RESUMO
The resistance of methicillin-resistant Staphylococcus aureus (MRSA) to all ß-lactam classes limits treatment options for serious infections involving this organism. Our goal is to discover new agents that restore the activity of ß-lactams against MRSA, an approach that has led to the discovery of two classes of natural product antibiotics, a cyclic depsipeptide (krisynomycin) and a lipoglycopeptide (actinocarbasin), which potentiate the activity of imipenem against MRSA strain COL. We report here that these imipenem synergists are inhibitors of the bacterial type I signal peptidase SpsB, a serine protease that is required for the secretion of proteins that are exported through the Sec and Tat systems. A synthetic derivative of actinocarbasin, M131, synergized with imipenem both in vitro and in vivo with potent efficacy. The in vitro activity of M131 extends to clinical isolates of MRSA but not to a methicillin-sensitive strain. Synergy is restricted to ß-lactam antibiotics and is not observed with other antibiotic classes. We propose that the SpsB inhibitors synergize with ß-lactams by preventing the signal peptidase-mediated secretion of proteins required for ß-lactam resistance. Combinations of SpsB inhibitors and ß-lactams may expand the utility of these widely prescribed antibiotics to treat MRSA infections, analogous to ß-lactamase inhibitors which restored the utility of this antibiotic class for the treatment of resistant Gram-negative infections.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Compostos de Bifenilo/farmacologia , Depsipeptídeos/farmacologia , Glicopeptídeos/farmacologia , Glicosídeos/farmacologia , Lipopeptídeos/farmacologia , Proteínas de Membrana/antagonistas & inibidores , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Oligopeptídeos/farmacologia , Infecções Estafilocócicas/tratamento farmacológico , beta-Lactamas/farmacologia , Animais , Antibacterianos/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Transporte Biológico , Compostos de Bifenilo/síntese química , Depsipeptídeos/isolamento & purificação , Sinergismo Farmacológico , Quimioterapia Combinada , Feminino , Glicopeptídeos/síntese química , Glicopeptídeos/isolamento & purificação , Glicosídeos/isolamento & purificação , Humanos , Lipopeptídeos/isolamento & purificação , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Família Multigênica , Oligopeptídeos/síntese química , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Infecções Estafilocócicas/microbiologia , Resistência beta-Lactâmica/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
Novel water-soluble amide analogs were synthesized from nocathiacin I (1) through the formation of the carboxylic acid intermediate followed by coupling to primary or secondary amines. Several compounds with potent antibacterial activity and adequate water solubility were identified. Of these, compound 19 was selected for more extensive evaluation because of its excellent in vitro antibacterial activity and in vivo efficacy, as well as clean off-target screening.
Assuntos
Amidas/química , Antibacterianos/síntese química , Peptídeos/química , Piperazinas/síntese química , Amidas/síntese química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular , Camundongos , Testes de Sensibilidade Microbiana , Piperazinas/química , Piperazinas/farmacocinética , Solubilidade , Relação Estrutura-Atividade , Água/químicaRESUMO
Parasite cGMP-dependent protein kinase (PKG) is one of the validated biochemical targets for the treatment of coccidiosis. We screened our library of natural product extracts for inhibitors of parasite PKG for the discovery of anticoccidial leads. Terferol (1) and three new terphenyls (2, 3, and 4) were isolated using bioassay-guided fractionation of the microbial extract of a Phoma sp. by a high-throughput two-step isolation method employing LH-20 and reversed-phase HPLC. These compounds inhibited parasite PKG with IC(50) values in the range 0.9-5.8 microM.
Assuntos
Ascomicetos/química , Coccidiose/tratamento farmacológico , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Eimeria tenella/efeitos dos fármacos , Inibidores Enzimáticos , Compostos de Terfenil , Animais , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia , França , Estrutura Molecular , Compostos de Terfenil/química , Compostos de Terfenil/isolamento & purificação , Compostos de Terfenil/farmacologiaRESUMO
Compounds 10a (IC50 110 pM) and 21 (IC50 40 pM) are the most potent inhibitors of Eimeria tenella cGMP-dependent protein kinase activity reported to date and are efficacious in the in vivo antiparasitic assay when administered to chickens at 12.5 and 6.25 ppm levels in the feed. However, both compounds are positive in the Ames microbial mutagenesis assay which precludes them from further development as antiprotozoal agents in the absence of negative lifetime rodent carcinogenicity studies.
Assuntos
Antiprotozoários/síntese química , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Eimeria tenella/efeitos dos fármacos , Inibidores Enzimáticos/síntese química , Imidazóis/síntese química , Piridinas/síntese química , Ração Animal , Animais , Antiprotozoários/química , Antiprotozoários/farmacologia , Galinhas , Coccidiose/tratamento farmacológico , Eimeria tenella/enzimologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Imidazóis/química , Imidazóis/farmacologia , Masculino , Estrutura Molecular , Testes de Mutagenicidade , Oocistos/efeitos dos fármacos , Testes de Sensibilidade Parasitária , Piridinas/química , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Parasite cGMP-dependent protein kinase (PKG) has been recently validated as a biochemical target for the treatment of coccidiosis. To discover new anticoccidial leads, we have screened our library of natural product extracts for inhibitors of parasite PKG. Bioassay-guided fractionation of the microbial extracts has led to the discovery of tenellones A (2) and B (3), two new highly substituted benzophenones. The isolation, structure, and activity of these compounds are described.