RESUMO
DNA gyrase is an essential enzyme in bacteria, and its inhibition results in the disruption of DNA synthesis and, subsequently, cell death. The pyrrolamides are a novel class of antibacterial agents targeting DNA gyrase. These compounds were identified by a fragment-based lead generation (FBLG) approach using nuclear magnetic resonance (NMR) screening to identify low-molecular-weight compounds that bind to the ATP pocket of DNA gyrase. A pyrrole hit with a binding constant of 1 mM formed the basis of the design and synthesis of a focused library of compounds that resulted in the rapid identification of a lead compound that inhibited DNA gyrase with a 50% inhibitory concentration (IC(50)) of 3 µM. The potency of the lead compound was further optimized by utilizing iterative X-ray crystallography to yield DNA gyrase inhibitors that also displayed antibacterial activity. Spontaneous mutants were isolated in Staphylococcus aureus by plating on agar plates containing pyrrolamide 4 at the MIC. The resistant variants displayed 4- to 8-fold-increased MIC values relative to the parent strain. DNA sequencing revealed two independent point mutations in the pyrrolamide binding region of the gyrB genes from these variants, supporting the hypothesis that the mode of action of these compounds was inhibition of DNA gyrase. Efficacy of a representative pyrrolamide was demonstrated against Streptococcus pneumoniae in a mouse lung infection model. These data demonstrate that the pyrrolamides are a novel class of DNA gyrase inhibitors with the potential to deliver future antibacterial agents targeting multiple clinical indications.
Assuntos
Amidas/farmacologia , Antibacterianos/farmacologia , Pirróis/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Inibidores da Topoisomerase II , Amidas/química , Animais , Antibacterianos/química , Sítios de Ligação , Cristalografia por Raios X , DNA Girase/química , DNA Girase/metabolismo , Farmacorresistência Bacteriana , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Camundongos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Mutação , Ligação Proteica , Pirróis/química , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Streptococcus pneumoniae/crescimento & desenvolvimentoRESUMO
The pyrrolamides are a new class of antibacterial agents targeting DNA gyrase, an essential enzyme across bacterial species and inhibition results in the disruption of DNA synthesis and subsequently, cell death. The optimization of biochemical activity and other drug-like properties through substitutions to the pyrrole, piperidine, and heterocycle portions of the molecule resulted in pyrrolamides with improved cellular activity and in vivo efficacy.
