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Recent Advances in the Development of Newer Antimicrobial Agents

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Pathology, Diagnostics, and Therapeutics".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 11270

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Guest Editor
Department of Chemistry, Iowa State University, Ames, IA 50011-3111, USA
Interests: antimicrobial drug discovery and development; medicinal chemistry; peptides and peptidomimetics; unnatural amino acids; fluorescent probes; peptide nucleic acids; anticancer drug discovery; phenotypic drug discovery; neurodegenerative diseases
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Special Issue Information

Dear Colleagues,

Due to rapid emergence of multidrug-resistant microbes to clinically approved antimicrobial agents, the discovery and development of novel antimicrobial agents is becoming an imperative need across the globe. As seen in the current COVID-19 crisis, drug-resistant microbial co-infections along with COVID-19 have witnessed higher hospitalization and mortality rate and also presented a big threat to the global healthcare system. Therefore, there is an imperative need to discover and develop novel antimicrobial agents with new mechanisms of action or new targets of action. In this quest, newer chemical methodologies, chemical biology, and other newly developed drug discovery technologies can be used to discover novel antimicrobial agents with different modes of actions to tackle the public health threat posed by antimicrobial resistance.

This Special Issue invites researchers across the globe to submit their original research articles, perspectives, and review articles on various aspects of discovery and developments of antimicrobial agents. Review articles by experts in this field are also welcomed to focus on highlights, current status, recent advances, and future perspectives. I believe this Special Issue would be of interest to a wide range of researchers working on addressing the challenges and advancement of antimicrobial agent research.

Dr. Krishna K. Sharma
Guest Editor

Manuscript Submission Information

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Keywords

  • antimicrobial agents
  • antibacterial agents
  • antifungal agents
  • antiviral agents 
  • anti-infective agents
  • organic synthesis and medicinal chemistry
  • biological activity
  • natural products
  • biosynthesis
  • coating and polymers
  • disinfectants
  • sterilizing agents
  • drug design and computational chemistry
  • drug discovery and development

Published Papers (7 papers)

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Research

19 pages, 3450 KiB  
Article
Enhancing the Antimicrobial Properties of Peptides through Cell-Penetrating Peptide Conjugation: A Comprehensive Assessment
by Sergey V. Kravchenko, Pavel A. Domnin, Sergei Y. Grishin, Nikita A. Vershinin, Elena V. Gurina, Anastasiia A. Zakharova, Viacheslav N. Azev, Leila G. Mustaeva, Elena Y. Gorbunova, Margarita I. Kobyakova, Alexey K. Surin, Roman S. Fadeev, Olga S. Ostroumova, Svetlana A. Ermolaeva and Oxana V. Galzitskaya
Int. J. Mol. Sci. 2023, 24(23), 16723; https://doi.org/10.3390/ijms242316723 - 24 Nov 2023
Cited by 1 | Viewed by 1120
Abstract
Combining antimicrobial peptides (AMPs) with cell-penetrating peptides (CPPs) has shown promise in boosting antimicrobial potency, especially against Gram-negative bacteria. We examined the CPP-AMP interaction with distinct bacterial types based on cell wall differences. Our investigation focused on AMPs incorporating penetratin CPP and dihybrid [...] Read more.
Combining antimicrobial peptides (AMPs) with cell-penetrating peptides (CPPs) has shown promise in boosting antimicrobial potency, especially against Gram-negative bacteria. We examined the CPP-AMP interaction with distinct bacterial types based on cell wall differences. Our investigation focused on AMPs incorporating penetratin CPP and dihybrid peptides containing both cell-penetrating TAT protein fragments from the human immunodeficiency virus and Antennapedia peptide (Antp). Assessment of the peptides TAT-AMP, AMP-Antp, and TAT-AMP-Antp revealed their potential against Gram-positive strains (Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA), and Bacillus cereus). Peptides TAT-AMP and AMP-Antp using an amyloidogenic AMP from S1 ribosomal protein Thermus thermophilus, at concentrations ranging from 3 to 12 μM, exhibited enhanced antimicrobial activity against B. cereus. TAT-AMP and TAT-AMP-Antp, using an amyloidogenic AMP from the S1 ribosomal protein Pseudomonas aeruginosa, at a concentration of 12 µM, demonstrated potent antimicrobial activity against S. aureus and MRSA. Notably, the TAT-AMP, at a concentration of 12 µM, effectively inhibited Escherichia coli (E. coli) growth and displayed antimicrobial effects similar to gentamicin after 15 h of incubation. Peptide characteristics determined antimicrobial activity against diverse strains. The study highlights the intricate relationship between peptide properties and antimicrobial potential. Mechanisms of AMP action are closely tied to bacterial cell wall attributes. Peptides with the TAT fragment exhibited enhanced antimicrobial activity against S. aureus, MRSA, and P. aeruginosa. Peptides containing only the Antp fragment displayed lower activity. None of the investigated peptides demonstrated cytotoxic or cytostatic effects on either BT-474 cells or human skin fibroblasts. In conclusion, CPP-AMPs offer promise against various bacterial strains, offering insights for targeted antimicrobial development. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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17 pages, 7469 KiB  
Article
Photo- and Sono-Active Food Colorants Inactivating Bacteria
by Efrat Hochma, Iryna Hovor, Faina Nakonechny and Marina Nisnevitch
Int. J. Mol. Sci. 2023, 24(20), 15126; https://doi.org/10.3390/ijms242015126 - 12 Oct 2023
Viewed by 979
Abstract
Food colorants are commonly used as excipients in pharmaceutical and nutraceutical fields, but they have a wide range of other potential applications, for instance, as cytotoxic drugs or mediators of physical antimicrobial treatments. The photodynamic antibacterial activity of several edible food colorants is [...] Read more.
Food colorants are commonly used as excipients in pharmaceutical and nutraceutical fields, but they have a wide range of other potential applications, for instance, as cytotoxic drugs or mediators of physical antimicrobial treatments. The photodynamic antibacterial activity of several edible food colorants is reported here, including E127, E129, E124, E122, E133, and E150a, alongside Rhein, a natural lipophilic antibacterial and anticancer compound found in medicinal plants. Minimal inhibitory concentration (MIC) values for S. aureus and E. coli showed that E127 and Rhein were effective against both bacteria, while other colorants exhibited low activity against E. coli. In some cases, dark pre-incubation of the colorants with Gram-positive S. aureus increased their photodynamic activity. Adding Rhein to E127 increased the photodynamic activity of the latter in a supportive mode. Optional sensing mechanism pathways of combined E127/Rhein action were suggested. The antibacterial activity of the studied colorants can be ranged as follows: E127/Rhein >> E127 >> E150a > E122 > E124 >> E129 ≈ E133. E127 was also found to exhibit photodynamic properties. Short ultrasonic treatment before illumination caused intensification of E127 photodynamic activity against E. coli when applied alone and especially in combination with Rhein. Food colorants exhibiting photo- and sonodynamic properties may have good potential in food preservation. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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14 pages, 3941 KiB  
Article
Tiger Nut Milk’s Antiviral Properties against Enveloped and Non-Enveloped Viruses: Effect of Concentration and Adding Sugar
by Alberto Tuñón-Molina, Alba Cano-Vicent and Ángel Serrano-Aroca
Int. J. Mol. Sci. 2023, 24(15), 12018; https://doi.org/10.3390/ijms241512018 - 27 Jul 2023
Viewed by 1048
Abstract
The global COVID-19 pandemic has warned scientists of the requirement to look for new antimicrobial compounds to prevent infection by this type of viral pathogen. Natural compounds are becoming a promising avenue of research thanks to their renewable, biodegradable, and non-toxic properties. In [...] Read more.
The global COVID-19 pandemic has warned scientists of the requirement to look for new antimicrobial compounds to prevent infection by this type of viral pathogen. Natural compounds are becoming a promising avenue of research thanks to their renewable, biodegradable, and non-toxic properties. In this work, tiger nut milk’s (TNM) antiviral properties, with and without sugar, were studied against enveloped and non-enveloped viruses. The antiviral properties of TNM were evaluated at different concentrations. The antiviral tests showed that TNM is antiviral against the enveloped bacteriophage phi 6, which is commonly used as a surrogate for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), although it did not have any antiviral effect against the non-enveloped bacteriophage MS2. We also found that adding sugar to this natural drink can improve its antiviral properties against enveloped viruses and render it antiviral against non-enveloped viruses like bacteriophage MS2. The antiviral activity of TNM depends on the TNM concentration. TNM is a natural bioproduct that could help to fight against viral infections and protect against a wide range of viral illnesses. These results confirm that the typical sweetened drink made from tiger nut extract and sugar (known as horchata in Spain) possesses broad-spectrum antiviral properties. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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23 pages, 7289 KiB  
Article
Boosting the Antibacterial Activity of Azithromycin on Multidrug-Resistant Escherichia coli by Efflux Pump Inhibition Coupled with Outer Membrane Permeabilization Induced by Phenylalanine-Arginine β-Naphthylamide
by Farah Al-Marzooq, Akela Ghazawi, Lana Daoud and Saeed Tariq
Int. J. Mol. Sci. 2023, 24(10), 8662; https://doi.org/10.3390/ijms24108662 - 12 May 2023
Cited by 2 | Viewed by 2367
Abstract
The global spread of multidrug-resistant (MDR) bacteria increases the demand for the discovery of new antibiotics and adjuvants. Phenylalanine-arginine β-naphthylamide (PAβN) is an inhibitor of efflux pumps in Gram-negative bacteria, such as the AcrAB-TolC complex in Escherichia coli. We aimed to explore [...] Read more.
The global spread of multidrug-resistant (MDR) bacteria increases the demand for the discovery of new antibiotics and adjuvants. Phenylalanine-arginine β-naphthylamide (PAβN) is an inhibitor of efflux pumps in Gram-negative bacteria, such as the AcrAB-TolC complex in Escherichia coli. We aimed to explore the synergistic effect and mechanism of action of PAβN combined with azithromycin (AZT) on a group of MDR E. coli strains. Antibiotic susceptibility was tested for 56 strains, which were screened for macrolide resistance genes. Then, 29 strains were tested for synergy using the checkerboard assay. PAβN significantly enhanced AZT activity in a dose-dependent manner in strains expressing the mphA gene and encoding macrolide phosphotransferase, but not in strains carrying the ermB gene and encoding macrolide methylase. Early bacterial killing (6 h) was observed in a colistin-resistant strain with the mcr-1 gene, leading to lipid remodeling, which caused outer membrane (OM) permeability defects. Clear OM damage was revealed by transmission electron microscopy in bacteria exposed to high doses of PAβN. Increased OM permeability was also proven by fluorometric assays, confirming the action of PAβN on OM. PAβN maintained its activity as an efflux pump inhibitor at low doses without permeabilizing OM. A non-significant increase in acrA, acrB, and tolC expression in response to prolonged exposure to PAβN was noted in cells treated with PAβN alone or with AZT, as a reflection of bacterial attempts to counteract pump inhibition. Thus, PAβN was found to be effective in potentiating the antibacterial activity of AZT on E. coli through dose-dependent action. This warrants further investigations of its effect combined with other antibiotics on multiple Gram-negative bacterial species. Synergetic combinations will help in the battle against MDR pathogens, adding new tools to the arsenal of existing medications. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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13 pages, 1021 KiB  
Article
In Vivo Efficacy and Toxicity of an Antimicrobial Peptide in a Model of Endotoxin-Induced Pulmonary Inflammation
by Laura Cresti, Giovanni Cappello, Silvia Vailati, Elsa Melloni, Jlenia Brunetti, Chiara Falciani, Luisa Bracci and Alessandro Pini
Int. J. Mol. Sci. 2023, 24(9), 7967; https://doi.org/10.3390/ijms24097967 - 27 Apr 2023
Cited by 1 | Viewed by 1085
Abstract
SET-M33 is a synthetic peptide that is being developed as a new antibiotic against major Gram-negative bacteria. Here we report two in vivo studies to assess the toxicity and efficacy of the peptide in a murine model of pulmonary inflammation. First, we present [...] Read more.
SET-M33 is a synthetic peptide that is being developed as a new antibiotic against major Gram-negative bacteria. Here we report two in vivo studies to assess the toxicity and efficacy of the peptide in a murine model of pulmonary inflammation. First, we present the toxicity study in which SET-M33 was administered to CD-1 mice by snout inhalation exposure for 1 h/day for 7 days at doses of 5 and 20 mg/kg/day. The results showed adverse clinical signs and effects on body weight at the higher dose, as well as some treatment-related histopathology findings (lungs and bronchi, nose/turbinates, larynx and tracheal bifurcation). On this basis, the no observable adverse effect level (NOAEL) was considered to be 5 mg/kg/day. We then report an efficacy study of the peptide in an endotoxin (LPS)-induced pulmonary inflammation model. Intratracheal administration of SET-M33 at 0.5, 2 and 5 mg/kg significantly inhibited BAL neutrophil cell counts after an LPS challenge. A significant reduction in pro-inflammatory cytokines, KC, MIP-1α, IP-10, MCP-1 and TNF-α was also recorded after SET-M33 administration. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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21 pages, 6738 KiB  
Article
Antibacterial Activity of Solvothermal Obtained ZnO Nanoparticles with Different Morphology and Photocatalytic Activity against a Dye Mixture: Methylene Blue, Rhodamine B and Methyl Orange
by Ludmila Motelica, Ovidiu-Cristian Oprea, Bogdan-Stefan Vasile, Anton Ficai, Denisa Ficai, Ecaterina Andronescu and Alina Maria Holban
Int. J. Mol. Sci. 2023, 24(6), 5677; https://doi.org/10.3390/ijms24065677 - 16 Mar 2023
Cited by 31 | Viewed by 2487
Abstract
In this paper, we report the synthesis of ZnO nanoparticles (NPs) by forced solvolysis of Zn(CH3COO)2·2H2O in alcohols with a different number of –OH groups. We study the influence of alcohol type (n-butanol, ethylene glycol and glycerin) [...] Read more.
In this paper, we report the synthesis of ZnO nanoparticles (NPs) by forced solvolysis of Zn(CH3COO)2·2H2O in alcohols with a different number of –OH groups. We study the influence of alcohol type (n-butanol, ethylene glycol and glycerin) on the size, morphology, and properties of the obtained ZnO NPs. The smallest polyhedral ZnO NPs (<30 nm) were obtained in n-butanol, while in ethylene glycol the NPs measured on average 44 nm and were rounded. Polycrystalline particles of 120 nm were obtained in glycerin only after water refluxing. In addition, here, we report the photocatalytic activity, against a dye mixture, of three model pollutants: methyl orange (MO), methylene blue (MB), and rhodamine B (RhB), a model closer to real situations where water is polluted with many chemicals. All samples exhibited good photocatalytic activity against the dye mixture, with degradation efficiency reaching 99.99%. The sample with smallest nanoparticles maintained a high efficiency >90%, over five catalytic cycles. Antibacterial tests were conducted against Gram-negative strains Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, and Escherichia coli, and Gram-positive strains Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, and Bacillus cereus. The ZnO samples presented strong inhibition of planktonic growth for all tested strains, indicating that they can be used for antibacterial applications, such as water purification. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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16 pages, 2212 KiB  
Article
Prevalence of Class 1 Integron and In Vitro Effect of Antibiotic Combinations of Multidrug-Resistant Enterococcus Species Recovered from the Aquatic Environment in the Eastern Cape Province, South Africa
by Oluwaseun Ola Adeniji, Nolonwabo Nontongana and Anthony Ifeanyin Okoh
Int. J. Mol. Sci. 2023, 24(3), 2993; https://doi.org/10.3390/ijms24032993 - 3 Feb 2023
Viewed by 1235
Abstract
Enterococci are regarded as a better indication of faecal pollution in freshwater and marine waters. Their levels in seawater are positively connected with swimming-related gastrointestinal disorders. This study used an Enterococcus-specific polymerase chain reaction (PCR) to characterize the isolates. Classes 1 and [...] Read more.
Enterococci are regarded as a better indication of faecal pollution in freshwater and marine waters. Their levels in seawater are positively connected with swimming-related gastrointestinal disorders. This study used an Enterococcus-specific polymerase chain reaction (PCR) to characterize the isolates. Classes 1 and 2 integrons were examined for environmental Enterococcus isolates using a standard biological procedure. All strains were assessed against a panel of 12 antibiotics from various classes using disc diffusion methods. The microdilution method was used to work out the minimum inhibitory concentration (MIC) according to the CLSI guiding principles. The combination therapy of the resistant drugs was evaluated using a checkerboard assay and a time-dependent test for assessing their bactericidal or bacteriostatic activity. The gene diversity of the tested organisms was analyzed with the aid of Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR. In total, 57 Enterococcus spp. environmental samples were recovered, in which Enterococcus faecalis (33.33%) and Enterococcus faecium (59.65%) were the dominant species. Resistance to linezolid, ciprofloxacin, erythromycin, gentamicin, vancomycin, rifampicin, and tetracycline was prevalent. Fifty (50) strains tested positive for class 1 integron, more frequent in Enterococcus faecium and Enterococcus faecalis isolates, with no gene cassette array discovered. A combination of gentamicin (MIC 4 µg/mL) with vancomycin (MIC 256 µg/mL) antibiotics against Enterococcus faecalis showed antibacterial activity. In contrast, the combination of ciprofloxacin (1 µg/mL) with Ampicillin (16 µg/mL) antibiotics against Enterococcus faecalis showed a bacteriostatic effect. The ERIC-PCR analysis pointed out that most of the assessed isolates have close genetic similarities. Full article
(This article belongs to the Special Issue Recent Advances in the Development of Newer Antimicrobial Agents)
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