RESUMO
Thrombin is a serine protease that plays a key role in blood clotting. Pyrrolidine 1 is a potent thrombin inhibitor discovered at Merck several years ago. Seven analogs (2-8) of 1 in which the pyrrolidine core was replaced with various heterocycles were prepared and evaluated for activity against thrombin, clotting factors VIIa, IXa, Xa, and XIIa, and trypsin. The thiomorpholine analog 6 was the most active, essentially matching the thrombin inhibitory activity of 1 with slightly improved selectivity over trypsin.
Assuntos
Inibidores Enzimáticos/farmacologia , Compostos Heterocíclicos/farmacologia , Trombina/antagonistas & inibidores , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/química , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-Atividade , Trombina/metabolismoRESUMO
Resistance to existing classes of antibiotics drives the need for discovery of novel compounds with unique mechanisms of action. Nargenicin A1, a natural product with limited antibacterial spectrum, was rediscovered in a whole-cell antisense assay. Macromolecular labeling in both Staphylococcus aureus and an Escherichia coli tolC efflux mutant revealed selective inhibition of DNA replication not due to gyrase or topoisomerase IV inhibition. S. aureus nargenicin-resistant mutants were selected at a frequency of â¼1 × 10(-9), and whole-genome resequencing found a single base-pair change in the dnaE gene, a homolog of the E. coli holoenzyme α subunit. A DnaE single-enzyme assay was exquisitely sensitive to inhibition by nargenicin, and other in vitro characterization studies corroborated DnaE as the target. Medicinal chemistry efforts may expand the spectrum of this novel mechanism antibiotic.
Assuntos
DNA Polimerase III/genética , Descoberta de Drogas , Antibacterianos/química , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Replicação do DNA/efeitos dos fármacos , DNA Polimerase Dirigida por DNA/metabolismo , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Concentração Inibidora 50 , Lactonas/química , Lactonas/metabolismo , Lactonas/farmacologia , Mutação , Inibidores da Síntese de Ácido Nucleico/química , Inibidores da Síntese de Ácido Nucleico/farmacologia , Staphylococcus aureus/efeitos dos fármacosRESUMO
Bacterial resistance to antibiotics, particularly to multiple antibiotics, is becoming a cause for significant concern. The only really viable course of action to counter this is to discover new antibiotics with novel modes of action. We have recently implemented a new antisense-based chemical genetic screening technology to accomplish this goal. The discovery and antibacterial activity of coelomycin, a fully substituted 2,6-dioxo pyrazine, illustrates the application of the Staphylococcus aureus fitness test strategy to natural products discovery.