RESUMO
We previously reported medicinal chemistry efforts that identified MK-5204, an orally efficacious ß-1,3-glucan synthesis inhibitor derived from the natural product enfumafungin. Further extensive optimization of the C2 triazole substituent identified 4-pyridyl as the preferred replacement for the carboxamide of MK-5204, leading to improvements in antifungal activity in the presence of serum, and increased oral exposure. Reoptimizing the aminoether at C3 in the presence of this newly discovered C2 substituent, confirmed that the (R) t-butyl, methyl aminoether of MK-5204 provided the best balance of these two key parameters, culminating in the discovery of ibrexafungerp, which is currently in phase III clinical trials. Ibrexafungerp displayed significantly improved oral efficacy in murine infection models, making it a superior candidate for clinical development as an oral treatment for Candida and Aspergillus infections.
Assuntos
Antifúngicos/farmacologia , Aspergillus/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Glicosídeos/química , Triterpenos/química , beta-Glucanas/metabolismo , Administração Oral , Animais , Antifúngicos/síntese química , Antifúngicos/farmacocinética , Antifúngicos/uso terapêutico , Aspergilose/tratamento farmacológico , Candidíase/tratamento farmacológico , Modelos Animais de Doenças , Glicosídeos/farmacocinética , Glicosídeos/farmacologia , Glicosídeos/uso terapêutico , Meia-Vida , Camundongos , Relação Estrutura-Atividade , Triterpenos/farmacocinética , Triterpenos/farmacologia , Triterpenos/uso terapêuticoRESUMO
Our previously reported efforts to produce an orally active ß-1,3-glucan synthesis inhibitor through the semi-synthetic modification of enfumafungin focused on replacing the C2 acetoxy moiety with an aminotetrazole and the C3 glycoside with a N,N-dimethylaminoether moiety. This work details further optimization of the C2 heterocyclic substituent, which identified 3-carboxamide-1,2,4-triazole as a replacement for the aminotetrazole with comparable antifungal activity. Alkylation of either the carboxamidetriazole at C2 or the aminoether at C3 failed to significantly improve oral efficacy. However, replacement of the isopropyl alpha amino substituent with a t-butyl, improved oral exposure while maintaining antifungal activity. These two structural modifications produced MK-5204, which demonstrated broad spectrum activity against Candida species and robust oral efficacy in a murine model of disseminated Candidiasis without the N-dealkylation liability observed for the previous lead.
Assuntos
Antifúngicos/química , Triazóis/química , beta-Glucanas/metabolismo , Administração Oral , Animais , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Antifúngicos/uso terapêutico , Candida/efeitos dos fármacos , Candidíase/tratamento farmacológico , Modelos Animais de Doenças , Glucosiltransferases/antagonistas & inibidores , Glucosiltransferases/metabolismo , Glicosídeos/química , Meia-Vida , Camundongos , Testes de Sensibilidade Microbiana , Estereoisomerismo , Relação Estrutura-Atividade , Triazóis/metabolismo , Triazóis/farmacologia , Triazóis/uso terapêutico , Triterpenos/química , beta-Glucanas/químicaRESUMO
Multidrug resistant Gram-negative bacterial infections are an increasing public health threat due to rapidly rising resistance toward ß-lactam antibiotics. The hydrolytic enzymes called ß-lactamases are responsible for a large proportion of the resistance phenotype. ß-Lactamase inhibitors (BLIs) can be administered in combination with ß-lactam antibiotics to negate the action of the ß-lactamases, thereby restoring activity of the ß-lactam. Newly developed BLIs offer some advantage over older BLIs in terms of enzymatic spectrum but are limited to the intravenous route of administration. Reported here is a novel, orally bioavailable diazabicyclooctane (DBO) ß-lactamase inhibitor. This new DBO, ETX1317, contains an endocyclic carbon-carbon double bond and a fluoroacetate activating group and exhibits broad spectrum activity against class A, C, and D serine ß-lactamases. The ester prodrug of ETX1317, ETX0282, is orally bioavailable and, in combination with cefpodoxime proxetil, is currently in development as an oral therapy for multidrug resistant and carbapenem-resistant Enterobacterales infections.
Assuntos
Antibacterianos/química , Compostos Azabicíclicos/química , Inibidores de beta-Lactamases/química , beta-Lactamases/química , Administração Oral , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Compostos Azabicíclicos/metabolismo , Compostos Azabicíclicos/farmacologia , Compostos Azabicíclicos/uso terapêutico , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Meia-Vida , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Proteínas de Ligação às Penicilinas/química , Proteínas de Ligação às Penicilinas/metabolismo , Pró-Fármacos/química , Pró-Fármacos/metabolismo , Ligação Proteica , Ratos , Dermatopatias/tratamento farmacológico , Dermatopatias/patologia , Dermatopatias/veterinária , Relação Estrutura-Atividade , Inibidores de beta-Lactamases/metabolismo , Inibidores de beta-Lactamases/farmacologia , Inibidores de beta-Lactamases/uso terapêutico , beta-Lactamases/metabolismoRESUMO
Multidrug-resistant (MDR) bacterial infections are a serious threat to public health. Among the most alarming resistance trends is the rapid rise in the number and diversity of ß-lactamases, enzymes that inactivate ß-lactams, a class of antibiotics that has been a therapeutic mainstay for decades. Although several new ß-lactamase inhibitors have been approved or are in clinical trials, their spectra of activity do not address MDR pathogens such as Acinetobacter baumannii. This report describes the rational design and characterization of expanded-spectrum serine ß-lactamase inhibitors that potently inhibit clinically relevant class A, C and D ß-lactamases and penicillin-binding proteins, resulting in intrinsic antibacterial activity against Enterobacteriaceae and restoration of ß-lactam activity in a broad range of MDR Gram-negative pathogens. One of the most promising combinations is sulbactam-ETX2514, whose potent antibacterial activity, in vivo efficacy against MDR A. baumannii infections and promising preclinical safety demonstrate its potential to address this significant unmet medical need.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Compostos Azabicíclicos/química , Compostos Azabicíclicos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Inibidores de beta-Lactamases/química , Inibidores de beta-Lactamases/farmacologia , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Animais , Compostos Azabicíclicos/uso terapêutico , Compostos Azabicíclicos/toxicidade , Carbapenêmicos/farmacologia , Cães , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Farmacorresistência Bacteriana Múltipla , Enterobacteriaceae/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Humanos , Camundongos , Modelos Moleculares , Proteínas de Ligação às Penicilinas/antagonistas & inibidores , Ratos , Sulbactam/química , Sulbactam/farmacologia , Inibidores de beta-Lactamases/uso terapêutico , Inibidores de beta-Lactamases/toxicidade , beta-Lactamases/metabolismo , beta-Lactamas/farmacologiaRESUMO
The effect of various conditions including pH, inoculum, temperature, atmosphere, divalent cations, and several body fluids on the in vitro activity of the novel antibacterial spiropyrimidinetrione ETX0914 in standard susceptibility tests was investigated against several species. None of the parameters investigated affected the activity of ETX0914, with the exception of pH. Whereas the MIC values for ETX0914 with S. aureus, E. faecalis, and E. coli did not change when the pH of the growth medium was varied from 5 to 8, they did increase at least 8-fold at pH values above 8. This loss of activity can be attributed to the deprotonation of the molecule at elevated pH. The data suggest that routine susceptibility testing with ETX0914 should result in reproducible MIC values.
Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Barbitúricos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Compostos de Espiro/farmacologia , Meios de Cultura/química , Humanos , Concentração de Íons de Hidrogênio , Isoxazóis , Morfolinas , Oxazolidinonas , Reprodutibilidade dos Testes , TemperaturaRESUMO
The clinical success of the echinocandins, which can only be administered parentally, has validated ß-1,3-glucan synthase (GS) as an antifungal target. Semi-synthetic modification of enfumafungin, a triterpene glycoside natural product, was performed with the aim of producing a new class of orally active GS inhibitors. Replacement of the C2 acetoxy moiety with various heterocycles did not improve GS or antifungal potency. However, replacement of the C3 glycoside with an aminoether moiety dramatically improved oral pharmacokinetic (PK) properties while maintaining GS and antifungal potency. Installing an aminotetrazole at C2 in conjunction with an N-alkylated aminoether at C3 produced derivatives with significantly improved GS and antifungal potency that exhibited robust oral efficacy in a murine model of disseminated candidiasis.
Assuntos
Antifúngicos/química , Glicosídeos/química , Triterpenos/química , beta-Glucanas/química , Administração Oral , Animais , Antifúngicos/farmacocinética , Antifúngicos/uso terapêutico , Aspergillus fumigatus/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Candidíase/tratamento farmacológico , Candidíase/veterinária , Glucosiltransferases/antagonistas & inibidores , Glucosiltransferases/metabolismo , Meia-Vida , Camundongos , Testes de Sensibilidade Microbiana , Relação Estrutura-Atividade , Terpenos/química , beta-Glucanas/farmacocinética , beta-Glucanas/uso terapêuticoRESUMO
Sulbactam is a class A ß-lactamase inhibitor with intrinsic whole-cell activity against certain bacterial species, including Acinetobacter baumannii. The clinical use of sulbactam for A. baumannii infections is of interest due to increasing multidrug resistance in this pathogen. However, the molecular drivers of its antibacterial activity and resistance determinants have yet to be precisely defined. Here we show that the antibacterial activities of sulbactam vary widely across contemporary A. baumannii clinical isolates and are mediated through inhibition of the penicillin-binding proteins (PBPs) PBP1 and PBP3, with very low frequency of resistance; the rare pbp3 mutants with high levels of resistance to sulbactam are attenuated in fitness. These results support further investigation of the potential clinical utility of sulbactam.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/fisiologia , Sulbactam/farmacologia , Proteínas de Ligação às Penicilinas/antagonistas & inibidoresRESUMO
Bacterially expressed ß-lactamases are rapidly eroding the clinical utility of the important ß-lactam class of antibacterials, significantly impairing our ability to fight serious bacterial infections. This paper describes a study of oxaborole-derived ß-lactamase inhibitors in which crystal structures and computational modeling aided in the rational design of analogues with improved spectrum of activity against class A, C, and D enzymes. Crystal structures of two of these inhibitors covalently bound to two different serine ß-lactamases, class C Pseudomonas aeruginosa AmpC and class D OXA-10, are described herein. Improved physicochemical properties as well as increased activity against an array of ß-lactamases resulted in substantial restoration of susceptibility to ceftazidime in Escherichia coli and Klebsiella pneumoniae.
RESUMO
AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, ß-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development.
Assuntos
Antibacterianos/farmacologia , Barbitúricos/farmacologia , DNA Girase/efeitos dos fármacos , Inibidores da Síntese de Ácido Nucleico/farmacologia , Compostos de Espiro/farmacologia , Inibidores da Topoisomerase II/farmacologia , Formas Bacterianas Atípicas/efeitos dos fármacos , Farmacorresistência Bacteriana , Fluoroquinolonas/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Isoxazóis , Testes de Sensibilidade Microbiana , Morfolinas , OxazolidinonasRESUMO
BACKGROUND: Extended-spectrum AmpC (ESAC) ß-lactamase enzymes, which are either chromosomally encoded or plasmid encoded, have minor structural changes that broaden their substrate hydrolysis profile. The derepressed AmpC enzyme found once in Enterobacter cloacae CHE was shown to contain a six residue deletion in the H-10 helix in close proximity to the active site. Avibactam is a non-ß-lactam inhibitor of Ambler class A, class C and some class D ß-lactamases that is in clinical development with several ß-lactam agents. It has been shown to inhibit AmpC enzymes, but its microbiological activity against isolates carrying different ESAC enzymes is less well understood. METHODS: MICs were determined using the broth microdilution technique. RT-PCR analyses were performed to measure the level of ampC expression and whole genome sequencing was performed to enable sequence-based analyses. RESULTS: Structural analyses of avibactam bound to a representative AmpC ß-lactamase suggested that the H-10 helix deletion would impact the potency of the inhibitor. Under standard conditions, the ceftazidime/avibactam and ceftaroline/avibactam MIC values for E. cloacae CHE were 64 and 4 mg/L, respectively, representing a significant decrease in susceptibility over control E. cloacae isolates. However, use of higher avibactam concentrations restored the susceptibility of E. cloacae CHE in a dose-dependent manner. Comparison with other E. cloacae isolates carrying derepressed AmpC enzymes suggested that this difference in inhibition by avibactam was unrelated to the level of AmpC being produced. CONCLUSIONS: The E. cloacae CHE ESAC enzyme is inhibited less efficiently by avibactam than other E. cloacae AmpC proteins due to a subtle rearrangement of the binding site. Although the variants are not commonly observed, the different ESAC enzymes may be inhibited to varied extents by avibactam.
Assuntos
Compostos Azabicíclicos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Enterobacter cloacae/efeitos dos fármacos , Inibidores de beta-Lactamases/farmacologia , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Enterobacter cloacae/enzimologia , Enterobacter cloacae/genética , Humanos , Dados de Sequência Molecular , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
Streptogramin antibiotics are divided into types A and B, which in combination can act synergistically. We compared the molecular interactions of the streptogramin combinations Synercid (type A, dalfopristin; type B, quinupristin) and NXL 103 (type A, flopristin; type B, linopristin) with the Escherichia coli 70S ribosome by X-ray crystallography. We further analyzed the activity of the streptogramin components individually and in combination. The streptogramin A and B components in Synercid and NXL 103 exhibit synergistic antimicrobial activity against certain pathogenic bacteria. However, in transcription-coupled translation assays, only combinations that include dalfopristin, the streptogramin A component of Synercid, show synergy. Notably, the diethylaminoethylsulfonyl group in dalfopristin reduces its activity but is the basis for synergy in transcription-coupled translation assays before its rapid hydrolysis from the depsipeptide core. Replacement of the diethylaminoethylsulfonyl group in dalfopristin by a nonhydrolyzable group may therefore be beneficial for synergy. The absence of general streptogramin synergy in transcription-coupled translation assays suggests that the synergistic antimicrobial activity of streptogramins can occur independently of the effects of streptogramin on translation.
Assuntos
Antibacterianos/uso terapêutico , Biossíntese de Proteínas/efeitos dos fármacos , Estreptograminas/uso terapêutico , Antibacterianos/administração & dosagem , Antibacterianos/farmacologia , Cristalografia por Raios X , Combinação de Medicamentos , Sinergismo Farmacológico , Enterococcus faecalis/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Haemophilus influenzae/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Ribossomos/efeitos dos fármacos , Ribossomos/ultraestrutura , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Estreptogramina A/administração & dosagem , Estreptogramina A/farmacologia , Estreptogramina A/uso terapêutico , Estreptogramina B/administração & dosagem , Estreptogramina B/farmacologia , Estreptogramina B/uso terapêutico , Estreptograminas/administração & dosagem , Estreptograminas/química , Estreptograminas/farmacologia , Virginiamicina/administração & dosagem , Virginiamicina/farmacologia , Virginiamicina/uso terapêuticoRESUMO
Orally bioavailable inhibitors of ß-(1,3)-D-glucan synthase have been pursued as new, broad-spectrum fungicidal therapies suitable for treatment in immunocompromised patients. Toward this end, a collaborative medicinal chemistry program was established based on semisynthetic derivatization of the triterpenoid glycoside natural product enfumafungin in order to optimize in vivo antifungal activity and oral absorption properties. In the course of these studies, it was hypothesized that the pharmacokinetic properties of the semisynthetic enfumafungin analog 3 could be improved by tethering the alkyl groups proximal to the basic nitrogen of the C3-aminoether side chain into an azacyclic system, so as to preclude oxidative N-demethylation. The results of this research effort are disclosed herein.
Assuntos
Antifúngicos/síntese química , Inibidores Enzimáticos/síntese química , Glucosiltransferases/antagonistas & inibidores , Glicosídeos/química , Triterpenos/química , Administração Oral , Animais , Antifúngicos/química , Antifúngicos/farmacocinética , Candida albicans/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Glucosiltransferases/metabolismo , Glicosídeos/síntese química , Glicosídeos/farmacocinética , Meia-Vida , Camundongos , Relação Estrutura-Atividade , Triterpenos/síntese química , Triterpenos/farmacocinéticaRESUMO
OBJECTIVES: The aim of this study was to develop an integrated system for in vitro pharmacodynamic modelling of antimicrobials with greater flexibility, easier control and better accuracy than existing in vitro models. METHODS: Custom-made bottle caps, fittings, valve controllers and a modified bench-top shaking incubator were used. A temperature-controlled automated sample collector was built. Computer software was developed to manage experiments and to control the entire system including solenoid pinch valves, peristaltic pumps and the sample collector. The system was validated by pharmacokinetic simulations of linezolid 600 mg infusion. The antibacterial effect of linezolid against multiple Staphylococcus aureus strains was also studied in this system. RESULTS: An integrated semi-automated bench-top system was built and validated. The temperature-controlled automated sample collector allowed unattended collection and temporary storage of samples. The system software reduced the labour necessary for many tasks and also improved the timing accuracy for performing simultaneous actions in multiple parallel experiments. The system was able to simulate human pharmacokinetics of linezolid 600 mg intravenous infusion accurately. A pharmacodynamic study of linezolid against multiple S. aureus strains with a range of MICs showed that the required 24 h free drug AUC/MIC ratio was approximately 30 in order to keep the organism counts at the same level as their initial inoculum and was about > or = 68 in order to achieve > 2 log(10) cfu/mL reduction in the in vitro model. CONCLUSIONS: The integrated semi-automated bench-top system provided the ability to overcome many of the drawbacks of existing in vitro models. It can be used for various simple or complicated pharmacokinetic/pharmacodynamic studies efficiently and conveniently.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/farmacocinética , Automação , Staphylococcus aureus/efeitos dos fármacos , Acetamidas/farmacocinética , Acetamidas/farmacologia , Contagem de Colônia Microbiana , Humanos , Técnicas In Vitro , Linezolida , Testes de Sensibilidade Microbiana , Viabilidade Microbiana , Oxazolidinonas/farmacocinética , Oxazolidinonas/farmacologia , Fatores de TempoRESUMO
Seventeen laboratories participated in a study of interlaboratory reproducibility with caspofungin microdilution susceptibility testing against panels comprising 30 isolates of Candida spp. and 20 isolates of Aspergillus spp. The laboratories used materials supplied from a single source to determine the influence of growth medium (RPMI 1640 with or without glucose additions and antibiotic medium 3 [AM3]), the same incubation times (24 h and 48 h), and the same end point definition (partial or complete inhibition of growth) for the MIC of caspofungin. All tests were run in duplicate, and end points were determined both spectrophotometrically and visually. The results from almost all of the laboratories for quality control and reference Candida and Aspergillus isolates tested with fluconazole and itraconazole matched the NCCLS published values. However, considerable interlaboratory variability was seen in the results of the caspofungin tests. For Candida spp. the most consistent MIC data were generated with visual "prominent growth reduction" (MIC(2)) end points measured at 24 h in RPMI 1640, where 73.3% of results for the 30 isolates tested fell within a mode +/- one dilution range across all 17 laboratories. MIC(2) at 24 h in RPMI 1640 or AM3 also gave the best interlaboratory separation of Candida isolates of known high and low susceptibility to caspofungin. Reproducibility of MIC data was problematic for caspofungin tests with Aspergillus spp. under all conditions, but the minimal effective concentration end point, defined as the lowest caspofungin concentration yielding conspicuously aberrant hyphal growth, gave excellent reproducibility for data from 14 of the 17 participating laboratories.