Research on Antimicrobial Activity of Natural Products, Second Edition

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Antimicrobial Agents and Resistance".

Deadline for manuscript submissions: 31 October 2025 | Viewed by 5049

Special Issue Editors


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Guest Editor
1. School of Health, Polytechnic Institute of Porto (ESS|P: PORTO), Porto, Portugal
2. Portugal/Interdisciplinary Centre of Marine and Environmental Research, (CIIMAR/CIMAR), Porto, Portugal
Interests: biotechnology; cyanobacteria; natural products
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Guest Editor
Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros de Leixões, AV. General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal
Interests: bioprospection; actinobacteria; bioactive metabolites; discovery of new natural compounds
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
School of Health, Polytechnic Institute of Porto (ESS|P: PORTO), Porto, Portugal
Interests: health biotechnology; analytical chromatography; quantification of biomolecules; antimicrobial resistance
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microbial infections are responsible for millions of deaths every year and worldwide. The increased resistance to antimicrobial drugs, such as antibiotics, is the main cause and is one of the biggest challenges in human and animal health and in food safety. It is well known that human pathogenic microorganisms resistant to major classes of antibiotics have increased due to the indiscriminate use of antimicrobial drugs. Therefore, the search for the discovery of new antimicrobial agents is in urgent demand.

Finding therapeutic powers in nature is an ancient but increasingly actual idea. In recent years, strategies to overcome the resistance of antibiotics have been suggested, namely the use of phytochemicals. Natural compounds have already proved to be effective and safe sources of antimicrobial compounds and eco-friendly methodologies focused on reducing the growth of pathogenic microorganisms. This Special Issue is directed to ethnopharmacologists, botanists, microbiologists, and natural-products chemists working on developing new approaches for the treatment of infectious diseases. Papers based on the investigation of new sources of natural antimicrobial compounds or mechanisms of action of natural compounds are most welcome.

Dr. Rosário Martins
Dr. Maria De Fátima Carvalho
Dr. Mónica Vieira
Guest Editors

Manuscript Submission Information

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Keywords

  • antimicrobial activity
  • bacteria
  • cyanobacteria
  • fungi
  • antibiotic resistance
  • natural compounds

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Related Special Issue

Published Papers (5 papers)

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Research

15 pages, 6783 KiB  
Article
Disruptive DNA Intercalation Is the Mode of Interaction Behind Niacinamide Antimicrobial Activity
by Michal Rasis, Noa Ziklo and Paul Salama
Microorganisms 2025, 13(7), 1636; https://doi.org/10.3390/microorganisms13071636 - 10 Jul 2025
Abstract
Niacinamide was recently shown to directly interact with bacterial DNA and interfere with cell replication; niacinamide mode of interaction and efficacy as a natural anti-microbial molecule were also described. The aim of this study is to elucidate the exact binding mechanism of niacinamide [...] Read more.
Niacinamide was recently shown to directly interact with bacterial DNA and interfere with cell replication; niacinamide mode of interaction and efficacy as a natural anti-microbial molecule were also described. The aim of this study is to elucidate the exact binding mechanism of niacinamide to microbial DNA. Intercalation is a binding mode where a small planar molecule, such as niacinamide, is inserted between base pairs, causing structural changes in the DNA. Melting curve analysis with various intercalating dyes demonstrated that niacinamide interaction with bacterial DNA reduces its melting temperature in a linear dose-dependent manner. Niacinamide’s effect on the melting temperature was found to be % GC-dependent, while purine stretches were also found to influence the binding kinetics. Finally, fluorescent intercalator displacement (FID) assays demonstrated that niacinamide strongly reduces SYBR Safe signal in a dose-dependent manner. Interestingly, competition assays with a minor groove binder also reduced Hoechst signal but in a non-linear manner, which can be attributed to strand lengthening and unwinding following niacinamide intercalation. Taken altogether; our results suggest a “disruptive intercalation” as the mode of interaction of niacinamide with bacterial DNA. Formation of locally destabilized DNA portions by niacinamide might interfere with protein–DNA interaction and potentially affect several crucial bacterial cellular processes, e.g., DNA repair and replication, subsequently leading to cell death. Full article
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16 pages, 8686 KiB  
Article
Potential Natural Inhibitors of MRSA ABC Transporters and MecA Identified Through In Silico Approaches
by Benson Otarigho, Paul M. Duffin and Mofolusho O. Falade
Microorganisms 2025, 13(6), 1431; https://doi.org/10.3390/microorganisms13061431 - 19 Jun 2025
Viewed by 404
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant clinical challenge due to its resistance to multiple antibiotics. The urgent need for new therapeutic approaches has led to the exploration of natural compounds as potential treatments, particularly those targeting the key bacterial proteins involved in [...] Read more.
Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant clinical challenge due to its resistance to multiple antibiotics. The urgent need for new therapeutic approaches has led to the exploration of natural compounds as potential treatments, particularly those targeting the key bacterial proteins involved in antibiotic resistance. This study focused on the multidrug ABC transporter and MecA proteins, which play crucial roles in MRSA′s pathogenicity and resistance mechanisms. Using computational techniques and molecular docking methods, we assessed the interactions of 80 natural compounds with S. aureus multidrug ABC transporter SAV1866 (SAV1866) and MecA proteins. Our analysis revealed 14 compounds with robust binding to SAV1866 and one compound with a strong affinity for MecA. Notably, these compounds showed weaker affinities for the MgrA, MepR, and arlR proteins, suggesting specificity in their interactions. Among the 15 promising compounds identified, 1′,2-Binaphthalen-4-one-2′,3-dimethyl-1,8′-epoxy-1,4′,5,5′,8,8′-hexahydroxy-8-O-β-glucopyranosyl-5′-O-β-xylopyranosyl(1→6)-β-glucopyranoside; Cis-3,4-dihydrohamacanthin b; and Mamegakinone exhibited the highest binding affinities to S. aureus SAV1866. These compounds represent diverse chemical classes, including alkaloids, indole derivatives, naphthalenes, and naphthoquinones, offering a range of structural scaffolds for further drug development. Our findings provide valuable insights into potential new antibacterial agents targeting S. aureus SAV1866 and MecA proteins. These results lay the groundwork for future in vitro and in vivo studies to validate these compounds′ efficacy for combating MRSA infections, potentially leading to the development of novel therapeutic strategies against antibiotic-resistant bacteria. Full article
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16 pages, 1432 KiB  
Article
Quorum-Quenching Activity of Myrtus communis Corsican Essential Oil Against the Marine Bacterium Aliivibrio fischeri
by Elisa Hardy, Jean-Pierre Poli, Ange Bighelli, Mathieu Paoli, Thomas Maroselli, Liliane Berti and Elodie Guinoiseau
Microorganisms 2025, 13(6), 1325; https://doi.org/10.3390/microorganisms13061325 - 6 Jun 2025
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Abstract
The quorum-quenching activity of essential oils (EOs) from Corsican aromatic plants was evaluated using the marine bacterium Aliivibrio fischeri as a model system. Among the eleven EOs screened, Myrtus communis EO showed significant interference with QS-regulated phenotypes (swimming motility, bioluminescence, and biofilm formation). [...] Read more.
The quorum-quenching activity of essential oils (EOs) from Corsican aromatic plants was evaluated using the marine bacterium Aliivibrio fischeri as a model system. Among the eleven EOs screened, Myrtus communis EO showed significant interference with QS-regulated phenotypes (swimming motility, bioluminescence, and biofilm formation). Its activity was compared to Origanum vulgaris EO, known for its high carvacrol content and potent QS inhibition. The fractionation of M. communis EO revealed that its most polar fractions exhibited comparable levels of QS-disrupting activity. These chromatographic fractions significantly affected QS-controlled traits, indicating that minor or less volatile compounds may contribute to, or enhance, the overall bioactivity. Furthermore, M. communis EO and its polar fractions displayed stronger anti-QS effects against A. fischeri than O. vulgaris EO. These results highlight M. communis EO as a promising source of natural QS inhibitors and underscore the importance of exploring both complete EOs and their active fractions. This study supports the valorization of Mediterranean endemic flora as a reservoir of bioactive compounds, tested on a model system A. fischeri, and encourages future research on the potential of Myrtus communis against clinical bacterial isolates and the development of novel anti-virulence strategies. Full article
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14 pages, 807 KiB  
Article
In Vitro Antimicrobial Activity of Volatile Compounds from the Lichen Pseudevernia furfuracea (L.) Zopf. Against Multidrug-Resistant Bacteria and Fish Pathogens
by Yasser Essadki, Adel Hilmi, Antonio Cascajosa-Lira, Mariana Girão, El Mehdi Darrag, Rosário Martins, Abderrahmane Romane, Soukaina El Amrani Zerrifi, Richard Mugani, Zakaria Tazart, El Mahdi Redouane, Angeles Jos, Ana M. Cameán, Vitor Vasconcelos, Alexandre Campos, Fatima El Khalloufi, Brahim Oudra, Mustapha Barakate and Maria de Fátima Carvalho
Microorganisms 2024, 12(11), 2336; https://doi.org/10.3390/microorganisms12112336 - 15 Nov 2024
Viewed by 1957
Abstract
Lichens are symbiotic organisms with unique secondary metabolism. Various metabolites from lichens have shown antimicrobial activity. Nevertheless, very few studies have investigated the antimicrobial potential of the volatile compounds they produce. This study investigates the chemical composition and antimicrobial properties of volatile compounds [...] Read more.
Lichens are symbiotic organisms with unique secondary metabolism. Various metabolites from lichens have shown antimicrobial activity. Nevertheless, very few studies have investigated the antimicrobial potential of the volatile compounds they produce. This study investigates the chemical composition and antimicrobial properties of volatile compounds from Pseudevernia furfuracea collected in two regions of Morocco. Hydrodistillation was used to obtain volatile compounds from samples collected in the High Atlas and Middle Atlas. Gas chromatography–mass spectrometry (GC-MS) analysis identified phenolic cyclic compounds as the primary constituents, with atraric acid and chloroatranol being the most abundant. Additionally, eight compounds were detected in lichens for the first time. The antimicrobial activity of these compounds was assessed using disc diffusion and broth microdilution methods. Both samples demonstrated significant antimicrobial effects against multidrug-resistant human bacteria, reference microorganisms, fish pathogens, and Candida albicans, with minimum inhibitory concentrations (MICs) ranging from 1000 µg/mL to 31.25 µg/mL. This study provides the first report on the volatile compounds from Pseudevernia furfuracea and their antimicrobial effects, particularly against fish pathogens, suggesting their potential as novel antimicrobial agents for human and veterinary use. Further research is warranted to explore these findings in more detail. Full article
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15 pages, 2760 KiB  
Article
Isolation, Antibacterial Activity and Molecular Identification of Avocado Rhizosphere Actinobacteria as Potential Biocontrol Agents of Xanthomonas sp.
by Jesús Rafael Trinidad-Cruz, Gabriel Rincón-Enríquez, Zahaed Evangelista-Martínez, Luis López-Pérez and Evangelina Esmeralda Quiñones-Aguilar
Microorganisms 2024, 12(11), 2199; https://doi.org/10.3390/microorganisms12112199 - 31 Oct 2024
Viewed by 1638
Abstract
Actinobacteria, especially the genus Streptomyces, have been shown to be potential biocontrol agents for phytopathogenic bacteria. Bacteria spot disease caused by Xanthomonas spp. may severely affect chili pepper (Capsicum annuum) crops with a subsequent decrease in productivity. Therefore, the objective of [...] Read more.
Actinobacteria, especially the genus Streptomyces, have been shown to be potential biocontrol agents for phytopathogenic bacteria. Bacteria spot disease caused by Xanthomonas spp. may severely affect chili pepper (Capsicum annuum) crops with a subsequent decrease in productivity. Therefore, the objective of the study was to isolate rhizospheric actinobacteria from soil samples treated by physical methods and evaluate the inhibitory activity of the isolates over Xanthomonas. Initially, soil samples collected from avocado tree orchards were treated by dry heat air and microwave irradiation; thereafter, isolation was implemented. Then, antibacterial activity (AA) of isolates was evaluated by the double-layer agar method. Furthermore, the positive/negative effect on AA for selected isolates was evaluated on three culture media (potato-dextrose agar, PDA; yeast malt extract agar, YME; and oat agar, OA). Isolates were identified by 16S rRNA sequence analysis. A total of 198 isolates were obtained; 76 (series BVEZ) correspond to samples treated by dry heat and 122 strains (series BVEZMW) were isolated from samples irradiated with microwaves. A total of 19 dry heat and 25 microwave-irradiated isolates showed AA with inhibition zones (IZ, diameter in mm) ranging from 12.7 to 82.3 mm and from 11.4 to 55.4 mm, respectively. An increment for the AA was registered for isolates cultured on PDA and YME, with an IZ from 21.1 to 80.2 mm and 14.1 to 69.6 mm, respectively. A lower AA was detected when isolates were cultured on OA media (15.0 to 38.1 mm). Based on the 16S rRNA gene sequencing analysis, the actinobacteria belong to the Streptomyces (6) and Amycolatopsis (2) genera. Therefore, the study showed that microwave irradiation is a suitable method to increase the isolation of soil bacteria with AA against Xanthomonas sp. In addition, Streptomyces sp. BVEZ 50 was the isolate with the highest IZ (80.2 mm). Full article
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