RESUMO
The relative non-toxicity of the diuretic amiloride, coupled with its selective inhibition of the protease urokinase plasminogen activator (uPA), makes this compound class attractive for structure-activity studies. Herein we substituted the C(2)-acylguanidine of C(5)-glycyl-amiloride with amidine and amidoxime groups. The data show the importance of maintaining C(5)-hydrophobicity. The C(5)-benzylglycine analogs containing either C(2)-acylguanidine or amidine inhibited uPA with an IC(50) ranging from 3 to 7 µM and were cytotoxic to human U87 malignant glioma cells.
Assuntos
Amidinas/síntese química , Amilorida/análogos & derivados , Amilorida/síntese química , Antineoplásicos/síntese química , Glicina/análogos & derivados , Glicina/síntese química , Inibidores de Serina Proteinase/síntese química , Ativador de Plasminogênio Tipo Uroquinase/antagonistas & inibidores , Amidinas/farmacologia , Amilorida/farmacologia , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Glicina/farmacologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Inibidores de Serina Proteinase/farmacologia , Relação Estrutura-Atividade , Ativador de Plasminogênio Tecidual/metabolismo , Ativador de Plasminogênio Tipo Uroquinase/metabolismoRESUMO
The development of targeted vehicles for systemic drug delivery relies on optimizing both the cell-targeting ligand and the physicochemical characteristics of the nanoparticle carrier. A versatile platform based on modification of gold nanoparticles with thiolated polymers is presented in which design parameters can be varied independently and systematically. Nanoparticle formulations of varying particle size, surface charge, surface hydrophilicity, and galactose ligand density were prepared by conjugation of PEG-thiol and galactose-PEG-thiol to gold colloids. This platform was applied to screen for nanoparticle formulations that demonstrate hepatocyte-targeted delivery in vivo. Nanoparticle size and the presence of galactose ligands were found to significantly impact the targeting efficiency. Thus, this platform can be readily applied to determine design parameters for targeted drug delivery systems.Modified gold nanoparticles are a suitable model for nanoparticle-based gene carriers.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Ouro/farmacologia , Nanoestruturas/química , Animais , Feminino , Galactose/química , Ouro/sangue , Ouro/química , Hepatócitos/metabolismo , Lectinas/metabolismo , Espectroscopia de Ressonância Magnética , Camundongos , Camundongos Endogâmicos C57BL , Polietilenoglicóis/química , Propriedades de SuperfícieRESUMO
The chemical syntheses of RNA oligomers containing modifications on the 5'-carbon of the 5'-terminal nucleoside for crystallographic and mechanistic studies of the hairpin ribozyme are reported. Phosphoramidites 4 and 8 were prepared and used in solid phase syntheses of RNA oligomers containing the sequence 5'-N'UCCUCUCC, where N' indicates either 5'-chloro-5'-deoxyguanosine or 5'-amino-5'-deoxyguanosine, respectively. A ribozyme ligation assay with the 5'-chloro- and 5'-amino-modified RNA oligomers demonstrated their inhibition of the hairpin-catalyzed RNA-RNA ligation reaction.
Assuntos
RNA Catalítico/metabolismo , RNA/metabolismo , Ribonucleotídeos/síntese química , Ribonucleotídeos/metabolismo , Sequência de Bases , Catálise , Compostos Organofosforados/síntese química , Compostos Organofosforados/química , RNA/química , Ribonucleotídeos/químicaRESUMO
The hairpin ribozyme catalyzes sequence-specific cleavage of RNA through transesterification of the scissile phosphate. Vanadate has previously been used as a transition state mimic of protein enzymes that catalyze the same reaction. Comparison of the 2.2 angstrom resolution structure of a vanadate-hairpin ribozyme complex with structures of precursor and product complexes reveals a rigid active site that makes more hydrogen bonds to the transition state than to the precursor or product. Because of the paucity of RNA functional groups capable of general acid-base or electrostatic catalysis, transition state stabilization is likely to be an important catalytic strategy for ribozymes.