{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T11:02:56Z","timestamp":1789642976964,"version":"4.0.0"},"reference-count":41,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pharmacol."],"abstract":"\n Introduction<\/jats:title>\n In the context of rapid rise of resistant pathogen strains, antimicrobial peptides (AMPs) represent promising scaffolds that complement conventional antibiotics, especially given the specific toxicities that limit classic drugs like fluoroquinolones and nitroimidazoles. AMP monotherapy faces major drawbacks, primarily due to inherent host-cell toxicity and a short half-life.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n To overcome these limitations, this study details the design and synthesis of dual-mechanism prodrugs by conjugating the membrane-active AMPs scaffolds of urechistachykinin I and decoralin to norfloxacin and metronidazole via a pathogen-cleavable ester linker. To minimize off-target toxicity, both AMP sequences were synthesized with a C-terminal carboxyl group, as these variants exhibit negligible hemolytic and neurotoxic activity compared to their amidated analogues. The designed antibiotic-peptide conjugates were synthesized on solid support starting from the C-terminus, followed by N-terminal chain elongation to attach the antibiotics. Specific derivatization methods ensured the covalent ester linkage of norfloxacin and metronidazole to the N-termini of urechistachykinin I (resulting in conjugates\n 1a<\/jats:bold>\n and\n 1b<\/jats:bold>\n ) and decoralin (resulting in conjugates\n 2a<\/jats:bold>\n and\n 2b<\/jats:bold>\n ). Structural behavior was assessed by 200 ns molecular dynamics simulations in water. Antimicrobial activity was evaluated by broth microdilution against Gram-negative, Gram-positive bacteria and fungi, and compared to parent peptides and reference antibiotics as positive controls.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n All conjugates exhibited increased flexibility and solvent exposure relative to their parent peptides, as evidenced by increased RMSD, radius of gyration, H-bonding with water and higher solvent accessible surface area. In vitro screening identified\n 1a<\/jats:bold>\n ,\n 2a<\/jats:bold>\n and\n 2b<\/jats:bold>\n as the most active conjugates. Norfloxacin conjugate\n 1a<\/jats:bold>\n exhibited potent activity against\n Escherichia coli<\/jats:italic>\n ATCC 8739 (MIC 0.56 \u03bcM) and\n Candida parapsilosis<\/jats:italic>\n (MIC 2.26 \u03bcM). Norfloxacin conjugate\n 2a<\/jats:bold>\n showed broad-spectrum inhibition, including\n Escherichia coli<\/jats:italic>\n ATCC 8739 (MIC 8.64 \u03bcM),\n Salmonella enterica<\/jats:italic>\n ATCC BAA-2162 (MIC 8.64 \u03bcM) and\n Listeria<\/jats:italic>\n monocytogenes<\/jats:italic>\n DSMZ 115292 (MIC 4.32 \u03bcM), with improved activity over unmodified decoralin. Metronidazole conjugate\n 2b<\/jats:bold>\n was active against\n Listeria monocytogenes<\/jats:italic>\n DSMZ 115292 (MIC 11.86 \u03bcM) and\n Enterococcus faecalis<\/jats:italic>\n ATCC 29212 (MIC 23.12 \u03bcM).\n <\/jats:p>\n <\/jats:sec>\n \n Discussion<\/jats:title>\n These in vitro assays demonstrate retained peptide membrane-disrupting properties and synergistic effects with the antibiotics. The dual-mechanism design represents a promising strategy to reduce toxicity and overcome antimicrobial resistance.<\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fphar.2026.1927384","type":"journal-article","created":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T10:22:59Z","timestamp":1789640579000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Synthesis, molecular dynamics, and antimicrobial evaluation of peptide-antibiotic conjugates designed for dual-mechanism pathogen inhibition"],"prefix":"10.3389","volume":"17","author":[{"given":"Denisa","family":"Leonte","sequence":"first","affiliation":[{"name":"Department of Organic Chemistry, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clemence","family":"Fartaoui","sequence":"additional","affiliation":[{"name":"Department of Organic Chemistry, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ioana","family":"Ionu\u021b","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R\u00f3bert","family":"T\u0151t\u0151s","sequence":"additional","affiliation":[{"name":"Enzymology and Applied Biocatalysis Research Center, Faculty of Chemistry and Chemical Engineering, Babe\u015f-Bolyai University","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabriel","family":"Marc","sequence":"additional","affiliation":[{"name":"Department of Organic Chemistry, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laurian","family":"Vlase","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Technology and Biopharmacy, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gheorghe-Adrian","family":"Mart\u0103u","sequence":"additional","affiliation":[{"name":"Institute of Life Sciences, University of Agricultural Sciences and Veterinary Medicine","place":["Cluj-Napoca, Romania"]},{"name":"Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dan Cristian","family":"Vodnar","sequence":"additional","affiliation":[{"name":"Institute of Life Sciences, University of Agricultural Sciences and Veterinary Medicine","place":["Cluj-Napoca, Romania"]},{"name":"Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ovidiu","family":"Cri\u015fan","sequence":"additional","affiliation":[{"name":"Department of Organic Chemistry, \u201cIuliu Ha\u021bieganu\u201d University of Medicine and Pharmacy","place":["Cluj-Napoca, Romania"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"19","DOI":"10.1016\/j.softx.2015.06.001","article-title":"GROMACS: high performance molecular simulations through multi-level parallelism from laptops to supercomputers","author":"Abraham","year":"2015","journal-title":"SoftwareX"},{"key":"B2","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1002\/ddr.70114","article-title":"Novel metronidazole conjugates as antimicrobial agents","volume":"86","author":"Akg\u00fcn","year":"2025","journal-title":"Drug Dev. Res."},{"key":"B3","doi-asserted-by":"publisher","first-page":"1565","DOI":"10.1021\/bi5000564","article-title":"Mechanism of quinolone action and resistance","volume":"53","author":"Aldred","year":"2014","journal-title":"Biochemistry"},{"key":"B4","doi-asserted-by":"publisher","first-page":"1545","DOI":"10.1002\/jcc.21287","article-title":"CHARMM: the biomolecular simulation program","volume":"30","author":"Brooks","year":"2009","journal-title":"J. Comput. Chem."},{"key":"B5","doi-asserted-by":"publisher","first-page":"212","DOI":"10.1016\/j.cjche.2023.01.015","article-title":"Enhanced adsorption of target branched compounds including antibiotic norfloxacin frameworks on mild steel surface for efficient protection: an experimental and molecular modelling study","volume":"60","author":"Chen","year":"2023","journal-title":"Chin. J. Chem. Eng."},{"key":"B6","doi-asserted-by":"publisher","first-page":"1982","DOI":"10.1021\/acs.jcim.5c02731","article-title":"Current status of molecular dynamics simulations of membrane permeabilization by antimicrobial peptides and pore-forming proteins: a review","volume":"66","author":"Cresca","year":"2026","journal-title":"J. Chem. Inf. Model."},{"key":"B7","doi-asserted-by":"publisher","first-page":"685","DOI":"10.1093\/jac\/33.4.685","article-title":"Structure-activity and structure-side-effect relationships for the quinolone antibacterials","volume":"33","author":"Domagala","year":"1994","journal-title":"J. Antimicrob. Chemother."},{"key":"B8","doi-asserted-by":"publisher","first-page":"41","DOI":"10.3390\/molecules26010041","article-title":"Development of radiogallium-labeled peptides for platelet-derived growth factor receptor \u03b2 (Pdgfr\u03b2) imaging: influence of different linkers","volume":"26","author":"Effendi","year":"2021","journal-title":"Molecules"},{"key":"B9","doi-asserted-by":"publisher","first-page":"199","DOI":"10.1038\/319199a0","article-title":"Solvation energy in protein folding and binding","volume":"319","author":"Eisenberg","year":"1986","journal-title":"Nature"},{"key":"B10","doi-asserted-by":"publisher","first-page":"545","DOI":"10.1007\/s10334-025-01313-8","article-title":"In-cell NMR spectroscopy: advancements, applications, challenges, and future directions in structural biology","volume":"39","author":"Eladl","year":"","journal-title":"Magn. Reson. Mater. Phy."},{"key":"B11","doi-asserted-by":"publisher","first-page":"36126","DOI":"10.1038\/s41598-025-22890-7","article-title":"Biophysical and transcriptomic characterization of LL-37-derived antimicrobial peptide targeting multidrug-resistant Escherichia coli and ESKAPE pathogens","volume":"15","author":"Eladl","year":"","journal-title":"Sci. Rep."},{"key":"B12","doi-asserted-by":"publisher","first-page":"153561","DOI":"10.1016\/j.bbrc.2026.153561","article-title":"Beyond the obvious: exploring the underappreciated dynamics and context-specific functions of lncRNAs","volume":"811","author":"Eladl","year":"2026","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"B13","doi-asserted-by":"publisher","first-page":"36397","DOI":"10.1038\/s41598-025-20519-3","article-title":"In-cell NMR spectra of chemically unmodified RNA at physiological temperature with extended lifetime through RNase inhibitor cocktail in living human cells","volume":"15","author":"Eladl","year":"","journal-title":"Sci. Rep."},{"key":"B14","doi-asserted-by":"publisher","first-page":"153673","DOI":"10.1016\/j.bbrc.2026.153673","article-title":"Epitranscriptomic RNA modifications in human disease: cooperative networks, molecular mechanisms, and therapeutic opportunities","volume":"815","author":"Eladl","year":"2026","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"B15","doi-asserted-by":"publisher","first-page":"250194","DOI":"10.1098\/rsob.250194","article-title":"tRNA-modifying enzymes in bacterial stress adaptation","volume":"15","author":"Fruchard","year":"2025","journal-title":"Open Biol."},{"key":"B16","doi-asserted-by":"publisher","first-page":"532","DOI":"10.3390\/antibiotics12030532","article-title":"Conjugation as a tool in therapeutics: role of amino Acids\/peptides-bioactive (including heterocycles) hybrid molecules in treating infectious diseases","volume":"12","author":"Gattu","year":"2023","journal-title":"Antibiotics"},{"key":"B17","doi-asserted-by":"publisher","first-page":"490","DOI":"10.1002\/(sici)1096-987x(199604)17:5\/6<490::aid-jcc1>3.0.co;2-p","article-title":"Merck molecular force field. I. Basis, form, scope, parameterization, and performance of MMFF94","volume":"17","author":"Halgren","year":"1996","journal-title":"J. Comput. Chem."},{"key":"B18","doi-asserted-by":"publisher","first-page":"33","DOI":"10.1016\/0263-7855(96)00018-5","article-title":"VMD: visual molecular dynamics","volume":"14","author":"Humphrey","year":"1996","journal-title":"J. Mol. Graph."},{"key":"B19","doi-asserted-by":"publisher","first-page":"1845134","DOI":"10.3389\/fimmu.2026.1845134","article-title":"RNA modifications shape innate immunity and cellular adaptation during bacterial respiratory infection","volume":"17","author":"Ivanova","year":"2026","journal-title":"Front. Immunol."},{"key":"B20","doi-asserted-by":"publisher","first-page":"102119","DOI":"10.1016\/j.progpolymsci.2026.102119","article-title":"Advances in computational and data-driven methodologies for accelerating antimicrobial peptide design and discovery","volume":"177","author":"Jayawardena","year":"2026","journal-title":"Prog. Polym. Sci."},{"key":"B21","doi-asserted-by":"publisher","first-page":"1859","DOI":"10.1002\/jcc.20945","article-title":"CHARMM-GUI: a web-based graphical user interface for CHARMM","volume":"29","author":"Jo","year":"2008","journal-title":"J. Comput. Chem."},{"key":"B22","doi-asserted-by":"publisher","first-page":"926","DOI":"10.1063\/1.445869","article-title":"Comparison of simple potential functions for simulating liquid water","volume":"79","author":"Jorgensen","year":"1983","journal-title":"J. Chem. Phys."},{"key":"B23","doi-asserted-by":"publisher","first-page":"43271","DOI":"10.1021\/acsomega.3c07221","article-title":"Design, synthesis, molecular modeling, biological activity, and mechanism of action of novel amino acid derivatives of norfloxacin","volume":"8","author":"Kamal El-Sagheir","year":"2023","journal-title":"ACS Omega"},{"key":"B24","doi-asserted-by":"publisher","first-page":"4238","DOI":"10.1046\/j.1432-1033.2002.03106.x","article-title":"A novel tachykinin-related peptide receptor: sequence, genomic organization, and functional analysis","volume":"269","author":"Kawada","year":"2002","journal-title":"Eur. J. Biochem."},{"key":"B25","doi-asserted-by":"publisher","first-page":"1879","DOI":"10.1002\/jcc.24829","article-title":"CHARMM-GUI ligand reader and modeler for CHARMM force field generation of small molecules","volume":"38","author":"Kim","year":"2017","journal-title":"J. Comput. Chem."},{"key":"B26","doi-asserted-by":"publisher","first-page":"2320","DOI":"10.1016\/j.peptides.2007.09.017","article-title":"Decoralin, a novel linear cationic \u03b1-helical peptide from the venom of the solitary eumenine wasp Oreumenes decoratus","volume":"28","author":"Konno","year":"2007","journal-title":"Peptides"},{"key":"B27","doi-asserted-by":"publisher","first-page":"405","DOI":"10.1021\/acs.jctc.5b00935","article-title":"CHARMM-GUI input generator for NAMD, GROMACS, AMBER, OpenMM, and CHARMM\/OpenMM simulations using the CHARMM36 additive force field","volume":"12","author":"Lee","year":"2016","journal-title":"J. Chem. Theory Comput."},{"key":"B28","doi-asserted-by":"publisher","first-page":"105718","DOI":"10.1016\/j.bioorg.2022.105718","article-title":"Novel metronidazole-derived three-component hybrids as promising broad-spectrum agents to combat oppressive bacterial resistance","volume":"122","author":"Li","year":"2022","journal-title":"Bioorg. Chem."},{"key":"B29","doi-asserted-by":"publisher","first-page":"107556","DOI":"10.1016\/j.jbc.2024.107556","article-title":"Two C-terminal isoforms of Aplysia tachykinin\u2013related peptide receptors exhibit phosphorylation-dependent and phosphorylation-independent desensitization mechanisms","volume":"300","author":"Mao","year":"2024","journal-title":"J. Biol. Chem."},{"key":"B30","doi-asserted-by":"publisher","first-page":"718","DOI":"10.3390\/ph17060718","article-title":"Antibacterial prodrugs to overcome bacterial antimicrobial resistance","volume":"17","author":"Maria","year":"2024","journal-title":"Pharmaceuticals"},{"key":"B31","doi-asserted-by":"publisher","first-page":"4142","DOI":"10.1016\/j.ejmech.2011.06.016","article-title":"Metronidazole prodrugs: synthesis, physicochemical properties, stability, and ex vivo release studies","volume":"46","author":"Mura","year":"2011","journal-title":"Eur. J. Med. Chem."},{"key":"B32","doi-asserted-by":"publisher","first-page":"112994","DOI":"10.1016\/j.ejmech.2020.112994","article-title":"Metronidazole-conjugates: a comprehensive review of recent developments towards synthesis and medicinal perspective","volume":"210","author":"Patel","year":"2021","journal-title":"Eur. J. Med. Chem."},{"key":"B33","doi-asserted-by":"publisher","first-page":"19751","DOI":"10.1039\/d5ra02932e","article-title":"Antibiotic-conjugated antimicrobial peptides for enhanced bacterial inhibition","volume":"15","author":"Peng","year":"2025","journal-title":"RSC Adv."},{"key":"B34","doi-asserted-by":"publisher","first-page":"3435","DOI":"10.1128\/AAC.47.11.3435-3441.2003","article-title":"Synthesis, degradation, and antimicrobial properties of targeted macromolecular prodrugs of norfloxacin","volume":"47","author":"Roseeuw","year":"2003","journal-title":"Antimicrob. Agents Chemother."},{"key":"B35","doi-asserted-by":"publisher","first-page":"e1011968","DOI":"10.1371\/journal.ppat.1011968","article-title":"Epitranscriptional m6A modification of rRNA negatively impacts translation and host colonization in Staphylococcus aureus","volume":"20","author":"Shields","year":"2024","journal-title":"PLoS Pathog."},{"key":"B36","doi-asserted-by":"publisher","first-page":"258","DOI":"10.3390\/foods13020258","article-title":"Characterization of the chemical composition and biological activities of Bog bilberry (Vaccinium uliginosum L.) leaf extracts obtained via various extraction techniques","volume":"13","author":"\u0218tef\u0103nescu","year":"2024","journal-title":"Foods"},{"key":"B37","doi-asserted-by":"publisher","first-page":"717","DOI":"10.1351\/pac200779040717","article-title":"Influence of C-terminal amidation on the antimicrobial and hemolytic activities of cationic \u03b1-helical peptides","volume":"79","author":"Strandberg","year":"2007","journal-title":"Pure Appl. Chem."},{"key":"B38","doi-asserted-by":"publisher","first-page":"2463","DOI":"10.1016\/j.febslet.2008.06.015","article-title":"Antimicrobial effect and membrane-active mechanism of urechistachykinins, neuropeptides derived from Urechis unicinctus","volume":"582","author":"Sung","year":"2008","journal-title":"FEBS Lett."},{"key":"B39","doi-asserted-by":"publisher","first-page":"3144","DOI":"10.1021\/ci300363c","article-title":"Automation of the CHARMM general force field (CGenFF) I: bond perception and atom typing","volume":"52","author":"Vanommeslaeghe","year":"2012","journal-title":"J. Chem. Inf. Model."},{"key":"B40","doi-asserted-by":"publisher","first-page":"671","DOI":"10.1002\/jcc.21367","article-title":"CHARMM general force field: a force field for drug-like molecules compatible with the CHARMM all-atom additive biological force fields","volume":"31","author":"Vanommeslaeghe","year":"2010","journal-title":"J. Comput. Chem."},{"key":"B41","doi-asserted-by":"publisher","first-page":"591","DOI":"10.1002\/bscb.198509408079","article-title":"Macromolecular prodrugs of metronidazole. 1. Esterification of hydroxyl containing polymers with metronidazole monosuccinate","volume":"94","author":"Vermeersch","year":"1985","journal-title":"Bull. Des. Soci\u00e9t\u00e9s Chim. Belg."}],"container-title":["Frontiers in Pharmacology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphar.2026.1927384\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T10:23:00Z","timestamp":1789640580000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphar.2026.1927384\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,17]]},"references-count":41,"alternative-id":["10.3389\/fphar.2026.1927384"],"URL":"https:\/\/doi.org\/10.3389\/fphar.2026.1927384","relation":{},"ISSN":["1663-9812"],"issn-type":[{"value":"1663-9812","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,17]]},"article-number":"1927384"}}