351
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von Nussbaum F, Brands M, Hinzen B, Weigand S, Häbich D. Antibacterial natural products in medicinal chemistry--exodus or revival? Angew Chem Int Ed Engl 2007; 45:5072-129. [PMID: 16881035 DOI: 10.1002/anie.200600350] [Citation(s) in RCA: 467] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To create a drug, nature's blueprints often have to be improved through semisynthesis or total synthesis (chemical postevolution). Selected contributions from industrial and academic groups highlight the arduous but rewarding path from natural products to drugs. Principle modification types for natural products are discussed herein, such as decoration, substitution, and degradation. The biological, chemical, and socioeconomic environments of antibacterial research are dealt with in context. Natural products, many from soil organisms, have provided the majority of lead structures for marketed anti-infectives. Surprisingly, numerous "old" classes of antibacterial natural products have never been intensively explored by medicinal chemists. Nevertheless, research on antibacterial natural products is flagging. Apparently, the "old fashioned" natural products no longer fit into modern drug discovery. The handling of natural products is cumbersome, requiring nonstandardized workflows and extended timelines. Revisiting natural products with modern chemistry and target-finding tools from biology (reversed genomics) is one option for their revival.
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Affiliation(s)
- Franz von Nussbaum
- Bayer HealthCare AG, Medicinal Chemistry Europe, 42096 Wuppertal, Germany.
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352
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Cha J, Vakulenko SB, Mobashery S. Characterization of the β-Lactam Antibiotic Sensor Domain of the MecR1 Signal Sensor/Transducer Protein from Methicillin-Resistant Staphylococcus aureus. Biochemistry 2007; 46:7822-31. [PMID: 17550272 DOI: 10.1021/bi7005459] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has evolved two mechanisms for resistance to beta-lactam antibiotics. One is production of a beta-lactamase, and the other is that of penicillin-binding protein 2a (PBP 2a). The expression of these two proteins is regulated by the bla and mec operons, respectively. BlaR1 and MecR1 are beta-lactam sensor/signal transducer proteins, which experience acylation by beta-lactam antibiotics on the cell surface and transduce the signal into the cytoplasm. The C-terminal surface domain of MecR1 (MecRS) has been cloned, expressed, and purified to homogeneity. This protein has been characterized by documenting that it has a critical and unusual Nzeta-carboxylated lysine at position 394. Furthermore, the kinetics of interactions with beta-lactam antibiotics were evaluated, a process that entails conformational changes for the protein that might be critical for the signal transduction event. Kinetics of acylation of MecRS are suggestive that signal sensing may be the step where the two systems are substantially different from one another.
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Affiliation(s)
- Jooyoung Cha
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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353
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Yacoby I, Bar H, Benhar I. Targeted drug-carrying bacteriophages as antibacterial nanomedicines. Antimicrob Agents Chemother 2007; 51:2156-63. [PMID: 17404004 PMCID: PMC1891362 DOI: 10.1128/aac.00163-07] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 03/15/2007] [Accepted: 03/19/2007] [Indexed: 11/20/2022] Open
Abstract
While the resistance of bacteria to traditional antibiotics is a major public health concern, the use of extremely potent antibacterial agents is limited by their lack of selectivity. As in cancer therapy, antibacterial targeted therapy could provide an opportunity to reintroduce toxic substances to the antibacterial arsenal. A desirable targeted antibacterial agent should combine binding specificity, a large drug payload per binding event, and a programmed drug release mechanism. Recently, we presented a novel application of filamentous bacteriophages as targeted drug carriers that could partially inhibit the growth of Staphylococcus aureus bacteria. This partial success was due to limitations of drug-loading capacity that resulted from the hydrophobicity of the drug. Here we present a novel drug conjugation chemistry which is based on connecting hydrophobic drugs to the phage via aminoglycoside antibiotics that serve as solubility-enhancing branched linkers. This new formulation allowed a significantly larger drug-carrying capacity of the phages, resulting in a drastic improvement in their performance as targeted drug-carrying nanoparticles. As an example for a potential systemic use for potent agents that are limited for topical use, we present antibody-targeted phage nanoparticles that carry a large payload of the hemolytic antibiotic chloramphenicol connected through the aminoglycoside neomycin. We demonstrate complete growth inhibition toward the pathogens Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli with an improvement in potency by a factor of approximately 20,000 compared to the free drug.
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Affiliation(s)
- Iftach Yacoby
- Green Building Room 202, Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Ramat Aviv 69978, Israel
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354
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Borisova SA, Zhang C, Takahashi H, Zhang H, Wong AW, Thorson JS, Liu HW. Substrate specificity of the macrolide-glycosylating enzyme pair DesVII/DesVIII: opportunities, limitations, and mechanistic hypotheses. Angew Chem Int Ed Engl 2007; 45:2748-53. [PMID: 16538696 DOI: 10.1002/anie.200503195] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Svetlana A Borisova
- Division of Medicinal Chemistry, College of Pharmacy and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
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355
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Bisht GS, Rawat DS, Kumar A, Kumar R, Pasha S. Antimicrobial activity of rationally designed amino terminal modified peptides. Bioorg Med Chem Lett 2007; 17:4343-6. [PMID: 17553680 DOI: 10.1016/j.bmcl.2007.05.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Revised: 04/08/2007] [Accepted: 05/09/2007] [Indexed: 11/24/2022]
Abstract
Series of short amino terminal modified cationic peptides were designed and synthesized. All of the synthesized compounds were tested against gram-positive as well as gram-negative bacterial strain. Some of the compounds exhibit potent antibacterial activity and no hemolytic activity even at high dose level (1000 microg/mL) in mammalian erythrocytes was observed.
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Affiliation(s)
- Gopal Singh Bisht
- Peptide Research Laboratory, Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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356
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Abstract
Antibiotic resistance has become a significant public health concern. Antibiotics that belong to new structural classes and manifest their biological activity via novel mechanisms are urgently needed. Lysobactin, a depsipeptide antibiotic has displayed very strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) as well as vancomycin-resistant enterococci (VRE) with minimum inhibitory concentrations (MICs) ranging from 0.39 to 0.78 microg/mL. The MIC values against VRE were more than 50-fold lower than those reported for vancomycin itself. Lysobactin was found to inhibit nascent peptidoglycan formation; however, this activity was not antagonized in the presence of N-acyl-L-Lys-D-Ala-D-Ala, the binding domain on the cell wall precursors that is utilized by vancomycin. Thus, lysobactin represents a promising agent for the treatment bacterial infections due to resistant pathogens. We describe a convergent synthesis of lysobactin that relies upon a highly efficient macrocyclization reaction to assemble the 28-membered cyclic depsipeptide. This synthesis provides the foundation for further study of the mode of action utilized by lysobactin and its analogues.
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Affiliation(s)
- Aikomari Guzman-Martinez
- Contribution from the Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093
| | - Ryan Lamer
- Contribution from the Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093
| | - Michael S. VanNieuwenhze
- Contribution from the Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093
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357
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Zhang C, Fu Q, Albermann C, Li L, Thorson JS. The in vitro characterization of the erythronolide mycarosyltransferase EryBV and its utility in macrolide diversification. Chembiochem 2007; 8:385-90. [PMID: 17262863 DOI: 10.1002/cbic.200600509] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Changsheng Zhang
- Laboratory for Biosynthetic Chemistry, University of Wisconsin, National Cooperative Drug Discovery Group, Pharmaceutical Sciences Division, School of Pharmacy, Madison, WI 53705, USA
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358
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Mutaz Al‐Ajlani M, Hasnain S. Simple and Rapid Isolation of a Novel Antibiotic fromBacillus subtilisMz‐7. J LIQ CHROMATOGR R T 2007. [DOI: 10.1080/10826070500509132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Muaaz Mutaz Al‐Ajlani
- a Department of Microbiology and Molecular Genetics , University of the Punjab, Quaid‐e‐Azam Campus , Lahore, Pakistan
| | - Shahida Hasnain
- a Department of Microbiology and Molecular Genetics , University of the Punjab, Quaid‐e‐Azam Campus , Lahore, Pakistan
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359
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Ejim LJ, Blanchard JE, Koteva KP, Sumerfield R, Elowe NH, Chechetto JD, Brown ED, Junop MS, Wright GD. Inhibitors of Bacterial Cystathionine β-Lyase: Leads for New Antimicrobial Agents and Probes of Enzyme Structure and Function. J Med Chem 2007; 50:755-64. [PMID: 17300162 DOI: 10.1021/jm061132r] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The biosynthesis of methionine is an attractive antibiotic target given its importance in protein and DNA metabolism and its absence in mammals. We have performed a high-throughput screen of the methionine biosynthesis enzyme cystathionine beta-lyase (CBL) against a library of 50 000 small molecules and have identified several compounds that inhibit CBL enzyme activity in vitro. These hit molecules were of two classes: those that blocked CBL activity with mixed steady-state inhibition and those that covalently interacted with the enzyme at the active site pyridoxal phosphate cofactor with slow-binding inhibition kinetics. We determined the crystal structure of one of the slow-binding inhibitors in complex with CBL and used this structure as a guide in the synthesis of a small, focused library of analogues, some of which had improved enzyme inhibition properties. These studies provide the first lead molecules for antimicrobial agents that target cystathionine beta-lyase in methionine biosynthesis.
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Affiliation(s)
- Linda J Ejim
- Antimicrobial Research Centre, McMaster High Throughput Screening Laboratory, Department of Biochemistry and Biomedical Sciences, McMaster University, Ontario L8N 3Z5, Canada
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360
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Cho SH, Warit S, Wan B, Hwang CH, Pauli GF, Franzblau SG. Low-oxygen-recovery assay for high-throughput screening of compounds against nonreplicating Mycobacterium tuberculosis. Antimicrob Agents Chemother 2007; 51:1380-5. [PMID: 17210775 PMCID: PMC1855511 DOI: 10.1128/aac.00055-06] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Screening for new antimicrobial agents is routinely conducted only against actively replicating bacteria. However, it is now widely accepted that a physiological state of nonreplicating persistence (NRP) is responsible for antimicrobial tolerance in many bacterial infections. In tuberculosis, the key to shortening the 6-month regimen lies in targeting this NRP subpopulation. Therefore, a high-throughput, luminescence-based low-oxygen-recovery assay (LORA) was developed to screen antimicrobial agents against NRP Mycobacterium tuberculosis. M. tuberculosis H37Rv containing a plasmid with an acetamidase promoter driving a bacterial luciferase gene was adapted to low oxygen conditions by extended culture in a fermentor with a 0.5 headspace ratio. The MICs of 31 established antimicrobial agents were determined in microplate cultures maintained under anaerobic conditions for 10 days and, for comparative purposes, under aerobic conditions for 7 days. Cultures exposed to drugs under anaerobic conditions followed by 28 h of "recovery" under ambient oxygen produced a luminescent signal that was, for most compounds, proportional to the number of CFU determined prior to the recovery phase. No agents targeting the cell wall were active against NRP M. tuberculosis, whereas drugs hitting other cellular targets had a range of activities. The calculated Z' factor was in the range of 0.58 to 0.84, indicating the suitability of the use of LORA for high-throughput assays. This LORA is sufficiently robust for use for primary high-throughput screening of compounds against NRP M. tuberculosis.
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Affiliation(s)
- Sang Hyun Cho
- Institute for Tuberculosis Research, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, MC 964, Rm. 412, Chicago, IL 60612, USA
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361
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Chapter 22 New Developments in Antibacterial Drug R&D. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2007. [DOI: 10.1016/s0065-7743(07)42022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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362
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Yang ST, Shin SY, Kim JI. Interaction mode of a symmetric Trp-rich undeca peptide PST11-RK with lipid bilayers. FEBS Lett 2006; 581:157-63. [PMID: 17184775 DOI: 10.1016/j.febslet.2006.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 12/05/2006] [Accepted: 12/05/2006] [Indexed: 11/22/2022]
Abstract
To better understand the mode of action of the antimicrobial peptide PST11-RK, we investigated its (1) bactericidal kinetics, (2) ability to induce bacterial membrane depolarization, (3) ability to bind to liposomes, (4) cis/trans prolyl isomerization, (5) lipid binding kinetics and (6) translocation across lipid bilayers. Our findings suggest that PST11-RK acts mainly by collapsing the cytoplasmic membrane potential; it first attaches to the membrane via cationic C- and N-terminal residues and then inserts its central hydrophobic residues into the lipid interior. In addition, it seems likely that cis/trans isomerization facilitates the translocation of PST11-RK across the lipid bilayer, where it may interact with secondary intracellular targets.
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Affiliation(s)
- Sung-Tae Yang
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, South Korea
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363
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Roodhouse A, Wellsted A. Safety in urine sampling: maintaining an infection-free environment. BRITISH JOURNAL OF NURSING (MARK ALLEN PUBLISHING) 2006; 15:870-2. [PMID: 17108858 DOI: 10.12968/bjon.2006.15.16.21851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The insertion of an indwelling urinary catheter is thought to be implicated in 80% of all urinary tract infections (UTI). In patients with an indwelling catheter, one of the most effective ways to determine whether or not there is evidence of a UTI is to aspirate a sample of urine for analysis, typically using a syringe and needle. Inevitably this puts the healthcare worker at risk of a percutaneous needle stick injury and accidental exposure to serious and potentially life-threatening viruses. Infection control is now taken increasingly seriously in UK hospitals, and the elimination of infection risk is regarded as a priority. In addition to training, and safer working practices the government recognizes the need for new technological innovation to help further reduce risks. In the urine sampling environment, there is a new needle-free port (EZ-Lok from Bard Ltd), designed specifically to reduce the occupational health risk of needle stick injuries.
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364
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Zhu JC, Liu Y, Wong WK, Zhou B, Yin J. Investigation of Antibacterial Activity of Two Kinds of Novel Schiff Bases onEscherichia coli by Microcalorimetry. CHINESE J CHEM 2006. [DOI: 10.1002/cjoc.200690241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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365
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Oblak M, Grdadolnik SG, Kotnik M, Poterszman A, Atkinson RA, Nierengarten H, Desplancq D, Moras D, Solmajer T. Biophysical characterization of an indolinone inhibitor in the ATP-binding site of DNA gyrase. Biochem Biophys Res Commun 2006; 349:1206-13. [PMID: 16979583 DOI: 10.1016/j.bbrc.2006.08.172] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 08/21/2006] [Indexed: 11/27/2022]
Abstract
Fighting bacterial resistance is a challenging task in the field of medicinal chemistry. DNA gyrase represents a validated antibacterial target and has drawn much interest in recent years. By a structure-based approach we have previously discovered compound 1, an indolinone derivative, possessing inhibitory activity against DNA gyrase. In the present paper, a detailed biophysical characterization of this inhibitor is described. Using mass spectrometry, NMR spectroscopy, and fluorescence experiments we have demonstrated that compound 1 binds reversibly to the ATP-binding site of the 24 kDa N-terminal fragment of DNA gyrase B from Escherichia coli (GyrB24) with low micromolar affinity. Based on these data, a plausible molecular model of compound 1 in the active site of GyrB24 was constructed. The predicted binding mode explains the competitive inhibitory mechanism with respect to ATP and forms a useful basis for further development of potent DNA gyrase inhibitors.
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Affiliation(s)
- Marko Oblak
- Laboratory of Molecular Modeling and NMR Spectroscopy, National Institute of Chemistry, POB660, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
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366
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Abstract
Catheter-associated urinary tract infections continue to be a major source of morbidity in hospital and the community. In part, this may be the result of ritualistic practices, compounded by poor communication on discharge from hospital. This article highlights many of the issues that lead to continued high rates of CAUTI, and challenges health professionals and health-care providers to use all available guidance and tools to reduce the incidence of CAUTI across the NHS.
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Affiliation(s)
- Jennie Potter
- Rapid Response Team Intermediate Care Selby and York PCT.
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367
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von Nussbaum F, Brands M, Hinzen B, Weigand S, Häbich D. Antibakterielle Naturstoffe in der medizinischen Chemie – Exodus oder Renaissance? Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200600350] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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368
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Yacoby I, Shamis M, Bar H, Shabat D, Benhar I. Targeting antibacterial agents by using drug-carrying filamentous bacteriophages. Antimicrob Agents Chemother 2006; 50:2087-97. [PMID: 16723570 PMCID: PMC1479106 DOI: 10.1128/aac.00169-06] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 03/23/2006] [Accepted: 03/31/2006] [Indexed: 12/27/2022] Open
Abstract
Bacteriophages have been used for more than a century for (unconventional) therapy of bacterial infections, for half a century as tools in genetic research, for 2 decades as tools for discovery of specific target-binding proteins, and for nearly a decade as tools for vaccination or as gene delivery vehicles. Here we present a novel application of filamentous bacteriophages (phages) as targeted drug carriers for the eradication of (pathogenic) bacteria. The phages are genetically modified to display a targeting moiety on their surface and are used to deliver a large payload of a cytotoxic drug to the target bacteria. The drug is linked to the phages by means of chemical conjugation through a labile linker subject to controlled release. In the conjugated state, the drug is in fact a prodrug devoid of cytotoxic activity and is activated following its dissociation from the phage at the target site in a temporally and spatially controlled manner. Our model target was Staphylococcus aureus, and the model drug was the antibiotic chloramphenicol. We demonstrated the potential of using filamentous phages as universal drug carriers for targetable cells involved in disease. Our approach replaces the selectivity of the drug itself with target selectivity borne by the targeting moiety, which may allow the reintroduction of nonspecific drugs that have thus far been excluded from antibacterial use (because of toxicity or low selectivity). Reintroduction of such drugs into the arsenal of useful tools may help to combat emerging bacterial antibiotic resistance.
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Affiliation(s)
- Iftach Yacoby
- Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel
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369
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Borisova SA, Zhang C, Takahashi H, Zhang H, Wong AW, Thorson JS, Liu HW. Substrate Specificity of the Macrolide-Glycosylating Enzyme Pair DesVII/DesVIII: Opportunities, Limitations, and Mechanistic Hypotheses. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503195] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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370
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Mutaz Al‐Ajlani M, Hasnain S. Simple and Rapid Isolation of a Novel Antibiotic from Bacillus subtilisMz‐7. J LIQ CHROMATOGR R T 2006; 29:639-647. [DOI: https:/doi.org/10.1080/10826070500509132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Affiliation(s)
- Muaaz Mutaz Al‐Ajlani
- a Department of Microbiology and Molecular Genetics , University of the Punjab, Quaid‐e‐Azam Campus , Lahore, Pakistan
| | - Shahida Hasnain
- a Department of Microbiology and Molecular Genetics , University of the Punjab, Quaid‐e‐Azam Campus , Lahore, Pakistan
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371
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Peláez F. The historical delivery of antibiotics from microbial natural products—Can history repeat? Biochem Pharmacol 2006; 71:981-90. [PMID: 16290171 DOI: 10.1016/j.bcp.2005.10.010] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 09/23/2005] [Accepted: 10/05/2005] [Indexed: 11/22/2022]
Abstract
Microbial natural products are the origin of most of the antibiotics on the market today. However, research in antibiotics and natural products has declined significantly during the last decade as a consequence of diverse factors, among which the lack of interest of industry in the field and the strong competition from collections of synthetic compounds as source of drug leads. As a consequence, there is an alarming scarcity of new antibiotic classes in the pipelines of the pharmaceutical industry. Still, microbial natural products remain the most promising source of novel antibiotics, although new approaches are required to improve the efficiency of the discovery process. The impact of microbial biodiversity, the influence of growth conditions on the production of secondary metabolites, the choice of the best approach at the screening step and the challenges faced during the isolation and identification of the active compounds are examined in this review as the critical factors contributing to success in the effort of antibiotic discovery from microbial natural products.
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Affiliation(s)
- Fernando Peláez
- Centro de Investigación Básica, Merck, Sharp & Dohme de España, S.A. Josefa Valcárcel 38, E-28027 Madrid, Spain.
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372
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Gao F, Yan X, Baettig OM, Berghuis AM, Auclair K. Regio- and chemoselective 6'-N-derivatization of aminoglycosides: bisubstrate inhibitors as probes to study aminoglycoside 6'-N-acetyltransferases. Angew Chem Int Ed Engl 2006; 44:6859-62. [PMID: 16206301 DOI: 10.1002/anie.200501399] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Feng Gao
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, H3A 2K6, Canada
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373
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Bhadury P, Mohammad BT, Wright PC. The current status of natural products from marine fungi and their potential as anti-infective agents. J Ind Microbiol Biotechnol 2006; 33:325-37. [PMID: 16429315 DOI: 10.1007/s10295-005-0070-3] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Accepted: 12/07/2005] [Indexed: 11/24/2022]
Abstract
A growing number of marine fungi are the sources of novel and potentially life-saving bioactive secondary metabolites. Here, we have discussed some of these novel antibacterial, antiviral, antiprotozoal compounds isolated from marine-derived fungi and their possible roles in disease eradication. We have also discussed the future commercial exploitation of these compounds for possible drug development using metabolic engineering and post-genomics approaches.
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Affiliation(s)
- Punyasloke Bhadury
- Plymouth Marine Laboratory, Prospect Place, The Hoe, PL1 3DH, Plymouth, UK
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374
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Baum EZ, Crespo-Carbone SM, Foleno B, Peng S, Hilliard JJ, Abbanat D, Goldschmidt R, Bush K. Identification of a dithiazoline inhibitor of Escherichia coli L,D-carboxypeptidase A. Antimicrob Agents Chemother 2006; 49:4500-7. [PMID: 16251288 PMCID: PMC1280138 DOI: 10.1128/aac.49.11.4500-4507.2005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzyme L,D-carboxypeptidase A is involved in the recycling of bacterial peptidoglycan and is essential in Escherichia coli during stationary phase. By high-throughput screening, we have identified a dithiazoline inhibitor of the enzyme with a 50% inhibitory concentration of 3 microM. The inhibitor appeared to cause lysis of E. coli during stationary phase, behavior that is similar to a previously described deletion mutant of L,D-carboxypeptidase A (M. F. Templin, A. Ursinus, and J.-V. Holtje, EMBO J. 18:4108-4117, 1999). As much as a one-log drop in CFU in stationary phase was observed upon treatment of E. coli with the inhibitor, and the amount of intracellular tetrapeptide substrate increased by approximately 33%, consistent with inhibition of the enzyme within bacterial cells. Stationary-phase targets such as L,D-carboxypeptidase A are largely underrepresented as targets of the antibiotic armamentarium but provide potential opportunities to interfere with bacterial growth and persistence.
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Affiliation(s)
- Ellen Z Baum
- Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 1000 Route 202, Raritan, New Jersey 08869, USA.
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375
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Abstract
Here we report the design, synthesis and antibacterial activity of 20 lysine-peptoid hybrids. The hybrids are based on the peptoid lead structure [N-(1-naphthalenemethyl)glycyl]-[N-(4-methylbenzyl)glycyl]-[N-(1-naphthalenemethyl)glycyl]-N-(butyl)glycin amide (1) and contain between one and six lysine residues each. The compounds were tested for antibacterial activity against S. aureus ATCC 25923 and E. coli ATCC 25922. Furthermore, the hemolytic activity toward human erythrocytes was assessed. Several compounds with potent antibacterial activity and low hemolytic activity were identified.
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Affiliation(s)
- Trine S Ryge
- Department of Natural Sciences, Section of Bioorganic Chemistry, Royal Veterinary and Agricultural University, Copenhagen, Denmark
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376
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Abstract
During the past two decades, the number of antibacterials that has reached the marketplace each year has declined, whilst resistance to existing antibacterials has increased. New antibacterials are needed to replace those that have become less effective as a result of the emergence of a high level of resistance amongst target bacteria. Antibacterials are developed by targeting live multiplying whole bacterial cells, or essential bacterial molecules such as enzymes. Using these targets, libraries of natural, recombinant or chemically synthesised compounds are screened. Most existing antibacterials have been developed by creating novel analogues of established antibacterials, which are themselves derivatives of natural compounds. Recently, live non-multiplying bacteria have been used as targets. Bacteria in such a phase are much more tolerant to antibacterials than logarithmic phase organisms. Targeting of non-multiplying bacteria has the potential to yield new antibacterials that would shorten the duration of therapy. This would be more convenient for the patient, could reduce the incidence of adverse effects of treatment, and might reduce the emergence of antibacterial resistance. However, there is much to learn about non-multiplying bacteria, particularly the mechanisms that lie behind their profound antibacterial tolerance. New terminology has been proposed for susceptibility tests for antibacterial agents against non-multiplying bacteria, namely: the minimum stationary-cidal concentration and the minimum dormicidal concentration, which are defined as the minimum concentrations of drug that will kill stationary and dormant bacteria, respectively. The relationship between the antibiotic susceptibility of stationary and logarithmic phase bacteria is the stationary/logarithmic ratio. This terminology is suitable for both planktonic and biofilm cultures. In the future, it is likely that most antibacterial drug design will be based on existing antibacterial structures, but an increasing number of new molecular antibacterial structures may emerge from screening against multiplying and perhaps non-multiplying bacteria. The genomic approach has been disappointing so far, but it is still hoped that this will produce novel antibacterial agents.
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Affiliation(s)
- Anthony R M Coates
- Department of Cellular and Molecular Medicine, Medical Microbiology, Centre for Infection, St George's University of London, London, UK.
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377
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Is the pharmaceutical industry responding to the challenge of increasing bacterial resistance? ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.clinmicnews.2005.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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378
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Ward M, Sanchez M, Elasri MO, Lowe AB. Antimicrobial activity of statistical polymethacrylic sulfopropylbetaines against gram-positive and gram-negative bacteria. J Appl Polym Sci 2006. [DOI: 10.1002/app.23269] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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379
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Saha A, Sharma A, Dhar A, Bhattacharyya B, Roy S, Das Gupta SK. Antagonists of Hsp16.3, a low-molecular-weight mycobacterial chaperone and virulence factor, derived from phage-displayed peptide libraries. Appl Environ Microbiol 2005; 71:7334-44. [PMID: 16269776 PMCID: PMC1287729 DOI: 10.1128/aem.71.11.7334-7344.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The persistence of Mycobacterium tuberculosis is a major cause of concern in tuberculosis (TB) therapy. In the persistent mode the pathogen can resist drug therapy, allowing the possibility of reactivation of the disease. Several protein factors have been identified that contribute to persistence, one of them being the 16-kDa low-molecular-weight mycobacterial heat shock protein Hsp16.3, a homologue of the mammalian eye lens protein alpha-crystallin. It is believed that Hsp16.3 plays a key role in the persistence phase by protecting essential proteins from being irreversibly denatured. Because of the close association of Hsp16.3 with persistence, an attempt has been made to develop inhibitors against it. Random peptide libraries displayed on bacteriophage M13 were screened for Hsp16.3 binding. Two phage clones were identified that bind to the Hsp16.3 protein. The corresponding synthetic peptides, an 11-mer and a 16-mer, were able to bind Hsp16.3 and inhibit its chaperone activity in vitro in a dose-dependent manner. Little or no effect of these peptides was observed on alphaB-crystallin, a homologous protein that is a key component of human eye lens, indicating that there is an element of specificity in the observed inhibition. Two histidine residues appear to be common to the selected peptides. Nuclear magnetic resonance studies performed with the 11-mer peptide indicate that in this case these two histidines may be the crucial binding determinants. The peptide inhibitors of Hsp16.3 thus obtained could serve as the basis for developing potent drugs against persistent TB.
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Affiliation(s)
- Abhik Saha
- Bose Institute, Department of Microbiology, P1/12 C.I.T. Scheme VIIM, Calcutta 700054, India
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380
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The potential for photodynamic therapy in the treatment of localized infections. Photodiagnosis Photodyn Ther 2005; 2:247-62. [DOI: 10.1016/s1572-1000(05)00099-2] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 09/20/2005] [Accepted: 09/21/2005] [Indexed: 11/22/2022]
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381
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Butler MS, Buss AD. Natural products--the future scaffolds for novel antibiotics? Biochem Pharmacol 2005; 71:919-29. [PMID: 16289393 DOI: 10.1016/j.bcp.2005.10.012] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 09/30/2005] [Accepted: 10/05/2005] [Indexed: 11/27/2022]
Abstract
Natural products have played a pivotal role in antibiotic drug discovery with most antibacterial drugs being derived from a natural product or natural product lead. However, the rapid onset of resistance to most antibacterial drugs diminishes their effectiveness considerably and necessitates a constant supply of new antibiotics for effective treatment of infections. The natural product templates of actinonin, pleuromutilin, ramoplanin and tiacumicin B, which are compounds undergoing clinical evaluation, represent templates not found in currently marketed antibacterial drugs. In addition, the new templates present in the recently discovered lead antibacterials arylomycin, GE23077, mannopeptimycin, muraymycin/caprazamycin, nocathiacin and ECO-0501, are discussed. Despite extensive efforts to identify antibiotic leads from molecular targets, only the peptide deformylase inhibitor LBM-415 is currently in clinical trials. It is proposed that new antibacterial assays which combine cell-based screening with molecular targets could offer better prospects for lead discovery.
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Affiliation(s)
- Mark S Butler
- MerLion Pharmaceuticals, 1 Science Park Road, The Capricorn #05-01, Singapore Science Park II, Singapore 117528, Singapore.
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382
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Gao F, Yan X, Baettig OM, Berghuis AM, Auclair K. Regio- and Chemoselective 6′-N-Derivatization of Aminoglycosides: Bisubstrate Inhibitors as Probes To Study Aminoglycoside 6′-N-Acetyltransferases. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200501399] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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383
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Brazas MD, Hancock REW. Using microarray gene signatures to elucidate mechanisms of antibiotic action and resistance. Drug Discov Today 2005; 10:1245-52. [PMID: 16213417 DOI: 10.1016/s1359-6446(05)03566-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Microarray analyses reveal global changes in gene expression in response to environmental changes and, thus, are well suited to providing a detailed picture of bacterial responses to antibiotic treatment. These responses are represented by patterns of gene expression, termed expression signatures, which provide insight into the mechanism of action of antibiotics as well as the general physiological responses of bacteria to antibiotic-related stresses. The complexity of such signatures is challenging the notion that antibiotics act on single targets and this is consistent with the concept that there are multiple targets coupled with common stress responses. A more detailed knowledge of how known antibiotics act should reveal new strategies for antimicrobial drug discovery.
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Affiliation(s)
- Michelle D Brazas
- Centre for Microbial Diseases and Immunity Research, 2259 Lower Mall Research Station, University of British Columbia, Vancouver, Canada, V6T 1Z4
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384
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Molteni V, Kreusch A. Peptide deformylase inhibitors: a survey of the patent literature. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.15.10.1423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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385
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Abdel-Aziz AAM, El-Subbagh HI, Kunieda T. Lewis acid-promoted transformation of 2-alkoxypyridines into 2-aminopyridines and their antibacterial activity. Part 2: Remarkably facile C–N bond formation. Bioorg Med Chem 2005; 13:4929-35. [PMID: 15993091 DOI: 10.1016/j.bmc.2005.05.027] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 05/15/2005] [Accepted: 05/18/2005] [Indexed: 11/25/2022]
Abstract
2-Alkoxy-3-cyano-4,6-diarylpyridines 1a,b which were synthesized by condensation of alpha,beta-unsaturated ketones with malononitrils were subjected to Lewis acid-catalyzed nucleophilic displacement reaction with various amines to afford the corresponding 2-aminopyridines 3-21. The potency of the results as antibacterial agents has been evaluated. The structure of the newly prepared compounds was assessed by microanalysis, IR, and NMR spectra. Molecular modeling and QSAR methods are used to study the antibacterial activity of the active compounds by means of the molecular mechanic method.
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Affiliation(s)
- Alaa A-M Abdel-Aziz
- Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt.
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386
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Matthew Hansen T, Gu YG, Rehm TM, Dandliker PJ, Chovan LE, Bui MH, Nilius AM, Beutel BA. Synthesis and antibacterial activity of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives. Bioorg Med Chem Lett 2005; 15:2716-9. [PMID: 15911248 DOI: 10.1016/j.bmcl.2005.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 03/31/2005] [Accepted: 04/04/2005] [Indexed: 11/17/2022]
Abstract
A series of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives were prepared and evaluated for cell-free bacterial protein synthesis inhibition and whole cell antibacterial activity. When compared to the analogous 5-hydrogen compounds, the presence of the 5-OH group negatively affects biochemical potency. However, a tolerance of the 5-methoxy group is indicated. Only moderate whole cell antibacterial activity is seen, but this could be due to poor cellular penetration. Because only a few 7-position variants were made for this study, further investigation into this novel series combining a broader range of 7-amino derivatives with these 5-position modifications is warranted.
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Affiliation(s)
- T Matthew Hansen
- Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064, USA.
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387
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Fisher JF, Meroueh SO, Mobashery S. Bacterial resistance to beta-lactam antibiotics: compelling opportunism, compelling opportunity. Chem Rev 2005; 105:395-424. [PMID: 15700950 DOI: 10.1021/cr030102i] [Citation(s) in RCA: 684] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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388
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Butler MS. Natural products to drugs: natural product derived compounds in clinical trials. Nat Prod Rep 2005; 22:162-95. [PMID: 15806196 DOI: 10.1039/b402985m] [Citation(s) in RCA: 339] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Natural product and natural product-derived compounds that are being evaluated in clinical trials or in registration (current 31 December 2004) have been reviewed. Natural product derived drugs launched in the United States of America, Europe and Japan since 1998 and new natural product templates discovered since 1990 are discussed.
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Affiliation(s)
- Mark S Butler
- MerLion Pharmaceuticals, 1 Science Park Road, The Capricorn #05-01, Singapore Science Park II, Singapore 117528.
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389
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Daub H, Specht K, Ullrich A. Strategies to overcome resistance to targeted protein kinase inhibitors. Nat Rev Drug Discov 2005; 3:1001-10. [PMID: 15573099 DOI: 10.1038/nrd1579] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Selective inhibition of protein tyrosine kinases is gaining importance as an effective therapeutic approach for the treatment of a wide range of human cancers. However, as extensively documented for the BCR-ABL oncogene in imatinib-treated leukaemia patients, clinical resistance caused by mutations in the targeted oncogene has been observed. Here, we look at how structural and mechanistic insights from imatinib-insensitive Bcr-Abl have been exploited to identify second-generation drugs that override acquired target resistance. These insights have created a rationale for the development of either multi-targeted protein kinase inhibitors or cocktails of selective antagonists as antitumour drugs that combine increased therapeutic potency with a reduced risk of the emergence of molecular resistance.
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Affiliation(s)
- Henrik Daub
- Axxima Pharmaceuticals AG, Max-Lebsche-Platz 32, 81377 München, Germany.
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390
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Hu Y, Coates ARM. Transposon mutagenesis identifies genes which control antimicrobial drug tolerance in stationary-phaseEscherichia coli. FEMS Microbiol Lett 2005; 243:117-24. [PMID: 15668009 DOI: 10.1016/j.femsle.2004.11.049] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 11/29/2004] [Accepted: 11/29/2004] [Indexed: 10/26/2022] Open
Abstract
Tolerance to antimicrobial agents is a universal phenomenon in bacteria which are no longer multiplying or whose growth rate slows. Since slowly multiplying bacteria occur in clinical infections, extended periods of antimicrobial chemotherapy are needed to eradicate these organisms and to achieve cure. In this study, the molecular basis of antibiotic tolerance was investigated using transposon mutagenesis. We screened 5000 Escherichia coli Tn10Cam mutants for reduction of kanamycin tolerance in late stationary phase and found that 4935 mutants were able to grow to late stationary phase. Reduced tolerance was observed in nine mutants which became sensitive to killing by kanamycin. The mutant KS639 was the most sensitive one to kanamycin, and its genome was disrupted in an intergenic region which lies between aldB and yiaW open reading frames. This mutant showed increased sensitivity not only to kanamycin but also to gentamicin, ciprofloxacin and rifampicin. Reduced tolerance of KS639 to kanamycin was also observed in a murine thigh infection model. P1 transduction to the wild type strains confirmed that the intergenic region was responsible for the tolerance of the bacterium to antibiotics. Using PCR-directed one-step gene replacement, we inactivated the genes aldB, yiaW and yiaV. We also deleted the intergenic region. There was no difference in kanamycin tolerance between each mutant (DeltaaldB, DeltayiaW and DeltayiaV) and the parental strain. But the mutant lacking the intergenic region showed reduced tolerance to kanamycin. These data suggest that the intergenic region between aldB and yiaW genes may be involved in tolerance to antimicrobial agents in E. coli. Furthermore, they show that it is important in murine infection during antibiotic treatment and lead to a faster kill of the mutant bacteria.
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Affiliation(s)
- Yanmin Hu
- Department of Medical Microbiology, St. George's Hospital Medical School, London SW17 ORE, UK
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391
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Pelzer S, Wohlert SE, Vente A. Tool-box: tailoring enzymes for bio-combinatorial lead development and as markers for genome-based natural product lead discovery. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2005:233-59. [PMID: 15645724 DOI: 10.1007/3-540-27055-8_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Affiliation(s)
- S Pelzer
- Microbiology/Biotechnology, Eberhard-Karls-Universität Tübingen, Germany.
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392
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Walker S, Chen L, Hu Y, Rew Y, Shin D, Boger DL. Chemistry and Biology of Ramoplanin: A Lipoglycodepsipeptide with Potent Antibiotic Activity. Chem Rev 2005; 105:449-76. [PMID: 15700952 DOI: 10.1021/cr030106n] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Suzanne Walker
- The Department of Microbiology & Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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393
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Brown ED, Wright GD. New Targets and Screening Approaches in Antimicrobial Drug Discovery. Chem Rev 2005; 105:759-74. [PMID: 15700964 DOI: 10.1021/cr030116o] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric D Brown
- Antimicrobial Research Centre, Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5
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394
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Abstract
Anoplin is a decapeptide amide, GLLKRIKTLL-NH2 derived from the venom sac of the solitary spider wasp, Anoplius samariensis. It is active against Gram-positive and Gram-negative bacteria and is not hemolytic towards human erythrocytes. The present paper reports a structure-activity study of anoplin based on 37 analogues including an Ala-scan, C- and N-truncations, and single and multiple residue substitutions with various amino acids. The analogues were tested for antibacterial activity against both S. aureus ATCC 25923 and E. coli ATCC 25922, and several potent antibacterial analogues were identified. The cytotoxicity of the analogues against human erythrocytes was assessed in a hemolytic activity assay. The antibacterial activity and selectivity of the analogues against S. aureus and E. coli varied considerably, depending on the hydrophobicity and position of the various substituted amino acids. In certain cases the selectivity for Gram-positive and Gram-negative bacteria was either reversed or altogether eliminated. In addition, it was generally found that antibacterial activity coincided with hemolytic activity.
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Affiliation(s)
- Dan Ifrah
- Department of Chemistry, Royal Veterinary and Agricultural University, 1871 Frederiksberg C, Denmark.
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395
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Stephan J, Mailaender C, Etienne G, Daffé M, Niederweis M. Multidrug resistance of a porin deletion mutant of Mycobacterium smegmatis. Antimicrob Agents Chemother 2004; 48:4163-70. [PMID: 15504836 PMCID: PMC525411 DOI: 10.1128/aac.48.11.4163-4170.2004] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacteria contain an outer membrane of unusually low permeability which contributes to their intrinsic resistance to many agents. It is assumed that small and hydrophilic antibiotics cross the outer membrane via porins, whereas hydrophobic antibiotics may diffuse through the membrane directly. A mutant of Mycobacterium smegmatis lacking the major porin MspA was used to examine the role of the porin pathway in antibiotic sensitivity. Deletion of the mspA gene caused high-level resistance of M. smegmatis to 256 microg of ampicillin/ml by increasing the MIC 16-fold. The permeation of cephaloridine in the mspA mutant was reduced ninefold, and the resistance increased eightfold. This established a clear relationship between the activity and the outer membrane permeation of cephaloridine. Surprisingly, the MICs of the large and/or hydrophobic antibiotics vancomycin, erythromycin, and rifampin for the mspA mutant were increased 2- to 10-fold. This is in contrast to those for Escherichia coli, whose sensitivity to these agents was not affected by deletion of porin genes. Uptake of the very hydrophobic steroid chenodeoxycholate by the mspA mutant was retarded threefold, which supports the hypothesis that loss of MspA indirectly reduces the permeability by the lipid pathway. The multidrug resistance of the mspA mutant highlights the prominent role of outer membrane permeability for the sensitivity of M. smegmatis to antibiotics. An understanding of the pathways across the outer membrane is essential to the successful design of chemotherapeutic agents with activities against mycobacteria.
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Affiliation(s)
- Joachim Stephan
- Department of Microbiology, University of Alabama at Birmingham, 609 Bevill Biomedical Research Building, 845 19th St. South, Birmingham, AL 35294, USA
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396
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Hall BG, Barlow M. Evolution of the serine beta-lactamases: past, present and future. Drug Resist Updat 2004; 7:111-23. [PMID: 15158767 DOI: 10.1016/j.drup.2004.02.003] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Accepted: 02/28/2004] [Indexed: 11/16/2022]
Abstract
We present a protein structure-based phylogeny of Classes A, C and D of the serine beta-lactamases, and a new, detailed, sequence-based phylogeny of the Class A beta-lactamases. In addition, we discuss the historical evolution of Classes C and D. The evolutionary histories of all three classes indicate that the serine beta-lactamases are ancient enzymes, originating over two billion years ago, and that some have been on plasmids for millions of years. We also discuss the recent, antibiotic-era, evolution of the serine beta-lactamases in response to the clinical use of beta-lactam antibiotics. We also discuss a method that is being used to predict the future evolution of beta-lactamases in response to selection with new drugs.
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Affiliation(s)
- Barry G Hall
- Department of Biology, University of Rochester, Rochester, NY, USA.
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397
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Affiliation(s)
- Carl Nathan
- Department of Microbiology & Immunology, Weill Cornell Medical College, and Weill Graduate School of Medical Sciences of Cornell University, 1300 York Avenue, New York 10021, USA
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398
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Chopra I. Antibiotic resistance in Staphylococcus aureus: concerns, causes and cures. Expert Rev Anti Infect Ther 2004; 1:45-55. [PMID: 15482101 DOI: 10.1586/14787210.1.1.45] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is currently a predominant and dangerous nosocomial pathogen. Unfortunately, infections caused by this organism are becoming more difficult to treat as further evolution of drug resistance occurs within the pathogen. Vancomycin has become the drug of choice for treating MRSA infections. However, treatment failures, adverse side effects and the emergence of vancomycin-resistant MRSA are leading to urgent requirements for alternative antiMRSA therapies. Linezolid is a new agent recently developed for Gram-positive infections, including MRSA. However, resistance to this drug is already developing. The need for superior antiMRSA drugs is therefore highly evident. This article explores some of the opportunities for the development of new treatments for MRSA. These arise principally from extensions of existing drug classes and the discovery of novel agents by genome-driven technologies. Other possibilities concern the re-evaluation of earlier pharmacophores that have not so far been developed as antiMRSA agents.
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Affiliation(s)
- Ian Chopra
- Antimicrobial Research Centre and, Division of Microbiology, University of Leeds, Leeds, LS2 9JT, UK.
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399
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400
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Nielsen SF, Boesen T, Larsen M, Schønning K, Kromann H. Antibacterial chalcones––bioisosteric replacement of the 4′-hydroxy group. Bioorg Med Chem 2004; 12:3047-54. [PMID: 15142563 DOI: 10.1016/j.bmc.2004.03.071] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Accepted: 03/05/2004] [Indexed: 10/26/2022]
Abstract
Hydroxy chalcones, for example, Licochalcone A, has for several years been known to be antibacterial. The low aqueous solubility and the medium antibacterial potency have limited the usefulness of the compounds. We describe the bioisosteric replacement of the essential 4'-hydroxy group in the hydroxy chalcones with bioisosters of varied degrees of acidity resulting in both more potent and more soluble compounds. The more acidic 4'-hydroxy analogues (e.g., 3'-fluoro- or 3',5'-difluoro-) gave almost inactive compounds whereas exchanging the hydroxy group with a carboxy group resulted in a potent compound with a high aqueous solubility. Further optimisation and SAR-analysis resulted in soluble and potent carboxy chalcones [e.g., 3,5-dibromo- and 3,5-di(trifluoromethyl)-].
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