Synthesis and structure-activity relationship of 4-(1,3-benzothiazol-2-yl)-thiophene-2-sulfonamides as cyclin-dependent kinase 5 (cdk5)/p25 inhibitors

4-(1,3-Benzothiazol-2-yl)thiophene-2-sulfonamide (4a) was found to be a moderately potent inhibitor of cyclin-dependent kinase 5 (cdk5) from a HTS screen. The synthesis and SAR around this hit is described. The X-ray coordinates of ligand 4a with cdk5 are also reported, showing an unusual binding mode to the hinge region via a water molecule.     

Synthesis and biological evaluation of 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-substituted-phenoxy)pyrimidines as dual EGFR/ErbB-2 kinase inhibitors

A series of 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-substituted-phenoxy)pyrimidine derivatives were elaborately designed based on the skeleton of Lapatinib, and evaluated for their potential to inhibit epidermal growth factor receptor (EGFR) and ErbB-2 tyrosine kinase activities and antiproliferative activities against A431 and SKOV-3 cell lines. Among these synthesized pyrimidine derivatives, 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-acrylamidophenoxy)pyrimidine (6), 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-cyanoacetamidophenoxy)pyrimidine (9), 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-{3-[6-(4-amino)pyrimidinyl]amino) phenoxy}pyrimidine (11) and 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-phenoxyacetamidophenoxy)pyrimidine (14) could significantly inhibit dual EGFR/ErbB-2 kinase activities (IC(50)=37/29 nM, 48/38 nM, 61/42 nM, 65/79 nM, respectively). And compounds 6 and 11 also showed the most potent antiproliferative activities in vitro, with the IC(50) value of 6 being 3.25 μM for A431 and 0.89 μM for SKOV-3, as for 11, 4.24 μM for A431 and 0.71 μM for SKOV-3, respectively. Docking study was also performed to determine the possible binding model.     

Synthesis and structure-activity relationship for new series of 4-phenoxyquinoline derivatives as specific inhibitors of platelet-derived growth factor receptor tyrosine kinase

We discovered a new series of 4-phenoxyquinoline derivatives as potent and selective inhibitors of the platelet-derived growth factor receptor (PDGFr) tyrosine kinase. We researched the highly potent and selective inhibitors on the basis of both PDGFr and epidermal growth factor receptor (EGFr) inhibitory activity. First, we found a compound, Ki6783 (1), which inhibited PDGFr autophosphorylation at 0.13 microM, but it did not inhibit EGFr autophosphorylation at 100 microM. After extensive explorations, we found the two desired compounds, Ki6896 (2) and Ki6945 (3), which are substituted by benzoyl and benzamide at the 4-position of the phenoxy group on 4-phenoxyquinoline, respectively. These inhibitory activities were 0.31 and 0.050 microM, respectively, but neither of them inhibited EGFr autophosphorylation at 100 microM. We further investigated the profile of both compounds toward various tyrosine and serine/threonine kinases. The three compounds specifically inhibited PDGFr rather than the other kinases.     

Synthesis and structure-activity relationships of 3-cyano-4-(phenoxyanilino)quinolines as MEK (MAPKK) inhibitors

A series of 3-cyano-4-(phenoxyanilino)cyanoquinolines has been prepared as MEK (MAP kinase kinase) inhibitors. The best activity is seen with alkoxy groups at both the 6- and 7-positions. The lead compounds show low nanomolar IC₅₀'s against MAP kinase kinase, and have potent inhibitory activity in tumor cells.     

4-Anilino-7-alkenylquinoline-3-carbonitriles as potent MEK1 kinase inhibitors

A series of substituted 7-alkenyl 4[3-chloro-4-(1-methyl-1H-imidazol-2-ylsulfanyl)]anilino-3-quinolinecarbonitrile analogs were synthesized and evaluated as MEK1 kinase inhibitors. The synthetic details, structure-activity relationships, biological activity, and selected oral exposure studies of these analogs are described. From these studies, compound 5m was chosen as a strong candidate for further evaluation. The selectivity of 5m was ascertained against a panel of 17 kinases, where activity was observed against EGFR, Src, Lyn, and IR kinases. Western blot studies in WM-266 cells demonstrated that 5m inhibited phosphorylation of ERK, while additional kinase pathways tested showed no inhibition at up to 10 microM of 5 m. PK studies, as well as a xenograft and in vivo biomarker studies are described for 5m.     

Synthesis and structure-activity relationship of aminopyridines with substituted benzoxazoles as c-Met kinase inhibitors

A series of hydroxybenzoxazole derivatives was synthesized, and their c-Met kinase inhibitory activity was evaluated. Described herein is a potent c-Met inhibitor by structural modification of the parent benzoxazole scaffold, with particular focus on the hydroxyl substituent of the benzoxazole moiety.     

Design and structure-activity relationship of heterocyclic analogs of 4-amino-3-benzimidazol-2-ylhydroquinolin-2-ones as inhibitors of receptor tyrosine kinases

Herein are described a series of novel heterocyclic analogs of the 4-amino-3-benzimidazol-2-ylhydroquinolin-2-one scaffold. These compounds are potent inhibitors of receptor tyrosine kinases and exhibit favorable pharmacokinetic profiles. The synthesis and SAR of these compounds are described.     

Design and structure-activity relationship of 3-benzimidazol-2-yl-1H-indazoles as inhibitors of receptor tyrosine kinases

3-Benzimidazol-2-yl-1H-indazole analogs were developed as inhibitors of receptor tyrosine kinases (RTK). The synthesis and SAR of this series is reported.     

Synthesis and biological evaluation of 7-substituted-1-(3-bromophenylamino)isoquinoline-4-carbonitriles as inhibitors of myosin light chain kinase and epidermal growth factor receptor

Here we present the synthesis and biological activity of a series of 7-substituted-1-(3-bromophenylamino)isoquinoline-4-carbonitriles as inhibitors of myosin light chain kinase (MLCK) and the epidermal growth factor receptor kinase (EGFR). The inhibitory effect of these molecules was found to be dependent on the nature of the substituents at the 7-position of the isoquinoline scaffold.     

Pharmacogenomics of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors

The EGFR is a validated anticancer target whose successful exploitation has added novel agents to our current treatment protocols. Subsets of patients have shown to benefit the most from these therapies, and though these differential responses have yet to be completely defined, they are mostly of genetic nature. Egfr amplifications have shown to increase sensitivity to both small molecule inhibitors and specific monoclonal antibodies targeting the EGFR. A somatic/germline egfr intron 1 CA repeat sequence polymorphism has shown to have an important role in the control of EGFR protein expression, and has been linked to an increased risk of familial breast cancer, a worse outcome in patients with colorectal cancer, and anti-EGFR treatment efficacy in preclinical models. Egfr activating mutations have been recently described in lung cancer linking a cluster of genotypes with sensitivity to EGFR tyrosine kinase pharmacological inhibition. Despite the initial excitement that this discovery elicited, follow-up reports have not unequivocally confirmed this finding, and these drugs have been solidly efficacious both in individual patients and in diseases generally lacking egfr mutations such as pancreas cancer. We are witnessing exciting developments in the field of the pharmacogenomics of cancer, and this has particularly evolved in the area pertaining EGFR tyrosine kinase inhibitors. This review will discuss the background and currently available preclinical and clinical data.     

Exploration of 3-methylisoquinoline-4-carbonitriles as protein kinase A inhibitors of Plasmodium falciparum

A series of isoquinolines have been evaluated in a homology model of Plasmodium falciparum Protein Kinase A (PfPKA) using molecular dynamics. Synthesis of these compounds was then undertaken to investigate their structure–activity relationships. One compound was found to inhibit parasite growth in an in vitro assay and provides a lead to further develop 3-methylisoquinoline-4-carbonitriles as antimalarial compounds. Development of a potent and selective PfPKA inhibitor would provide a useful tool to shed further insight into the mechanisms enabling malaria parasites to establish infection.     

Exploring structure-activity relationship of S-substituted 2-mercaptoquinazolin-4(3H)-one including 4-ethylbenzenesulfonamides as human carbonic anhydrase inhibitors

Abstract

Inhibitory action of newly synthesised 4-(2-(2-substituted-thio-4-oxoquinazolin-3(4H)-yl)ethyl)benzenesulfonamides compounds 2–13 against human carbonic anhydrase (CA, EC 4.2.1.1) (hCA) isoforms I, II, IX, and XII, was evaluated. hCA I was efficiently inhibited by compounds 2–13 with inhibition constants (K_Is) ranging from 57.8–740.2?nM. Compounds 2, 3, 4, and 12 showed inhibitory action against hCA II with K_Is between 6.4 and 14.2?nM. CA IX exhibited significant sensitivity to inhibition by derivatives 2–13 with K_I values ranging from 7.1 to 93.6?nM. Compounds 2, 3, 4, 8, 9, and 12 also exerted potent inhibitory action against hCA XII (K_Is ranging from 3.1 to 20.2?nM). Molecular docking studies for the most potent compounds 2 and 3 were conducted to exhibit the binding mode towards hCA isoforms as a promising step for SAR analyses which showed similar interaction with co-crystallized ligands. As such, a subset of these mercaptoquinazolin-4(3H)-one compounds represented interesting leads for developing new efficient and selective carbonic anhydrase inhibitors (CAIs) for the management of a variety of diseases including glaucoma, epilepsy, arthritis and cancer.     

Synthesis and structure-activity relationship (SAR) study of 4-azabenzoxazole analogues as H3 antagonists

The synthesis and SAR of a novel series of 4-azabenzoxazole histamine H(3) antagonists is described. Introduction of substituted phenyl, pyridyl and fused heterocyclic groups to the 6-position of the 4-azabenzoxazole core gave a series of compounds with good H(3) antagonist activity in both ex vivo and in vivo assays.     

Synthesis and SAR of 4-(pyrazol-3-yl)-pyridines as novel c-jun N-terminal kinase inhibitors

The design and synthesis of a novel series of c-jun N-terminal kinase (JNK) inhibitors is described. The development of the 4-(pyrazol-3-yl)-pyridine series was discovered from an earlier pyrimidine series of JNK inhibitors. Through the optimization of the scaffold 2, several potent compounds with good in vivo profiles were discovered.     

Synthesis and preliminary structure-activity relationship study of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones as potential checkpoint kinase 1 (Chk1) inhibitors

The serine-threonine checkpoint kinase 1 (Chk1) plays a critical role in the cell cycle arrest in response to DNA damage. In the last decade, Chk1 inhibitors have emerged as a novel therapeutic strategy to potentiate the anti-tumour efficacy of cytotoxic chemotherapeutic agents. In the search for new Chk1 inhibitors, a congeneric series of 2-aryl-2?H-pyrazolo[4,3-c]quinolin-3-one (PQ) was evaluated by in-vitro and in-silico approaches for the first time. A total of 30 PQ structures were synthesised in good to excellent yields using conventional or microwave heating, highlighting that 14 of them are new chemical entities. Noteworthy, in this preliminary study two compounds 4e₂ and 4h₂ have shown a modest but significant reduction in the basal activity of the Chk1 kinase. Starting from these preliminary results, we have designed the second generation of analogous in this class and further studies are in progress in our laboratories.     

Synthesis and structure-activity relationship of aminopyrimidine IKK2 inhibitors

The synthesis and structure-activity relationship of a novel series of aminopyrimidines are exemplified. Results of key compounds from within this series in the E-selectin reporter cell assay are also reported.     

Identification and structure-activity relationship of 2-morpholino 6-(3-hydroxyphenyl) pyrimidines, a class of potent and selective PI3 kinase inhibitors

PI3 Kinases are a family of lipid kinases mediating numerous cell processes such as proliferation, migration, and differentiation. The PI3 kinase pathway is often de-regulated in cancer through PI3Kα overexpression, gene amplification, mutations, and PTEN phosphatase deletion. PI3K inhibitors represent therefore an attractive therapeutic modality for cancer treatment. Herein we describe a novel series of PI3K inhibitors sharing a pyrimidine core and showing significant potency against class I PI3 kinases in the biochemical assay and in cells. The discovery, synthesis and SAR of this chemotype are described.     

Discovery of novel thienoquinoline-2-carboxamide chalcone derivatives as antiproliferative EGFR tyrosine kinase inhibitors

Novel thienoquinoline carboxamide-chalcone derivatives were prepared via the cyclization of acylated chalcones and 2-mercaptoquinoline-3-carbaldehyde in DMF with K₂CO₃. Thienoquinolines 9a–f, h exhibited promising antiproliferative effect against all the tested cell lines and gave a significant activity as EGFR inhibitors, with IC₅₀ values ranging from 0.5 and 3.2?µM, and compounds 9e and 9f being the most active of the series. They also showed better activity than Erlotinib against melanoma cancer cell line A375. Moreover, compound 9f influenced pre G1 apoptosis and cell cycle arrest at G2/M phase. The binding mode of the best EGFR inhibitor 9e in the EGFR active site revealed that the thienoquinoline ring occupied the ATP-binding site while the chalcone moiety is located in the allosteric site and is responsible for the enhanced activity of these compounds.     

Synthesis of 2-amino-4-(7-azaindol-3-yl)pyrimidines as cyclin dependent kinase 1 (CDK1) inhibitors

A novel series of 2-amino-4-(7-azaindol-3-yl)pyrimidines was discovered as cyclin dependent kinase 1 (CDK1) inhibitors. The core structure was synthesized via Pd(II) catalyzed coupling reaction. A number of analogues showed good potency for CDK1 and exhibited cellular antiproliferation activity. The structure-activity relationship is described.     

Discovery of 6-substituted 4-anilinoquinazolines with dioxygenated rings as novel EGFR tyrosine kinase inhibitors

It had been reported that some dioxygenated rings fusing with the quinazoline scaffold could lead to new EGFR inhibitors. Based on this, several kinds of oxygenated alkane quinazoline derivatives were synthetized and evaluated as EGFR inhibitors. Their antiproliferative activities were tested against four cancer cell lines: A431, MCF-7, A549, and B16-F10. Most derivatives could counteract EGF-induced EGFR phosphorylation, and their potency was comparable to the reference compound Erlotinib. The size of the fused dioxygenated ring was crucial for the biological activity and the heptatomic ring derivative 19 showed potent in vitro inhibitory activity in the enzymatic assay as well as in the cellular assay.