RESUMO
We describe the biological evaluation of isothiazoloquinolones (ITQs) having structural modifications at the 6-, 7-, and 8-positions. Addition of a methoxy substituent to C-8 effected an increase in antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and a decrease in cytotoxic activity against Hep2 cells. Removal of fluorine from C-6 or replacement of the C-8 carbon with a nitrogen compromised anti-MRSA activity. When the groups attached at C-7 were compared, the anti-MRSA activity decreased in the order 6-isoquinolinyl > 4-pyridinyl > 5-dihydroisoindolyl > 6-tetrahydroisoquinolinyl. The compound with the most desirable in vitro biological profile was 9-cyclopropyl-6-fluoro-8-methoxy-7-(2-methylpyridin-4-yl)-9H-isothiazolo[5,4-b]quinoline-3,4-dione (7g). This ITQ demonstrated (i) strong in vitro anti-MRSA activity (MIC90 = 0.5 microg/mL), (ii) strong inhibitory activities against S. aureus DNA gyrase and topoisomerase IV, with weak activity against human topoisomerase II, (iii) weak cytotoxic activities against three cell lines, and (iv) efficacy in an in vivo murine thigh model of infection employing MRSA.
Assuntos
Antibacterianos/síntese química , Quinolonas/síntese química , Staphylococcus aureus/efeitos dos fármacos , Tiazóis/síntese química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular Tumoral , Farmacorresistência Bacteriana Múltipla , Feminino , Humanos , Resistência a Meticilina , Camundongos , Quinolonas/química , Quinolonas/farmacologia , Staphylococcus aureus/enzimologia , Relação Estrutura-Atividade , Tiazóis/química , Tiazóis/farmacologia , Inibidores da Topoisomerase IIRESUMO
The synthesis and biological activity of a new series of LpxC inhibitors represented by pyridone methylsulfone hydroxamate 2a is presented. Members of this series have improved solubility and free fraction when compared to compounds in the previously described biphenyl methylsulfone hydroxamate series, and they maintain superior Gram-negative antibacterial activity to comparator agents.
Assuntos
Amidoidrolases/antagonistas & inibidores , Antibacterianos/síntese química , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Ácidos Hidroxâmicos/síntese química , Piridonas/síntese química , Ácidos Sulfônicos/síntese química , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Cristalografia por Raios X , Humanos , Ácidos Hidroxâmicos/farmacocinética , Ácidos Hidroxâmicos/farmacologia , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Conformação Proteica , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , Piridonas/farmacocinética , Piridonas/farmacologia , Ratos , Estereoisomerismo , Relação Estrutura-Atividade , Ácidos Sulfônicos/farmacocinética , Ácidos Sulfônicos/farmacologiaRESUMO
In this paper, we present the synthesis and SAR as well as selectivity, pharmacokinetic, and infection model data for representative analogues of a novel series of potent antibacterial LpxC inhibitors represented by hydroxamic acid.
Assuntos
Amidoidrolases/antagonistas & inibidores , Antibacterianos/síntese química , Compostos de Bifenilo/síntese química , Ácidos Hidroxâmicos/síntese química , Éteres Fenílicos/síntese química , Infecções por Pseudomonas/tratamento farmacológico , Sulfetos/síntese química , Sulfonas/síntese química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Domínio Catalítico , Cristalografia por Raios X , Farmacorresistência Bacteriana , Ligação de Hidrogênio , Ácidos Hidroxâmicos/química , Ácidos Hidroxâmicos/farmacologia , Camundongos , Modelos Moleculares , Conformação Molecular , Éteres Fenílicos/química , Éteres Fenílicos/farmacologia , Pseudomonas aeruginosa , Ratos , Estereoisomerismo , Relação Estrutura-Atividade , Sulfetos/química , Sulfetos/farmacologia , Sulfonas/química , Sulfonas/farmacologiaRESUMO
Heteroaryl isothiazolones (HITZs) are antibacterial agents that display excellent in vitro activity against Staphylococcus aureus. We recently identified a series of these compounds that show potent bactericidal activities against methicillin-resistant Staphylococcus aureus (MRSA). We report here the results of in vitro resistance studies that reveal potential underlying mechanisms of action. HITZs selected gyrA mutations exclusively in first-step mutants of wild-type S. aureus, indicating that in contrast to the case with most quinolones, DNA gyrase is the primary target. The compounds displayed low mutation frequencies (10(-9) to 10(-10)) at concentrations close to the MICs and maintained low MICs (< or =0.016 microg/ml) against mutants with single mutations in either gyrA or grlA (parC). These data suggested that HITZs possess significant inhibitory activities against target enzymes, DNA gyrase and topoisomerase IV. This dual-target inhibition was supported by low 50% inhibitory concentrations against topoisomerase IV as measured in a decatenation activity assay and against DNA gyrase as measured in a supercoiling activity assay. Good antibacterial activities (< or =1 microg/ml) against staphylococcal gyrA grlA double mutants, as well as low frequencies (10(-9) to 10(-10)) of selection of still higher-level mutants, also suggested that HITZs remained active against mutant enzymes. We further demonstrated that HITZs exhibit good inhibition of both S. aureus mutant enzymes and thus continue to possess a novel dual-targeting mode of action against these mutant strains. In stepwise acquisition of mutations, HITZs selected quinolone resistance determining region mutations gyrA(Ser84Leu), grlA(Ser80Phe), grlA(Ala116Val), and gyrA(Glu88Lys) sequentially, suggesting that the corresponding amino acids are key amino acids involved in the binding of HITZs to topoisomerases. The overall profile of these compounds suggests the potential utility of HITZs in combating infections caused by S. aureus, including multidrug-resistant MRSA.
Assuntos
Antibacterianos/farmacologia , DNA Topoisomerase IV/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Inibidores da Topoisomerase II , Antibacterianos/química , DNA Girase/genética , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Inibidores Enzimáticos/química , Humanos , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mutação , Quinolonas/farmacologia , Staphylococcus aureus/enzimologia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Tiazóis/farmacologiaRESUMO
The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gram-positive and gram-negative clinical isolates were assessed. These compounds target bacterial DNA replication and were found to possess broad-spectrum activities especially against gram-positive strains, including antibiotic-resistant staphylococci and streptococci. These included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-nonsusceptible staphylococci, and quinolone-resistant strains. The HITZs were more active than the comparator antimicrobials in most cases. For gram-negative bacteria, the tested compounds were less active against members of the family Enterobacteriaceae but showed exceptional potencies against Haemophilus influenzae, Moraxella catarrhalis, and Neisseria spp. Good activity against several anaerobes, as well as Legionella pneumophila and Mycoplasma pneumoniae, was also observed. Excellent bactericidal activity against staphylococci was observed in time-kill assays, with an approximately 3-log drop in the numbers of CFU/ml occurring after 4 h of exposure to compound. Postantibiotic effects (PAEs) of 2.0 and 1.7 h for methicillin-susceptible S. aureus and MRSA strains, respectively, were observed, and these were similar to those seen with moxifloxacin at 10x MIC. In vivo efficacy was demonstrated in murine infections by using sepsis and thigh infection models. The 50% protective doses were Assuntos
Anti-Infecciosos/farmacologia
, Bactérias Gram-Positivas/efeitos dos fármacos
, Animais
, Farmacorresistência Bacteriana
, Infecções por Bactérias Gram-Positivas/tratamento farmacológico
, Camundongos
, Testes de Sensibilidade Microbiana
, Quinolonas/farmacologia
, Tiazóis/farmacologia
RESUMO
Bacterial primase is essential for DNA replication in Gram-positive and Gram-negative bacteria. It is also structurally distinct from eukaryotic primases, and therefore an attractive, but under-explored, target for therapeutic intervention. We applied virtual screening to discover primase inhibitors, and subsequently several commercially available analogs of these initial hits showed potent primase inhibition and in vitro antibacterial activity. This work provides a 3D pharmacophore for primase ligands, SAR trends, and leads that can be further optimized.
Assuntos
Antibacterianos/farmacologia , DNA Primase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Escherichia coli/enzimologia , Antibacterianos/química , DNA Primase/fisiologia , Replicação do DNA/efeitos dos fármacos , Desenho de Fármacos , Inibidores Enzimáticos/química , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Peso MolecularRESUMO
We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaromatic groups at the 7-position via palladium-catalyzed cross-coupling. Many of these compounds demonstrated potent antistaphylococcal activity (MICs 2 microg/mL) against a multi-drug-resistant strain (ATCC 700699) and low cytotoxic activity (CC(50)>100 microM) against the human cell line Hep2 (laryngeal carcinoma).
Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Compostos Azo/farmacologia , Resistência a Meticilina , Quinolonas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Compostos de Sulfidrila/química , Antibacterianos/síntese química , Antibacterianos/toxicidade , Compostos Azo/síntese química , Compostos Azo/química , Compostos Azo/toxicidade , Linhagem Celular Tumoral , Ciclização , Flúor/química , Humanos , Estrutura Molecular , Quinolonas/síntese química , Quinolonas/química , Quinolonas/toxicidade , Staphylococcus aureus/fisiologia , Relação Estrutura-AtividadeRESUMO
This report describes 9H-isothiazolo[5,4-b]quinoline-3,4-diones (ITQs) containing aromatic groups at the 7-position that were prepared using palladium-catalyzed cross-coupling and tested against a panel of susceptible and resistant bacteria. In general, these compounds were more effective against Gram-positive than Gram-negative organisms. Many of the ITQs were more potent than contemporary quinolones and displayed a particularly strong antistaphylococcal activity against a clinically important, multi-drug-resistant strain. In contrast with ITQs reported previously, several of the analogues described in this Letter demonstrated low cytotoxic activity against a human cell line.