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Abrahams KA, Cox JAG, Spivey VL, Loman NJ, Pallen MJ, Constantinidou C, Fernández R, Alemparte C, Remuiñán MJ, Barros D, Ballell L, Besra GS. Identification of novel imidazo[1,2-a]pyridine inhibitors targeting M. tuberculosis QcrB. PLoS One 2012; 7:e52951. [PMID: 23300833 PMCID: PMC3534098 DOI: 10.1371/journal.pone.0052951] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 11/22/2012] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium tuberculosis is a major human pathogen and the causative agent for the pulmonary disease, tuberculosis (TB). Current treatment programs to combat TB are under threat due to the emergence of multi-drug and extensively-drug resistant TB. Through the use of high throughput whole cell screening of an extensive compound library a number of imidazo[1,2-a]pyridine (IP) compounds were obtained as potent lead molecules active against M. tuberculosis and Mycobacterium bovis BCG. The IP inhibitors (1-4) demonstrated minimum inhibitory concentrations (MICs) in the range of 0.03 to 5 µM against a panel of M. tuberculosis strains. M. bovis BCG spontaneous resistant mutants were generated against IP 1, 3, and 4 at 5× MIC and subsequent whole genome sequencing identified a single nucleotide polymorphism (937)ACC>(937)GCC (T313A) in qcrB, which encodes the b subunit of the electron transport ubiquinol cytochrome C reductase. This mutation also conferred cross-resistance against IP 1, 3 and 4 demonstrating a common target. Gene dosage experiments confirmed M. bovis BCG QcrB as the target where over-expression in M. bovis BCG led to an increase in MIC from 0.5 to >8 µM for IP 3. An acute murine model of TB infection established bacteriostatic activity of the IP series, which await further detailed characterization.
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Affiliation(s)
- Katherine A. Abrahams
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Jonathan A. G. Cox
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Vickey L. Spivey
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Nicholas J. Loman
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mark J. Pallen
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | | | - Raquel Fernández
- Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - Carlos Alemparte
- Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - Modesto J. Remuiñán
- Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - David Barros
- Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Madrid, Spain
| | - Lluis Ballell
- Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Madrid, Spain
- * E-mail: (GSB); (LB)
| | - Gurdyal S. Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail: (GSB); (LB)
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Zelmer A, Carroll P, Andreu N, Hagens K, Mahlo J, Redinger N, Robertson BD, Wiles S, Ward TH, Parish T, Ripoll J, Bancroft GJ, Schaible UE. A new in vivo model to test anti-tuberculosis drugs using fluorescence imaging. J Antimicrob Chemother 2012; 67:1948-60. [PMID: 22635525 PMCID: PMC3394442 DOI: 10.1093/jac/dks161] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/03/2012] [Accepted: 04/05/2012] [Indexed: 12/02/2022] Open
Abstract
OBJECTIVES The current method for testing new drugs against tuberculosis in vivo is the enumeration of bacteria in organs by cfu assay. Owing to the slow growth rate of Mycobacterium tuberculosis (Mtb), these assays can take months to complete. Our aim was to develop a more efficient, fluorescence-based imaging assay to test new antibiotics in a mouse model using Mtb reporter strains. METHODS A commercial IVIS Kinetic® system and a custom-built laser scanning system with fluorescence molecular tomography (FMT) capability were used to detect fluorescent Mtb in living mice and lungs ex vivo. The resulting images were analysed and the fluorescence was correlated with data from cfu assays. RESULTS We have shown that fluorescent Mtb can be visualized in the lungs of living mice at a detection limit of ∼8 × 10⁷ cfu/lung, whilst in lungs ex vivo a detection limit of ∼2 × 10⁵ cfu/lung was found. These numbers were comparable between the two imaging systems. Ex vivo lung fluorescence correlated to numbers of bacteria in tissue, and the effect of treatment of mice with the antibiotic moxifloxacin could be visualized and quantified after only 9 days through fluorescence measurements, and was confirmed by cfu assays. CONCLUSIONS We have developed a new and efficient method for anti-tuberculosis drug testing in vivo, based on fluorescent Mtb reporter strains. Using this method instead of, or together with, cfu assays will reduce the time required to assess the preclinical efficacy of new drugs in animal models and enhance the progress of these candidates into clinical trials against human tuberculosis.
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Affiliation(s)
- Andrea Zelmer
- Immunology and Infection Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK
| | - Paul Carroll
- Centre for Immunology and Infectious Disease, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | - Nuria Andreu
- Microbiology, Department of Medicine, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Kristine Hagens
- Cellular Microbiology, Department of Molecular Infection Research, Research Centre Borstel, Parkallee 22, 23845 Borstel, Germany
| | - Jacqueline Mahlo
- Cellular Microbiology, Department of Molecular Infection Research, Research Centre Borstel, Parkallee 22, 23845 Borstel, Germany
| | - Natalja Redinger
- Cellular Microbiology, Department of Molecular Infection Research, Research Centre Borstel, Parkallee 22, 23845 Borstel, Germany
| | - Brian D. Robertson
- Microbiology, Department of Medicine, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Siouxsie Wiles
- Infectious Diseases & Immunity, Department of Medicine, Imperial College London, Hammersmith Campus, London W12 0NN, UK
- Department of Molecular Medicine and Pathology, University of Auckland, 85 Park Rd, Auckland, 1142, New Zealand
| | - Theresa H. Ward
- Immunology and Infection Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK
| | - Tanya Parish
- Centre for Immunology and Infectious Disease, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
- Infectious Disease Research Institute, 1124 Columbia St., Seattle, WA 98104, USA
| | - Jorge Ripoll
- Institute for Electronic Structure and Laser, Foundation for Research and Technology—Hellas, PO Box 1527, 71110 Heraklion, Greece
| | - Gregory J. Bancroft
- Immunology and Infection Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK
| | - Ulrich E. Schaible
- Immunology and Infection Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK
- Cellular Microbiology, Department of Molecular Infection Research, Research Centre Borstel, Parkallee 22, 23845 Borstel, Germany
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53
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Usha V, Hobrath JV, Gurcha SS, Reynolds RC, Besra GS. Identification of novel Mt-Guab2 inhibitor series active against M. tuberculosis. PLoS One 2012; 7:e33886. [PMID: 22479467 PMCID: PMC3315515 DOI: 10.1371/journal.pone.0033886] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 02/23/2012] [Indexed: 12/17/2022] Open
Abstract
Tuberculosis (TB) remains a leading cause of mortality worldwide. With the emergence of multidrug resistant TB, extensively drug resistant TB and HIV-associated TB it is imperative that new drug targets be identified. The potential of Mycobacterium tuberculosis inosine monophosphate dehydrogenase (IMPDH) as a novel drug target was explored in the present study. IMPDH exclusively catalyzes the conversion of inosine monophosphate (IMP) to xanthosine monophosphate (XMP) in the presence of the cofactor nicotinamide adenine dinucleotide (NAD+). Although the enzyme is a dehydrogenase, the enzyme does not catalyze the reverse reaction i.e. the conversion of XMP to IMP. Unlike other bacteria, M. tuberculosis harbors three IMPDH-like genes, designated as Mt-guaB1, Mt-guaB2 and Mt-guaB3 respectively. Of the three putative IMPDH's, we previously confirmed that Mt-GuaB2 was the only functional ortholog by characterizing the enzyme kinetically. Using an in silico approach based on designed scaffolds, a series of novel classes of inhibitors was identified. The inhibitors possess good activity against M. tuberculosis with MIC values in the range of 0.4 to 11.4 µg mL−1. Among the identified ligands, two inhibitors have nanomolar Kis against the Mt-GuaB2 enzyme.
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Affiliation(s)
- Veeraraghavan Usha
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Judith V. Hobrath
- Drug Discovery Division, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Sudagar S. Gurcha
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Robert C. Reynolds
- Drug Discovery Division, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Gurdyal S. Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
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Escribano J, Rivero-Hernández C, Rivera H, Barros D, Castro-Pichel J, Pérez-Herrán E, Mendoza-Losana A, Angulo-Barturen I, Ferrer-Bazaga S, Jiménez-Navarro E, Ballell L. 4-Substituted thioquinolines and thiazoloquinolines: potent, selective, and Tween-80 in vitro dependent families of antitubercular agents with moderate in vivo activity. ChemMedChem 2011; 6:2252-63. [PMID: 21922671 DOI: 10.1002/cmdc.201100309] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/24/2011] [Indexed: 11/08/2022]
Abstract
Two new families of closely related selective, non-cytotoxic, and potent antitubercular agents were discovered: thioquinolines and thiazoloquinolines. The compounds were found to possess potent antitubercular properties in vitro, an activity that is dependent on experimental conditions of MIC determination (resazurin test and the presence or absence of Tween-80). To clarify the therapeutic potential of these compound families, a medicinal chemistry effort was undertaken to generate a lead-like structure that would enable murine efficacy studies and help elucidate the in vivo implications of the in vitro observations. Although the final compounds showed only limited levels of systemic exposure in mice, modest levels of efficacy in vivo at nontoxic doses were observed.
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Affiliation(s)
- Jaime Escribano
- Diseases of the Developing World (DDW), Tres Cantos Medicines Development Campus (TCMDC), GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos Madrid, Spain
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Dose-dependent activity of pyrazinamide in animal models of intracellular and extracellular tuberculosis infections. Antimicrob Agents Chemother 2011; 55:1527-32. [PMID: 21282447 DOI: 10.1128/aac.01524-10] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Recent in vitro pharmacokinetic data suggest that the currently recommended dose of pyrazinamide may be suboptimal for killing intracellular bacilli in humans. We evaluated a range of pyrazinamide doses against intracellular and extracellular Mycobacterium tuberculosis in chronically infected mice and guinea pigs, respectively. Antibiotics were given five times weekly for 4 weeks beginning 28 days after infection. Human-equivalent doses of isoniazid reduced lung bacterial counts 10-fold in each species. Pyrazinamide given at 1/4 and 1/2 the human-equivalent dose was minimally active, while human-equivalent doses reduced lung bacterial counts by ∼1.0 log(10) in each species. Doubling the human-equivalent dose of pyrazinamide reduced the lung bacillary burden by 1.7 and 3.0 log(10) in mice and guinea pigs, respectively. As in humans and mice, pyrazinamide showed significant synergy with rifampin in guinea pigs. Clinical studies are warranted to investigate the sterilizing activity and tolerability of higher doses of pyrazinamide in combination tuberculosis regimens.
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56
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Comparative studies evaluating mouse models used for efficacy testing of experimental drugs against Mycobacterium tuberculosis. Antimicrob Agents Chemother 2010; 55:1237-47. [PMID: 21135176 DOI: 10.1128/aac.00595-10] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methodologies for preclinical animal model testing of drugs against Mycobacterium tuberculosis vary from laboratory to laboratory; however, it is unknown if these variations result in different outcomes. Thus, a series of head-to-head comparisons of drug regimens in three commonly used mouse models (intravenous, a low-dose aerosol, and a high-dose aerosol infection model) and in two strains of mice are reported here. Treatment with standard tuberculosis (TB) drugs resulted in similar efficacies in two mouse species after a low-dose aerosol infection. When comparing the three different infection models, the efficacies in mice of rifampin and pyrazinamide were similar when administered with either isoniazid or moxifloxacin. Relapse studies revealed that the standard drug regimen showed a significantly higher relapse rate than the moxifloxacin-containing regimen. In fact, 4 months of the moxifloxacin-containing combination regimen showed similar relapse rates as 6 months of the standard regimen. The intravenous model showed slower bactericidal killing kinetics with the combination regimens tested and a higher relapse of infection than either aerosol infection models. All three models showed similar outcomes for in vivo efficacy and relapse of infection for the drug combinations tested, regardless of the mouse infection model used. Efficacy data for the drug combinations used also showed similar results, regardless of the formulation used for rifampin or timing of the drugs administered in combination. In all three infection models, the dual combination of rifampin and pyrazinamide was less sterilizing than the standard three-drug regimen, and therefore the results do not support the previously reported antagonism between standard TB agents.
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