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Sreekumar A, Kumar A, Biswas R, Biswas L. Emerging and alternative strategies for the treatment of nontuberculous mycobacterial infections. Expert Rev Anti Infect Ther 2024:1-19. [PMID: 39161153 DOI: 10.1080/14787210.2024.2395003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Accepted: 08/18/2024] [Indexed: 08/21/2024]
Abstract
INTRODUCTION Nontuberculous mycobacteria (NTM) infections have emerged as a significant clinical challenge due to their intrinsic multidrug resistance and the limited efficacy of existing treatments. These infections are becoming increasingly prevalent, with a need for new and effective therapeutic strategies. AREAS COVERED This review addresses several key aspects of NTM infections: i) pathogenesis and epidemiology; ii) the limitations and challenges of current treatment options; iii) emerging and alternative therapeutic strategies; iv) advanced drug delivery systems such as nanoparticles and efflux pump inhibitors; v) innovative antibacterial alternatives like antimicrobial peptides, bacteriophage therapy, and phytochemicals; and vi) other potential treatment modalities such as inhaled nitric oxide, small molecules, surgical debridement, phototherapy, and immunomodulatory therapy. EXPERT OPINION Personalized medicine, advanced drug delivery systems, and alternative therapies hold promise for the future of NTM treatment. Early and accurate identification of NTM species, enabled by improved diagnostic methods, is critical for tailoring treatment regimens. Emerging therapies show promise against drug-resistant NTM strains, but overcoming barriers like clinical trials, regulatory hurdles, and high production costs is crucial. Continued research and innovation are essential to improve treatment efficacy and patient outcomes.
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Affiliation(s)
| | - Anil Kumar
- Department of Microbiology, Amrita Institute of Medical Sciences & Research Centre, Amrita Vishwa Vidyapeetham, Kochi, India
| | - Raja Biswas
- Amrita Center for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, India
| | - Lalitha Biswas
- Amrita Center for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, India
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Velázquez M, Fernández R, Lassaletta JM, Monge D. Asymmetric Dearomatization of Phthalazines by Anion-Binding Catalysis. Org Lett 2023; 25:8797-8802. [PMID: 38039188 PMCID: PMC10729020 DOI: 10.1021/acs.orglett.3c03325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/12/2023] [Accepted: 11/29/2023] [Indexed: 12/03/2023]
Abstract
A straightforward methodology for the enantioselective synthesis of 1,2-dihydrophthalazines via dearomatization of phthalazines by anion-binding catalysis has been developed. The process involves the Mannich-type addition of silyl ketene acetals to in situ generated N-acylphthalazinium chlorides using a tert-leucine derived thiourea as a H-bond donor catalyst. Ensuing selective and high-yielding transformations provide appealing dihydro- and tetrahydro-phthalazines, phthalazones, and piperazic acid homologues, en route to biologically relevant molecules.
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Affiliation(s)
- Marta Velázquez
- Departamento
de Química Orgánica, Facultad de Química, Universidad de Sevilla and Centro de Innovación
en Química Avanzada (ORFEO-CINQA), C/Prof. García González, 1, 41012 Sevilla, Spain
| | - Rosario Fernández
- Departamento
de Química Orgánica, Facultad de Química, Universidad de Sevilla and Centro de Innovación
en Química Avanzada (ORFEO-CINQA), C/Prof. García González, 1, 41012 Sevilla, Spain
| | - José M. Lassaletta
- Instituto
de Investigaciones Químicas (CSIC-US) and Centro de Innovación
en Química Avanzada (ORFEO-CINQA), Avenida Américo Vespucio, 49, 41092 Sevilla, Spain
| | - David Monge
- Departamento
de Química Orgánica, Facultad de Química, Universidad de Sevilla and Centro de Innovación
en Química Avanzada (ORFEO-CINQA), C/Prof. García González, 1, 41012 Sevilla, Spain
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Nammalwar B, Bourne CR, Wakeham N, Bourne PC, Barrow EW, Muddala NP, Bunce RA, Berlin KD, Barrow WW. Modified 2,4-diaminopyrimidine-based dihydrofolate reductase inhibitors as potential drug scaffolds against Bacillus anthracis. Bioorg Med Chem 2014; 23:203-11. [PMID: 25435253 DOI: 10.1016/j.bmc.2014.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 10/29/2014] [Accepted: 11/05/2014] [Indexed: 12/14/2022]
Abstract
The current Letter describes the synthesis and biological evaluation of dihydrophthalazine-appended 2,4-diaminopyrimidine (DAP) inhibitors (1) oxidized at the methylene bridge linking the DAP ring to the central aromatic ring and (2) modified at the central ring ether groups. Structures 4a-b incorporating an oxidized methylene bridge showed a decrease in activity, while slightly larger alkyl groups (CH2CH3 vs CH3) on the central ring oxygen atoms (R(2) and R(3)) had a minimal impact on the inhibition. Comparison of the potency data for previously reported RAB1 and BN-53 with the most potent of the new derivatives (19 b and 20a-b) showed similar values for inhibition of cellular growth and direct enzymatic inhibition (MICs 0.5-2 μg/mL). Compounds 29-34 with larger ester and ether groups containing substituted aromatic rings at R(3) exhibited slightly reduced activity (MICs 2-16 μg/mL). One explanation for this attenuated activity could be encroachment of the extended R(3) into the neighboring NADPH co-factor. These results indicate that modest additions to the central ring oxygen atoms are well tolerated, while larger modifications have the potential to act as dual-site inhibitors of dihydrofolate reductase (DHFR).
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Affiliation(s)
- Baskar Nammalwar
- Department of Chemistry, Oklahoma State University, 107 Physical Sciences, Stillwater, OK 74078, USA
| | - Christina R Bourne
- Department of Veterinary Pathobiology, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA
| | - Nancy Wakeham
- Department of Veterinary Pathobiology, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA
| | - Philip C Bourne
- Department of Veterinary Pathobiology, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA
| | - Esther W Barrow
- Department of Veterinary Pathobiology, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA
| | - N Prasad Muddala
- Department of Chemistry, Oklahoma State University, 107 Physical Sciences, Stillwater, OK 74078, USA
| | - Richard A Bunce
- Department of Chemistry, Oklahoma State University, 107 Physical Sciences, Stillwater, OK 74078, USA.
| | - K Darrell Berlin
- Department of Chemistry, Oklahoma State University, 107 Physical Sciences, Stillwater, OK 74078, USA
| | - William W Barrow
- Department of Veterinary Pathobiology, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA
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Nurjadi D, Olalekan AO, Layer F, Shittu AO, Alabi A, Ghebremedhin B, Schaumburg F, Hofmann-Eifler J, Van Genderen PJJ, Caumes E, Fleck R, Mockenhaupt FP, Herrmann M, Kern WV, Abdulla S, Grobusch MP, Kremsner PG, Wolz C, Zanger P. Emergence of trimethoprim resistance gene dfrG in Staphylococcus aureus causing human infection and colonization in sub-Saharan Africa and its import to Europe. J Antimicrob Chemother 2014; 69:2361-8. [PMID: 24855123 DOI: 10.1093/jac/dku174] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVES Co-trimoxazole (trimethoprim/sulfamethoxazole) is clinically valuable in treating skin and soft tissue infections (SSTIs) caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA). The genetic basis of emerging trimethoprim/sulfamethoxazole resistance in S. aureus from Africa is unknown. Such knowledge is essential to anticipate its further spread. We investigated the molecular epidemiology of trimethoprim resistance in S. aureus collected in and imported from Africa. METHODS Five hundred and ninety-eight human S. aureus isolates collected at five locations across sub-Saharan Africa [Gabon, Namibia, Nigeria (two) and Tanzania] and 47 isolates from travellers treated at six clinics in Europe because of SSTIs on return from Africa were tested for susceptibility to trimethoprim, sulfamethoxazole and trimethoprim/sulfamethoxazole, screened for genes mediating trimethoprim resistance in staphylococci [dfrA (dfrS1), dfrB, dfrG and dfrK] and assigned to spa genotypes and clonal complexes. RESULTS In 313 clinical and 285 colonizing S. aureus from Africa, 54% of isolates were resistant to trimethoprim, 21% to sulfamethoxazole and 19% to trimethoprim/sulfamethoxazole. We found that 94% of trimethoprim resistance was mediated by the dfrG gene. Of the 47 S. aureus isolates from travellers with SSTIs, 27 (57%) were trimethoprim resistant and carried dfrG. Markers of trimethoprim resistance other than dfrG were rare. The presence of dfrG genes in S. aureus was neither geographically nor clonally restricted. CONCLUSIONS dfrG, previously perceived to be an uncommon cause of trimethoprim resistance in human S. aureus, is widespread in Africa and abundant in imported S. aureus from ill returning travellers. These findings may foreshadow the loss of trimethoprim/sulfamethoxazole for the empirical treatment of SSTIs caused by community-associated MRSA.
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Affiliation(s)
- Dennis Nurjadi
- Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Tropenmedizin, Universitätsklinikum, Wilhelmstraße 27, 72074 Tübingen, Germany Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum, Elfriede-Aulhorn-Straße 6, 72076 Tübingen, Germany
| | - Adesola O Olalekan
- Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Tropenmedizin, Universitätsklinikum, Wilhelmstraße 27, 72074 Tübingen, Germany Department of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, PO Box 4000, Ogbomoso, Nigeria
| | - Franziska Layer
- Nationales Referenzzentrum für Staphylokokken und Enterokokken, Robert Koch Institut, Burgstraße 37, 38855 Wernigerode, Germany
| | - Adebayo O Shittu
- Department of Microbiology, Obafemi Awolowo University, Ile-Ife 22005, Nigeria
| | - Abraham Alabi
- Centre de Recherches Médicales de Lambaréné (CERMEL), B.P. 118, Lambaréné, Gabon
| | - Beniam Ghebremedhin
- Institut für Medizinische Mikrobiologie, Universitätsklinikum, Leipziger Straße 44, 39120 Magdeburg, Germany/Department Humanmedizin, Universität Witten/Herdecke, Alfred-Herrhausen-Straße 50, 58448 Witten, Germany/Helios Clinic, Heusnerstraße 40, 42283 Wuppertal, Germany
| | - Frieder Schaumburg
- Institut für Medizinische Mikrobiologie, Universitätsklinikum Münster, Domagkstraße 10, 48149 Münster, Germany
| | - Jonas Hofmann-Eifler
- Bagamoyo Research and Training Center, Ifakara Health Institute, PO Box 74, Bagamoyo, Tanzania Universitätsklinikum Freiburg, Abteilung Infektiologie, Hugstetter Straße 55, 79106 Freiburg, Germany
| | - Perry J J Van Genderen
- Instituut voor Tropische Ziekten, Havenziekenhuis, Haringvliet 72, 3011 TG Rotterdam, The Netherlands
| | - Eric Caumes
- Service de Maladies Infectieuses et Tropicales, groupe hospitalier Pitié-Salpêtrière, 47-83 boulevard de l'Hôpital, 75651 Paris cedex 13, France/Sorbonne Universités, UPMC Univ Paris 06, F-75005, Paris, France
| | - Ralf Fleck
- Tropenklinik, Paul-Lechler-Krankenhaus, 72076 Tübingen, Germany
| | - Frank P Mockenhaupt
- Institut für Tropenmedizin und Internationale Gesundheit, Charité-Universitätsmedizin Berlin, Spandauer Damm 130, 14050 Berlin, Germany
| | - Mathias Herrmann
- Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum des Saarlandes, Kirrberger Straße, 66421 Homburg/Saar, Germany
| | - Winfried V Kern
- Universitätsklinikum Freiburg, Abteilung Infektiologie, Hugstetter Straße 55, 79106 Freiburg, Germany
| | - Salim Abdulla
- Bagamoyo Research and Training Center, Ifakara Health Institute, PO Box 74, Bagamoyo, Tanzania
| | - Martin P Grobusch
- Centre de Recherches Médicales de Lambaréné (CERMEL), B.P. 118, Lambaréné, Gabon Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 Amsterdam, The Netherlands
| | - Peter G Kremsner
- Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Tropenmedizin, Universitätsklinikum, Wilhelmstraße 27, 72074 Tübingen, Germany Centre de Recherches Médicales de Lambaréné (CERMEL), B.P. 118, Lambaréné, Gabon
| | - Christiane Wolz
- Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum, Elfriede-Aulhorn-Straße 6, 72076 Tübingen, Germany
| | - Philipp Zanger
- Deutsches Zentrum für Infektionsforschung (DZIF), Institut für Tropenmedizin, Universitätsklinikum, Wilhelmstraße 27, 72074 Tübingen, Germany
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Bourne CR, Wakeham N, Webb N, Nammalwar B, Bunce RA, Berlin KD, Barrow WW. The structure and competitive substrate inhibition of dihydrofolate reductase from Enterococcus faecalis reveal restrictions to cofactor docking. Biochemistry 2014; 53:1228-38. [PMID: 24495113 PMCID: PMC3985486 DOI: 10.1021/bi401104t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
We
are addressing bacterial resistance to antibiotics by repurposing
a well-established classic antimicrobial target, the dihydrofolate
reductase (DHFR) enzyme. In this work, we have focused on Enterococcus faecalis, a nosocomial pathogen that frequently
harbors antibiotic resistance determinants leading to complicated
and difficult-to-treat infections. An inhibitor series with a hydrophobic
dihydrophthalazine heterocycle was designed from the anti-folate trimethoprim.
We have examined the potency of this inhibitor series based on inhibition
of DHFR enzyme activity and bacterial growth, including in the presence
of the exogenous product analogue folinic acid. The resulting preferences
were rationalized using a cocrystal structure of the DHFR from this
organism with a propyl-bearing series member (RAB-propyl). In a companion
apo structure, we identify four buried waters that act as placeholders
for a conserved hydrogen-bonding network to the substrate and indicate
an important role in protein stability during catalytic cycling. In
these structures, the nicotinamide of the nicotinamide adenine dinucleotide
phosphate cofactor is visualized outside of its binding pocket, which
is exacerbated by RAB-propyl binding. Finally, homology models of
the TMPR sequences dfrK and dfrF were constructed. While the dfrK-encoded protein
shows clear sequence changes that would be detrimental to inhibitor
binding, the dfrF-encoded protein model suggests
the protein would be relatively unstable. These data suggest a utility
for anti-DHFR compounds for treating infections arising from E. faecalis. They also highlight a role for water in stabilizing
the DHFR substrate pocket and for competitive substrate inhibitors
that may gain advantages in potency by the perturbation of cofactor
dynamics.
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Affiliation(s)
- Christina R Bourne
- Department of Veterinary Pathobiology, Oklahoma State University , Stillwater, Oklahoma 74078, United States
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Aljaar N, Conrad J, Beifuss U. Synthesis of 2-aryl-1,2-dihydrophthalazines via reaction of 2-(bromomethyl)benzaldehydes with arylhydrazines. J Org Chem 2013; 78:1045-53. [PMID: 23256775 DOI: 10.1021/jo302491x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The reaction of 2-(bromomethyl)benzaldehydes with arylhydrazines employing K(2)CO(3) as a base and FeCl(3) as a catalyst in CH(3)CN at 100 °C delivers 2-aryl-1,2-dihydrophthalazines with yields ranging from 60 to 91%. The transformation is considered to proceed as an intermolecular condensation/intramolecular nucleophilic substitution.
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Affiliation(s)
- Nayyef Aljaar
- Bioorganische Chemie, Institut für Chemie, Universität Hohenheim, Garbenstrasse 30, D-70599 Stuttgart, Germany
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7
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Bourne CR, Wakeham N, Nammalwar B, Tseitin V, Bourne PC, Barrow EW, Mylvaganam S, Ramnarayan K, Bunce RA, Berlin KD, Barrow WW. Structure-activity relationship for enantiomers of potent inhibitors of B. anthracis dihydrofolate reductase. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1834:46-52. [PMID: 22999981 PMCID: PMC3530638 DOI: 10.1016/j.bbapap.2012.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/09/2012] [Accepted: 09/04/2012] [Indexed: 01/07/2023]
Abstract
BACKGROUND Bacterial resistance to antibiotic therapies is increasing and new treatment options are badly needed. There is an overlap between these resistant bacteria and organisms classified as likely bioterror weapons. For example, Bacillus anthracis is innately resistant to the anti-folate trimethoprim due to sequence changes found in the dihydrofolate reductase enzyme. Development of new inhibitors provides an opportunity to enhance the current arsenal of anti-folate antibiotics while also expanding the coverage of the anti-folate class. METHODS We have characterized inhibitors of B. anthracis dihydrofolate reductase by measuring the K(i) and MIC values and calculating the energetics of binding. This series contains a core diaminopyrimidine ring, a central dimethoxybenzyl ring, and a dihydrophthalazine moiety. We have altered the chemical groups extended from a chiral center on the dihydropyridazine ring of the phthalazine moiety. The interactions for the most potent compounds were visualized by X-ray structure determination. RESULTS We find that the potency of individual enantiomers is divergent with clear preference for the S-enantiomer, while maintaining a high conservation of contacts within the binding site. The preference for enantiomers seems to be predicated largely by differential interactions with protein residues Leu29, Gln30 and Arg53. CONCLUSIONS These studies have clarified the activity of modifications and of individual enantiomers, and highlighted the role of the less-active R-enantiomer in effectively diluting the more active S-enantiomer in racemic solutions. This directly contributes to the development of new antimicrobials, combating trimethoprim resistance, and treatment options for potential bioterrorism agents.
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Affiliation(s)
- Christina R. Bourne
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078,Corresponding authors: CRB: phone +1 (405) 744-6737 fax +1 (405) 744-5275 , WWB: phone +1 (405) 744-1842 fax +1 (405) 744-3738
| | - Nancy Wakeham
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078
| | - Baskar Nammalwar
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | | | - Philip C. Bourne
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078
| | - Esther W. Barrow
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078
| | | | | | - Richard A. Bunce
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | - K. Darrell Berlin
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | - William W. Barrow
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078,Corresponding authors: CRB: phone +1 (405) 744-6737 fax +1 (405) 744-5275 , WWB: phone +1 (405) 744-1842 fax +1 (405) 744-3738
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Li G, Ding Z, Xu B. Rhodium-catalyzed oxidative annulation of sulfonylhydrazones with alkenes. Org Lett 2012; 14:5338-41. [PMID: 23039134 DOI: 10.1021/ol302522n] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
An efficient rhodium-catalyzed tandem C-H bond olefination and annulation approach was developed to afford 1,2-dihydrophthalazines in good to excellent yields from easily accessible sulfonylhydrazones and alkenes.
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Affiliation(s)
- Guifei Li
- Department of Chemistry, Shanghai University, Shanghai 200444, China
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Nammalwar B, Bunce RA, Berlin KD, Bourne CR, Bourne PC, Barrow EW, Barrow WW. Synthesis and biological activity of substituted 2,4-diaminopyrimidines that inhibit Bacillus anthracis. Eur J Med Chem 2012; 54:387-96. [PMID: 22703705 PMCID: PMC3408765 DOI: 10.1016/j.ejmech.2012.05.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/26/2012] [Accepted: 05/11/2012] [Indexed: 12/01/2022]
Abstract
A series of substituted 2,4-diaminopyrimidines 1 has been prepared and evaluated for activity against Bacillus anthracis using previously reported (±)-3-{5-[(2,4-diamino-5-pyrimidinyl)methyl]-2,3-dimethoxyphenyl}-1-(1-propyl-2(1H)-phthalazinyl)-2-propen-1-one (1a), with a minimum inhibitory concentration (MIC) value of 1-3 μg/mL, as the standard. In the current work, the corresponding isobutenyl (1e) and phenyl (1h) derivatives displayed the most significant activity in terms of the lowest MICs with values of 0.5 μg/mL and 0.375-1.5 μg/mL, respectively. It is likely that the S isomers of 1 will bind the substrate-binding pocket of dihydrofolate reductase (DHFR) as in B. anthracis was found for (S)-1a. The final step in the convergent synthesis of target systems 1 from (±)-1-(1-substituted-2(1H)-phthalazinyl)-2-propen-1-ones 6 with 2,4-diamino-5-(5-iodo-3,4-dimethoxybenzyl)pyrimidine (13) was accomplished via a novel Heck coupling reaction under sealed-tube conditions.
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Affiliation(s)
- Baskar Nammalwar
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | - Richard A. Bunce
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | - K. Darrell Berlin
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078
| | - Christina R. Bourne
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078
| | - Philip C. Bourne
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078
| | - Esther W. Barrow
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078
| | - William W. Barrow
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078
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10
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Brown-Elliott BA, Nash KA, Wallace RJ. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria. Clin Microbiol Rev 2012; 25:545-82. [PMID: 22763637 PMCID: PMC3416486 DOI: 10.1128/cmr.05030-11] [Citation(s) in RCA: 335] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria.
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11
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Inhibition of antibiotic-resistant Staphylococcus aureus by the broad-spectrum dihydrofolate reductase inhibitor RAB1. Antimicrob Agents Chemother 2010; 54:3825-33. [PMID: 20606069 DOI: 10.1128/aac.00361-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterial burden on human health is quickly outweighing available therapeutics. Our long-term goal is the development of antimicrobials with the potential for broad-spectrum activity. We previously reported phthalazine-based inhibitors of dihydrofolate reductase (DHFR) with potent activity against Bacillus anthracis, a major component of Project BioShield. The most active molecule, named RAB1, performs well in vitro and, in a cocrystal structure, was found deep within the active site of B. anthracis DHFR. We have now examined the activity of RAB1 against a panel of bacteria relevant to human health and found broad-spectrum applicability, particularly with regard to gram-positive organisms. RAB1 was most effective against Staphylococcus aureus, including methicillin- and vancomycin-resistant (MRSA/VRSA) strains. We have determined the cocrystal structure of the wild-type and trimethoprim-resistant (Phe 98 Tyr) DHFR enzyme from S. aureus with RAB1, and we found that rotational freedom of the acryloyl linker region allows the phthalazine moiety to occupy two conformations. This freedom in placement also allows either enantiomer of RAB1 to bind to S. aureus, in contrast to the specificity of B. anthracis for the S-enantiomer. Additionally, one of the conformations of RAB1 defines a unique surface cavity that increases the strength of interaction with S. aureus. These observations provide insights into the binding capacity of S. aureus DHFR and highlight atypical features critical for future exploitation in drug development.
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