Special Issue "Mechanisms of Antimicrobial Peptides on Pathogens"

A special issue of Antibiotics (ISSN 2079-6382). This special issue belongs to the section "Antimicrobial Peptides".

Deadline for manuscript submissions: 30 September 2021.

Special Issue Editor

Dr. Malgorzata Paduszynska
E-Mail
Guest Editor
Medical University of Gdansk, Faculty of Pharmacy Department of Inorganic Chemistry
Interests: antimicrobial peptides; peptide synthesis; peptide drug formulation;combination antibiotic therapy; bacterial biofilm; microbial resistance

Special Issue Information

Dear Colleagues,

Antimicrobial peptides (AMPs) are considered as promising alternative for conventional antimicrobials. They are widely distributed in nature as developmental components of the innate immunity of living organisms. The majority of AMPs are cationic, amphipathic molecules that exhibit strong activity against a broad spectrum of pathogens including multi-drug resistant strains. Their ability to eliminate and prevent biofilm structures has been proven in in vitro and in vivo studies.

The most common mode of action of AMPs is disruption of cell membranes leading to microbial lysis. Due to their unique mechanism of action based on interactions with the microbial cell membrane, AMPs can act on slow-growing or even non-growing bacteria and are active against biofilm. This mode has also less risk of acquired resistance or cross-resistance with other agents than other modes of action, which makes it an attractive template for the design of new antimicrobials for specific applications.

Several mechanisms of membrane perturbation are discussed on a molecular level (e.g. toroidal pore formation, the carpet model, void formation, clustering of lipids, and membrane curvature). However, also numerous AMPs with non-conventional modes of action have been described so far. Determination and understanding the modes of action of AMPs are crucial for the rational design of improved antimicrobial compounds.

The aim of this special issue is to extend the scientific knowledge on AMPs in order to examine  their modes of action, understand possible mechanims of microbial resistance, explore potential clinical applications and to survey recent achievements in this field of research.

Dr. Malgorzata Paduszynska
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antibiotics is an international peer-reviewed open access monthly journal published by MDPI.

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Keywords

  • Antimicrobial peptides
  • mechanisms of antimicrobial activities
  • interactions with bacterial membrane
  • microbial resistance
  • inhibition of biofilm formation
  • biofilm eradication

Published Papers (2 papers)

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Research

Open AccessArticle
Novel Cecropin-4 Derived Peptides against Methicillin-Resistant Staphylococcus aureus
Antibiotics 2021, 10(1), 36; https://doi.org/10.3390/antibiotics10010036 - 01 Jan 2021
Viewed by 667
Abstract
Increasing microbial resistance, coupled with a lack of new antimicrobial discovery, has led researchers to refocus on antimicrobial peptides (AMPs) as novel therapeutic candidates. Significantly, the less toxic cecropins have gained widespread attention for potential antibacterial agent development. However, the narrow activity spectrum [...] Read more.
Increasing microbial resistance, coupled with a lack of new antimicrobial discovery, has led researchers to refocus on antimicrobial peptides (AMPs) as novel therapeutic candidates. Significantly, the less toxic cecropins have gained widespread attention for potential antibacterial agent development. However, the narrow activity spectrum and long sequence remain the primary limitations of this approach. In this study, we truncated and modified cecropin 4 (41 amino acids) by varying the charge and hydrophobicity balance to obtain smaller AMPs. The derivative peptide C18 (16 amino acids) demonstrated high antibacterial activity against Gram-negative and Gram-positive bacteria, as well as yeasts. Moreover, C18 demonstrated a minimal inhibitory concentration (MIC) of 4 µg/mL against the methicillin-resistant Staphylococcus aureus (MRSA) and showed synergy with daptomycin with a fractional inhibition concentration index (FICI) value of 0.313. Similar to traditional cecropins, C18 altered the membrane potential, increased fluidity, and caused membrane breakage at 32 µg/mL. Importantly, C18 eliminated 99% persisters at 10 × MIC within 20 min and reduced the biofilm adherence by ~40% and 35% at 32 and 16 µg/mL. Besides, C18 possessed a strong binding ability with DNA at 7.8 μM and down-regulated the expression of virulence factor genes like agrA, fnb-A, and clf-1 by more than 5-fold (p < 0.05). Interestingly, in the Galleria mellonella model, C18 rescued more than 80% of larva infected with the MRSA throughout 120-h post-infection at a single dose of 8 mg/kg (p < 0.05). In conclusion, this study provides a reference for the transformation of cecropin to derive small peptides and presents C18 as an attractive therapeutic candidate to be developed to treat severe MRSA infections. Full article
(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)
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Open AccessArticle
Powerful Antibacterial Peptides from Egg Albumin Hydrolysates
Antibiotics 2020, 9(12), 901; https://doi.org/10.3390/antibiotics9120901 - 13 Dec 2020
Cited by 1 | Viewed by 568
Abstract
Native egg albumin (NEA) was isolated from hen eggs and hydrolyzed by pepsin to produce hydrolyzed egg albumin (HEA). HEA was chemically characterized and screened for its antibacterial activity against 10 pathogenic bacteria (6 Gram (+) and 4 Gram (−)). The SDS-PAGE pattern [...] Read more.
Native egg albumin (NEA) was isolated from hen eggs and hydrolyzed by pepsin to produce hydrolyzed egg albumin (HEA). HEA was chemically characterized and screened for its antibacterial activity against 10 pathogenic bacteria (6 Gram (+) and 4 Gram (−)). The SDS-PAGE pattern of NEA showed molecular weights of hen egg albumin subunits ranging from 30 to 180 kDa. The highest intensive bands appeared at a molecular mass of about 50 and 97 kDa. Ultra-performance liquid chromatography (UPLC) of the peptic HEA revealed 44 peptides, 17 of them were dipeptides, and the other 27 fractions corresponded to bigger peptides (3–9 amino acids). The dipeptides and big peptides represented 26% and 74% of the total hydrolysate, respectively. The MIC of HEA was about 100 μg/L for Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella typhimurium, Streptococcus pyogenes, and Klebsiella oxytoca and 150 μg/L for Pseudomonas aeruginosa, Bacillus subtilis, and Listeria ivanovii and 200 μg/L for Escherichia coli. L. monocytogenes was the most sensitive organism to HEA. Mixtures of HEA with antibiotics showed more significant antibacterial activity than individually using them. Transmission electron microscopy (TEM) revealed various signs of cellular deformation in the protein-treated bacteria. HEA may electrostatically and hydrophobically interact with the cell wall and cell membrane of the susceptible bacteria, engendering large pores and pore channels leading to cell wall and cell membrane disintegration. Higher cell permeability may, thus, occur, leading to cell emptiness, lysis, and finally death. Alternatively, no toxicity signs appeared when HEA was administrated to Wistar Albino rats as one single dose (2000, 5000 mg/kg body weight) or repeated daily dose (500 and 2500 mg/kg body weight/day) for 28 days to disclose the possible toxicity hazards. HEA did not produce any death. Full article
(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)
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