RESUMO
Stereocalpin A is a cyclic depsipeptide with cytotoxic activity isolated from the Antarctic lichen Stereocaulon alpinum. Although a number of synthetic investigations of the unprecedented 12-membered macrocycle of stereocalpin A with a dipeptide segment and a polyketide substructure have been conducted, the configurational assignment has not been completed. In this study, we achieved the first total synthesis and stereochemical revision of stereocalpin A. To facilitate the comprehensive assessment of eight possible stereocalpin A isomers, four stereoisomers of polyketide precursors were conjugated with l-Phe-l-MePhe and d-Phe-d-MePhe dipeptides (MePhe: N-methylphenylalanine) to provide four possible isomers and four mirror-image structures of the remaining isomers, respectively. The comparative NMR analysis of a series of stereoisomers revealed that stereocalpin A possesses 2 R,4 S,5 R-configurations, which is unique among the related 12-membered hybrid peptide-polyketide natural products reported recently. The NOE correlations in the polyketide substructure of stereocalpin A were also retrospectively analyzed among the eight possible stereoisomers.
Assuntos
Depsipeptídeos/química , Depsipeptídeos/síntese química , Policetídeos/química , Técnicas de Química Sintética , EstereoisomerismoRESUMO
A head-to-tail macrocyclization protocol for the preparation of cysteine-free cyclic peptides was investigated. The o-aminoanilide linker constructed in the peptide sequence by a standard Fmoc-based peptide synthesis procedure was subjected to nitrite-mediated activation under acidic conditions toward N-acyl benzotriazole as the active ester species. The subsequent cyclization smoothly proceeded by neutralization in the presence of additives such as 1-hydroxybenzotriazole (HOBt) and 1-hydroxy-7-azabenzotriazole (HOAt) to afford the expected cyclic pentapeptide, a CXCR4 antagonist. The cyclization efficiencies were dependent on the precursor open-chain sequence. The application of this step-wise activation-cyclization protocol to microflow reaction systems is also described.
Assuntos
Anilidas/química , Peptídeos Cíclicos/síntese química , Peptídeos/química , Sequência de Aminoácidos , Anilidas/síntese química , Compostos Aza/química , Ciclização , Peptídeos Cíclicos/química , Triazóis/químicaRESUMO
1,3a,6a-Triazapentalene is a compact fluorescent chromophore. In this study, triazapentalene was used to modify a series of biphenyl-type inhibitors of kinesin spindle protein (KSP) to develop fluorescent probes for the intracellular visualization of this protein. Microscopic studies demonstrated that these novel triazapentalene-labeled compounds exhibited inhibitory activity towards KSP in cultured cells and provided important information concerning the intracellular distribution.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacologia , Cinesinas/antagonistas & inibidores , Cinesinas/análise , Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Proliferação de Células/efeitos dos fármacos , Células HeLa , Humanos , Microscopia de FluorescênciaRESUMO
Odoamide is a novel cyclic depsipeptide with highly potent cytotoxic activity isolated from the Okinawan marine cyanobacterium Okeania sp. It contains a 26-membered macrocycle composed of a fatty acid moiety, a peptide segment and isoleucic acid. Four possible stereoisomers of the odoamide polyketide substructure were synthesised using a chiral pool approach. The first total synthesis of odoamide was also successfully achieved. The structure of synthetic odoamide was verified by comparing its NMR spectra with those of the natural product.
Assuntos
Antineoplásicos/síntese química , Cianobactérias/química , Depsipeptídeos/síntese química , Policetídeos/síntese química , Células A549 , Antineoplásicos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Depsipeptídeos/química , Depsipeptídeos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Neoplasias/tratamento farmacológico , Policetídeos/química , Policetídeos/farmacologia , EstereoisomerismoRESUMO
Acrolein, a toxic unsaturated aldehyde generated as a result of oxidative stress, readily reacts with a variety of nucleophilic biomolecules. Polyamines, which produced acrolein in the presence of amine oxidase, were then found to react with acrolein to produce 1,5-diazacyclooctane, a previously unrecognized but significant downstream product of oxidative stress. Although diazacyclooctane formation effectively neutralized acrolein toxicity, the diazacyclooctane hydrogel produced through a sequential diazacyclooctane polymerization reaction was highly cytotoxic. This study suggests that diazacyclooctane formation is involved in the mechanism underlying acrolein-mediated oxidative stress.
Assuntos
Acroleína/toxicidade , Azocinas/toxicidade , Células Epiteliais/efeitos dos fármacos , Hidrogéis/química , Espermidina/metabolismo , Espermina/metabolismo , Acroleína/metabolismo , Amina Oxidase (contendo Cobre)/antagonistas & inibidores , Amina Oxidase (contendo Cobre)/metabolismo , Azocinas/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Células Epiteliais/citologia , Células Epiteliais/enzimologia , Guanidinas/farmacologia , Células HeLa , Heme Oxigenase-1/metabolismo , Humanos , Estresse Oxidativo/efeitos dos fármacos , Polimerização , Espermidina/química , Espermina/químicaRESUMO
Structure-activity relationship studies of diaryl amine-type KSP inhibitors were carried out. Diaryl amine derivatives with a pyridine ring or urea group were less active when compared with the parent carboline and carbazole derivatives. Optimization studies of a lactam-fused diphenylamine-type KSP inhibitor revealed that the aniline NH group and 3-CF3 phenyl group were indispensable for potent KSP inhibition. Modification with a seven-membered lactam-fused phenyl group and a 4-(trifluoromethyl)pyridin-2-yl group improved aqueous solubility while maintaining potent KSP inhibitory activity. From these studies, we identified novel diaryl amine-type KSP inhibitors with a favorable balance of potency and solubility.
Assuntos
Difenilamina/química , Difenilamina/farmacologia , Cinesinas/antagonistas & inibidores , Mitose/efeitos dos fármacos , Humanos , Cinesinas/metabolismo , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
Kisspeptins are neuropeptides that induce the secretion of gonadotropin-releasing hormone via the activation of the cognate receptor, G-protein coupled receptor 54 (GPR54). The kisspeptin-GPR54 axis is associated with the onset of puberty and the maintenance of the reproductive system. In this study, several fluorescent probes have been designed and synthesized for rat GPR54 through the modification of the N-terminus of rat kisspeptins to allow for the visualization of the expression and localization of kisspeptin receptor(s) in living cells and native tissues. The tetramethylrhodamine (TMR) and rhodamine green (RG)-labeled kisspeptins exhibited good binding and agonistic activities towards GPR54, and the results of the application studies demonstrated that these fluorescent probes could be used effectively for the detection of GPR54 receptors in flow cytometry and confocal microscopy experiments.
Assuntos
Desenho de Fármacos , Corantes Fluorescentes/química , Kisspeptinas/química , Receptores Acoplados a Proteínas G/análise , Animais , Células CHO , Linhagem Celular , Cricetulus , Relação Dose-Resposta a Droga , Corantes Fluorescentes/administração & dosagem , Corantes Fluorescentes/farmacologia , Humanos , Injeções Intravenosas , Kisspeptinas/administração & dosagem , Kisspeptinas/farmacologia , Masculino , Estrutura Molecular , Ratos , Receptores Acoplados a Proteínas G/agonistas , Receptores de Kisspeptina-1 , Relação Estrutura-AtividadeRESUMO
Kisspeptins, endogenous peptide ligands for GPR54, play an important role in GnRH secretion. Since in vivo administration of kisspeptins induces increased plasma LH levels, GPR54 agonists hold promise as therapeutic agents for the treatment of hormonal secretion diseases. To facilitate the design of novel potent GPR54 ligands, residues in kisspeptins that involve in the interaction with GPR54 were investigated by kisspeptin-based photoaffinity probes. Herein, we report the design and synthesis of novel kisspeptin-based photoaffinity probes, and the application to crosslinking experiments for GPR54-expressing cells.
Assuntos
Marcadores de Afinidade/química , Kisspeptinas/agonistas , Peptídeos/química , Raios Ultravioleta , Sequência de Aminoácidos , Biotina/química , Hormônio Liberador de Gonadotropina/metabolismo , Células HEK293 , Humanos , Kisspeptinas/metabolismo , Dados de Sequência Molecular , Peptídeos/metabolismo , Ligação Proteica , Receptores de Neuropeptídeos/química , Receptores de Neuropeptídeos/metabolismo , Relação Estrutura-AtividadeRESUMO
MDM2 and MDMX are oncoproteins that negatively regulate the activity and stability of the tumor suppressor protein p53. The inhibitors of protein-protein interactions (PPIs) of MDM2-p53 and MDMX-p53 represent potential anticancer agents. In this study, a novel approach for identifying MDM2-p53 and MDMX-p53 PPI inhibitor candidates by affinity-based screening using a chemical array has been established. A number of compounds from an in-house compound library, which were immobilized onto a chemical array, were screened for interaction with fluorescence-labeled MDM2 and MDMX proteins. The subsequent fluorescent polarization assay identified several compounds that inhibited MDM2-p53 and MDMX-p53 interactions.
Assuntos
Ensaios de Triagem em Larga Escala , Proteínas Nucleares/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-mdm2/antagonistas & inibidores , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteína Supressora de Tumor p53/antagonistas & inibidores , Proteínas de Ciclo Celular , Relação Dose-Resposta a Droga , Humanos , Modelos Moleculares , Estrutura Molecular , Proteínas Nucleares/metabolismo , Ligação Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/metabolismoRESUMO
Odoamide is a cytotoxic peptide-polyketide hybrid molecule isolated from the Okinawan marine cyanobacterium Okeania sp. For an efficient structure-activity relationship study of the peptide part of odoamide, a facile synthetic protocol was established using a solid-phase peptide synthesis. Among a series of peptides, the d-MeAla6 isomer exhibited a more potent cytotoxicity than natural odoamide. It was also demonstrated that the 26-membered macrocyclic natural odoamide and the 24-membered isomer with comparable cytotoxicities were slowly interconvertible, and both isomers contributed to the potent cytotoxicity of odoamide. Examination of the physicochemical properties revealed that the in vitro cytotoxicity was affected by the serum protein binding of odoamide derivatives, while the differences in the macrocyclic structures had no significant effect on the membrane permeability.
RESUMO
Diaryl amine derivatives have been designed and synthesized as novel kinesin spindle protein (KSP) inhibitors based on planar carbazole-type KSP inhibitors with poor aqueous solubility. The new generation of inhibitors was found to show comparable inhibitory activity and high selectivity for KSP, and this was accompanied with improved solubility. Kinetic analysis and molecular modeling studies suggested that these inhibitors work in an ATP-competitive manner via binding to the secondary allosteric site formed by α4 and α6 helices of KSP. Comparative structural investigations on a series of compounds revealed that the higher solubility of diaryl amine-type inhibitors was attributed to fewer van der Waals interactions in the crystal packing and the hydrogen-bond acceptor nitrogen of the aniline moiety for favorable solvation.