RESUMO
This study describes a novel series of UDP-N-acetylglucosamine acyltransferase (LpxA) inhibitors that was identified through affinity-mediated selection from a DNA-encoded compound library. The original hit was a selective inhibitor of Pseudomonas aeruginosa LpxA with no activity against Escherichia coli LpxA. The biochemical potency of the series was optimized through an X-ray crystallography-supported medicinal chemistry program, resulting in compounds with nanomolar activity against P. aeruginosa LpxA (best half-maximal inhibitory concentration (IC50) <5 nM) and cellular activity against P. aeruginosa (best minimal inhibitory concentration (MIC) of 4 µg/mL). Lack of activity against E. coli was maintained (IC50 > 20 µM and MIC > 128 µg/mL). The mode of action of analogues was confirmed through genetic analyses. As expected, compounds were active against multidrug-resistant isolates. Further optimization of pharmacokinetics is needed before efficacy studies in mouse infection models can be attempted. To our knowledge, this is the first reported LpxA inhibitor series with selective activity against P. aeruginosa.
Assuntos
Aciltransferases/antagonistas & inibidores , Antibacterianos/farmacologia , Descoberta de Drogas , Inibidores Enzimáticos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/química , Cristalografia por Raios X , Farmacorresistência Bacteriana/efeitos dos fármacos , Inibidores Enzimáticos/química , Escherichia coli/enzimologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
The effect of various conditions including pH, inoculum, temperature, atmosphere, divalent cations, and several body fluids on the in vitro activity of the novel antibacterial spiropyrimidinetrione ETX0914 in standard susceptibility tests was investigated against several species. None of the parameters investigated affected the activity of ETX0914, with the exception of pH. Whereas the MIC values for ETX0914 with S. aureus, E. faecalis, and E. coli did not change when the pH of the growth medium was varied from 5 to 8, they did increase at least 8-fold at pH values above 8. This loss of activity can be attributed to the deprotonation of the molecule at elevated pH. The data suggest that routine susceptibility testing with ETX0914 should result in reproducible MIC values.
Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Barbitúricos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Compostos de Espiro/farmacologia , Meios de Cultura/química , Humanos , Concentração de Íons de Hidrogênio , Isoxazóis , Morfolinas , Oxazolidinonas , Reprodutibilidade dos Testes , TemperaturaRESUMO
Sulbactam is a class A ß-lactamase inhibitor with intrinsic whole-cell activity against certain bacterial species, including Acinetobacter baumannii. The clinical use of sulbactam for A. baumannii infections is of interest due to increasing multidrug resistance in this pathogen. However, the molecular drivers of its antibacterial activity and resistance determinants have yet to be precisely defined. Here we show that the antibacterial activities of sulbactam vary widely across contemporary A. baumannii clinical isolates and are mediated through inhibition of the penicillin-binding proteins (PBPs) PBP1 and PBP3, with very low frequency of resistance; the rare pbp3 mutants with high levels of resistance to sulbactam are attenuated in fitness. These results support further investigation of the potential clinical utility of sulbactam.
