Synthesis of pyrazoles and isoxazoles as potent alpha(v)beta3 receptor antagonists

We describe a series of pyrazole and isoxazole analogs as antagonists of the alpha(v)beta3 receptor. Compounds showed low to sub-nanomolar potency against alpha(v)beta3, as well as good selectivity against alpha(IIb)beta3. In HT29 cells, most analogs also demonstrated significant selectivity against alpha(v)beta6. Several compounds showed good pharmacokinetic properties in rats, in addition to anti-angiogenic activity in a mouse corneal micropocket model. Compounds were synthesized in a straightforward manner from readily available glutarate precursors.     

Non-acidic pyrazole EP1 receptor antagonists with in vivo analgesic efficacy

Replacement of the carboxylic acid group in a series of previously described methylene-linked pyrazole EP(1) receptor antagonists led to the discovery of amide, reversed amide and carbamate derivatives. Two compounds, 10a and 10b, were identified as brain penetrant compounds and both demonstrated efficacy in the CFA model of inflammatory pain.     

Design, synthesis, and biological evaluation of 4-arylmethyl-1-phenylpyrazole and 4-aryloxy-1-phenylpyrazole derivatives as novel androgen receptor antagonists

A series of 4-arylmethyl-1-phenylpyrazole and 4-aryloxy-1-phenylpyrazole compounds B were designed, synthesized, and evaluated for their potential as new-generation androgen receptor (AR) antagonists therapeutically effective against castration-resistant prostate cancer (CRPC). Introduction of a bulky amide substituent (R(2)) to the terminal aryl ring of the 4-arylmethyl group favored the reduction of agonistic activity and improved the pharmacokinetic (PK) properties. Similarly, introduction of a bulky substituent in the 4-aryloxy derivatives also resulted in improved PK properties. Compounds 28 h and 44b exhibited potent antitumor effects against a CRPC model of LNCaP-hr cell line in a mouse xenograft model. On the contrary, bicalutamide showed only partial suppression of tumor growth. These results suggest that the novel pyrazole derivatives are new-generation AR antagonists, different from the 'first-generation' antagonists such as bicalutamide in a CRPC treatment model.     

Design,synthesis and biological evaluation of novel 1,3,4-trisubstituted pyrazole derivatives as potential chemotherapeutic agents for hepatocellular carcinoma

A series of novel 1,3,4-trisubstituted pyrazole derivatives were synthesized and evaluated for their cytotoxic activity against three different cancer cell lines namely HCT116, UO-31 and HepG2. Compounds 3b, 3d, 7b and 9 showed excellent anticancer activity against all the tested cancer cell lines and had better cytotoxic activities than the reference drug, Sorafenib. Therefore, these compounds were chosen to be further evaluated in a panel of HCC cell lines. Among them, 3b and 7b were the most active compounds against HCC cells used here. Further studies on the mechanism demonstrated that 3b and 7b induced apoptosis in addition to induction of cell cycle arrest at G2/M phase in HepG2 and Huh7 cells. Consistent with these results, caspase-3 assay was done and the results revealed that the pro-apoptotic activity of the target compounds could be due to the stimulation of caspases-3. In addition, CDK1 inhibition assay was done and it was found that compounds 3b and 7b inhibited CDK1 activities with IC₅₀ values of 2.38 and 1.52 µM, respectively. Finally, pyrazole derivatives 3b and 7b showed potent bioactivities, indicating that these compounds could be potent anticancer drugs in the future.     

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.     

Novel pyrazole derivatives: Synthesis and evaluation of anti-angiogenic activity

The synthesis of a series of novel trisubstituted pyrazole derivatives and their PIFA-mediated conversion to molecules bearing the fused pyrazolo[4,3-c]quinoline ring system is reported. The anti-angiogenic activity of these compounds was evaluated by using in vitro assays for endothelial cell proliferation and migration, and in the chicken chorioallantoic membrane (CAM) assay. Compounds containing the fused pyrazolo[4,3-c]quinoline motifs emerged as potent anti-angiogenic compounds, which also had the ability to inhibit the growth of human breast (MCF-7) and cervical (Hela) carcinoma cells in vitro.     

Synthesis and discovery of a novel pyrazole derivative as an inhibitor of apoptosis through modulating integrin beta4, ROS, and p53 levels in vascular endothelial cells

Recently, pyrazole derivatives as high affinity and selective A2A adenosine receptor antagonists have been reported. But, so far, there are no reports about the inhibitory effects of multi-substituted pyrazole derivatives on apoptosis of vascular endothelial cells (VECs). In this study, we synthesized six pyrazole derivatives and characterized the structures of the compounds by IR, ¹H NMR, mass spectroscopy, and element analysis. The biology assay showed that a novel pyrazole derivative, ethyl 3-(o-chlorophenyl)-5-methyl-1-phenyl-1H-pyrazole-4-carboxylate (MPD) at low concentration (25 μM) increased VECs viability and inhibited VECs apoptosis induced by deprivation of serum and FGF-2. During this process, the levels of integrin β4, reactive oxygen species (ROS), and p53 were depressed obviously. The data suggested that MPD was a potential inhibitor of apoptosis associated with the signal pathway mediated by integrin β4, ROS, and p53 in VECs.     

Synthesis, biological evaluation and SAR study of novel pyrazole analogues as inhibitors of Mycobacterium tuberculosis

As a continuation of our previous work that turned toward the identification of antimycobacterial compounds with innovative structures, two series of pyrazole derivatives were synthesized by parallel solution-phase synthesis and were assayed as inhibitors of Mycobacterium tuberculosis (MTB), which is the causative agent of tuberculosis. One of these compounds showed high activity against MTB (MIC = 4 microg/mL). The newly synthesized pyrazoles were also computationally investigated to analyze their fit properties to the pharmacophoric model for antitubercular compounds previously built by us and to refine structure-activity relationship analysis.     

Design, synthesis, and evaluation of 3,4-disubstituted pyrazole analogues as anti-tumor CDK inhibitors

Two series of 3,4-disubstituted pyrazole analogues, 3-(benzimidazol-2-yl)-4-[2-(pyridin-3-yl)-vinyl]-pyrazoles (2) and 3-(imidazol-2-yl)-4-[2-(pyridin-3-yl)-vinyl]-pyrazoles (3), were synthesized as novel cyclin-dependent kinase (CDK) inhibitors. Representative compounds showed potent and selective CDK inhibitory activities and inhibited in vitro cellular proliferation in various human tumor cells. The design, synthesis, and preliminary biological evaluation of these pyrazole compounds are reported.     

Steroidal dihydrocarbothioic acid amido pyrazoles: synthesis,characterization, cytotoxicity and genotoxicity studies

A new series of steroidal dihydrocarbothioic acid amido pyrazole analogues were synthesized, and after characterization, evaluation for cytotoxicity, comet assay and western blotting was carried out. The synthesis of these analogues is convenient and involves two steps, i.e. aldol condensation as first step followed by nucleophilic addition of thiosemicarbazide across α, β-unsaturated carbonyl as a later step. Quantitative yields of more than 80 % are obtained in both the steps. After characterization by IR, ¹H NMR, ¹³C NMR, MS and analytical data, all the compounds of both series were tested for cytotoxic activity against a panel of different human cancer cell lines by MTT assay, during which compound 3e, 3f, 4e, 4f and 4h are very potent especially against HepG2 and MCF-7 cancer cell lines. Cell cycle analysis depicted the cell death in S-phase while as annexin V-FITC/PI analysis showed that compounds effectively induce apoptosis. Apoptotic degradation of DNA of MCF-7 cells in the presence of different steroidal derivatives was analysed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay). In western blotting analysis, the relative expressions of relevant apoptotic markers depicted an apoptosis by steroidal dihydropyrazole in MCF-7 cancer cells.     

New progesterone receptor antagonists: phosphorus-containing 11beta-aryl-substituted steroids

A new series of phosphorus-containing 11beta-aryl-substituted steroids have been synthesized in an eight-step sequence involving a palladium-catalyzed coupling reaction to introduce a phosphorus group onto the aromatic ring. The compounds were evaluated for progesterone receptor (PR) antagonist activity in a T47D cell-based assay and for glucocorticoid receptor (GR) antagonist activity in an A549 cell-based assay. The structure-activity relationships of these compounds are discussed. Selected compounds were tested in vivo in a rat complement C3 assay.     

Comparative structure-activity relationship studies of 1-(5-methylsulfonylpyrid-2-yl)-5-alkyl and (hetero)aryl triazoles and pyrazoles in canine COX inhibition

Structure-activity relationship (SAR) studies of novel 5-alkyl and 5-aryl/heteroaryl substituted 1,2,4-triazoles are described. The in vitro activity is compared to the pyrazole class of compounds with analogous side chains to delineate the contribution of the triazole ring nitrogen in binding to the active site. Both series are quite potent and selective in the canine whole blood (CWB) COX-2 assay, suggesting the increased binding contribution of the hydrophobic side chains.     

Synthesis and biological validation of novel pyrazole derivatives with anticancer activity guided by 3D-QSAR analysis

Using literature data on anticancer activity of pyrazole derivatives, 3D-QSAR models were developed and 3D-QSAR analysis was performed. The 3D-QSAR analysis enabled identification of molecular properties that have the highest impact on antitumor activity against lung cancer cells. The results of 3D-QSAR analysis were taken into account while new compounds were designed. Obtained 3D-QSAR models were used for prediction of activity of new compounds. In this way, design of new compounds was guided by 3D-QSAR analysis which was performed on literature data. Ten new pyrazole derivatives were synthesised and their antitumor activities against A549 and NCIH23 lung cancer cells were validated. In order to obtain full profile of anticancer activity, cells viability (MTS) assays were combined with cell proliferation (BrdU) assays which measure actively dividing cells in treated sample. Experimental measurements showed good agreement between predicted and measured activities for majority of compounds. Also, anticancer activities of new pyrazole derivatives pointed to the chemical groups that can be useful in designing antitumor molecules. Substitution of hydrazine linker with rigid, 1,2,4-oxadiazole moiety resulted in compound 10, which has low (if any) cytotoxic activity and high potential cytostatic activity. Therefore, compound 10 presents a good starting point for design of new, more potent and safer anticancer therapeutics.     

Novel 5-substituted, 2,4-diaminofuro[2,3-d]pyrimidines as multireceptor tyrosine kinase and dihydrofolate reductase inhibitors with antiangiogenic and antitumor activity

Recent evidence suggests that combination therapy of cancer with receptor tyrosine kinase (RTK) inhibitors, which are usually cytostatic, with conventional chemotherapeutic agents, which are usually cytotoxic, provide an improved treatment option. We have designed, synthesized, and evaluated a series of novel 2,4-diamino-5-substituted furo[2,3-d]pyrimidines with RTK and dihydrofolate reductase (DHFR) inhibitory activity in single molecules, as potential cytostatic and cytotoxic agents with antitumor activity. These compounds were synthesized from 2,4-diamino-5-chloromethyl furo[2,3-d]pyrimidine and aryl methyl ketones using the Wittig reaction to afford the C-8-C-9 unsaturated analogs followed by catalytic reduction to the corresponding saturated compounds. The saturated and unsaturated C-8-C-9 bridged compounds were evaluated as inhibitors of vascular endothelial growth factor receptor (VEGFR-2, Flk, KDR), epidermal growth factor receptor, and platelet-derived growth factor receptor-beta (PDGFR-beta). Selected analogs were also evaluated as antiangiogenic agents in the chicken embryo chorioallantoic membrane (CAM) assay. The compounds were also evaluated as inhibitors of human (h) DHFR and Toxoplasma gondii (tg) DHFR. In each evaluation, a known standard compound was used as a comparison. Of the compounds evaluated, compound 32 was as potent as the standard compounds against VEGFR-2 and PDGFR-beta, showing dual inhibitory activity against RTK. This analog was also highly effective in the CAM assay. A second analog 18 also demonstrated dual VEGFR-2 and PDGFR-beta inhibitory activity as well as potent antiangiogenic activity in the CAM assay. Four additional analogs were also effective against PDGFR-beta and in the CAM assay. An unsaturated C-8-C-9 moiety was necessary for RTK inhibitory activity. Compound 32 also showed inhibitory activity against hDHFR and tgDHFR, illustrating the multitarget inhibitory potential of these analogs. The biological activity of these analogs also suggests the necessity of an unsaturated C-8-C-9 bridge for dual RTK and DHFR inhibitory activity. Compounds 18 and 32 were also evaluated in a B16 melanoma mouse model and were found to be more active as antitumor agents than methotrexate. In addition, both 18 and 32 were also active in decreasing lung metastases in a mouse model of B16 melanomas.     

In vitro and in vivo models for the evaluation of new inhibitors of human steroid sulfatase,devoid of residual estrogenic activity

The goal of our research project is to develop a new class of orally active drugs, estrone sulfatase inhibitors, for the treatment of estrogen-dependent (receptor positive) breast cancer. Several compounds were synthesized and their pharmacological potencies explored. Based on encouraging preliminary results, three of them, TX 1299, TX 1492 and TX 1506 were further studied in vitro as well as in vivo. They proved to be strong inhibitors of estrone sulfatase when measured on the whole human JEG-3 choriocarcinoma and MCF-7 breast cancer cells and their IC(50)s found to be in the range of known standard inhibitors. Their residual estrogenic activity was checked as negative in the test of induction of alkaline phosphatase (APase) activity in whole human endometrial adenocarcinoma Ishikawa cells. In addition, their effect on aromatase activity in JEG-3 cells was also examined, since the goal of inhibiting both sulfatase and aromatase activities appears very attractive. However, it has been unsuccessful so far. Then, in vivo potencies of TX 1299, the lead compound in our chemical series, were evaluated in comparison with 6,6,7-COUMATE, a non-steroidal standard, in two different rat models and by oral route. First, the absence of any residual estrogenic activity for these compounds was checked in the uterotrophic model in prepubescent female rats. Second, antiuterotrophic activity in adult ovariectomized rat supplemented with estrone sulfate (E(1)S), showed that both compounds were potent inhibitors, the power of TX 1299 relative to 6,6,7-COUMATE being around 80%. This assay was combined with uterine sulfatase level determination and confirmed the complete inhibition of this enzyme within the target organ.Preliminary studies indicated that other non-steroid compounds in the Théramex series were potent in vitro and in vivo inhibitors of estrone sulfatase in rats and further studies are in progress.     

Nelumal A, the active principle from Ligularia nelumbifolia, is a novel farnesoid X receptor agonist

A series of 29 oxyprenylated and azoprenylated phenylpropanoids were chemically synthesized and tested in transfected cultured HepG2 cells by means of the dual-luciferase assay as farnesoid X receptor (FXR) agonists, using the endogenous ligand chenodeoxycholic acid (CDCA) as reference drug. Among the tested molecules, three compounds, namely auraptene, nelumol A, and nelumal A showed a potency comparable to the endogenous ligand, with the latter natural product having a level of activity slightly superior to CDCA. Nelumal A is thus of interest as a valuable potential novel lead compound in the search for FXR agonists.     

Synthesis and activity of new aryl- and heteroaryl-substituted 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole inhibitors of the transforming growth factor-beta type I receptor kinase domain

We have expanded our previously reported series of pyrazole-based inhibitors of the TGF-beta type I receptor kinase domain (TbetaR-I) to now include new 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole analogues. Limited examination of the SAR of this new series in both enzyme and cell based in vitro assays has revealed selectivity differences with respect to p38 MAP kinase (p38 MAPK) depending on the nature of the 'warhead' group on the dihydropyrrolopyrazole ring. As with our original pyrazole series, phenyl substituents tended to show greater selectivity against p38 MAPK than those comprised of the quinoline-4-yl moiety. We have also achieved co-crystallization and X-ray analysis of compounds 3 and 15, two potent examples of this new series, with the TbetaR-I receptor kinase domain.     

Trypanocidal properties, structure-activity relationship and computational studies of quinoxaline 1,4-di-N-oxide derivatives

Pyrazole and propenone quinoxaline derivatives were tested against intracellular forms of Leishmania peruviana and Trypanosoma cruzi. Both series were tested for toxicity against proliferative and non-proliferative cells. The pyrazole quinoxaline series was quite inactive against T. cruzi; however, the compound 2,6-dimethyl-3-f-quinoxaline 1,4-dioxide was found to inhibit 50% of Leishmania growth at 8.9 μM, with no impact against proliferative kidney cells and with low toxicity against THP-1 cells and murine macrophages. The compounds belonging to the propenone quinoxaline series were moderately active against T. cruzi. Among these compounds, two were particularly interesting, (2E)-1-(7-fluoro-3-methyl-quinoxalin-2-yl)-3-(3,4,5-trimethoxy-phenyl)-propenone and (2E)-3-(3,4,5-trimethoxy-phenyl)-1-(3,6,7-trimethyl-quinoxalin-2-yl)-propenone. The former possessed selective activity against proliferative cells (cancer and parasites) and was inactive against murine peritoneal macrophages; the latter was active against Leishmania and inactive against the other tested cells. Furthermore, insilico studies showed that both series respected Lipinski’s rules and that they confirmed a linear correlation between trypanocidal activities and LogP. Docking studies revealed that compounds of the second series could interact with the poly (ADP-ribose) polymerase protein of Trypanosoma cruzi.     

Novel retinoic acid receptor alpha agonists: syntheses and evaluation of pyrazole derivatives

We have designed and synthesized a series of pyrazole derivatives as candidate retinoic acid receptor (RAR) agonists. One of them, 4-[5-(1, 5-diisopropyl-1H-3-pyrazolyl)-1H-2-pyrrolyl]benzoic acid (11b), which possesses a 2,5-disubstituted pyrrole moiety, showed selective transactivation activity for the RAR alpha receptor, and had highly potent cell-differentiating activity on HL-60 cells.     

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.