Antimicrobial Activity of Natural Products and Plants Extracts

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

Deadline for manuscript submissions: closed (31 March 2024) | Viewed by 10894

Special Issue Editors


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Guest Editor
Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Cluj-Napoca, Romania
Interests: antimicrobial assays; biological activities of natural products; herbal extracts; antimicrobial resistance; zoonotic bacteria
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Guest Editor
Faculty of Pharmacy, Iuliu Hațieganu Medicine and Pharmacy University, 400012 Cluj-Napoca, Romania
Interests: phytochemistry; biological activities of plant-origin bioactive compounds; chromatography
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

There is an urgent need to discover new antimicrobial products that are suitable to tackle microbial resistance. Pathogenic and commensal, human, veterinary, foodborne, and environmental bacteria are constantly associated with elevated levels of antimicrobial resistance. Natural products (NPs) are regarded to be valuable alternatives to conventional medicine given their complex therapeutical properties. Over time, the contribution of NPs to the field of pharmacotherapy has been proven to be significant; multidisciplinary studies are required to assess their suitability as sources of biologically active compounds that could be further utilized in therapy. In this regard, chemical-profile-based standardization of the proposed antimicrobial sources is fundamental. 

This Special Issue aims to extend and update the knowledge regarding the antimicrobial potential of natural products. Potential topics include but are not limited to the following: screening of antimicrobial potential, the antimicrobial efficacy of natural products and plant extracts correlated to their chemical composition and/or other biological properties, interconnected pathways, and mechanisms of action, synergism, and standardization. Original articles as well as reviews of studies on these topics are welcome.

Dr. Mihaela Niculae
Dr. Daniela Hanganu
Guest Editors

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Keywords

  • natural products
  • plant extracts
  • bioactive compounds
  • phytoconstituents
  • antibacterial efficacy
  • in vitro screening
  • in vivo evaluation
  • antibiofilm
  • anti-quorum

Published Papers (7 papers)

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Research

33 pages, 2045 KiB  
Article
Specific Antimicrobial Activities Revealed by Comparative Evaluation of Selected Gemmotherapy Extracts
by Melinda Héjja, Emőke Mihok, Amina Alaya, Maria Jolji, Éva György, Noemi Meszaros, Violeta Turcus, Neli Kinga Oláh and Endre Máthé
Antibiotics 2024, 13(2), 181; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics13020181 - 13 Feb 2024
Viewed by 2264
Abstract
Nowadays, unprecedented health challenges are urging novel solutions to address antimicrobial resistance as multidrug-resistant strains of bacteria, yeasts and moulds are emerging. Such microorganisms can cause food and feed spoilage, food poisoning and even more severe diseases, resulting in human death. In order [...] Read more.
Nowadays, unprecedented health challenges are urging novel solutions to address antimicrobial resistance as multidrug-resistant strains of bacteria, yeasts and moulds are emerging. Such microorganisms can cause food and feed spoilage, food poisoning and even more severe diseases, resulting in human death. In order to overcome this phenomenon, it is essential to identify novel antimicrobials that are naturally occurring, biologically effective and increasingly safe for human use. The development of gemmotherapy extracts (GTEs) using plant parts such as buds and young shoots has emerged as a novel approach to treat/prevent human conditions due to their associated antidiabetic, anti-inflammatory and/or antimicrobial properties that all require careful evaluations. Seven GTEs obtained from plant species like the olive (Olea europaea L.), almond (Prunus amygdalus L.), black mulberry (Morus nigra L.), walnut (Juglans regia L.), blackberry (Rubus fruticosus L.), blackcurrant (Ribes nigrum L.) and bilberry (Vaccinium myrtillus L.) were tested for their antimicrobial efficiency via agar diffusion and microbroth dilution methods. The antimicrobial activity was assessed for eight bacterial (Bacillus cereus, Staphylococcus aureus, Salmonella enterica subsp. enterica, Proteus vulgaris, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Listeria monocytogenes), five moulds (Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum) and one yeast strain (Saccharomyces cerevisiae). The agar diffusion method revealed the blackberry GTE as the most effective since it inhibited the growth of three bacterial, four moulds and one yeast species, having considered the total number of affected microorganism species. Next to the blackberry, the olive GTE appeared to be the second most efficient, suppressing five bacterial strains but no moulds or yeasts. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were then determined for each GTE and the microorganisms tested. Noticeably, the olive GTE appeared to feature the strongest bacteriostatic and bactericidal outcome, displaying specificity for S. aureus, E. faecalis and L. monocytogenes. The other GTEs, such as blueberry, walnut, black mulberry and almond (the list indicates relative strength), were more effective at suppressing microbial growth than inducing microbial death. However, some species specificities were also evident, while the blackcurrant GTE had no significant antimicrobial activity. Having seen the antimicrobial properties of the analysed GTEs, especially the olive and black mulberry GTEs, these could be envisioned as potential antimicrobials that might enhance antibiotic therapies efficiency, while the blackberry GTE would act as an antifungal agent. Some of the GTE mixtures analysed have shown interesting antimicrobial synergies, and all the antimicrobial effects observed argue for extending these studies to include pathological microorganisms. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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17 pages, 2498 KiB  
Article
Applications of Romanian Propolis in Phyto-Inhibitory Activity and Antimicrobial Protection: A Comparative Study
by Ramona Cristina Heghedűş-Mîndru, Mirel Glevitzky, Gabriel Heghedűş-Mîndru, Gabriela-Alina Dumitrel, Maria Popa, Doriana Maria Popa, Isidora Radulov and Mihaela Laura Vică
Antibiotics 2023, 12(12), 1682; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12121682 - 30 Nov 2023
Viewed by 1055
Abstract
Propolis use in medicine, pharmaceutical, cosmetic, and food industries is well known. This study aimed to investigate propolis’ phyto-inhibitory and antimicrobial potential. Nine propolis samples obtained from distinct Romanian regions and characterized in terms of physical–chemical parameters, phenols and flavonoid contents, and antioxidant [...] Read more.
Propolis use in medicine, pharmaceutical, cosmetic, and food industries is well known. This study aimed to investigate propolis’ phyto-inhibitory and antimicrobial potential. Nine propolis samples obtained from distinct Romanian regions and characterized in terms of physical–chemical parameters, phenols and flavonoid contents, and antioxidant properties were prepared as dry propolis and aqueous extracts. The phyto-inhibitory effect was comparatively tested on different cereals: hexaploid bread wheat (Triticum aestivum), maize (Zea mays L.), oats (Avena sativa L.), and barley (Hordeum vulgare L.), while their in vitro antimicrobial activity was evaluated against bacterial and fungal strains specific to cereals: Bacillus subtilis, B. cereus, Proteus mirabilis, Fusarium oxysporum, Penicillium chrysogenum, and Aspergillus niger. All propolis samples showed a phyto-inhibitory effect on the cereals, the most pronounced being corn and oats. Propolis powder samples displayed a lower phyto-inhibitory activity than propolis extracts. Also, all tested products showed inhibitory efficacy against both bacteria and fungi. Furthermore, principal component analysis showed differences between the samples’ phyto-inhibitory and antimicrobial properties depending on the geographical origin. Positive correlations were found between the polyphenols, flavonoid content, and antioxidant activity, respectively. These data support propolis’ phyto-pharmaceutical potential related to its use in plant crop management as an alternative in ecological agriculture. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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16 pages, 883 KiB  
Article
Stachys Species: Comparative Evaluation of Phenolic Profile and Antimicrobial and Antioxidant Potential
by Daniela Benedec, Ilioara Oniga, Daniela Hanganu, Brîndușa Tiperciuc, Adriana Nistor, Ana-Maria Vlase, Laurian Vlase, Cristina Pușcaș, Mihaela Duma, Cristian Cezar Login, Mihaela Niculae and Radu Silaghi-Dumitrescu
Antibiotics 2023, 12(11), 1644; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12111644 - 20 Nov 2023
Cited by 2 | Viewed by 2005
Abstract
This study aimed to investigate the polyphenolic composition and antioxidant and antimicrobial potential of six Romanian Stachys species: S. officinalis, S. germanica, S. byzantina, S. sylvatica, S. palustris, and S. recta. The LC-MS/MS method was used to [...] Read more.
This study aimed to investigate the polyphenolic composition and antioxidant and antimicrobial potential of six Romanian Stachys species: S. officinalis, S. germanica, S. byzantina, S. sylvatica, S. palustris, and S. recta. The LC-MS/MS method was used to analyze the polyphenolic profile, while the phenolic contents were spectrophotometrically determined. The antioxidant activity was evaluated using the following methods: DPPH, FRAP, nitrite-induced autooxidation of hemoglobin, inhibition of cytochrome c-catalyzed lipid peroxidation, and electron paramagnetic resonance spectroscopy. The in vitro antimicrobial properties were assessed using agar-well diffusion, broth microdilution, and antibiofilm assays. Fifteen polyphenols were identified using LC-MS and chlorogenic acid was the major component in all the samples (1131.8–6761.4 μg/g). S. germanica, S. palustris, and S. byzantina extracts each displayed an intense antiradical action in relation to high contents of TPC (6.40 mg GAE/mL), flavonoids (3.90 mg RE/mL), and caffeic acid derivatives (0.89 mg CAE/mL). In vitro antimicrobial and antibiofilm properties were exhibited towards Candida albicans, Gram-positive and Gram-negative strains, with the most intense efficacy recorded for S. germanica and S. byzantina when tested against S. aureus. These results highlighted Stachys extracts as rich sources of bioactive compounds with promising antioxidant and antimicrobial efficacies and important perspectives for developing phytopharmaceuticals. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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16 pages, 911 KiB  
Article
Antibacterial Efficiency of Tanacetum vulgare Essential Oil against ESKAPE Pathogens and Synergisms with Antibiotics
by Horațiu Roman, Adelina-Gabriela Niculescu, Veronica Lazăr and Mihaela Magdalena Mitache
Antibiotics 2023, 12(11), 1635; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12111635 - 17 Nov 2023
Cited by 1 | Viewed by 1169
Abstract
Medicinal plants with multiple targets of action have become one of the most promising solutions in the fight against multidrug-resistant (MDR) bacterial infections. Tanacetum vulgare (Tansy) is one of the medicinal plants with antibacterial qualities that deserve to be studied. Thus, this research [...] Read more.
Medicinal plants with multiple targets of action have become one of the most promising solutions in the fight against multidrug-resistant (MDR) bacterial infections. Tanacetum vulgare (Tansy) is one of the medicinal plants with antibacterial qualities that deserve to be studied. Thus, this research takes a closer look at tansy extract’s composition and antibacterial properties, aiming to highlight its potential against clinically relevant bacterial strains. In this respect, the antibacterial test was performed against several drug-resistant pathogenic strains, and we correlated them with the main isolated compounds, demonstrating the therapeutic properties of the extract. The essential oil was extracted via hydrodistillation, and its composition was characterized via gas chromatography. The main isolated compounds known for their antibacterial effects were α-Thujone, β-Thujone, Eucalyptol, Sabinene, Chrysanthenon, Camphor, Linalool oxide acetate, cis-Carveol, trans-Carveyl acetate, and Germacrene. The evaluation of the antibacterial activity was carried out using the Kirby–Bauer and binary microdilution methods on Gram-positive and Gram-negative MDR strains belonging to the ESKAPE group (i.e., Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). Tansy essential oil showed MIC values ranging from 62.5 to 500 μg/mL against the tested strains. Synergistic activity with different classes of antibiotics (penicillins, cephalosporins, carbapenems, monobactams, aminoglycosides, and quinolones) has also been noted. The obtained results demonstrate that tansy essential oil represents a promising lead for developing new antimicrobials active against MDR alone or in combination with antibiotics. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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23 pages, 6383 KiB  
Article
Biological Characterization of Cleome felina L.f. Extracts for Phytochemical, Antimicrobial, and Hepatoprotective Activities in Wister Albino Rats
by Heena Yaqub Shaikh, Shaik Kalimulla Niazi, Asmatanzeem Bepari, Mary Anne Wong Cordero, Shazima Sheereen, Syed Arif Hussain, Muthuraj Rudrappa, Shashiraj Kariyellappa Nagaraja and Shekappa Ningappa Agadi
Antibiotics 2023, 12(10), 1506; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12101506 - 02 Oct 2023
Cited by 1 | Viewed by 1268
Abstract
The present study aims to explore the phytochemical constitution and biological activities of Cleome felina L.f. (Cleomaceae). C. felina (leaves, stem, and root) extracts (acetone, methanol, and water) were qualitatively assessed for phytochemical presence. Methanolic leaves extract revealed more positive phyto-compounds among all [...] Read more.
The present study aims to explore the phytochemical constitution and biological activities of Cleome felina L.f. (Cleomaceae). C. felina (leaves, stem, and root) extracts (acetone, methanol, and water) were qualitatively assessed for phytochemical presence. Methanolic leaves extract revealed more positive phyto-compounds among all the extracts; further, methanolic leaves extract was evaluated for FTIR, EDX, GCMS, antimicrobial assay, acute toxicity, and paracetamol-induced hepatoprotective activity in Wister albino rats. FTIR and EDX analysis unveiled important functional groups and elements in the leaves. GCMS analysis of methanolic leaves extract exposed 12 active phyto-compounds: major constituents detected were 1-Butanol, 3-methyl-, formate-48.79%; 1-Decanol, 2-ethyl-13.40%; 1,6-Anhydro-β-d-talopyranose-12.49%; Ethene, 1,2-bis(methylthio)-7.22%; Decane-4.02%; 3-Methylene-7, 11-dimethyl-1-dodecene-3.085%; Amlexanox-2.50%; 1,2,3,4-Cyclopentanetetrol, (1α,2β,3β,4α)-2.07%; L-Cysteine S-sulfate-1.84%; n-Hexadecanoic acid-1.70%; and Flucarbazone-1.55%. The antimicrobial assay showed a moderate zone of inhibition against S. aureus, B. cereus, E. coli, P. aeruginosa, C. albicans, and C. glabrata at 100 µL/mL concentration. Additionally, acute toxicity revealed no behavioral sign of the toxic effect. The significant results were obtained for methanolic leaves extract (low-50 and high-100 mg/kg b.wt. dose) for hepatoprotective activity, where it dramatically reduced serum blood biochemical markers (AST, ALT, ALP, Total bilirubin, and cholesterol) and exhibited elevated hepatic antioxidant enzymes (SOD, CAT, and GSH) concentration with lipid peroxidation retardation. To conclude, C. felina methanolic leaves extract ameliorated important phytochemical compounds and showed significant antimicrobial and hepatoprotective efficacy; therefore, utilization of C. felina leaves suggested in pharmacological applications, and in numerous cosmetics, herbicides, and food industries, would be a great scope for future hepatoprotective drug designing. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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13 pages, 1313 KiB  
Article
The Direction of the Antibacterial Effect of Rutin Hydrate and Amikacin
by Maria Miklasińska-Majdanik, Małgorzata Kępa, Tomasz J. Wąsik, Karolina Zapletal-Pudełko, Magdalena Klim and Robert D. Wojtyczka
Antibiotics 2023, 12(9), 1469; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12091469 - 21 Sep 2023
Cited by 3 | Viewed by 1071
Abstract
The aim of the presented study was to examine the in vitro antimicrobial activity of rutin hydrate (RH) alone and in combination with amikacin against 12 reference strains of Gram-positive and Gram-negative bacteria. The antibacterial activity assay was evaluated in the concentration range [...] Read more.
The aim of the presented study was to examine the in vitro antimicrobial activity of rutin hydrate (RH) alone and in combination with amikacin against 12 reference strains of Gram-positive and Gram-negative bacteria. The antibacterial activity assay was evaluated in the concentration range of 2–2048 µg/mL. A serial microdilution method was used to determine the minimal inhibitory concentration (MIC) of the examined compound against reference strains. RH showed varying potential against the tested strains with MICs ranging from 128 to 1024 µg/mL. In order to examine the combinatory profile of RH and amikacin, the fractional inhibitory concentrations (FICs) were determined. The RH–amikacin combination was more active against Gram-negative bacteria where four synergism and two additive interactions were noted. For four out of six Gram-positive isolates, an indifferent effect of RH and amikacin was demonstrated, and for two strains, the tested combination had an additive effect. The results of this study showed that RH possesses antimicrobial potential in vitro towards the tested reference isolates. Moreover, it shows a promising combined effect with amikacin against Gram-negative bacteria. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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18 pages, 2926 KiB  
Article
Streptomyces rugosispiralis sp. nov., a Novel Actinobacterium Isolated from Peat Swamp Forest Soil That Produces Ansamycin Derivatives and Nocardamines
by Trinset Weeraphan, Khomsan Supong, Paranee Sripreechasak, Rumpa Jutakanoke, Supalerk Kowinthanaphat, Somboon Tanasupawat, Pattama Pittayakhajonwut and Wongsakorn Phongsopitanun
Antibiotics 2023, 12(9), 1467; https://0-doi-org.brum.beds.ac.uk/10.3390/antibiotics12091467 - 20 Sep 2023
Viewed by 1245
Abstract
Actinomycetes, especially the genus Streptomyces, are one of the most promising sources of bioactive natural products. In this study, a novel Streptomyces strain, RCU-064T, was isolated from a soil sample collected from a peat swamp forest in Thailand. Strain RCU-064 [...] Read more.
Actinomycetes, especially the genus Streptomyces, are one of the most promising sources of bioactive natural products. In this study, a novel Streptomyces strain, RCU-064T, was isolated from a soil sample collected from a peat swamp forest in Thailand. Strain RCU-064T showed the highest 16S rRNA gene sequence similarity (99.06%) with Streptomyces malaysiensis NBRC 16446T. Based on a polyphasic approach, strain RCU-064T represents a novel species of the genus Streptomyces, for which the name Streptomyces rugosispiralis sp. nov. is proposed. The chemical isolation of the crude ethyl acetate extracts of the strain led to the isolation of six compounds: (1) geldanamycin, (2) 17-O-demethylgeldanamycin, (3) reblastatin, (4) 17-demethoxyreblastatin, (5) nocardamine, and (6) dehydroxynocardamine. These compounds were evaluated for their biological activities. All compounds showed no antimicrobial activity against tested microorganisms used in this study. Compounds (1)–(4) displayed cytotoxic activity against the NCI-H187 cell line, with IC50 values ranging from 0.045–4.250 µg/mL. Cytotoxicity against the MCF-7 cell line was found in compounds (1) and (3) with IC50 values of 3.51 and 1.27 µg/mL, respectively. Compounds (5) and (6) exhibited cytotoxicity only against Vero cells (IC50 of 16.57 µg/mL) and NCI-H187 cells (IC50 of 13.96 µg/mL), respectively. These results indicate that peat swamp forest soil remains a promising reservoir of novel actinomycetes capable of producing bioactive natural products. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Natural Products and Plants Extracts)
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