RESUMO
The mechanism of action of AFN-1252, a selective inhibitor of Staphylococcus aureus enoyl-acyl carrier protein reductase (FabI), which is involved in fatty acid biosynthesis, was confirmed by using biochemistry, macromolecular synthesis, genetics, and cocrystallization of an AFN-1252-FabI complex. AFN-1252 demonstrated a low propensity for spontaneous resistance development and a time-dependent reduction of the viability of both methicillin-susceptible and methicillin-resistant S. aureus, achieving a ≥2-log(10) reduction in S. aureus counts over 24 h, and was extremely potent against clinical isolates of S. aureus (MIC(90), 0.015 µg/ml) and coagulase-negative staphylococci (MIC(90), 0.12 µg/ml), regardless of their drug resistance, hospital- or community-associated origin, or other clinical subgroup. AFN-1252 was orally available in mouse pharmacokinetic studies, and a single oral dose of 1 mg/kg AFN-1252 was efficacious in a mouse model of septicemia, providing 100% protection from an otherwise lethal peritoneal infection of S. aureus Smith. A median effective dose of 0.15 mg/kg indicated that AFN-1252 was 12 to 24 times more potent than linezolid in the model. These studies, demonstrating a selective mode of action, potent in vitro activity, and in vivo efficacy, support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections.
Assuntos
Antibacterianos/uso terapêutico , Proteínas de Bactérias/antagonistas & inibidores , Benzofuranos/uso terapêutico , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/antagonistas & inibidores , Pironas/uso terapêutico , Sepse/tratamento farmacológico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Administração Oral , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Benzofuranos/farmacologia , Infecções Comunitárias Adquiridas/tratamento farmacológico , Infecções Comunitárias Adquiridas/microbiologia , Infecção Hospitalar/tratamento farmacológico , Infecção Hospitalar/microbiologia , Esquema de Medicação , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/metabolismo , Feminino , Humanos , Cinética , Camundongos , Testes de Sensibilidade Microbiana , Pironas/farmacologia , Sepse/microbiologia , Sepse/mortalidade , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/enzimologia , Staphylococcus aureus/crescimento & desenvolvimento , Taxa de SobrevidaRESUMO
Spiropiperidine naphthyridinone inhibitors of Staphylococcus aureus and Escherichia coli FabI have been prepared. Compounds 14a and 14c were identified as having sub-nanomolar E. coli FabI activity and are among the most potent FabI inhibitors yet described. The structural model of 14a bound to E. coli FabI is shown.
Assuntos
Antibacterianos/farmacologia , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/antagonistas & inibidores , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/metabolismo , Escherichia coli/enzimologia , Naftiridinas/farmacologia , Piperidinas/farmacologia , Compostos de Espiro/farmacologia , Staphylococcus aureus/enzimologia , Antibacterianos/química , Domínio Catalítico , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/química , Modelos Moleculares , Naftiridinas/química , Piperidinas/química , Ligação Proteica , Compostos de Espiro/química , Relação Estrutura-AtividadeRESUMO
In the search for new antibacterial agents, the enzyme FabI has been identified as an attractive target. Employing a structure guided approach, the previously reported ene-amide series of FabI inhibitors were expanded to include 2,3,4,5-tetrahydro-1H-pyrido[2,3-b and e][1,4]diazepines. These novel series incorporate additional H-bonding functions and can be more water soluble than their naphthyridinone progenitors; diazepine 16c is shown to be efficacious in a mouse infection model.
Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Azepinas/química , Azepinas/farmacologia , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/antagonistas & inibidores , Enoil-(Proteína de Transporte de Acila) Redutase (NADH)/metabolismo , Animais , Antibacterianos/uso terapêutico , Azepinas/uso terapêutico , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Infecções por Escherichia coli/tratamento farmacológico , Camundongos , Modelos Moleculares , Ligação Proteica , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/enzimologiaRESUMO
AFN-1252 is a novel inhibitor of FabI, an essential enzyme in fatty acid biosynthesis in Staphylococcus spp. AFN-1252 exhibits typical MIC(90) values of ≤0·015 µg/ml against diverse clinical isolates of S. aureus, oral absorption, long elimination half-live and efficacy in animal models. We now report high binding (â¼95%) to serum proteins of mouse, rat, dog and humans, associated with an eight-fold increase in minimal inhibitory concentration (MIC) and which may be responsible for the long elimination half-lives on pharmacokinetic studies. Unlike daptomycin, AFN-1252 activity is not reduced in the presence of lung surfactant. AFN-1252 exhibits a short post-antibiotic effect of 1·1 hours against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) following a 4-hour exposure period. The AFN-1252 unique spectrum of activity is not compromised by interactions with major antibiotic classes, but demonstrates synergy with low concentrations of gentamicin against MSSA and MRSA. These studies support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections.
Assuntos
Antibacterianos/sangue , Antibacterianos/farmacologia , Benzofuranos/sangue , Benzofuranos/farmacologia , Proteínas Sanguíneas/metabolismo , Pironas/sangue , Pironas/farmacologia , Animais , Daptomicina/sangue , Daptomicina/farmacologia , Cães , Gentamicinas/sangue , Gentamicinas/farmacologia , Meia-Vida , Humanos , Masculino , Meticilina/sangue , Meticilina/farmacologia , Resistência a Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos , Testes de Sensibilidade Microbiana , Surfactantes Pulmonares/metabolismo , Ratos , Infecções Estafilocócicas/metabolismo , Staphylococcus aureus/efeitos dos fármacosRESUMO
The ability of non-tuberculous mycobacteria to form biofilms may allow for their increased resistance to currently used biocides in medical and industrial settings. This study examines the biofilm growth of Mycobacterium fortuitum and Mycobacterium marinum, using the MBEC trade mark assay system, and compares the susceptibility of planktonic and biofilm cells to commercially available biocides. With scanning electron microscopy, both M. fortuitum and M. marinum form biofilms that are morphologically distinct. Biocide susceptibility testing suggested that M. fortuitum biofilms displayed increased resistance over their planktonic state. This is contrasted with M. marinum biofilms, which were generally as or more susceptible over their planktonic state.