RESUMO
Two novel series of Dihydropyrimidine-hydroxamic acid hybrids (4a-4l and 5a-5l) were designed, synthesized and evaluated for in vitro Helicobacter pylori urease inhibition. In vitro enzyme inhibition screening led to the discovery of three potent urease inhibitors 2-[[4-(4-hydroxy phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy acetamide (4g), 2-[[4-(4-chloro phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy acetamide (4b) and 3-[[4-(3-methoxy phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy propanamide (5l). Compound 4g showed excellent urease inhibition with IC50 value of 14 ± 1 nM, indicated by its strong interactions with both metallic Ni++ ions, Gly279, His221, Ala365, Asp362, Asn168, Arg338 and His322 residues of the active site of urease. Further, compounds 4b and 5l displayed very good activity with IC50 value of 0.082 ± 0.004 µM and 0.14 ± 0.013 µM respectively compared to standard Acetohydroxamic acid (IC50 - 27.4 ± 1.2 µM). Kinetic studies revealed that a mixed inhibition with both competitive and non-competitive aspects is involved in the urease inhibition mechanism. The in vitro urease inhibition results were supported by molecular docking studies. Collectively, this study indicates that 4g could be considered as promising lead molecule that can be further developed as a potent drug molecule for the treatment of Helicobacter pylori caused gastritis for further studies.
Assuntos
Antibacterianos/química , Inibidores Enzimáticos/química , Helicobacter pylori/enzimologia , Ácidos Hidroxâmicos/química , Pirimidinas/química , Urease/antagonistas & inibidores , Antibacterianos/síntese química , Antibacterianos/metabolismo , Domínio Catalítico , Ensaios Enzimáticos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/metabolismo , Ácidos Hidroxâmicos/síntese química , Ácidos Hidroxâmicos/metabolismo , Cinética , Simulação de Acoplamento Molecular , Ligação Proteica , Pirimidinas/síntese química , Pirimidinas/metabolismo , Urease/química , Urease/metabolismoRESUMO
Restoration of the p53 tumor suppressor for personalised cancer therapy is a promising treatment strategy. However, several high-affinity MDM2 inhibitors have shown substantial side effects in clinical trials. Thus, elucidation of the molecular mechanisms of action of p53 reactivating molecules with alternative functional principle is of the utmost importance. Here, we report a discovery of a novel allosteric mechanism of p53 reactivation through targeting the p53 N-terminus which promotes inhibition of both p53/MDM2 (murine double minute 2) and p53/MDM4 interactions. Using biochemical assays and molecular docking, we identified the binding site of two p53 reactivating molecules, RITA (reactivation of p53 and induction of tumor cell apoptosis) and protoporphyrin IX (PpIX). Ion mobility-mass spectrometry revealed that the binding of RITA to serine 33 and serine 37 is responsible for inducing the allosteric shift in p53, which shields the MDM2 binding residues of p53 and prevents its interactions with MDM2 and MDM4. Our results point to an alternative mechanism of blocking p53 interaction with MDM2 and MDM4 and may pave the way for the development of novel allosteric inhibitors of p53/MDM2 and p53/MDM4 interactions.
RESUMO
Macrocyclization is a commonly used strategy to preorganize HCV NS3 protease inhibitors in their bioactive conformation. Moreover, macrocyclization generally leads to greater stability and improved pharmacokinetic properties. In HCV NS3 protease inhibitors, it has been shown to be beneficial to include a vinylated phenylglycine in the P2 position in combination with alkenylic P1' substituents. A series of 14-, 15- and 16-membered macrocyclic HCV NS3 protease inhibitors with the linker connecting the P2 phenylglycine and the alkenylic P1' were synthesized by ring-closing metathesis, using both microwave and conventional heating. Besides formation of the expected macrocycles in cis and trans configuration as major products, both ring-contracted and double-bond migrated isomers were obtained, in particular during formation of the smaller rings (14- and 15-membered rings). All inhibitors had K(i)-values in the nanomolar range, but only one inhibitor type was improved by rigidification. The loss in inhibitory effect can be attributed to a disruption of the beneficial π-π interaction between the P2 fragment and H57, which proved to be especially deleterious for the d-phenylglycine epimers.
Assuntos
Antivirais/síntese química , Inibidores Enzimáticos/síntese química , Hepacivirus/efeitos dos fármacos , Hepatite C Crônica/tratamento farmacológico , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/química , Antivirais/farmacologia , Antivirais/uso terapêutico , Linhagem Celular Tumoral , Desenho de Fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Glicina/análogos & derivados , Glicina/síntese química , Glicina/química , Hepatite C Crônica/epidemiologia , Hepatite C Crônica/patologia , Humanos , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/química , Compostos Macrocíclicos/farmacologia , Micro-Ondas , Terapia de Alvo Molecular , Proteínas não Estruturais Virais/química , Replicação Viral/efeitos dos fármacosRESUMO
Phenylglycine has proved to be a useful P2 residue in HCV NS3 protease inhibitors. A novel pi-pi-interaction between the phenylglycine and the catalytic H57 residue of the protease is postulated. We hypothesized that the introduction of a vinyl on the phenylglycine might strengthen this pi-pi-interaction. Thus, herein is presented the synthesis and inhibitory potency of a series of acyclic vinylated phenylglycine-based HCV NS3 protease inhibitors. Surprisingly, inhibitors based on both D- and L-phenylglycine were found to be effective inhibitors, with a slight preference for the d-epimers. Furthermore, prime-side alkenylic extension of the C-terminal acylsulfonamide group gave significantly improved inhibitors with potencies in the nanomolar range (approximately 35 nM), potencies which were retained on mutant variants of the protease.
Assuntos
Antivirais/química , Antivirais/farmacologia , Glicina/análogos & derivados , Hepacivirus/enzimologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Glicina/química , Glicina/farmacologia , Hepacivirus/efeitos dos fármacos , Hepatite C/tratamento farmacológico , Humanos , Modelos Moleculares , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/metabolismoRESUMO
Herein, the design, synthesis and inhibitory potency of a series of novel hepatitis C virus (HCV) NS3 protease inhibitors are presented. These inhibitors are based on a 2(1H)-pyrazinone P3 scaffold in combination with either a P2 phenylglycine or a glycine, and they were evaluated on the wild type as well as on two resistant variants of the enzyme, A156T and D168V. Molecular modelling suggested that the aromatic side-chain of the P2 phenylglycine occupies the same space as the substituent in position 6 on the pyrazinone core. The versatile synthetic route applied for the pyrazinone synthesis made a switch between the two positions easily feasible, resulting in phenyl- or benzyl substituted pyrazinones and leaving glycine as the P2 residue. Of several P1-P1' residues evaluated, an aromatic P1-P1' scaffold was found superior in combination with the new P3-P2 building block. As a result, an entirely new type of achiral and rigidified inhibitors was discovered, with the best of the novel inhibitors having fourfold improved potency compared to the corresponding tripeptide lead. We consider these achiral inhibitors highly suitable as starting points for further optimization.
Assuntos
Antivirais/síntese química , Hepacivirus/enzimologia , Inibidores de Proteases/síntese química , Pirazinas/síntese química , Pirazinas/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/química , Antivirais/farmacologia , Sítios de Ligação , Desenho de Fármacos , Humanos , Modelos Moleculares , Estrutura Molecular , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Ligação Proteica , Pirazinas/química , Relação Estrutura-AtividadeRESUMO
BACKGROUND: HCV infections are a serious threat to public health. An important drug target is the NS3 protease, for which several inhibitors are in clinical trials. Because of the high mutation rate of the virus, resistance against any HCV-specific drug is likely to become a substantial problem. Structure-activity data for the major resistant variants are therefore needed to guide future designs of protease inhibitors. METHODS: The inhibitory potency of tripeptide NS3 protease inhibitors, with either a P2 proline or phenylglycine, in combination with different P3 and P1-P1' groups, was assessed in enzyme activity assays using the full-length NS3 protein with known resistance-conferring substitutions A156T or D168V. The results obtained from these variants were compared with the inhibition of the wild-type enzyme. Molecular modelling was used to rationalize the biochemical results. RESULTS: Inhibitors combining the P2 proline and P1 (1R,2S)-1-amino-2-vinylcyclopropyl-carboxylic acid (vinylACCA) lost much of their potency on the resistant variants. Exchange of the P2 proline for phenylglycine yielded inhibitors that were equipotent on the wild-type and on the A156T and D168V variants. The same result was obtained from the combination of either the P2 residue with a norvaline or an aromatic scaffold in the P1 position. CONCLUSIONS: The combination of a substituted P2 proline and P1 vinylACCA appears to be the main problem behind the observed resistance. Molecular modelling suggests an enforced change in binding conformation for the P2 proline-based inhibitors, whereas the phenylglycine-based inhibitors retained their wild-type binding conformation in the substituted forms of the enzyme.
Assuntos
Farmacorresistência Viral , Hepacivirus/efeitos dos fármacos , Inibidores de Proteases/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Proteínas não Estruturais Virais/metabolismo , Hepacivirus/enzimologia , Modelos Moleculares , Inibidores de Proteases/química , Ligação Proteica , Relação Estrutura-AtividadeRESUMO
Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed for 100 anilinoquinazolines, inhibiting epidermal growth factor receptor (EGFR) kinase. The studies included molecular field analysis (MFA) and receptor surface analysis (RSA). The cross-validated r2 (r2cv) values are 0.81 and 0.79 for MFA and RSA, respectively. The predictive ability of these models was validated by 28 test set molecules. The results of the best QSAR model were further compared with structure-based investigations using docking studies with the crystal structure of EGFR kinase domain. The results helped to understand the nature of substituents at the 6- and 7-positions, thereby providing new guidelines for the design of novel inhibitors.