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Huang YJ, Yang MH, Lin LY, Liu J, Zang YP, Lin J, Chen WM. Exploring the Localization of Siderophore-Mediated Cargo Delivery in Gram-Negative Bacteria Using 3-Hydroxypyridin-4(1 H)-one-Fluorescein Probes. ACS Infect Dis 2024; 10:2303-2317. [PMID: 38725130 DOI: 10.1021/acsinfecdis.4c00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
The design of siderophore-antibiotic conjugates is a promising strategy to overcome drug resistance in negative bacteria. However, accumulating studies have shown that only those antibiotics acting on the cell wall or cell membrane multiply their antibacterial effects when coupled with siderophores, while antibiotics acting on targets in the cytoplasm of bacteria do not show an obvious enhancement of their antibacterial effects when coupled with siderophores. To explore the causes of this phenomenon, we synthesized several conjugate probes using 3-hydroxypyridin-4(1H)-ones as siderophores and replacing the antibiotic cargo with 5-carboxyfluorescein (5-FAM) or malachite green (MG) cargo. By monitoring changes in the fluorescence intensity of FAM conjugate 20 in bacteria, the translocation of the conjugate across the outer membranes of Gram-negative pathogens was confirmed. Further, the use of the fluorogen activating protein(FAP)/MG system revealed that 3-hydroxypyridin-4(1H)-one-MG conjugate 26 was ultimately distributed mainly in the periplasm rather than being translocated into the cytosol of Escherichia coli and Pseudomonas aeruginosa PAO1. Additional mechanistic studies suggested that the uptake of the conjugate involved the siderophore-dependent iron transport pathway and the 3-hydroxypyridin-4(1H)-ones siderophore receptor-dependent mechanism. Meanwhile, we demonstrated that the conjugation of 3-hydroxypyridin-4(1H)-ones to the fluorescein 5-FAM can reduce the possibility of the conjugates crossing the membrane layers of mammalian Vero cells by passive diffusion, and the advantages of the mono-3-hydroxypyridin-4(1H)-ones as a delivery vehicle in the design of conjugates compared to the tri-3-hydroxypyridin-4(1H)-ones. Overall, this work reveals the localization rules of 3-hydroxypyridin-4(1H)-ones as siderophores to deliver the cargo into Gram-negative bacteria. It provides a theoretical basis for the subsequent design of siderophore-antibiotic conjugates, especially based on 3-hydroxypyridin-4(1H)-ones as siderophores.
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Affiliation(s)
- Yong-Jun Huang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Ming-Han Yang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Ling-Yin Lin
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Jun Liu
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Yi-Peng Zang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Jing Lin
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
| | - Wei-Min Chen
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou 511400, China
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Huang YJ, Zang YP, Peng LJ, Yang MH, Lin J, Chen WM. Cajaninstilbene acid derivatives conjugated with siderophores of 3-hydroxypyridin-4(1H)-ones as novel antibacterial agents against Gram-negative bacteria based on the Trojan horse strategy. Eur J Med Chem 2024; 269:116339. [PMID: 38537513 DOI: 10.1016/j.ejmech.2024.116339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/14/2024] [Accepted: 03/15/2024] [Indexed: 04/07/2024]
Abstract
The low permeability of the outer membrane of Gram-negative bacteria is a serious obstacle to the development of new antibiotics against them. Conjugation of antibiotic with siderophore based on the "Trojan horse strategy" is a promising strategy to overcome the outer membrane obstacle. In this study, series of antibacterial agents were designed and synthesized by conjugating the 3-hydroxypyridin-4(1H)-one based siderophores with cajaninstilbene acid (CSA) derivative 4 which shows good activity against Gram-positive bacteria by targeting their cell membranes but is ineffective against Gram-negative bacteria. Compared to the inactive parent compound 4, the conjugates 45c or 45d exhibits significant improvement in activity against Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae and especially P. aeruginosa (minimum inhibitory concentrations, MICs = 7.8-31.25 μM). The antibacterial activity of the conjugates is attributed to the CSA derivative moiety, and the action mechanism is by disruption of bacterial cell membranes. Further studies on the uptake mechanisms showed that the bacterial siderophore-dependent iron transport system was involved in the uptake of the conjugates. In addition, the conjugates 45c and 45d showed a lower cytotoxic effects in vivo and in vitro and a positive therapeutic effect in the treatment of C. elegans infected by P. aeruginosa. Overall, our work describes a new class and a promising 3-hydroxypyridin-4(1H)-one-CSA derivative conjugates for further development as antibacterial agents against Gram-negative bacteria.
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Affiliation(s)
- Yong-Jun Huang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China
| | - Yi-Peng Zang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China
| | - Li-Jun Peng
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China
| | - Ming-Han Yang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China
| | - Jing Lin
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China.
| | - Wei-Min Chen
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, #855 Xingye Avenue, Guangzhou, 511400, China.
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Rayner B, Verderosa AD, Ferro V, Blaskovich MAT. Siderophore conjugates to combat antibiotic-resistant bacteria. RSC Med Chem 2023; 14:800-822. [PMID: 37252105 PMCID: PMC10211321 DOI: 10.1039/d2md00465h] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 02/21/2023] [Indexed: 10/31/2023] Open
Abstract
Antimicrobial resistance (AMR) is a global threat to society due to the increasing emergence of multi-drug resistant bacteria that are not susceptible to our last line of defence antibiotics. Exacerbating this issue is a severe gap in antibiotic development, with no new clinically relevant classes of antibiotics developed in the last two decades. The combination of the rapidly increasing emergence of resistance and scarcity of new antibiotics in the clinical pipeline means there is an urgent need for new efficacious treatment strategies. One promising solution, known as the 'Trojan horse' approach, hijacks the iron transport system of bacteria to deliver antibiotics directly into cells - effectively tricking bacteria into killing themselves. This transport system uses natively produced siderophores, which are small molecules with a high affinity for iron. By linking antibiotics to siderophores, to make siderophore antibiotic conjugates, the activity of existing antibiotics can potentially be reinvigorated. The success of this strategy was recently exemplified with the clinical release of cefiderocol, a cephalosporin-siderophore conjugate with potent antibacterial activity against carbapenem-resistant and multi-drug resistant Gram-negative bacilli. This review discusses the recent advancements in siderophore antibiotic conjugates and the challenges associated with the design of these compounds that need to be overcome to deliver more efficacious therapeutics. Potential strategies have also been suggested for new generations of siderophore-antibiotics with enhanced activity.
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Affiliation(s)
- Beth Rayner
- Centre for Superbug Solutions, Institute for Molecular Bioscience, University of Queensland Brisbane Queensland Australia
- Australian Infectious Disease Research Centre, The University of Queensland Brisbane Queensland Australia
| | - Anthony D Verderosa
- Centre for Superbug Solutions, Institute for Molecular Bioscience, University of Queensland Brisbane Queensland Australia
- Australian Infectious Disease Research Centre, The University of Queensland Brisbane Queensland Australia
| | - Vito Ferro
- Australian Infectious Disease Research Centre, The University of Queensland Brisbane Queensland Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, University of Queensland Brisbane Queensland Australia
- Australian Infectious Disease Research Centre, The University of Queensland Brisbane Queensland Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland Australia
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Du GF, Dong Y, Fan X, Yin A, Le YJ, Yang XY. Proteomic Investigation of the Antibacterial Mechanism of Cefiderocol against Escherichia coli. Microbiol Spectr 2022; 10:e0109322. [PMID: 35980225 PMCID: PMC9603102 DOI: 10.1128/spectrum.01093-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 08/01/2022] [Indexed: 12/30/2022] Open
Abstract
This study aimed to investigate the antibacterial mechanism of cefiderocol (CFDC) using data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays. Numerous differentially expressed proteins related to the production of NADH, reduced cofactor flavin adenine dinucleotide (FADH2), NADPH and reactive oxygen species (ROS), iron-sulfur cluster binding, and iron ion homeostasis were found to be upregulated by CFDC. Furthermore, parallel reaction monitoring analysis validated these results. Meanwhile, we confirmed that the levels of NADH, ROS, H2O2, and iron ions were induced by CFDC, and the sensitivity of Escherichia coli to CFDC was inhibited by the antioxidant vitamin C, N-acetyl-l-cysteine, and deferoxamine. Moreover, deferoxamine also suppressed the H2O2 stress induced by CFDC. In addition, knockout of the NADH-quinone oxidoreductase genes (nuoA, nuoC, nuoE, nuoF, nuoG, nuoJ, nuoL, nuoM) in the respiratory chain attenuated the sensitivity of E. coli to CFDC far beyond the effects of cefepime and ceftazidime; in particular, the E. coli BW25113 ΔnuoJ strain produced 60-fold increases in MIC to CFDC compared to that of the wild-type E. coli BW25113 strain. The present study revealed that CFDC exerts its antibacterial effects by inducing ROS stress by elevating the levels of NADH and iron ions in E. coli. IMPORTANCE CFDC was the first FDA-approved siderophore cephalosporin antibiotic in 2019 and is known for its Trojan horse tactics and broad antimicrobial activity against Gram-negative bacteria. However, its antibacterial mechanism is not fully understood, and whether it has an impact on in vivo iron ion homeostasis remains unknown. To comprehensively reveal the antibacterial mechanisms of CFDC, data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays were performed in this study. The findings will further facilitate our understanding of the antibacterial mechanism of CFDC and may provide a theoretical foundation for controlling CFDC resistance in the future.
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Affiliation(s)
- Gao-Fei Du
- Key Laboratory of Laboratory Diagnostics, Medical Technology School, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yu Dong
- Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xiaolu Fan
- NHC Key Laboratory of Technical Evaluation of Fertility Regulation for Non-human Primate (Fujian Maternity and Child Health Hospital), Fuzhou, China
| | - Ankang Yin
- Key Laboratory of Laboratory Diagnostics, Medical Technology School, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yao-Jin Le
- Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Zhuhai, Guangdong, China
| | - Xiao-Yan Yang
- Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Zhuhai, Guangdong, China
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Nazli A, He DL, Liao D, Khan MZI, Huang C, He Y. Strategies and progresses for enhancing targeted antibiotic delivery. Adv Drug Deliv Rev 2022; 189:114502. [PMID: 35998828 DOI: 10.1016/j.addr.2022.114502] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 08/10/2022] [Accepted: 08/16/2022] [Indexed: 01/24/2023]
Abstract
Antibiotic resistance is a global health issue and a potential risk for society. Antibiotics administered through conventional formulations are devoid of targeting effect and often spread to various undesired body sites, leading to sub-lethal concentrations at the site of action and thus resulting in emergence of resistance, as well as side effects. Moreover, we have a very slim antibiotic pipeline. Drug-delivery systems have been designed to control the rate, time, and site of drug release, and innovative approaches for antibiotic delivery provide a glint of hope for addressing these issues. This review elaborates different delivery strategies and approaches employed to overcome the limitations of conventional antibiotic therapy. These include antibiotic conjugates, prodrugs, and nanocarriers for local and targeted antibiotic release. In addition, a wide range of stimuli-responsive nanocarriers and biological carriers for targeted antibiotic delivery are discussed. The potential advantages and limitations of targeted antibiotic delivery strategies are described along with possible solutions to avoid these limitations. A number of antibiotics successfully delivered through these approaches with attained outcomes and potentials are reviewed.
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Affiliation(s)
- Adila Nazli
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, PR China
| | - David L He
- College of Chemistry, University of California, Berkeley, CA 94720, United States
| | - Dandan Liao
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, PR China
| | | | - Chao Huang
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, PR China.
| | - Yun He
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, PR China.
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Pandey A, Cao M, Boros E. Tracking Uptake and Metabolism of Xenometallomycins Using a Multi-Isotope Tagging Strategy. ACS Infect Dis 2022; 8:878-888. [PMID: 35319188 DOI: 10.1021/acsinfecdis.2c00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthetic and naturally occurring siderophores and their conjugates provide access to the bacterial cytoplasm via active membrane transport. Previously, we displaced iron with the radioactive isotope 67Ga to quantify and track in vitro and in vivo uptake and distribution of siderophore Trojan Horse antibiotic conjugates. Here, we introduce a multi-isotope tagging strategy to individually elucidate the fate of metal cargo and the ligand construct with radioisotopes 67Ga and 124I. We synthesized gallium(III) model complexes of a ciprofloxacin-functionalized linear desferrichrome (Ga-D6) and deferoxamine (Ga-D7) incorporating an iodo-tyrosine linker to enable radiolabeling using the metal-binding (67Ga) and the cargo-conjugation site (124I). Radiochemical experiments with Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa wt strains show that 67Ga-D6/D7 and Ga-D6-124I/D7-124I have comparable uptake, indicating intact complex import and siderophore-mediated uptake. In naive mice, 67Ga-D6/D7 and Ga-D6-124I/D7-124I demonstrate predominantly renal clearance; urine metabolite analysis indicates in vivo dissociation of Ga(III) is a likely mechanism of degradation for 67Ga-D6/D7 when compared to ligand radiolabeled compounds, Ga-D6-124I/D7-124I, which remain >60% intact in urine. Cumulatively, this work demonstrates that a multi-isotope tagging strategy effectively elucidates the in vitro uptake, pharmacokinetics, and in vivo stability of xenometallomycins with modular chemical structures.
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Affiliation(s)
- Apurva Pandey
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
| | - Minhua Cao
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
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Pandey A, Śmiłowicz D, Boros E. Galbofloxacin: a xenometal-antibiotic with potent in vitro and in vivo efficacy against S. aureus. Chem Sci 2021; 12:14546-14556. [PMID: 34881006 PMCID: PMC8580130 DOI: 10.1039/d1sc04283a] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/14/2021] [Indexed: 11/21/2022] Open
Abstract
Siderophore-antibiotic drug conjugates are considered potent tools to deliver and potentiate the antibacterial activity of antibiotics, but only few have seen preclinical and clinical success. Here, we introduce the gallium(iii) complex of a ciprofloxacin-functionalized linear desferrichrome, Galbofloxacin, with a cleavable serine linker as a potent therapeutic for S. aureus bacterial infections. We employed characterization using in vitro inhibitory assays, radiochemical, tracer-based uptake and pharmacokinetic assessment of our lead compound, culminating in in vivo efficacy studies in a soft tissue model of infection. Galbofloxacin exhibits a minimum inhibitory concentration of (MIC98) 93 nM in wt S. aureus, exceeding the potency of the parent antibiotic ciprofloxacin (0.9 μM). Galbofloxacin is a protease substrate that can release the antibiotic payload in the bacterial cytoplasm. Radiochemical experiments with wt bacterial strains reveal that 67Galbofloxacin is taken up efficiently using siderophore mediated, active uptake. Biodistribution of 67Galbofloxacin in a mouse model of intramuscular S. aureus infection revealed renal clearance and enhanced uptake in infected muscle when compared to 67Ga-citrate, which showed no selectivity. A subsequent in vivo drug therapy study reveals efficient reduction in S. aureus infection burden and sustained survival with Galbofloxacin for 7 days. Ciprofloxacin had no treatment efficacy at identical molecular dose (9.3 μmol kg−1) and resulted in death of all study animals in <24 hours. Taken together, the favorable bacterial growth inhibitory, pharmacokinetic and in vivo efficacy properties qualify Galbofloxacin as the first rationally designed Ga-coordination complex for the management of S. aureus bacterial infections. Galbofloxacin, a novel theranostic xenosiderophore antibiotic, exhibits unparalleled potency in combating S. aureus infections in vivo.![]()
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Affiliation(s)
- Apurva Pandey
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook New York 11790 USA
| | - Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook New York 11790 USA
| | - Eszter Boros
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook New York 11790 USA
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Pandey A, Boros E. Coordination Complexes to Combat Bacterial Infections: Recent Developments, Current Directions and Future Opportunities. Chemistry 2021; 27:7340-7350. [PMID: 33368662 DOI: 10.1002/chem.202004822] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/22/2020] [Indexed: 12/29/2022]
Abstract
Drug discovery aimed at the efficient eradication of life-threatening bacterial infections, especially in light of the emergence of multi-drug resistance of pathogenic bacteria, has remained a challenge for medicinal chemists over the past several decades. As nutrient acquisition and metabolism at the host-pathogen interface become better elucidated, new drug targets continue to emerge. Metal homeostasis is among these processes, and thus provides opportunities for medicinal inorganic chemists to alter or disrupt these processes selectively to impart bacteriostatic or bacteriotoxic effects. In this minireview, we showcase some of the recent work from the field of metal-based antibacterial agents and highlight divergent strategies and mechanisms of action.
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Affiliation(s)
- Apurva Pandey
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, USA
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, USA
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Terra L, Ratcliffe N, Castro HC, Vicente ACP, Dyson P. Biotechnological Potential of Streptomyces Siderophores as New Antibiotics. Curr Med Chem 2021; 28:1407-1421. [PMID: 32389112 DOI: 10.2174/0929867327666200510235512] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 02/29/2020] [Accepted: 03/23/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Siderophores are small-molecule iron-chelators produced by microorganisms and plants growing mostly under low iron conditions. Siderophores allow iron capture and transport through cell membranes into the cytoplasm, where iron is released for use in biological processes. These bacterial iron uptake systems can be used for antibiotic conjugation or as targets for killing pathogenic bacteria. Siderophores have been explored recently because of their potential applications in environmental and therapeutic research. They are present in Streptomyces, Grampositive bacteria that are an important source for discovering new siderophores. OBJECTIVE This review summarizes siderophore molecules produced by the genus Streptomyces emphasizing their potential as biotechnological producers and also illustrating genomic tools for discovering siderophores useful for treating bacterial infections. METHODS The literature search was performed using PUBMED and MEDLINE databases with keywords siderophore, secondary metabolites, Trojan horse strategy, sideromycin and Streptomyces. The literature research focused on bibliographic databases including all siderophores identified in the genus Streptomyces. In addition, reference genomes of Streptomyces from GenBank were used to identify siderophore biosynthetic gene clusters by using the antiSMASH platform. RESULTS This review has highlighted some of the many siderophore molecules produced by Streptomyces, illustrating the diversity of their chemical structures and a wide spectrum of bioactivities against pathogenic bacteria. Furthermore, the possibility of using siderophores conjugated with antibiotics could be an alternative to overcome bacterial resistance to drugs and could improve their therapeutic efficacy. CONCLUSION This review confirms the importance of Streptomyces as a rich source of siderophores, and underlines their potential as antibacterial agents.
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Affiliation(s)
- Luciana Terra
- Programa de Pos-Graduacao em Ciencias e Biotecnologia, Instituto de Biologia, UFF, Brazil
| | - Norman Ratcliffe
- Programa de Pos-Graduacao em Ciencias e Biotecnologia, Instituto de Biologia, UFF, Brazil
| | - Helena Carla Castro
- Programa de Pos-Graduacao em Ciencias e Biotecnologia, Instituto de Biologia, UFF, Brazil
| | | | - Paul Dyson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea SA2 8PP, United Kingdom
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Miller MJ, Liu R. Design and Syntheses of New Antibiotics Inspired by Nature's Quest for Iron in an Oxidative Climate. Acc Chem Res 2021; 54:1646-1661. [PMID: 33684288 DOI: 10.1021/acs.accounts.1c00004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This Account describes fundamental chemistry that promoted the discovery of new antibiotics. Specifically, the NH acidity of simple hydroxamic acid derivatives facilitated the syntheses of novel β-lactams (oxamazins and monobactams), siderophore mimics that limit bacterial iron uptake and bacterially targeted sideromycins (siderophore-antibiotic conjugates). The development of resistance to our current limited set of antibiotic scaffolds has created a dire medical situation. As recently stated, "if you weren't taking antibiotic resistance seriously before, now would be a good time to start." A project commissioned by the British government (https://amr-review.org/) has released estimates of the near-future global toll of antibiotic resistance that are jaw-dropping in their seriousness and scale: 10 million deaths per year and at least $100 trillion in sacrificed gross national product. The 2020 COVID pandemic confirmed that infectious disease problems are no longer localized but worldwide. Many classical antibiotics, especially β-lactams, previously provided economical cures, but the evolution of antibiotic destructive enzymes (i.e., β-lactamases), efflux pumps, and bacterial cell wall permeability barriers has made many types of bacteria, especially Gram-negative strains, resistant. Still, and in contrast to other therapies, the public expectation is that any new antibiotic must be inexpensive. This creates market limitations that have caused most major pharmaceutical companies to abandon antibiotic research. Much needs to be done to address this significant problem.The critical need for bacteria to sequester essential iron provides an Achilles' heel for new antibiotic development. Although ferric iron is extremely insoluble, bacteria need micromolar intracellular concentrations for growth and virulence. To this end, they biosynthesize siderophores (Gr. iron bearer) and excrete them into their environment, where they bind iron with high affinity. The iron complexes are recognized by specific outer-membrane transporters, and once actively internalized, the iron is released for essential processes. To conserve biosynthetic energy, some bacteria recognize and utilize siderophores made by competing strains. As a counter-revolution in the never-ending fight for survival, bacteria have also evolved sideromycins, which are siderophores conjugated to warheads that are lethal to rogue bacteria. While none are now used therapeutically, natural sideromycins called albomycins have been used clinically, and others have been shown to be well tolerated and active in animal infection models. Herein we describe practical methods to synthesize new antibiotics and artificial sideromycins with the generalized structure shown above (siderophore-linker drug). Utilizing the molecular-recognition-based siderophore/sideromycin bacterial assimilation processes, it is possible to design both broad spectrum and exquisitely narrow spectrum (targeted) sideromycins and even repurpose older or more classical antibiotics. Relevant microbiological assays, in vivo animal infection studies, and the recent FDA approval of cefiderocol demonstrate their effectiveness.
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Affiliation(s)
- Marvin J. Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Rui Liu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Fan D, Fang Q. Siderophores for medical applications: Imaging, sensors, and therapeutics. Int J Pharm 2021; 597:120306. [PMID: 33540031 DOI: 10.1016/j.ijpharm.2021.120306] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 01/07/2023]
Abstract
Siderophores are low-molecular-weight chelators produced by microorganisms to scavenge iron from the environment and deliver it to cells via specific receptors. Tremendous researches on the molecular basis of siderophore regulation, synthesis, secretion, and uptake have inspired their diverse applications in the medical field. Replacing iron with radionuclides in siderophores, such as the most prominent Ga-68 for positron emission tomography (PET), carves out ways for targeted imaging of infectious diseases and cancers. Additionally, the high affinity of siderophores for metal ions or microorganisms makes them a potent detecting moiety in sensors that can be used for diagnosis. As for therapeutics, the notable Trojan horse-inspired siderophore-antibiotic conjugates demonstrate enhanced toxicity against multi-drug resistant (MDR) pathogens. Besides, siderophores can tackle iron overload diseases and, when combined with moieties such as hydrogels and nanoparticles, a wide spectrum of iron-induced diseases and even cancers. In this review, we briefly outline the related mechanisms, before summarizing the siderophore-based applications in imaging, sensors, and therapeutics.
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Affiliation(s)
- Di Fan
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Ambient Particles Health Effects and Prevention Techniques, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, PR China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, PR China
| | - Qiaojun Fang
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Ambient Particles Health Effects and Prevention Techniques, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, PR China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, PR China; Sino-Danish Center for Education and Research, Beijing 101408, PR China.
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Chemistry and Biomedical Applications of Fungal Siderophores. Fungal Biol 2021. [DOI: 10.1007/978-3-030-53077-8_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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13
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Boyce JH, Dang B, Ary B, Edmondson Q, Craik CS, DeGrado WF, Seiple IB. Platform to Discover Protease-Activated Antibiotics and Application to Siderophore-Antibiotic Conjugates. J Am Chem Soc 2020; 142:21310-21321. [PMID: 33301681 DOI: 10.1021/jacs.0c06987] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Here we present a platform for discovery of protease-activated prodrugs and apply it to antibiotics that target Gram-negative bacteria. Because cleavable linkers for prodrugs had not been developed for bacterial proteases, we used substrate phage to discover substrates for proteases found in the bacterial periplasm. Rather than focusing on a single protease, we used a periplasmic extract of E. coli to find sequences with the greatest susceptibility to the endogenous mixture of periplasmic proteases. Using a fluorescence assay, candidate sequences were evaluated to identify substrates that release native amine-containing payloads. We next designed conjugates consisting of (1) an N-terminal siderophore to facilitate uptake, (2) a protease-cleavable linker, and (3) an amine-containing antibiotic. Using this strategy, we converted daptomycin-which by itself is active only against Gram-positive bacteria-into an antibiotic capable of targeting Gram-negative Acinetobacter species. We similarly demonstrated siderophore-facilitated delivery of oxazolidinone and macrolide antibiotics into a number of Gram-negative species. These results illustrate this platform's utility for development of protease-activated prodrugs, including Trojan horse antibiotics.
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Affiliation(s)
- Jonathan H Boyce
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
| | - Bobo Dang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China.,Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China.,Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Beatrice Ary
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - Quinn Edmondson
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
| | - Ian B Seiple
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
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14
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Hydroxamate siderophores: Natural occurrence, chemical synthesis, iron binding affinity and use as Trojan horses against pathogens. Eur J Med Chem 2020; 208:112791. [DOI: 10.1016/j.ejmech.2020.112791] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 12/11/2022]
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15
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Skwarecki AS, Nowak MG, Milewska MJ. Synthetic strategies in construction of organic low molecular-weight carrier-drug conjugates. Bioorg Chem 2020; 104:104311. [PMID: 33142423 DOI: 10.1016/j.bioorg.2020.104311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/31/2020] [Accepted: 09/20/2020] [Indexed: 12/30/2022]
Abstract
Inefficient transportation of polar metabolic inhibitors through cell membranes of eukaryotic and prokaryotic cells precludes their direct use as drug candidates in chemotherapy. One of the possible solutions to this problem is application of the 'Trojan horse' strategy, i.e. conjugation of an active substance with a molecular carrier of organic or inorganic nature, facilitating membrane penetration. In this work, the synthetic strategies used in rational design and preparation of conjugates of bioactive agents with three types of organic low molecular-weight carriers have been reviewed. These include iron-chelating agents, siderophores and cell-penetrating peptides. Moreover, a less known but very promising "molecular umbrella" conjugation strategy has been presented. Special attention has been paid on appropriate linking strategies, especially these allowing intracellular drug release after internalisation of a conjugate.
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Affiliation(s)
- Andrzej S Skwarecki
- Department of Pharmaceutical Technology and Biochemistry, Gdańsk University of Technology, 11/12 Gabriela Narutowicza Street, 80-233 Gdańsk, Poland.
| | - Michał G Nowak
- Department of Organic Chemistry, Gdańsk University of Technology, 11/12 Gabriela Narutowicza Street, 80-233 Gdańsk, Poland
| | - Maria J Milewska
- Department of Organic Chemistry, Gdańsk University of Technology, 11/12 Gabriela Narutowicza Street, 80-233 Gdańsk, Poland
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16
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Pandey A, Savino C, Ahn SH, Yang Z, Van Lanen SG, Boros E. Theranostic Gallium Siderophore Ciprofloxacin Conjugate with Broad Spectrum Antibiotic Potency. J Med Chem 2019; 62:9947-9960. [PMID: 31580658 DOI: 10.1021/acs.jmedchem.9b01388] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pathogenic bacteria scavenge ferric iron from the host for survival and proliferation using small-molecular chelators, siderophores. Here, we introduce and assess the gallium(III) complex of ciprofloxacin-functionalized desferrichrome (D2) as a potential therapeutic for bacterial infection using an in vitro assay and radiochemical, tracer-based approach. Ga-D2 exhibits a minimum inhibitory concentration of 0.23 μM in Escherichia coli, in line with the parent fluoroquinolone antibiotic. Competitive and mutant strain assays show that Ga-D2 relies on FhuA-mediated transport for internalization. Ga-D2 is potent against Pseudomonas aeruginosa (3.8 μM), Staphylococcus aureus (0.94 μM), and Klebsiella pneumoniae (12.5 μM), while Fe-D2 is inactive in these strains. Radiochemical experiments with E. coli reveal that 67Ga-D2 is taken up more efficiently than 67Ga-citrate. In naive mice, 67Ga-D2 clears renally and is excreted 13% intact in the urine. These pharmacokinetic and bacterial growth inhibitory properties qualify Ga-D2 for future investigations as a diagnosis and treatment tool for infection.
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Affiliation(s)
- Apurva Pandey
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Chloé Savino
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Shin Hye Ahn
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
| | - Zhaoyong Yang
- Institute of Medicinal Biotechnology , Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050 , People's Republic of China
| | - Steven G Van Lanen
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Kentucky , Lexington 40536 , Kentucky , United States
| | - Eszter Boros
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook 11790 , New York , United States
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17
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Negash KH, Norris JKS, Hodgkinson JT. Siderophore-Antibiotic Conjugate Design: New Drugs for Bad Bugs? Molecules 2019; 24:molecules24183314. [PMID: 31514464 PMCID: PMC6767078 DOI: 10.3390/molecules24183314] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 12/18/2022] Open
Abstract
Antibiotic resistance is a global health concern and a current threat to modern medicine and society. New strategies for antibiotic drug design and delivery offer a glimmer of hope in a currently limited pipeline of new antibiotics. One strategy involves conjugating iron-chelating microbial siderophores to an antibiotic or antimicrobial agent to enhance uptake and antibacterial potency. Cefiderocol (S-649266) is a promising cephalosporin–catechol conjugate currently in phase III clinical trials that utilizes iron-mediated active transport and demonstrates enhanced potency against multi-drug resistant (MDR) Gram-negative pathogens. Such molecules demonstrate that siderophore–antibiotic conjugates could be important future medicines to add to our antibiotic arsenal. This review is written in the context of the chemical design of siderophore–antibiotic conjugates focusing on the differing siderophore, linker, and antibiotic components that make up conjugates. We selected chemically distinct siderophore–antibiotic conjugates as exemplary conjugates, rather than multiple analogues, to highlight findings to date. The review should offer a general guide to the uninitiated in the molecular design of siderophore–antibiotic conjugates.
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Affiliation(s)
- Kokob H Negash
- Leicester Institute of Structural and Chemical Biology, School of Chemistry, University of Leicester, George Porter Building, University Road, Leicester LE1 7RH, UK
| | - James K S Norris
- Leicester Institute of Structural and Chemical Biology, School of Chemistry, University of Leicester, George Porter Building, University Road, Leicester LE1 7RH, UK
| | - James T Hodgkinson
- Leicester Institute of Structural and Chemical Biology, School of Chemistry, University of Leicester, George Porter Building, University Road, Leicester LE1 7RH, UK.
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18
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Kong H, Cheng W, Wei H, Yuan Y, Yang Z, Zhang X. An overview of recent progress in siderophore-antibiotic conjugates. Eur J Med Chem 2019; 182:111615. [PMID: 31434038 DOI: 10.1016/j.ejmech.2019.111615] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/01/2019] [Accepted: 08/09/2019] [Indexed: 01/09/2023]
Abstract
Multi-drug resistant infections caused by Gram-negative bacteria have become one of the most important reasons for the failure of clinical anti-infective treatment. Siderophore-antibiotic conjugates, which were designed based on a "Trojan horse" strategy wherein features enabled active uptake to bypass the Gram-negative cell wall, have been expected to be a weapon for anti-infective treatment in the clinic. Herein, we review antibiotic drug design strategies based on mimics of nature siderophores reported in recent years, we also focus our attention on the relationship between the type of linker and the corresponding antibacterial activity.
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Affiliation(s)
- Huimin Kong
- Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Weiyan Cheng
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Han Wei
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Yongliang Yuan
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Zhiheng Yang
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
| | - Xiaojian Zhang
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China; Henan Key Laboratory of Precision Clinical Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
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19
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Cheng AV, Wuest WM. Signed, Sealed, Delivered: Conjugate and Prodrug Strategies as Targeted Delivery Vectors for Antibiotics. ACS Infect Dis 2019; 5:816-828. [PMID: 30969100 PMCID: PMC6570538 DOI: 10.1021/acsinfecdis.9b00019] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Innate and developed resistance mechanisms of bacteria to antibiotics are obstacles in the design of novel drugs. However, antibacterial prodrugs and conjugates have shown promise in circumventing resistance and tolerance mechanisms via directed delivery of antibiotics to the site of infection or to specific species or strains of bacteria. The selective targeting and increased permeability and accumulation of these prodrugs not only improves efficacy over unmodified drugs but also reduces off-target effects, toxicity, and development of resistance. Herein, we discuss some of these methods, including sideromycins, antibody-directed prodrugs, cell penetrating peptide conjugates, and codrugs.
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Affiliation(s)
- Ana V. Cheng
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - William M. Wuest
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
- Emory Antibiotic Resistance Center, Emory School of Medicine, 201 Dowman Drive, Atlanta, Georgia 30322, United States
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20
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Exploration of tautomerizations of succinimide and maleimide assisted by ammonia and methanol: a theoretical perspective. Theor Chem Acc 2019. [DOI: 10.1007/s00214-019-2446-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Jiang D. 4-Quinolone Derivatives and Their Activities Against Gram-negative Pathogens. J Heterocycl Chem 2018. [DOI: 10.1002/jhet.3244] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Dan Jiang
- School of Nuclear Technology and Chemistry & Biology; Hubei University of Science and Technology; Xianning Hubei China
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22
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Evaluation of a reducible disulfide linker for siderophore-mediated delivery of antibiotics. J Biol Inorg Chem 2018; 23:1025-1036. [PMID: 29968176 DOI: 10.1007/s00775-018-1588-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/22/2018] [Indexed: 12/12/2022]
Abstract
Bacterial iron uptake machinery can be hijacked for the targeted delivery of antibiotics into pathogens by attaching antibiotics to siderophores, iron chelators that are employed by bacteria to obtain this essential nutrient. We synthesized and evaluated Ent-SS-Cipro, a siderophore-antibiotic conjugate comprised of the triscatecholate siderophore enterobactin and the fluoroquinolone antibiotic ciprofloxacin that contains a self-immolative disulfide linker. This linker is designed to be cleaved after uptake into the reducing environment of the bacterial cytoplasm. We show that the disulfide bond of Ent-SS-Cipro is cleaved by reducing agents, including the cellular reductant glutathione, which results in release of the unmodified fluoroquinolone antibiotic. Antibacterial activity assays against a panel of Escherichia coli show that Ent-SS-Cipro exhibits activity against some, but not all, E. coli. This work informs the design of siderophore-antibiotic conjugates, particularly those carrying antibiotics with cytoplasmic targets that require release after uptake into bacterial cells, and indicates that disulfide linkers may not be generally applicable for conjugation strategies of antibiotics.
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23
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Fedorowicz J, Sączewski J. Modifications of quinolones and fluoroquinolones: hybrid compounds and dual-action molecules. MONATSHEFTE FUR CHEMIE 2018; 149:1199-1245. [PMID: 29983452 PMCID: PMC6006264 DOI: 10.1007/s00706-018-2215-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/01/2018] [Indexed: 01/27/2023]
Abstract
ABSTRACT This review is aimed to provide extensive survey of quinolones and fluoroquinolones for a variety of applications ranging from metal complexes and nanoparticle development to hybrid conjugates with therapeutic uses. The review covers the literature from the past 10 years with emphasis placed on new applications and mechanisms of pharmacological action of quinolone derivatives. The following are considered: metal complexes, nanoparticles and nanodrugs, polymers, proteins and peptides, NO donors and analogs, anionic compounds, siderophores, phosphonates, and prodrugs with enhanced lipophilicity, phototherapeutics, fluorescent compounds, triazoles, hybrid drugs, bis-quinolones, and other modifications. This review provides a comprehensive resource, summarizing a broad range of important quinolone applications with great utility as a resource concerning both chemical modifications and also novel hybrid bifunctional therapeutic agents. GRAPHICAL ABSTRACT
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Affiliation(s)
- Joanna Fedorowicz
- Department of Organic Chemistry, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
| | - Jarosław Sączewski
- Department of Organic Chemistry, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
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24
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Neumann W, Sassone-Corsi M, Raffatellu M, Nolan EM. Esterase-Catalyzed Siderophore Hydrolysis Activates an Enterobactin-Ciprofloxacin Conjugate and Confers Targeted Antibacterial Activity. J Am Chem Soc 2018; 140:5193-5201. [PMID: 29578687 DOI: 10.1021/jacs.8b01042] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enteric Gram-negative bacteria, including Escherichia coli, biosynthesize and deploy the triscatecholate siderophore enterobactin (Ent) in the vertebrate host to acquire iron, an essential nutrient. We report that Ent-Cipro, a synthetic siderophore-antibiotic conjugate based on the native Ent platform that harbors an alkyl linker at one of the catechols with a ciprofloxacin cargo attached, affords targeted antibacterial activity against E. coli strains that express the pathogen-associated iroA gene cluster. Attachment of the siderophore to ciprofloxacin, a DNA gyrase inhibitor and broad-spectrum antibiotic that is used to treat infections caused by E. coli, generates an inactive prodrug and guides the antibiotic into the cytoplasm of bacteria that express the Ent uptake machinery (FepABCDG). Intracellular hydrolysis of the siderophore restores the activity of the antibiotic. Remarkably, Fes, the cytoplasmic Ent hydrolase expressed by all E. coli, does not contribute to Ent-Cipro activation. Instead, this processing step requires IroD, a cytoplasmic hydrolase that is expressed only by E. coli that harbor the iroA gene cluster and are predominantly pathogenic. In the uropathogenic E. coli UTI89 and CFT073, Ent-Cipro provides antibacterial activity comparable to unmodified ciprofloxacin. This work highlights the potential of leveraging and targeting pathogen-associated microbial enzymes in narrow-spectrum antibacterial approaches. Moreover, because E. coli include harmless gut commensals as well as resident microbes that can contribute to disease, Ent-Cipro may provide a valuable chemical tool for strain-selective modulation of the microbiota.
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Affiliation(s)
- Wilma Neumann
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Martina Sassone-Corsi
- Department of Microbiology and Molecular Genetics , University of California , Irvine , California 92697 , United States
| | - Manuela Raffatellu
- Department of Microbiology and Molecular Genetics , University of California , Irvine , California 92697 , United States
| | - Elizabeth M Nolan
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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25
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Laurent Q, Batchelor LK, Dyson PJ. Applying a Trojan Horse Strategy to Ruthenium Complexes in the Pursuit of Novel Antibacterial Agents. Organometallics 2018. [DOI: 10.1021/acs.organomet.7b00885] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Quentin Laurent
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lucinda K. Batchelor
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Paul J. Dyson
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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26
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Zhang GF, Liu X, Zhang S, Pan B, Liu ML. Ciprofloxacin derivatives and their antibacterial activities. Eur J Med Chem 2018; 146:599-612. [PMID: 29407984 DOI: 10.1016/j.ejmech.2018.01.078] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/13/2018] [Accepted: 01/24/2018] [Indexed: 02/06/2023]
Abstract
Bacterial infections represent a significant health threat globally, and are responsible for the majority of hospital-acquired infections, leading to extensive mortality and burden on global healthcare systems. The second generation fluoroquinolone ciprofloxacin which exhibits excellent antimicrobial activity and pharmacokinetic properties as well as few side effects is introduced into clinical practice for the treatment of various bacterial infections for around 3 decades. The emergency and widely spread of drug-resistant pathogens making ciprofloxacin more and more ineffective, so it's imperative to develop novel antibacterials. Numerous of ciprofloxacin derivatives have been synthesized for seeking for new antibacterials, and some of them exhibited promising potency. This review aims to summarize the recent advances made towards the discovery of ciprofloxacin derivatives as antibacterial agents and the structure-activity relationship of these derivatives was also discussed.
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Affiliation(s)
- Gui-Fu Zhang
- School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Hubei, PR China
| | - Xiaofeng Liu
- Zhejiang Xianju Junye Pharmaceutical Co., Ltd, Xianju, Zhejiang, 317300, PR China; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, Hubei 430081, PR China.
| | - Shu Zhang
- Pony Testing International Group (Wuhan), Hubei, PR China.
| | - Baofeng Pan
- Zhejiang Xianju Junye Pharmaceutical Co., Ltd, Xianju, Zhejiang, 317300, PR China
| | - Ming-Liang Liu
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, PR China.
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27
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Codd R, Richardson-Sanchez T, Telfer TJ, Gotsbacher MP. Advances in the Chemical Biology of Desferrioxamine B. ACS Chem Biol 2018; 13:11-25. [PMID: 29182270 DOI: 10.1021/acschembio.7b00851] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Desferrioxamine B (DFOB) was discovered in the late 1950s as a hydroxamic acid metabolite of the soil bacterium Streptomyces pilosus. The exquisite affinity of DFOB for Fe(III) identified its potential for removing excess iron from patients with transfusion-dependent hemoglobin disorders. Many studies have used semisynthetic chemistry to produce DFOB adducts with new properties and broad-ranging functions. More recent approaches in chemical biology have revealed some nuances of DFOB biosynthesis and discovered new DFOB-derived drugs and radiometal imaging agents. The current and potential applications of DFOB continue to inspire a rich body of chemical biology research focused on this bacterial metabolite.
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Affiliation(s)
- Rachel Codd
- School of Medical Sciences
(Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Tomas Richardson-Sanchez
- School of Medical Sciences
(Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Thomas J. Telfer
- School of Medical Sciences
(Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Michael P. Gotsbacher
- School of Medical Sciences
(Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
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28
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Merk D, Schubert-Zsilavecz M. The Linker Approach. METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2017. [DOI: 10.1002/9783527674381.ch8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Daniel Merk
- Goethe University Frankfurt; Institute of Pharmaceutical Chemistry; Max-von-Laue-Str. 9 60438 Frankfurt Germany
| | - Manfred Schubert-Zsilavecz
- Goethe University Frankfurt; Institute of Pharmaceutical Chemistry; Max-von-Laue-Str. 9 60438 Frankfurt Germany
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29
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4-Quinolone hybrids and their antibacterial activities. Eur J Med Chem 2017; 141:335-345. [DOI: 10.1016/j.ejmech.2017.09.050] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 09/11/2017] [Accepted: 09/24/2017] [Indexed: 01/28/2023]
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30
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Zhang GF, Zhang S, Pan B, Liu X, Feng LS. 4-Quinolone derivatives and their activities against Gram positive pathogens. Eur J Med Chem 2017; 143:710-723. [PMID: 29220792 DOI: 10.1016/j.ejmech.2017.11.082] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/24/2017] [Accepted: 11/27/2017] [Indexed: 11/17/2022]
Abstract
Gram-positive bacteria are responsible for a broad range of infectious diseases, and the emergency and wide spread of drug-resistant Gram-positive pathogens including MRSA and MRSE has caused great concern throughout the world. 4-Quinolones which are exemplified by fluoroquinolones are mainstays of chemotherapy against various bacterial infections including Gram-positive pathogen infections, and their value and role in the treatment of bacterial infections continues to expand. However, the resistance of Gram-positive organisms to 4-quinolones develops rapidly and spreads widely, making them more and more ineffective. To overcome the resistance and reduce the toxicity, numerous of 4-quinolone derivatives were synthesized and screened for their in vitro and in vivo activities against Gram-positive pathogens, and some of them exhibited excellent potency. This review aims to outlines the recent advances made towards the discovery of 4-quinolone-based derivatives as anti-Gram-positive pathogens agents and the critical aspects of design as well as the structure-activity relationship of these derivatives. The enriched SAR paves the way to the further rational development of 4-quinolones with a unique mechanism of action different from that of the currently used drugs to overcome the resistance, well-tolerated and low toxic profiles.
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Affiliation(s)
- Gui-Fu Zhang
- School of Nuclear Technology and Chemistry & Life Science, Hubei University of Science and Technology, Hubei, PR China
| | - Shu Zhang
- Pony Testing International Group (Wuhan), Hubei, PR China
| | - Baofeng Pan
- Zhejiang Xianju Junye Pharmaceutical Co., Ltd, Xianju, Zhejiang, 317300, PR China
| | - Xiaofeng Liu
- Zhejiang Xianju Junye Pharmaceutical Co., Ltd, Xianju, Zhejiang, 317300, PR China; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430081, PR China.
| | - Lian-Shun Feng
- Synthetic and Functional Biomolecules Center, Peking University, Beijing, PR China.
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31
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Klahn P, Brönstrup M. Bifunctional antimicrobial conjugates and hybrid antimicrobials. Nat Prod Rep 2017; 34:832-885. [PMID: 28530279 DOI: 10.1039/c7np00006e] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: up to the end of 2016Novel antimicrobial drugs are continuously needed to counteract bacterial resistance development. An innovative molecular design strategy for novel antibiotic drugs is based on the hybridization of an antibiotic with a second functional entity. Such conjugates can be grouped into two major categories. In the first category (antimicrobial hybrids), both functional elements of the hybrid exert antimicrobial activity. Due to the dual targeting, resistance development can be significantly impaired, the pharmacokinetic properties can be superior compared to combination therapies with the single antibiotics, and the antibacterial potency is often enhanced in a synergistic manner. In the second category (antimicrobial conjugates), one functional moiety controls the accumulation of the other part of the conjugate, e.g. by mediating an active transport into the bacterial cell or blocking the efflux. This approach is mostly applied to translocate compounds across the cell envelope of Gram-negative bacteria through membrane-embedded transporters (e.g. siderophore transporters) that provide nutrition and signalling compounds to the cell. Such 'Trojan Horse' approaches can expand the antibacterial activity of compounds against Gram-negative pathogens, or offer new options for natural products that could not be developed as standalone antibiotics, e.g. due to their toxicity.
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Affiliation(s)
- P Klahn
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. and Institute for Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
| | - M Brönstrup
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany.
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Skwarecki AS, Milewski S, Schielmann M, Milewska MJ. Antimicrobial molecular nanocarrier–drug conjugates. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2016; 12:2215-2240. [DOI: 10.1016/j.nano.2016.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/17/2016] [Accepted: 06/06/2016] [Indexed: 01/07/2023]
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Zheng T, Nolan EM. Evaluation of (acyloxy)alkyl ester linkers for antibiotic release from siderophore–antibiotic conjugates. Bioorg Med Chem Lett 2015; 25:4987-4991. [DOI: 10.1016/j.bmcl.2015.02.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Revised: 02/11/2015] [Accepted: 02/16/2015] [Indexed: 02/02/2023]
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Kim HS, Song WY, Kim HJ. Development of a novel fluorescence probe capable of assessing the cytoplasmic entry of siderophore-based conjugates. Org Biomol Chem 2015; 13:73-6. [DOI: 10.1039/c4ob01810a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel fluorescence probe capable of assessing the cytoplasmic entry of siderophore-based conjugates was synthesized and evaluated by photochemical characterization and cell-based assays.
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Affiliation(s)
- Hyeon Seok Kim
- Department of Chemistry
- College of Science
- Korea University
- Seoul 136-701
- Republic of Korea
| | - Woon Young Song
- Department of Chemistry
- College of Science
- Korea University
- Seoul 136-701
- Republic of Korea
| | - Hak Joong Kim
- Department of Chemistry
- College of Science
- Korea University
- Seoul 136-701
- Republic of Korea
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Górska A, Sloderbach A, Marszałł MP. Siderophore–drug complexes: potential medicinal applications of the ‘Trojan horse’ strategy. Trends Pharmacol Sci 2014; 35:442-9. [DOI: 10.1016/j.tips.2014.06.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 12/11/2022]
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Zheng T, Nolan EM. Enterobactin-mediated delivery of β-lactam antibiotics enhances antibacterial activity against pathogenic Escherichia coli. J Am Chem Soc 2014; 136:9677-91. [PMID: 24927110 PMCID: PMC4353011 DOI: 10.1021/ja503911p] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Indexed: 02/08/2023]
Abstract
The design, synthesis, and characterization of enterobactin-antibiotic conjugates, hereafter Ent-Amp/Amx, where the β-lactam antibiotics ampicillin (Amp) and amoxicillin (Amx) are linked to a monofunctionalized enterobactin scaffold via a stable poly(ethylene glycol) linker are reported. Under conditions of iron limitation, these siderophore-modified antibiotics provide enhanced antibacterial activity against Escherichia coli strains, including uropathogenic E. coli CFT073 and UTI89, enterohemorrhagic E. coli O157:H7, and enterotoxigenic E. coli O78:H11, compared to the parent β-lactams. Studies with E. coli K-12 derivatives defective in ferric enterobactin transport reveal that the enhanced antibacterial activity observed for this strain requires the outer membrane ferric enterobactin transporter FepA. A remarkable 1000-fold decrease in minimum inhibitory concentration (MIC) value is observed for uropathogenic E. coli CFT073 relative to Amp/Amx, and time-kill kinetic studies demonstrate that Ent-Amp/Amx kill this strain more rapidly at 10-fold lower concentrations than the parent antibiotics. Moreover, Ent-Amp and Ent-Amx selectively kill E. coli CFT073 co-cultured with other bacterial species such as Staphylococcus aureus, and Ent-Amp exhibits low cytotoxicity against human T84 intestinal cells in both the apo and iron-bound forms. These studies demonstrate that the native enterobactin platform provides a means to effectively deliver antibacterial cargo across the outer membrane permeability barrier of Gram-negative pathogens utilizing enterobactin for iron acquisition.
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Affiliation(s)
- Tengfei Zheng
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Elizabeth M. Nolan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Milner SJ, Snelling AM, Kerr KG, Abd-El-Aziz A, Thomas GH, Hubbard RE, Routledge A, Duhme-Klair AK. Probing linker design in citric acid-ciprofloxacin conjugates. Bioorg Med Chem 2014; 22:4499-505. [PMID: 24794750 DOI: 10.1016/j.bmc.2014.04.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/01/2014] [Accepted: 04/06/2014] [Indexed: 11/29/2022]
Abstract
A series of structurally related citric acid-ciprofloxacin conjugates was synthesised to investigate the influence of the linker between citric acid and ciprofloxacin on antibacterial activities. Minimum inhibitory concentrations (MICs) were determined against a panel of reference strains and clinical isolates of bacteria associated with infection in humans and correlated with the DNA gyrase inhibitory activity. The observed trend was rationalised by computational modelling.
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Affiliation(s)
- Stephen J Milner
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Anna M Snelling
- Bradford Infection Group, University of Bradford, Bradford BD7 1DP, UK
| | - Kevin G Kerr
- Department of Microbiology, Fewston Wing, Harrogate District Hospital, Harrogate HG2 7SX, UK; Department of Biology (Area 10), University of York, Heslington, York YO10 5DD, UK; Hull York Medical School, Heslington, York YO10 5DD, UK
| | - Ahmad Abd-El-Aziz
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK; Department of Biology (Area 10), University of York, Heslington, York YO10 5DD, UK
| | - Gavin H Thomas
- Department of Biology (Area 10), University of York, Heslington, York YO10 5DD, UK
| | - Roderick E Hubbard
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK; Vernalis (R&D) Ltd, Granta Park, Cambridge CB21 6GB, UK
| | - Anne Routledge
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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Minandri F, Bonchi C, Frangipani E, Imperi F, Visca P. Promises and failures of gallium as an antibacterial agent. Future Microbiol 2014; 9:379-97. [DOI: 10.2217/fmb.14.3] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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Mislin GLA, Schalk IJ. Siderophore-dependent iron uptake systems as gates for antibiotic Trojan horse strategies against Pseudomonas aeruginosa. Metallomics 2014; 6:408-20. [PMID: 24481292 DOI: 10.1039/c3mt00359k] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen responsible for nosocomial infections. The prevalence of antibiotic-resistant P. aeruginosa strains is increasing, necessitating the urgent development of new strategies to improve the control of this pathogen. Its bacterial envelope constitutes of an outer and an inner membrane enclosing the periplasm. This structure plays a key role in the resistance of the pathogen, by decreasing the penetration and the biological impact of many antibiotics. However, this barrier may also be seen as the "Achilles heel" of the bacterium as some of its functions provide opportunities for breaching bacterial defenses. Siderophore-dependent iron uptake systems act as gates in the bacterial envelope and could be used in a "Trojan horse" strategy, in which the conjugation of an antibiotic to a siderophore could significantly increase the biological activity of the antibiotic, by enhancing its transport into the bacterium. In this review, we provide an overview of the various siderophore-antibiotic conjugates that have been developed for use against P. aeruginosa and show that an accurate knowledge of the structural and functional features of the proteins involved in this transmembrane transport is required for the design and synthesis of effective siderophore-antibiotic Trojan horse conjugates.
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Affiliation(s)
- Gaëtan L A Mislin
- UMR 7242, Université de Strasbourg-CNRS, ESBS, 300 Boulevard, Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
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Abstract
In a fundamental process throughout nature, reduced iron unleashes the oxidative power of hydrogen peroxide into reactive intermediates. However, notwithstanding much work, the mechanism by which Fe(2+) catalyzes H2O2 oxidations and the identity of the participating intermediates remain controversial. Here we report the prompt formation of O=Fe(IV)Cl3(-) and chloride-bridged di-iron O=Fe(IV) · Cl · Fe(II)Cl4(-) and O=Fe(IV) · Cl · Fe(III)Cl5(-) ferryl species, in addition to Fe(III)Cl4(-), on the surface of aqueous FeCl2 microjets exposed to gaseous H2O2 or O3 beams for <50 μs. The unambiguous identification of such species in situ via online electrospray mass spectrometry let us investigate their individual dependences on Fe(2+), H2O2, O3, and H(+) concentrations, and their responses to tert-butanol (an · OH scavenger) and DMSO (an O-atom acceptor) cosolutes. We found that (i) mass spectra are not affected by excess tert-butanol, i.e., the detected species are primary products whose formation does not involve · OH radicals, and (ii) the di-iron ferryls, but not O=Fe(IV)Cl3(-), can be fully quenched by DMSO under present conditions. We infer that interfacial Fe(H2O)n(2+) ions react with H2O2 and O3 >10(3) times faster than Fe(H2O)6(2+) in bulk water via a process that favors inner-sphere two-electron O-atom over outer-sphere one-electron transfers. The higher reactivity of di-iron ferryls vs. O=Fe(IV)Cl3(-) as O-atom donors implicates the electronic coupling of mixed-valence iron centers in the weakening of the Fe(IV)-O bond in poly-iron ferryl species.
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Affiliation(s)
- Shinichi Enami
- The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Yosuke Sakamoto
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo 060-0610, Japan; and
| | - Agustín J. Colussi
- Linde Center for Global Environmental Science, California Institute of Technology, CA 91125
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Joshi T, Patra M, Spiccia L, Gasser G. Di-heterometalation of thiol-functionalized peptide nucleic acids. ARTIFICIAL DNA, PNA & XNA 2013; 4:11-8. [PMID: 23422249 PMCID: PMC3654725 DOI: 10.4161/adna.24019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/14/2013] [Accepted: 02/15/2013] [Indexed: 12/21/2022]
Abstract
As a proof-of-principle, two hetero-bimetallic PNA oligomers containing a ruthenium(II) polypyridyl and a cyclopentadienyl manganese tricarbonyl complex have been prepared by serial combination of solid-phase peptide coupling and in-solution thiol chemistry. Solid-phase N-terminus attachment of Ru(II)-polypyridyl carboxylic acid derivative, C1, onto the thiol-functionalized PNA backbone (H-a-a-g-t-c-t-g-c-linker-cys-NH 2) has been performed by standard peptide coupling method. As two parallel approaches, the strong affinity of thiols for maleimide and haloacetyl group has been exploited for subsequent post-SPPS addition of cymantrene-based organometallic cores, C2 and C3. Michael-like addition and thioether ligation of thiol functionalized PNA1 (H-gly-a-a-g-t-c-t-g-c-linker-cys-NH 2) and PNA2 (C1-a-a-g-t-c-t-g-c-linker-cys-NH 2) to cymantrene maleimide and chloroacetyl derivatives, C2 and C3, respectively, has been performed. The synthesized ruthenium(II)-cymantrenyl PNA oligomers have been characterized by mass spectrometry (ESI-MS) and IR spectroscopy. The distinct Mn-CO vibrational IR stretches, between 1,924-2,074 cm (-1) , have been used as markers to confirm the presence of cymantrenyl units in the PNA sequences and the purity of the HPLC-purified PNA thioethers assessed using LC-MS.
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Affiliation(s)
- Tanmaya Joshi
- Institute of Inorganic Chemistry; University of Zurich; Zurich, Switzerland
| | - Malay Patra
- Institute of Inorganic Chemistry; University of Zurich; Zurich, Switzerland
| | - Leone Spiccia
- ARC Centre of Excellence for Electromaterials Science and School of Chemistry; Monash University; Clayton, VIC Australia
| | - Gilles Gasser
- Institute of Inorganic Chemistry; University of Zurich; Zurich, Switzerland
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