Design and SAR of thienopyrimidine and thienopyridine inhibitors of VEGFR-2 kinase activity

Antibacterial and cytotoxicity studies of pyrrolo-based organic scaffolds and their binding interaction with bovine serum albumin

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 104 M-1 for L1 and 2.29 ± 0.11 × 104 M-1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = -40 ± 2 kcal/mol, ∆rG = -4.57 ± 0.22 kcal/mol and -T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenes and E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila.

In silico studies of a novel scaffold of benzoxazole derivatives as anticancer agents by 3D-QSAR, molecular docking and molecular dynamics simulations

The vascular endothelial growth factor receptor-2 kinases (VEGFR-2) expressed on tumor cells and vessels are attractive targets for cancer treatment. Potent inhibitors for the VEGFR-2 receptor are novel strategies to develop anti-cancer drugs. In this work, template ligand-based 3D-QSAR studies were performed on a series of benzoxazole derivatives toward different cell lines (HepG2, HCT-116 and MCF-7). Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques were used to generate 3D-QSAR models. Good predictability was derived for the optimal CoMFA models (HepG2: R_cv² = 0.509, R_pred² = 0.5128; HCT-116: R_cv² = 0.574, R_pred² = 0.5597; MCF-7: R_cv² = 0.568, R_pred² = 0.5057) and CoMSIA models (HepG2: R_cv² = 0.711, R_pred² = 0.6198; HCT-116: R_cv² = 0.531, R_pred² = 0.5804; MCF-7: R_cv² = 0.669, R_pred² = 0.6577). In addition, the contour maps derived from CoMFA and CoMSIA models were also generated to illustrate the relationship between different fields and the inhibitory activities. Moreover, molecular docking and molecular dynamics (MD) simulations were also conducted to understand the binding modes and the potential interactions between the receptor and the inhibitors. Some key residues (Leu35, Val43, Lys63, Leu84, Gly117, Leu180 and Asp191) were pointed out for stabilizing the inhibitors in the binding pocket. The binding free energies for the inhibitors agreed well with the experimental inhibitory activity and indicated that steric, electrostatic and hydrogen bond interactions are the main driving force for inhibitor-receptor binding. Overall, a good consistency between theoretical 3D-SQAR and molecular docking and MD simulation studies would provide directions for the design of new candidates, avoiding time-consuming and costly synthesis and biological evaluations. On the whole, the results derived from this study could expand the understanding of benzoxazole derivatives as anticancer agents and would be of great help in lead optimization for early drug discovery of highly potent anticancer activity targeting VEGFR-2.

In Vitro Anticancer Activity Screening of Novel Fused Thiophene Derivatives as VEGFR-2/AKT Dual Inhibitors and Apoptosis Inducers

Protein kinases are seen as promising targets in controlling cell proliferation and survival in treating cancer where fused thiophene synthon was utilized in many kinase inhibitors approved by the FDA. Accordingly, this work focused on adopting fused thienopyrrole and pyrrolothienopyrimidine scaffolds in preparing new inhibitors, which were evaluated as antiproliferative agents in the HepG2 and PC-3 cell lines. The compounds 3b (IC₅₀ = 3.105 and 2.15 μM) and 4c (IC₅₀ = 3.023 and 3.12 μM) were the most promising candidates on both cells with good selective toxicity-sparing normal cells. A further mechanistic evaluation revealed promising kinase inhibitory activity, where 4c inhibited VEGFR-2 and AKT at IC₅₀ = 0.075 and 4.60 μM, respectively, while 3b showed IC₅₀ = 0.126 and 6.96 μM, respectively. Moreover, they resulted in S phase cell cycle arrest with subsequent caspase-3-induced apoptosis. Lastly, docking studies evaluated the binding patterns of these active derivatives and demonstrated a similar fitting pattern to the reference ligands inside the active sites of both VEGFR-2 and AKT (allosteric pocket) crystal structures. To conclude, these thiophene derivatives represent promising antiproliferative leads inhibiting both VEGFR-2 and AKT and inducing apoptosis in liver cell carcinoma.

Dual target inhibitors based on EGFR: Promising anticancer agents for the treatment of cancers (2017-)

The EGFR family play a significant role in cell signal transduction and their overexpression is implicated in the pathogenesis of numerous human solid cancers. Inhibition of the EGFR-mediated signaling pathways by EGFR inhibitors is a widely used strategy for the treatment of cancers. In most cases, the EGFR inhibitors used in clinic were only effective when the cancer cells harbored specific activating EGFR mutations which appeared to preserve the ligand-dependency of receptor activation but altered the pattern of downstream signaling pathways. Moreover, cancer is a kind of multifactorial disease, and therefore manipulating a single target may result in treatment failure. Although drug combinations for the treatment of cancers proved to be successful, the use of two or more drugs concurrently still was a challenge in clinical therapy owing to various dose-limiting toxicities and drug-drug interactions caused by pharmacokinetic profiles changed. Therefore, a single drug targeting two or multiple targets could serve as an effective strategy for the treatment of cancers. In recent, drugs with diverse pharmacological effects have been shown to be more advantageous than combination therapies due to their lower incidences of side effects and more resilient therapies. Accordingly, dual target-single-agent strategy has become a popular field for cancer treatment, and researchers became more and more interest in the development of novel dual-target drugs in recent years. In this review, we briefly introduce the EGFR family proteins and synergisms between EGFR and other anticancer targets, and summarizes the development of potential dual target inhibitors based on wild-type and/or mutant EGFR for the treatment of solid cancers in the past five years. Additionally, the rational design and SARs of these dual target agents are also presented in detailed, which will lay a significant foundation for the further development of novel EGFR-based dual inhibitors with excellent druggability.

New thieno[3,2-d]pyrimidine-based derivatives: Design, synthesis and biological evaluation as antiproliferative agents, EGFR and ARO inhibitors inducing apoptosis in breast cancer cells

An array of newly synthesized thieno[3,2-d]pyrimidine-based derivatives and thienotriazolopyrimidines hybridized with some pharmacophoric anticancer fragments were designed, synthesized and assessed for their in vitro antiproliferative activity against MCF-7 and MDA-MB-231 breast cancer cell lines using erlotinib and pictilisib as reference standards in the MTT assay. In general, many compounds were endowed with considerable antiproliferative activity (IC₅₀ = 0.43-1.31 µM). Some of the tested compounds, namely 3c, 5b, 5c, 9d, 10, 11b and 13 displayed remarkable antiproliferative activity against both cell lines. Meanwhile, compounds 2c-e, 3b, 4a, 5a, 9c and 15b showed noticeable selectivity against MCF-7 cells while compounds 2b, 3a, 4b, 6a-c, 7, 8, 9b and 12 exhibited considerable selectivity against MDA-MB-231 cells. Further mechanistic evidences for their anticancer activities were provided by screening the most potent compounds against MCF-7 and/or MDA-MB-231 cells for EGFR and ARO inhibitory activities using erlotinib and letrozole as reference standards respectively. Results proved that, in general, tested compounds were better EGFRIs than ARIs. In addition, significant overexpression in caspase-9 level in treated MCF-7 breast cell line samples was observed for all tested compounds with the 4-fluorophenylhydrazone derivative 2d exhibiting the highest activation. In treated MDA-MB-231 breast cell line samples, 11b was found to highly induce caspase-9 level thereby inducing apoptosis. Cell cycle analysis and Annexin V-FITC/PI assay were also assessed for active compounds where results indicated that all tested compounds induced preG1 apoptosis and cell cycle arrest at G2/M phase. Compound 9d, as an inhibitor of ARO, was observed to downregulate the downstream signaling proteins HSP27 and p-ERK in MCF-7 cells. Furthermore, compound 11b downregulated EGFR expression as well as the downstream signaling protein p-AKT. Docking experiments on EGFR and ARO enzymes supported their in vitro results. Thus, the thienotriazolopyrimidines 11b and 12 showing good EGFR inhibition and the thieno[3,2-d]-pyrimidine derivatives 3b and 9d, eliciting the best ARO inhibition activity, can be considered as new candidates as anti-breast cancer agents that necessitate further development.

Discovery of thieno[2,3-d]pyrimidine-based derivatives as potent VEGFR-2 kinase inhibitors and anti-cancer agents

Vascular endothelial growth factor-2 (VEGFR-2) is considered one of the most important factors in tumor angiogenesis, and consequently a number of anticancer therapeutics have been developed to inhibit VEGFR-2 signaling. Accordingly, eighteen derivatives of thieno[2,3-d]pyrimidines having structural characteristics similar to VEGFR-2 inhibitors were designed and synthesized. Anticancer activities of the new derivatives were assessed against three human cancer cell lines (HCT-116, HepG2, and MCF-7) using MTT. Sorafenib was used as positive control. Compounds 17c-i, and 20b showed excellent anticancer activities against HCT-116 and HepG2 cell lines, while compounds 17i and 17g was found to be active against MCF-7 cell line. Compound 17f exhibited the highest cytotoxic activities against the examined cell lines, HCT-116 and HepG2, with IC₅₀ values of 2.80 ± 0.16 and 4.10 ± 0.45 µM, respectively. Aiming at exploring the mechanism of action of these compounds, the most active cytotoxic derivatives were in vitro tested for their VEGFR-2 inhibitory activity. Compound 17f showed high activity against VEGFR-2 with an IC₅₀ value of 0.23 ± 0.03 µM, that is equal to that of reference, sorafenib (IC₅₀ = 0.23 ± 0.04 µM). Molecular docking studies also were performed to investigate the possible binding interactions of the target compounds with the active sites of VEGFR-2. The synthesized compounds were analyzed for their ADMET and toxicity properties. Results showed that most of the compounds have low to very low BBB penetration levels and they have non-inhibitory effect against CYP2D6. All compounds were predicted to be non-toxic against developmental toxicity potential model except compounds 17b and 20b.

Synthesis of Novel Methyl 3-(hetero)arylthieno[3,2-b]pyridine-2-carboxylates and Antitumor Activity Evaluation: Studies In Vitro and In Ovo Grafts of Chick Chorioallantoic Membrane (CAM) with a Triple Negative Breast Cancer Cell Line

A series of novel functionalized methyl 3-(hetero)arylthieno[3,2-b]pyridine-2-carboxylates 2a–2h were synthesized by C-C Pd-catalyzed Suzuki-Miyaura cross-coupling of methyl 3-bromothieno[3,2-b]pyridine-2-carboxylate with (hetero)aryl pinacol boranes, trifluoro potassium boronate salts or boronic acids. Their antitumoral potential was evaluated in two triple negative breast cancer (TNBC) cell lines—MDA-MB-231 and MDA-MB-468, by sulforhodamine B assay. Their effects on the non-tumorigenic MCF-12A cells were also evaluated. The results demonstrated that three compounds caused growth inhibition in both TNBC cell lines, with little or no effect against the non-tumorigenic cells. The most promising compound was further studied concerning possible effects on cell viability (by trypan blue exclusion assay), cell proliferation (by bromodeoxyuridine assay) and cell cycle profile (by flow cytometry). The results demonstrated that the GI₅₀ concentration of compound 2e (13 μM) caused a decreased in MDA-MB-231 cell number, which was correlated with a decreased in the % of proliferating cells. Moreover, this compound increased G0/G1 phase and decreased S phases, when compared to control cells (although was not statistic significant). Interestingly, compound 2e also reduced tumor size using an in ovo CAM (chick chorioallantoic membrane) model. This work highlights the potential antitumor effect of a novel methyl 3-arylthieno[3,2-b]pyridine-2-carboxylate derivative.

Design, synthesis and biological evaluation of novel N-sulfonylamidine-based derivatives as c-Met inhibitors via Cu-catalyzed three-component reaction

In our continuing efforts to develop novel c-Met inhibitors as potential anticancer candidates, a series of new N-sulfonylamidine derivatives were designed, synthesized via Cu-catalyzed multicomponent reaction (MCR) as the key step, and evaluated for their in vitro biological activities against c-Met kinase and four cancer cell lines (A549, HT-29, MKN-45 and MDA-MB-231). Most of the target compounds showed moderate to significant potency at both the enzyme-based and cell-based assay and possessed selectivity for A549 and HT-29 cancer cell lines. The preliminary SAR studies demonstrated that compound 26af (c-Met IC₅₀ = 2.89 nM) was the most promising compound compared with the positive foretinib, which exhibited the remarkable antiproliferative activities, with IC₅₀ values ranging from 0.28 to 0.72 μM. Mechanistic studies of 26af showed the anticancer activity was closely related to the blocking phosphorylation of c-Met, leading to cell cycle arresting at G2/M phase and apoptosis of A549 cells by a concentration-dependent manner. The promising compound 26af was further identified as a relatively selective inhibitor of c-Met kinase, which also possessed an acceptable safety profile and favorable pharmacokinetic properties in BALB/c mouse. The favorable drug-likeness of 26af suggested that N-sulfonylamidines may be used as a promising scaffold for antitumor drug development. Additionally, the docking study and molecular dynamics simulations of 26af revealed a common mode of interaction with the binding site of c-Met. These positive results indicated that compound 26af is a potential anti-cancer candidate for clinical trials, and deserves further development as a selective c-Met inhibitor.

Design, synthesis and biological evaluation of novel 2,4-bismorpholinothieno[3,2-d]pyrimidine and 2-morpholinothieno[3,2-d]pyrimidinone derivatives as potent antitumor agents

To develop novel therapeutic agents with anticancer activities, two series of novel 2,4-bismorpholinyl-thieno[3,2-d]pyrimidine and 2-morpholinothieno[3,2-d]pyrimidinone derivatives were designed, synthesized and evaluated for their biological activities. Among them, compound A₁₂ showed the most potent antitumor activities against HCT116, PC-3, MCF-7, A549 and MDA-MB-231 cell lines with IC₅₀ values of 3.24 μM, 14.37 μM, 7.39 μM, 7.10 μM, and 16.85 μM, respectively. Further explorations in bioactivity were conducted to clarify the anticancer mechanism of compound A₁₂. The results showed that compound A₁₂ obviously inhibited the proliferation of A549 cell lines and decreased mitochondrial membrane potential, which led to the apoptosis of cancer cells and suppressed the migration of tumor cells.

Utilization of tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidinone as a cap moiety in design of novel histone deacetylase inhibitors

A series of novel 5,6,7,8-Tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one derivatives bearing a hydroxamic acid, 2-aminoanilide and hydrazide moieties as zinc-binding group (ZBG) were designed, synthesized and evaluated for the HDAC inhibition activity and antiproliferative activity. Most of the tested compounds displayed strong to moderate HDAC inhibitory activity. Some of these compounds showed potent anti-proliferative activity against human HepG2, MCF-7 and HCT-116 cell lines. In particular, compounds IVa, IVb, IXa and IXb exhibited significant anti-proliferative activity against the three cell lines tested compared to SAHA as a reference. Compound IVb is equipotent inhibitor for HDAC1 and HDAC2 as SAHA. It is evident that the presence of free hydroxamic acid group is essential for Zn binding affinity with maximal activity with a linker of aliphatic 6 carbons. Docking study results revealed that compound IVb could occupy the HDAC2 binding site and had the potential to exhibit antitumor activity through HDAC inhibition, which merits further investigation.

In Vitro and In Vivo Anti-Breast Cancer Activities of Some Newly Synthesized 5-(thiophen-2-yl)thieno-[2,3-d]pyrimidin-4-one Candidates

In this study, some of new thiophenyl thienopyrimidinone derivatives 2–15 were prepared and tested as anti-cancer agents by using thiophenyl thieno[2,3-d]pyrimidinone derivative 2 as a starting material, which was prepared from cyclization of ethyl ester derivative 1 with formamide. Treatment of 2 with ethyl- chloroacetate gave thienopyrimidinone N-ethylacetate 3, which was reacted with hydrazine hydrate or anthranilic acid to afford acetohydrazide 4 and benzo[d][1,3]oxazin-4-one 5, respectively. Condensation of 4 with aromatic aldehydes or phenylisothiocyanate yielded Schiff base derivatives 6,7, and thiosemicarbazise 10, which were treated with 2-mercaptoacetic acid or chloroacetic acid to give the corresponding thiazolidinones 8, 9, and phenylimino-thiazolidinone 11, respectively. Treatment of 4 with ethylacetoacetate or acetic acid/acetic anhydride gave pyrazole 12 and acetyl acetohydrazide 13 derivatives, respectively. The latter compound 13 was reacted with ethyl cycno-acetate or malononitrile to give 14 and 15, respectively. In this work, we have studied the anti-cancer activity of the synthesized thienopyrimidinone derivatives against MCF-7 and MCF-10A cancer cells. Furthermore, in vivo experiments showed that the synthesized compounds significantly reduced tumor growth up to the 8^th day of treatment in comparison to control animal models. Additionally, the synthesized derivatives showed potential inhibitory effects against pim-1 kinase activities.

Phenyl and Diaryl Ureas with Thiazolo[5,4-d]pyrimidine Scaffold as Angiogenesis Inhibitors: Design, Synthesis and Biological Evaluation

Angiogenesis is crucial for tumor growth and inhibition of angiogenesis has been regarded as a promising approach for cancer therapy. Vascular endothelial growth factor receptor-2 (VEGFR-2) is an important factor in angiogenesis. In this work, a novel series of thiazolo[5,4-d]pyrimidine derivatives inhibiting angiogenesis were rationally designed and synthesized. Their inhibitory activities against human umbilical vein endothelial cells (HUVEC) were investigated in vitro. 1-(4-Fluorophenyl)-3-{4-[(5-methyl-2-phenyl[1,3]thiazolo[5,4-d]pyrimidin-7-yl)amino]phenyl}urea (19b) and 1-(3-Fluorophenyl)-3-{4-[(5-methyl-2-phenyl[1,3]thiazolo[5,4-d]pyrimidin-7-yl)amino]phenyl}urea (19g) exhibited the most potent inhibitory effect on HUVEC proliferation (IC₅₀ =12.8 and 5.3 μm, respectively). Compound 19g could inhibit the migration of human umbilical vein endothelial cells. These results support the further investigation of these compounds as potent anticancer agents.

Design, Synthesis, and Biological Evaluation of 6-Substituted Thieno[3,2- d]pyrimidine Analogues as Dual Epidermal Growth Factor Receptor Kinase and Microtubule Inhibitors

The clinical evidence for the success of tyrosine kinase inhibitors in combination with microtubule-targeting agents prompted us to design and develop single agents that possess both epidermal growth factor receptor (EGFR) kinase and tubulin polymerization inhibitory properties. A series of 6-aryl/heteroaryl-4-(3',4',5'-trimethoxyanilino)thieno[3,2- d]pyrimidine derivatives were discovered as novel dual tubulin polymerization and EGFR kinase inhibitors. The 4-(3',4',5'-trimethoxyanilino)-6-( p-tolyl)thieno[3,2- d]pyrimidine derivative 6g was the most potent compound of the series as an antiproliferative agent, with half-maximal inhibitory concentration (IC₅₀) values in the single- or double-digit nanomolar range. Compound 6g bound to tubulin in the colchicine site and inhibited tubulin assembly with an IC₅₀ value of 0.71 μM, and 6g inhibited EGFR activity with an IC₅₀ value of 30 nM. Our data suggested that the excellent in vitro and in vivo profile of 6g may be derived from its dual inhibition of tubulin polymerization and EGFR kinase.

Pyrimidinylacetamide-based 2-pyridylureas as Angiogenesis Inhibitors: Design, Synthesis and Biological Evaluation

BACKGROUND

VEGFR-2 inhibitors have been widely used in the treatment of cancer. In our continued efforts to search for potent and novel VEGFR-2 inhibitors as antitumor agents, we have identified a series of ureas and amides bearing a oxazolopyrimidine scaffold.

AIM OF THE STUDY

To discover more potent VEGFR-2 inhibitors with stronger binding affinity and better physical and chemical properties.

METHODS

23 pyrimidinylacetamide-based ureas were designed and synthesized. Replacement of oxazolopyrimidine with a pyrimidinylacetamide generated a series of novel VEGFR-2 inhibitors.

RESULTS AND CONCLUSIONS

In HUVEC inhibition assay, the most potent compound (compound 16) possessed an IC₅₀ value of 0.43 μM. Compound 16 also inhibited the migration and capillary like tube formation of HUVECs with inhibition rate at 22% (1 μM) and 17.5% (0.8 μM) respectively. These results support the further investigation of compound 16 as a potential anti-cancer agent.

Novel Sulfonamide Derivatives Carrying a Biologically Active 3,4-Dimethoxyphenyl Moiety as VEGFR-2 Inhibitors

Novel sulfonamides 3-19 with a biologically active 3,4-dimethoxyphenyl moiety were designed and synthesized. The structures of the synthesized compounds were established using elemental analyses, IR, ¹H-NMR, ¹³C-NMR spectral data and mass spectroscopy. All the synthesized compounds were evaluated for their in vitro anticancer activity against four cancer cell lines, namely human hepatocellular carcinoma (HepG2), human medulloblastoma (Daoy), human cervical cancer (HeLa), and human colon cancer (HT-29), by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and dasatinib as the reference drug. Among the tested derivatives, compounds 4, 10, 16, and 19 showed good activity as cytotoxic agents. The most active derivatives were evaluated for their ability to inhibit vascular endothelial growth factor receptor (VEGFR)-2. Compounds Z-4-(3-(3,4-dimethoxyphenyl)-3-oxoprop-1-enylamino)-N-(5-methyl-1,3,4-thiadiazol-2-yl)-benzenesulfonamide 10 and Z-4-(3-(3,4-dimethoxyphenyl)-3-oxoprop-1-enylamino)-N-(1H-indazol-6-yl)-benzenesulfonamide 19 were more active as VEGFR-2 inhibitors than dasatinib. Molecular docking of the most active derivatives on the active site of VEGFR-2 revealed that compound 19 exhibited favorable and promising results.

Access to functionalized thienopyridines via a reagent-capsule-assisted coupling, thiolation and cyclization cascade sequence

Thienopyridines and related heterocycles were prepared by a reagent-capsule-assisted palladium-catalyzed cross-coupling, thiolation and cyclization process in moderate to good yields.

Magnetoliposomes as carriers for promising antitumor thieno[3,2-b]pyridin-7-arylamines: photophysical and biological studies

Magnetoliposomes containing MnFe₂O₄ nanoparticles were used as nanocarriers for new potent antitumor thieno[3,2-b]pyridin-7-arylamines, inhibiting the growth of human tumor cells.

Design, Synthesis and Biological Evaluation of Some 5-Arylthieno[2,3-d]pyrimidines as Potential Anti-cancer Agents

Structure-based design, synthesis and biological evaluation of new small molecules anti-cancer agents were described. On continuation of applying scaffold hopping theory, a series of 5-arylthieno[2,3-d]pyrimidines based on the structural features of lapatinib was designed, synthesized and characterized using IR, (1)H-NMR, (13)C-NMR, mass and microanalyses. Biological evaluation of the cytotoxic activity against MCF-7 cell line and the inhibition of the enzymatic activity of epidermal growth factor tyrosine kinase were carried out in vitro for the target compounds. Substituting the 4-anilino-5-arylthieno[2,3-d]pyrimidines with different pharmacophoric groups at ortho, meta and/or para positions led to discovery of two potent lead compounds 3b and f with excellent cytotoxic activity and enzymatic inhibition activity.

Synthesis and biological evaluation of novel oxazolo[5,4-d]pyrimidines as potent VEGFR-2 inhibitors

Tumor angiogenesis is mediated by vascular endothelial growth factor receptor (VEGFR) and other protein kinases. Inhibition of these kinases presents an attractive approach for developing anticancer therapeutics. In this work, a series of 2,5,7-trisubstituted oxazolo[5,4-d]pyrimidines were synthesized, and their inhibitory activities were investigated against VEGFR-2 and human umbilical vein endothelial cells (HUVEC) in vitro. Compound 9n exhibited the most potent inhibitory activity with IC50 values of 0.33 and 0.29 μM for VEGFR-2 kinase and HUVEC, respectively. A further kinase selectivity assay revealed that these compounds exhibit good VEGFR and moderate EGFR inhibitory activities. Docking analysis suggested a common mode of interaction at the ATP-binding site of VEGFR-2.

Discovery of novel tricyclic pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4-amine derivatives as VEGFR-2 inhibitors

In an effort to develop ATP-competitive VEGFR-2 selective inhibitors, a novel series of tricyclic pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4-amine derivatives were designed and synthesized. These compounds were characterized by IR, (1)H NMR, (13)C NMR, elemental and mass spectral analyses. Docking studies have given a partial insight into the molecular determinants of the activity of this novel series in VEGFR-2 kinase active site. Moreover, these compounds were assessed at 10μM for their selective inhibitory activities over a panel of 6 human kinases, namely VEGFR-1/Flt-1, VEGFR-2/KDR, EGFR, CDK5/p25, GSK3α and GSK3β. Compound N-(4,6-dimethylthieno[2,3-b]pyridine)-7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4-amine (9d) exhibited the most potent and selective inhibitory activity against VEGFR-2/KDR over the six human kinases, with an IC50 value 2.6μM. The identification of this hit candidate could aid the design of new tricyclic-based VEGFR-2 kinase modulators.

A new antitumoral Heteroarylaminothieno[3,2-b]pyridine derivative: its incorporation into liposomes and interaction with proteins monitored by fluorescence

The fluorescence properties of the new potent antitumoral methyl 3-amino-6-(benzo[d]thiazol-2-ylamino)thieno[3,2-b]pyridine-2-carboxylate in solution and when encapsulated in several different nanoliposome formulations were investigated. The compound exhibits very reasonable fluorescence quantum yields and a solvent sensitive emission in several polar and non-polar media, despite not being fluorescent in protic solvents. Fluorescence anisotropy measurements of the compound incorporated into liposomes revealed that this thienopyridine derivative can be carried in the hydrophobic region of the lipid membrane. Liposome formulations including this antitumor compound are nanometric in size, with a diameter lower than 130 nm and generally low polydispersity, and are promising for future drug delivery developments. The interaction of the compound with bovine serum albumin (BSA) and the multidrug resistance protein MDR1 was monitored by FRET, the compound acting as an energy acceptor. It was observed that the drug had a lower interaction with the MDR1 protein than with the native form of BSA, which is an important result regarding applications of this antitumoral drug.

Antiproliferative activities of halogenated thieno[3,2-d]pyrimidines

The in vitro evaluation of thieno[3,2-d]pyrimidines identified halogenated compounds 1 and 2 with antiproliferative activity against three different cancer cell lines. A structure activity relationship study indicated the necessity of the chlorine at the C4-position for biological activity. The two most active compounds 1 and 2 were found to induce apoptosis in the leukemia L1210 cell line. Additionally, the compounds were screened against a variety of other microbial targets and as a result, selective activity against several fungi was also observed. The synthesis and preliminary biological results are reported herein.

Synthesis of Some 4,5-Dihydrothieno[3,2-e][1,2,4]Triazolo[4,3-a] Pyrimi-dine-2-Carboxamides as Anti-Inflammatory and Analgesic Agents

A new series 4,5-dihydrothieno[3,2-e][1,2,4]triazolo[4,3-a]pyrimidine-2-carboxamide was synthesized. Twenty one newly synthesized compounds were investigated for their anti-inflammatory and analgesic activity using acute and subacute formalin-induced paw edema models and diclofenac Na as a reference. The acute toxicity (ALD50) and ulcerogenic effects of the active compounds were also determined. The thienotriazolopyrimidines 10a, 10c and 11c were found to exhibit remarkable anti-inflammatory activity at both models in addition to good analgesic activity with a delayed onset of action. Moreover, the active compounds showed high GI safety level and are well tolerated by experimental animals with high safety margin (ALD50 > 0.4 g/kg). Docking study using Molecular Operating Environment (MOE) version 2008.10 into COX-2 has been made for derivatives of highest anti-inflammatory activity.

New di(hetero)arylethers and di(hetero)arylamines in the thieno[3,2-b]pyridine series: synthesis, growth inhibitory activity on human tumor cell lines and non-tumor cells, effects on cell cycle and on programmed cell death

New fluorinated and methoxylated di(hetero)arylethers and di(hetero)arylamines were prepared functionalizing the 7-position of the thieno[3,2-b]pyridine, using copper (C-O) or palladium (C-N) catalyzed couplings, respectively, of the 7-bromothieno[3,2-b]pyridine, also prepared, with ortho, meta and para fluoro or methoxy phenols and anilines. The compounds obtained were evaluated for their growth inhibitory activity on the human tumor cell lines MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HCT15 (colon carcinoma), HepG2 (hepatocellular carcinoma) and HeLa (cervical carcinoma). The most active compounds, a di(hetero)arylether with a methoxy group in the meta position relative to the ether function and two di(hetero)arylamines with a methoxy group either in the ortho or in the meta position relative to the NH, were further tested at their GI50 concentrations on NCI-H460 cells causing pronounced alterations in the cell cycle profile and a strong and significant increase in the programmed death of these cells. The fluorinated and the other methoxylated compounds did not show important activity, presenting high GI₅₀ values in all the cell lines tested. Furthermore, the hepatotoxicity of the compounds was assessed using porcine liver primary cells (PLP2), established by some of us. Results showed that one of the most active compounds was not toxic to the non-tumor cells at their GI₅₀ concentrations showing to be the most promising as antitumoral.