RESUMO
Here we present a natural product discovery approach, whereby structures are bioinformatically predicted from primary sequence and produced by chemical synthesis (synthetic-bioinformatic natural products, syn-BNPs), circumventing the need for bacterial culture and gene expression. When we applied the approach to nonribosomal peptide synthetase gene clusters from human-associated bacteria, we identified the humimycins. These antibiotics inhibit lipid II flippase and potentiate ß-lactam activity against methicillin-resistant Staphylococcus aureus in mice, potentially providing a new treatment regimen.
Assuntos
Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Produtos Biológicos/isolamento & purificação , Produtos Biológicos/farmacologia , Descoberta de Drogas/métodos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Microbiota/genética , Antibacterianos/síntese química , Antibacterianos/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Humanos , Lipopeptídeos/síntese química , Lipopeptídeos/química , Lipopeptídeos/genética , Lipopeptídeos/farmacologia , Staphylococcus aureus Resistente à Meticilina/enzimologia , Testes de Sensibilidade Microbiana , Conformação Molecular , Peptídeo Sintases/genética , beta-Lactamas/agonistas , beta-Lactamas/metabolismoRESUMO
Morin, a plant-derived flavonol, is known to be an effective inhibitor of Gram-positive bacteria. In this study, we explored the combined effect of morin with ß-lactam antibiotics against methicillin-resistant Staphylococcus aureus (MRSA), a multidrug-resistant pathogen. The anti-MRSA activity of morin was investigated by the broth microdilution method, checkerboard dilution test, and time-kill curve assay. The expression of the resistant protein, penicillin-binding protein (PBP2a) encoded by mecA, was analyzed by the Western blotting method in the presence of morin and oxacillin. An increased susceptibility of MRSA toward oxacillin was observed in the presence of morin. The protein level of PBP2a was reduced when MRSA (ATCC 33591) was treated with the combination of morin and oxacillin, indicating that the combination of morin and oxacillin potentiates the killing effect against MRSA. The present study indicates that the killing effect by the combinative treatment of morin and ß-lactam antibiotic is dependent on the PBP2a-mediated resistance mechanism.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Flavonoides/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Proteínas de Ligação às Penicilinas/antagonistas & inibidores , beta-Lactamas/agonistas , Ampicilina/agonistas , Ampicilina/farmacologia , Antibacterianos/química , Proteínas de Bactérias/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/ultraestrutura , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Contagem de Colônia Microbiana , Citoplasma/efeitos dos fármacos , Citoplasma/ultraestrutura , Sinergismo Farmacológico , Humanos , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/metabolismo , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Oxacilina/agonistas , Oxacilina/farmacologia , Proteínas de Ligação às Penicilinas/metabolismo , República da Coreia , Infecções Estafilocócicas/microbiologia , beta-Lactamas/farmacologiaRESUMO
Antibiotic-resistant bacterial infections have seen a marked increase in recent years, while antibiotic discovery has waned. Resistance-modifying agents (RMA) offer an intriguing alternative strategy to fight against resistant bacteria. Here we report the discovery, antibiotic profiling, and structure-activity relationships of a novel class of RMAs, tetracyclic indolines. These selectively potentiate ß-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) without antibacterial or ß-lactamase inhibitory activity on their own. The most potent analogue, 6a, showed strong potentiation of amoxicillin/clavulanic acid in a variety of hospital-acquired and community-acquired MRSA strains with low mammalian toxicity. These compounds may be further developed to extend the clinic life span of ß-lactam antibiotics.
Assuntos
Farmacorresistência Bacteriana/efeitos dos fármacos , Indóis/farmacologia , Tetraciclinas/farmacologia , beta-Lactamas/agonistas , Animais , Antibacterianos/farmacologia , Infecções Comunitárias Adquiridas/tratamento farmacológico , Infecções Comunitárias Adquiridas/microbiologia , Sinergismo Farmacológico , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Relação Estrutura-Atividade , beta-Lactamas/metabolismoRESUMO
Tripropeptin C (TPPC) is a natural calcium-ion-dependent lipopeptide antibiotic that inhibits peptidoglycan biosynthesis by binding to prenyl pyrophosphate. It displays very potent antimicrobial activity both in vitro and in a mouse model of methicillin-resistant Staphylococcus aureus (MRSA) septicemia. The combination of TPPC with all classes of beta-lactams tested (including penam, carbapenem, cephem and oxacephem) showed highly synergistic (SYN) effects against MRSA strains, but not against methicillin-sensitive S. aureus strains. These SYN effects were observed with both a checkerboard methodology and a time-kill analysis. The TPPC analog, bis-methyl ester-TPPC, which has neither antimicrobial activity nor the ability to bind prenyl pyrophosphate, also potentiated the activity of beta-lactams. This result indicates that the mechanism of the SYN activity of TPPC is independent of its binding to prenyl pyrophosphate. Therefore, synergistically enhancing the anti-MRSA activities of TPPC and beta-lactams by combining them is a novel and potentially powerful therapeutic strategy for MRSA infections.