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There is an urgent need for new antibiotics against Gram-negative pathogens that are resistant to carbapenem and third-generation cephalosporins, against which antibiotics of last resort have lost most of their efficacy. Here we describe a class of synthetic antibiotics inspired by scaffolds derived from natural products. These chimeric antibiotics contain a ß-hairpin peptide macrocycle linked to the macrocycle found in the polymyxin and colistin family of natural products. They are bactericidal and have a mechanism of action that involves binding to both lipopolysaccharide and the main component (BamA) of the ß-barrel folding complex (BAM) that is required for the folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. Extensively optimized derivatives show potent activity against multidrug-resistant pathogens, including all of the Gram-negative members of the ESKAPE pathogens1. These derivatives also show favourable drug properties and overcome colistin resistance, both in vitro and in vivo. The lead candidate is currently in preclinical toxicology studies that-if successful-will allow progress into clinical studies that have the potential to address life-threatening infections by the Gram-negative pathogens, and thus to resolve a considerable unmet medical need.
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Antibacterianos/química , Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos , Bactérias Gram-Negativas/efeitos dos fármacos , Peptidomiméticos/química , Peptidomiméticos/farmacologia , Animais , Antibacterianos/efeitos adversos , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Produtos Biológicos/química , Descoberta de Drogas , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Fluorescência , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/patogenicidade , Humanos , Lipopolissacarídeos/química , Compostos Macrocíclicos/efeitos adversos , Compostos Macrocíclicos/química , Compostos Macrocíclicos/farmacologia , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Mutação , Peptidomiméticos/efeitos adversos , Marcadores de FotoafinidadeRESUMO
BACKGROUND: The clinical candidate alpibectir augments the activity of, and overcomes resistance to, the anti-TB drug ethionamide in vitro and in vivo. OBJECTIVES: A Phase 1, double-blind, randomized, placebo-controlled study to investigate the safety, tolerability, pharmacokinetics (PK) and food effect of alpibectir administered as single and multiple oral doses in healthy volunteers (NCT04654143). METHODS: Eighty participants were randomized. In single ascending dose (SAD), a total of six dose levels of alpibectir (0.5 to 40â mg) were tested under fasted and fed (10â mg) conditions as single daily doses in sequential cohorts. In multiple ascending dose (MAD), repeat doses (5 to 30â mg) were administered once daily for 7â days in three sequential cohorts. RESULTS: No serious adverse event was reported. Thirteen participants across groups experienced a total of 13 mild or moderate treatment-emergent adverse events. Alpibectir showed rapid absorption after single dose (mean Tmax range of 0.88 to 1.53â h). Food affected the PK of alpibectir, characterized by a slower absorption (mean Tmax 3.87â h), a lower Cmax (-17.7%) and increased AUC0-t (+19.6%) compared with the fasted condition. Following repeat dosing, dose proportionality was shown for both Cmax and AUC0-tau. Accumulation of alpibectir was observed across all doses, with a more profound effect on AUC during a dosing interval (AUC0-tau) compared with Cmax (1.8- and 1.3-fold on average), respectively. Steady state was considered to have been achieved by Day 7 of dosing. CONCLUSIONS: Alpibectir was generally well tolerated, and no clinically relevant safety findings were identified in the participants treated during SAD or MAD. The PK is dose-proportional and affected by food.
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Antituberculosos , Voluntários Saudáveis , Humanos , Adulto , Masculino , Feminino , Método Duplo-Cego , Adulto Jovem , Pessoa de Meia-Idade , Antituberculosos/farmacocinética , Antituberculosos/administração & dosagem , Antituberculosos/efeitos adversos , Interações Alimento-Droga , Administração Oral , Adolescente , Placebos/administração & dosagem , Efeitos Colaterais e Reações Adversas Relacionados a MedicamentosRESUMO
The objective was to determine the in vitro antimicrobial susceptibility of Pseudomonas aeruginosa isolates cultured from cystic fibrosis (CF) patients and explore associations between strain sequence type and susceptibility. Fourteen antibiotics and antibiotic combinations, including the novel antibacterial peptide murepavadin, were tested for activity against 414 Pseudomonas aeruginosa isolates cultured from respiratory samples of CF patients. The complete genomes of the isolates were sequenced, and minimum spanning trees were constructed based on the sequence types (STs). Percentages of resistance according to CLSI 2019 breakpoints were as follows: cefepime, 14%; ceftazidime, 11%; ceftazidime-avibactam, 7%; ceftolozane-tazobactam, 3%; piperacillin-tazobactam, 12%; meropenem, 18%; imipenem, 32%; aztreonam, 23%; ciprofloxacin, 30%; gentamicin, 30%; tobramycin, 12%; amikacin, 18%; and colistin, 4%. Murepavadin MIC50 and MIC90 were 0.12 mg/liter and 2 mg/liter, respectively. There were no apparent clonal clusters associated with resistance, but higher MICs did appear to occur more often in STs with multiple isolates than in single ST isolates. In general, the CF isolates showed a wide genetic distribution. P. aeruginosa CF isolates exhibited the lowest resistance rates against ceftolozane-tazobactam, ceftazidime-avibactam, and colistin. Murepavadin demonstrated the highest activity on a per-weight basis and may therefore become a valuable addition to the currently available antibiotics for treatment of respiratory infection in people with CF.
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Antibacterianos/farmacologia , Fibrose Cística/microbiologia , Peptídeos Cíclicos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Farmacorresistência Bacteriana Múltipla , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Infecções por Pseudomonas , Pseudomonas aeruginosa/genéticaRESUMO
BACKGROUND: POL7306 belongs to a new class of peptidomimetic outer-membrane-protein-targeting antibiotics with a novel mechanism of action. POL7306 is in development for the treatment of infections caused by antimicrobial-resistant Gram-negative bacteria and has demonstrated low cytotoxicity and nephrotoxicity. METHODS: A total of 891 isolates were collected by the SENTRY Antimicrobial Surveillance Program from 134 medical centres in Europe (n = 424; 41 centres in 18 nations), the USA (n = 411 isolates from 67 centres), the Asia-Pacific region (n = 24; 15 centres in 6 nations) and Latin America (n = 32; 11 centres in 9 nations) and included 558 Enterobacterales, 310 non-fermenters and 23 fastidious organisms. Susceptibility testing was performed using the reference broth microdilution method and the medium was supplemented with 0.002% polysorbate-80 for testing POL7306. Resistant subsets were characterized by WGS. RESULTS: POL7306 demonstrated potent in vitro activity against Enterobacterales [including carbapenem-resistant (MIC50/90, 0.06/0.25 mg/L), ESBL-producing (MIC50/90, 0.06/0.12 mg/L), KPC-producing (MIC50/90, 0.12/0.25 mg/L), MBL-producing (MIC50/90, 0.06/0.25 mg/L), colistin-non-susceptible, mcr-negative (MIC50/90, 0.5/2 mg/L) and mcr-positive (MIC50/90, 0.12/0.25 mg/L) Enterobacterales], Pseudomonas aeruginosa (MIC50/90, 0.25/0.25 mg/L), Acinetobacter baumannii (MIC50/90, 0.06/0.12 mg/L) and Stenotrophomonas maltophilia (MIC50/90, 0.06/0.25 mg/L). CONCLUSIONS: POL7306 demonstrated potent activity against a large collection of Gram-negative organisms collected worldwide that included colistin-resistant, XDR and ESBL- and carbapenemase-producing isolates for which there are currently limited treatment options.
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Farmacorresistência Bacteriana Múltipla , Bactérias Gram-Negativas , Antibacterianos/farmacologia , Ásia , Europa (Continente) , América Latina , Testes de Sensibilidade MicrobianaRESUMO
BACKGROUND: Rifabutin, an oral drug approved to treat Mycobacterium avium infections, demonstrated potent activity against Acinetobacter baumannii in nutrient-limited medium enabled by rifabutin cellular uptake through the siderophore receptor FhuE. OBJECTIVES: To determine rifabutin in vitro activity and resistance mechanisms in a large panel of A. baumannii isolates. METHODS: Two hundred and ninety-three carbapenem-resistant A. baumannii clinical isolates collected from Europe, the USA and Asia during 2017-19 were used for MIC determination. Sequencing/genotyping of fhuE, rpoB and arr-2 genes in isolates with elevated rifabutin MIC combined with genetic engineering and gene expression quantification was used to characterize rifabutin's mode of action and resistance mechanisms. RESULTS: Rifabutin showed excellent activity on the strain panel, with an MIC50/90 of 0.008/1 mg/L, and was superior to all other antibiotics tested, including colistin, tigecycline and cefiderocol (MIC90 of 8 mg/L). Rifabutin remained active on resistant subpopulations, including strains resistant to the siderophore-drug conjugate cefiderocol (MIC90 of 2 mg/L, n = 23). At least two independent resistance mechanisms were required to abolish rifabutin activity, which is in line with the dose-dependent mutational resistance frequency reaching 10-9 at rifabutin concentrations at or above 2 mg/L. CONCLUSIONS: This study demonstrated the potent activity of rifabutin against carbapenem-resistant A. baumannii. We propose that FhuE-mediated active uptake of rifabutin enables activity against rifampicin-resistant isolates. To achieve clinically meaningful strain coverage and to avoid rapid resistance development, rifabutin concentrations ≥2 mg/L are required, something rifabutin oral formulations cannot deliver.
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Acinetobacter baumannii , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Ásia , Carbapenêmicos/farmacologia , Farmacorresistência Bacteriana Múltipla , Europa (Continente) , Testes de Sensibilidade Microbiana , Rifabutina/farmacologiaRESUMO
Murepavadin is the first in class of the outer membrane protein-targeting antibiotics (OMPTA) and a pathogen-specific peptidomimetic antibacterial with a novel, nonlytic mechanism of action targeting Pseudomonas aeruginosa Murepavadin is being developed for the treatment of hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP). The pharmacokinetics (PK) and safety of single and multiple doses of murepavadin were investigated in healthy male subjects. Part A of the study was a double-blind, randomized, placebo-controlled, single-ascending-dose investigation in 10 sequential cohorts where each cohort comprised 6 healthy male subjects; 4 subjects were randomized to murepavadin, and 2 subjects were randomized to placebo. Part B was a double-blind, randomized, placebo-controlled, multiple-ascending-dose investigation in 3 sequential cohorts. After a single dose of murepavadin, the geometric mean half-life (2.52 to 5.30 h), the total clearance (80.1 to 114 ml/h/kg), and the volume of distribution (415 to 724 ml/kg) were consistent across dose levels. The pharmacokinetics of the dosing regimens evaluated were dose proportional and linear. Murepavadin was well tolerated, adverse events were transient and generally mild, and no dose-limiting toxicity was identified.
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Antibacterianos/efeitos adversos , Antibacterianos/farmacocinética , Peptídeos Cíclicos/efeitos adversos , Peptídeos Cíclicos/farmacocinética , Adulto , Antibacterianos/administração & dosagem , Relação Dose-Resposta a Droga , Método Duplo-Cego , Voluntários Saudáveis , Humanos , Infusões Intravenosas , Masculino , Peptídeos Cíclicos/administração & dosagem , Adulto JovemRESUMO
Murepavadin (formerly POL7080), a 14-amino-acid cyclic peptide, and comparators were tested by the broth microdilution method against 1,219 Pseudomonas aeruginosa isolates from 112 medical centers. Murepavadin (MIC50/90, 0.12/0.12 mg/liter) was 4- to 8-fold more active than colistin (MIC50/90, 1/1 mg/liter) and polymyxin B (MIC50/90, 0.5/1 mg/liter) and inhibited 99.1% of isolates at ≤0.5 mg/liter. Only 4 isolates (0.3%) exhibited murepavadin MICs of >2 mg/liter. Murepavadin was equally active against isolates from Europe, the United States, and China.
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Antibacterianos/farmacologia , Peptídeos Cíclicos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , China , Colistina/farmacologia , Farmacorresistência Bacteriana Múltipla , Europa (Continente) , Humanos , Testes de Sensibilidade Microbiana , Polimixina B/farmacologia , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/isolamento & purificação , Estados UnidosRESUMO
This open-label, nonrandomized, single-dose, phase 1 study evaluated the pharmacokinetics and safety of murepavadin, a novel peptide antibiotic for the treatment of serious Pseudomonas aeruginosa infections. The study was conducted in 32 subjects of either sex in 4 groups (up to 8 per group) with mild (group 1), moderate (group 2), and severe (group 3) renal function impairment or with normal renal function (group 4). The degree of renal impairment of the subjects was classified at screening according to the estimated creatinine clearance (CLCr) according to the Cockcroft-Gault equation. All subjects received a single 2.2-mg/kg of body weight intravenous infusion of murepavadin administered over 3 h. Exposure to murepavadin in plasma increased in subjects with renal function impairment, with the area under the plasma concentration-time curve from zero to infinity (AUC0-∞) increasing about 2.0- to 2.5-fold for subjects with renal function impairment compared to subjects with normal renal function, whereas the increases in maximum observed plasma concentration (Cmax) were about 1.5-fold for subjects with renal function impairment compared to subjects with normal renal function. The total clearance (CL) of murepavadin was lower in all groups of subjects with renal function impairment, with group means ranging from 2.4 liters/h to 3.8 liters/h, compared to 7.0 liters/h in subjects with normal renal function. Accordingly, the terminal elimination half-life (t1/2) prolonged up to 24 h with decreasing renal function compared to 7.7 h in subjects with normal renal function. Murepavadin was well tolerated in all renal function groups. As the elimination of murepavadin is affected by renal function, a dose adjustment is warranted in subjects with impaired renal function. (This paper has been registered at ClinicalTrials.gov under identifier NCT02110459.).
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Antibacterianos/efeitos adversos , Antibacterianos/farmacocinética , Peptídeos Cíclicos/efeitos adversos , Peptídeos Cíclicos/farmacocinética , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/efeitos dos fármacos , Insuficiência Renal/metabolismo , Adulto , Idoso , Área Sob a Curva , Feminino , Humanos , Rim/metabolismo , Masculino , Pessoa de Meia-Idade , Infecções por Pseudomonas/metabolismoRESUMO
Background: Murepavadin (POL7080) represents the first member of a novel class of outer membrane protein-targeting antibiotics. Murepavadin acts by binding to LPS transport protein D and is being developed for the treatment of hospital-acquired and ventilator-associated pneumonia caused by Pseudomonas aeruginosa. Objectives: To evaluate the antimicrobial activity of murepavadin against XDR P. aeruginosa. Methods: A total of 785 clinical isolates of XDR P. aeruginosa were collected in 2016-17 through the SENTRY Antimicrobial Surveillance Program from 34 medical centres in 21 European nations (n = 353) and 75 medical centres in North America (n = 432). Isolates were categorized as XDR when susceptible (CLSI) to ≤2 of the following antimicrobial classes: antipseudomonal cephalosporins, carbapenems, broad-spectrum penicillin/ß-lactamase inhibitor combinations, fluoroquinolones, aminoglycosides and polymyxins. Susceptibility testing was performed by the reference broth microdilution method and EUCAST and CLSI interpretative criteria were applied. Results: Murepavadin (MIC50/90, 0.12/0.25 mg/L) inhibited 96.7% of isolates at ≤0.5 mg/L and was 8-fold more active than colistin (MIC50/90, 1/2 mg/L). Only seven isolates (0.9%) exhibited murepavadin MIC values >4 mg/L. Colistin (MIC50/90, 1/2 mg/L; 93.6% susceptible) was the most active comparator, followed by ceftolozane/tazobactam (MIC50/90, 2/>32 mg/L; 70.6% susceptible) and tobramycin (MIC50/90, 8/>8 mg/L; 47.5% susceptible). Murepavadin remained active against isolates that were non-susceptible to colistin (n = 50; MIC50/90, 0.25/0.25 mg/L), ceftolozane/tazobactam (n = 231; MIC50/90, 0.12/0.25 mg/L) and/or tobramycin (n = 412; MIC50/90, 0.12/0.25 mg/L). Conclusions: Murepavadin exhibited potent activity against a large collection of clinical XDR P. aeruginosa isolates from Europe and North America, including isolates that were non-susceptible to colistin, ceftolozane/tazobactam and/or tobramycin.
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Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Peptídeos Cíclicos/farmacologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Aspartato Aminotransferases/sangue , Europa (Continente) , Humanos , Testes de Sensibilidade Microbiana , América do Norte , Pseudomonas aeruginosa/isolamento & purificaçãoRESUMO
The clinical development of antibiotics with a new mode of action combined with efficient pulmonary drug delivery is a priority against untreatable Pseudomonas aeruginosa lung infections. POL7001 is a macrocycle antibiotic belonging to the novel class of protein epitope mimetic (PEM) molecules with selective and potent activity against P. aeruginosa We investigated ventilator-associated pneumonia (VAP) and cystic fibrosis (CF) as indications of the clinical potential of POL7001 to treat P. aeruginosa pulmonary infections. MICs of POL7001 and comparators were measured for reference and clinical P. aeruginosa strains. The therapeutic efficacy of POL7001 given by pulmonary administration was evaluated in murine models of P. aeruginosa acute and chronic pneumonia. POL7001 showed potent in vitro activity against a large panel of P. aeruginosa isolates from CF patients, including multidrug-resistant (MDR) isolates with adaptive phenotypes such as mucoid or hypermutable phenotypes. The efficacy of POL7001 was demonstrated in both wild-type and CF mice. In addition to a reduced bacterial burden in the lung, POL7001-treated mice showed progressive body weight recovery and reduced levels of inflammatory markers, indicating an improvement in general condition. Pharmacokinetic studies indicated that POL7001 reached significant concentrations in the lung after pulmonary administration, with low systemic exposure. These results support the further evaluation of POL7001 as a novel therapeutic agent for the treatment of P. aeruginosa pulmonary infections.
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Antibacterianos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Animais , Antibacterianos/farmacocinética , Fibrose Cística/microbiologia , Pulmão/efeitos dos fármacos , Pulmão/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Pneumonia Associada à Ventilação Mecânica/microbiologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/patogenicidade , Infecções Respiratórias/microbiologiaRESUMO
Acinetobacter baumannii is a gram-negative bacterium causing severe hospital-acquired infections such as bloodstream infections or pneumonia. Moreover, multidrug resistant A. baumannii becomes prevalent in many hospitals. Consequently, the World Health Organization made this bacterium a critical priority for the research and development of new antibiotics. Rifabutin, a semisynthetic product from the rifamycin class, was recently found to be very active in nutrient-limited eukaryotic cell culture medium against various A. baumannii strains, including extremely drug-resistant strains, with minimal inhibitory concentrations as low as 0.008 µg/mL. Moreover, this in vitro potency translates into in vivo efficacy. Thus, rifabutin appears to be an attractive novel antibiotic against A. baumannii. In this work, our objective was to design and synthetize rifabutin prodrugs with increased aqueous solubility to allow intraveneous use. Synthetic methodologies were developed to selectively functionalize the hydroxyl group in position 21 and to afford 17 prodrugs. We measured the water solubility of the prodrugs, the stability in human and mouse plasma and their antimicrobial activity against A. baumannii after incubation in human serum. Finally, a pharmacokinetic release study of rifabutin was performed in CD1 mice with three selected prodrugs as a proof of concept.
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Infecções por Acinetobacter , Acinetobacter baumannii , Pró-Fármacos , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Farmacorresistência Bacteriana Múltipla , Camundongos , Testes de Sensibilidade Microbiana , Pró-Fármacos/farmacologia , Rifabutina/farmacologia , ÁguaRESUMO
Rifamycin antibiotics were discovered during the 1950s, and their main representative, rifampicin, remains a cornerstone treatment for TB. The clinical use of rifamycin is restricted to mycobacteria and Gram-positive infections because of its poor ability to penetrate the Gram-negative outer membrane. Rifabutin, a rifamycin antibiotic approved for the prevention of Mycobacterium avium complex disease, makes an exception to this rule by hijacking the iron uptake system of Acinetobacter baumannii, resulting in potent activity against this important Gram-negative pathogen. Here, we describe recent findings on the specific activity of rifabutin and provide evidence of the need for the development of an intravenous formulation of rifabutin (BV100) for the treatment of difficult-to-treat carbapenem-resistant A.baumannii infections.
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Infecções por Acinetobacter/tratamento farmacológico , Antibacterianos/administração & dosagem , Rifabutina/administração & dosagem , Acinetobacter baumannii/efeitos dos fármacos , Animais , Antibacterianos/farmacocinética , Carbapenêmicos , Farmacorresistência Bacteriana , Humanos , Infusões Intravenosas , Rifabutina/farmacocinéticaRESUMO
Industry screens of large chemical libraries have traditionally relied on rich media to ensure rapid bacterial growth in high-throughput testing. We used eukaryotic, nutrient-limited growth media in a compound screen that unmasked a previously unknown hyperactivity of the old antibiotic, rifabutin (RBT), against highly resistant Acinetobacter baumannii. In nutrient-limited, but not rich, media, RBT was 200-fold more potent than rifampin. RBT was also substantially more effective in vivo. The mechanism of enhanced efficacy was a Trojan horse-like import of RBT, but not rifampin, through fhuE, only in nutrient-limited conditions. These results are of fundamental importance to efforts to discover antibacterial agents.
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Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Nutrientes/metabolismo , Rifabutina/farmacologia , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/genética , Animais , Proteínas de Bactérias/efeitos dos fármacos , Proteínas de Bactérias/genética , Colistina/farmacologia , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla/genética , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Ensaios de Triagem em Larga Escala , Masculino , Camundongos , Camundongos Endogâmicos C3H , Testes de Sensibilidade Microbiana , Receptores de Superfície Celular/efeitos dos fármacos , Receptores de Superfície Celular/genética , Rifampina/farmacologiaRESUMO
Iclaprim is a novel dihydrofolate reductase (DHFR) inhibitor belonging to the 2,4-diaminopyrimidine class of antibiotics, of which trimethoprim (TMP) is the most well known representative. Iclaprim exhibits potent bactericidal activity against major Gram-positive pathogens, notably methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) phenotypes, including TMP-resistant strains. The inhibition properties of racemic iclaprim and of the two enantiomers, termed AR-101 and AR-102, towards S. aureus wild-type DHFR and TMP-resistant F98Y mutant DHFR were determined and compared. Similar to TMP, AR-101, AR-102 and iclaprim are all competitive inhibitors with respect to the substrate dihydrofolate. Iclaprim, AR-101 and AR-102 demonstrated little or no difference in activity towards these enzymes and were significantly more potent than TMP. The crystal structures of S. aureus DHFR and F98Y mutant DHFR were determined as ternary complexes with NADPH and either AR-101, AR-102 or iclaprim. The binding modes of the inhibitors were analysed and compared. The X-ray crystallographic data explain the binding modes of all molecules well and can be used to rationalize the equipotent affinity of AR-101, AR-102 and iclaprim, which is also reflected in their antibacterial properties.
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Antibacterianos/química , Inibidores Enzimáticos/química , Staphylococcus aureus Resistente à Meticilina/enzimologia , Proteínas Mutantes/metabolismo , Pirimidinas/química , Tetra-Hidrofolato Desidrogenase/metabolismo , Trimetoprima/química , Antibacterianos/metabolismo , Cristalização , Cristalografia por Raios X , Inibidores Enzimáticos/metabolismo , Isomerismo , Resistência a Meticilina , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , Proteínas Mutantes/química , Proteínas Mutantes/genética , NADP/química , NADP/metabolismo , Estrutura Terciária de Proteína , Pirimidinas/metabolismo , Tetra-Hidrofolato Desidrogenase/química , Tetra-Hidrofolato Desidrogenase/genética , Trimetoprima/metabolismoRESUMO
OBJECTIVES: Iclaprim is a novel 2,4-diaminopyrimidine that exhibits potent, rapid bactericidal activity against major Gram-positive pathogens, including methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus, and is currently in clinical development for the treatment of complicated skin and skin structure infections. An understanding of the known mechanism of resistance to trimethoprim led to the design of this new inhibitor, with improved affinity towards dihydrofolate reductase (DHFR) from S. aureus and clinically useful activity against S. aureus including isolates resistant to trimethoprim. The objective of this study was to characterize the mode of action of iclaprim and its inhibitory properties against DHFR. METHODS: The mode of action of iclaprim was assessed by enzymatic analysis, direct binding studies, macromolecular synthesis profiles, synergy and antagonism studies to define its role as an inhibitor of DHFR. The binding properties of iclaprim to DHFR were compared with those of trimethoprim by X-ray crystallography. RESULTS: The enzymatic properties, direct binding and X-ray crystallographic studies delineated the mode of interaction with DHFR and the reason for the increased affinity of iclaprim towards the enzyme. The effect of iclaprim on bacterial physiology suggests that iclaprim behaves as a classical antibacterial DHFR inhibitor, as previously documented for trimethoprim. CONCLUSIONS: Iclaprim binds and inhibits bacterial DHFR in a similar manner to trimethoprim. However, the increased hydrophobic interactions between iclaprim and DHFR account for increased affinity and, unlike trimethoprim, enable iclaprim to inhibit even the resistant enzyme with nanomolar affinity, thus overcoming the mechanism of trimethoprim resistance. The increased antibacterial activity and lower propensity for resistance make iclaprim a clinically promising and useful inhibitor.
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Antibacterianos/farmacologia , Inibidores Enzimáticos/farmacologia , Pirimidinas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/enzimologia , Tetra-Hidrofolato Desidrogenase/metabolismo , Antibacterianos/metabolismo , Cristalografia por Raios X , Inibidores Enzimáticos/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Pirimidinas/metabolismo , Trimetoprima/metabolismo , Trimetoprima/farmacologiaRESUMO
INTRODUCTION: With the increase in multi-drug resistant P. aeruginosa, antimicrobials with a novel mechanism of action are needed that can target these infections. Areas covered: Intravenous murepavadin is in Phase 3 development for the treatment of HABP/VABP due to P. aeruginosa. This paper summarizes the available information on the discovery, the in vitro activity, pharmacokinetic and pharmacodynamic properties and the clinical pharmacology of murepavadin to date. Expert commentary: P. aeruginosa has an intrinsic resistance to many antibiotics due to high cellular impermeability and efficient drug efflux mechanisms, and the recent increase in prevalence of multidrug-resistant P. aeruginosa infections are particularly threatening in ICU settings. Murepavadin is a pathogen specific antimicrobial peptidomimetic with a novel, non-lytic mechanism of action, and is the first in class of outer membrane protein targeting antibiotics which are being developed. Murepavadin displays a potent in vitro activity including carbapenemase-producing and colistin-resistant P. aeruginosa. Murepavadin is active in pre-clinical animal models including infections with XDR isolates. The Pharmacokinetics is well characterized including subjects with impaired renal function and patients with VABP. Intravenous murepavadin is currently under clinical development for the treatment of HABP/VABP due to P. aeruginosa infection.
Assuntos
Antibacterianos/farmacologia , Peptídeos Cíclicos/farmacologia , Infecções por Pseudomonas/tratamento farmacológico , Animais , Antibacterianos/administração & dosagem , Antibacterianos/farmacocinética , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Humanos , Peptídeos Cíclicos/administração & dosagem , Peptídeos Cíclicos/farmacocinética , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/isolamento & purificaçãoRESUMO
In many respiratory diseases characterized by an intense inflammatory response, the balance between proteolytic enzymes (proteases, including elastases) and their inhibitors (proteinases inhibitors) is not neutral. Excess activity of neutrophil elastase (NE) and similar proteases has been reported to cause tissue damage and to alter the remodeling process in many clinical conditions such as pneumonia, respiratory distress, and acute lung injury (ALI). Several experimental NE inhibitors have been tested in preclinical and clinical studies of different conditions of inflammatory lung injury such as ALI and pneumonia, with contrasting results. This study reviews the literature regarding NE inhibitors in the field of respiratory diseases and reflects on possible future developments. In particular, we highlight potential gaps in the scientific evidence and discuss potential strategies for focusing investigation on antielastases in clinical practice through the selection of targeted populations and proper outcomes.
Assuntos
Pneumopatias/tratamento farmacológico , Proteínas Secretadas Inibidoras de Proteinases/farmacologia , Lesão Pulmonar Aguda/tratamento farmacológico , Lesão Pulmonar Aguda/enzimologia , Animais , Bronquiectasia/tratamento farmacológico , Bronquiectasia/enzimologia , Fibrose Cística/tratamento farmacológico , Fibrose Cística/enzimologia , Modelos Animais de Doenças , Humanos , Elastase de Leucócito/fisiologia , Pneumopatias/enzimologia , Proteínas Secretadas Inibidoras de Proteinases/fisiologia , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Doença Pulmonar Obstrutiva Crônica/enzimologia , Síndrome do Desconforto Respiratório/tratamento farmacológico , Síndrome do Desconforto Respiratório/enzimologiaRESUMO
The key enzyme in the non-mevalonate pathway of isoprenoid biosynthesis, 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) has been shown to be the target enzyme of fosmidomycin, an antimalarial, antibacterial and herbicidal compound. Here we report the crystal structure of selenomethionine-labelled Escherichia coli DXR in a ternary complex with NADPH and fosmidomycin at 2.2 A resolution. The structure reveals a considerable conformational rearrangement upon fosmidomycin binding and provides insights into the slow, tight binding inhibition mode of the inhibitor. Although the inhibitor displays an unusual non-metal mediated mode of inhibition, which is an artefact most likely due to the low metal affinity of DXR at the pH used for crystallization, the structural data add valuable information for the rational design of novel DXR inhibitors. Using this structure together with the published structural data and the 1.9 A crystal structure of DXR in a ternary complex with NADPH and the substrate 1-deoxy-D-xylulose 5-phosphate, a model for the physiologically relevant tight-binding mode of inhibition is proposed. The structure of the substrate complex must be interpreted with caution due to the presence of a second diastereomer in the active site.
Assuntos
Aldose-Cetose Isomerases/química , Antimaláricos/química , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Fosfomicina/análogos & derivados , Fosfomicina/química , Complexos Multienzimáticos/química , NADP/química , Oxirredutases/química , Conformação Proteica , Aldose-Cetose Isomerases/genética , Aldose-Cetose Isomerases/metabolismo , Antimaláricos/metabolismo , Cristalografia por Raios X , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Fosfomicina/metabolismo , Substâncias Macromoleculares , Modelos Moleculares , Estrutura Molecular , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , NADP/metabolismo , Oxirredutases/genética , Oxirredutases/metabolismo , Ligação ProteicaRESUMO
Methionyl aminopeptidases (MetAPs) represent a unique class of protease that are responsible for removing the N-terminal methionine residue from proteins and peptides. There are two major classes of MetAPs (type I and type II) described and each class can be subdivided into two subclasses. Eukaryotes contain both the type I and type II MetAPs, whereas prokaryotes possess only the type I enzyme. Due to the physiological importance of these enzymes there is considerable interest in inhibitors to be used as antiangiogenic and antimicrobial agents. Here, we describe the 1.15A crystal structure of the Staphylococcus aureus MetAP-I as an apo-enzyme and its complexes with various 1,2,4-triazole-based derivatives at high-resolution. The protein has a typical "pita-bread" fold as observed for the other MetAP structures. The inhibitors bind in the active site with the N1 and N2 atoms of the triazole moiety complexing two divalent ions. The 1,2,4-triazols represent a novel class of potent non-peptidic inhibitors for the MetAP-Is.