-QSAR provided the detail structural insights as well as highlighted the important binding features of novel 2,4,6-tri-substituted pyridine derivatives and can be developed as potent topoisomerase inhibitors.

Figure

Open in a separate windowKey structural requirement for topoisomerase activity