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Antibacterial Properties of Plant Extracts: Preparation and Application

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 23469

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National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Interests: nanomaterials; water treatment; extraction; plant stress; bioactive compounds
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Special Issue Information

Dear Colleagues,

Biologically active compounds obtained from different plants present various properties, such as antibacterial and antioxidant activity, colour, flavour etc. Due to their properties, the plant extracts can be used in the food industry as replacements for synthetic food additives. Thus, natural extracts of plant origin are good alternatives for preservatives, dyes, and synthetic aromas, with the added benefit of enriching the nutritional value of the food. Additionally, due to their properties, the plant extracts can be used in the pharmaceutical and cosmetic industries.

In this Special Issue, we invite investigators to contribute original research and review articles related to the preparation and characterization of plant extracts, as well as applications of plant extracts based on antibacterial and antioxidant properties. Potential topics include, but are not limited to, the following:

  • New techniques for obtaining plant extracts with a high content of bioactive compounds;
  • Characterization of plant extracts, including antibacterial properties;
  • Applications of plant extracts as antibacterial and antioxidants agents.

Dr. Soran Maria Loredana
Guest Editor

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Keywords

  • plant extracts
  • preparation
  • antibacterial
  • antioxidant

Published Papers (10 papers)

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Research

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20 pages, 1813 KiB  
Article
Effect of Microencapsulated Basil Extract on Cream Cheese Quality and Stability
by Liliana Popescu, Daniela Cojocari, Ildiko Lung, Irina Kacso, Alexandra Ciorîţă, Aliona Ghendov-Mosanu, Greta Balan, Adela Pintea and Rodica Sturza
Molecules 2023, 28(8), 3305; https://doi.org/10.3390/molecules28083305 - 07 Apr 2023
Cited by 3 | Viewed by 1322
Abstract
The antimicrobial and antioxidant effects of plant extracts are well known, but their use is limited because they affect the physicochemical and sensory characteristics of products. Encapsulation presents an option to limit or prevent these changes. The paper presents the composition of individual [...] Read more.
The antimicrobial and antioxidant effects of plant extracts are well known, but their use is limited because they affect the physicochemical and sensory characteristics of products. Encapsulation presents an option to limit or prevent these changes. The paper presents the composition of individual polyphenols (HPLC–DAD-ESI-MS) from basil (Ocimum basilicum L.) extracts (BE), and their antioxidant activity and inhibitory effects against strains of Staphylococcus aureus, Geobacillus stearothermophilus, Bacillus cereus, Candida albicans, Enterococcus faecalis, Escherichia coli, and Salmonella Abony. The BE was encapsulated in sodium alginate (Alg) using the drop technique. The encapsulation efficiency of microencapsulated basil extract (MBE) was 78.59 ± 0.01%. SEM and FTIR analyses demonstrated the morphological aspect of the microcapsules and the existence of weak physical interactions between the components. Sensory, physicochemical and textural properties of MBE-fortified cream cheese were evaluated over a 28-day storage time at 4 °C. In the optimal concentration range of 0.6–0.9% (w/w) MBE, we determined the inhibition of the post-fermentation process and the improvement in the degree of water retention. This led to the improvement of the textural parameters of the cream cheese, contributing to the extension of the shelf life of the product by 7 days. Full article
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19 pages, 3310 KiB  
Article
Antibacterial and Antibiofilm Effects of Allelopathic Compounds Identified in Medicago sativa L. Seedling Exudate against Escherichia coli
by Sara Abouzeid, Ulrike Beutling, Engy Elekhnawy and Dirk Selmar
Molecules 2023, 28(6), 2645; https://doi.org/10.3390/molecules28062645 - 14 Mar 2023
Cited by 2 | Viewed by 2352
Abstract
In this study, the allelopathic properties of Medicago sativa L. (alfalfa) seedling exudates on the germination of seeds of various species were investigated. The compounds responsible for the allelopathic effects of alfalfa were identified and characterized by employing liquid chromatography ion mobility high-resolution [...] Read more.
In this study, the allelopathic properties of Medicago sativa L. (alfalfa) seedling exudates on the germination of seeds of various species were investigated. The compounds responsible for the allelopathic effects of alfalfa were identified and characterized by employing liquid chromatography ion mobility high-resolution mass spectrometry. Crude exudates inhibited the germination of seeds of all various plant species tested. Overall, nine compounds in alfalfa were identified and quantified. The most predominant compounds were a hyperoside representing a flavonoid glucoside, the non-proteinogenic amino acid canavanine, and two dipeptides, identified as H-Glu-Tyr-OH and H-Phe-Glu-OH. The latter corresponds to the first finding that dipeptides are exuded from alfalfa seedlings. In addition, the antibacterial and antibiofilm activities of alfalfa exudate and its identified compounds were elucidated. Both hyperoside and canavanine revealed the best antibacterial activity with minimum inhibitory concentration (MIC) values that ranged from 8 to 32 and 32 to 256 µg/mL, respectively. Regarding the antibiofilm action, hyperoside and canavanine caused a decline in the percentage of E. coli isolates that possessed a strong and moderate biofilm-forming potential from 68.42% to 21.05% and 31.58%, respectively. Studies on their inhibiting effects exhibit that these major substances are predominantly responsible for the allelopathic and antimicrobial effects of the crude exudates. Full article
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19 pages, 33238 KiB  
Article
Functionalized Sulfur-Containing Heterocyclic Analogs Induce Sub-G1 Arrest and Apoptotic Cell Death of Laryngeal Carcinoma In Vitro
by B. Haridevamuthu, Tamilvelan Manjunathan, Carlton Ranjith Wilson Alphonse, Rajendran Saravana Kumar, Sundaram Thanigaivel, Somasundaram Chandra Kishore, Vickram Sundaram, Pushparathinam Gopinath, Jesu Arockiaraj and Stefano Bellucci
Molecules 2023, 28(4), 1856; https://doi.org/10.3390/molecules28041856 - 15 Feb 2023
Cited by 5 | Viewed by 2125
Abstract
In this study, we speculate that the hydroxyl-containing benzo[b]thiophene analogs, 1-(3-hydroxybenzo[b]thiophen-2-yl) ethanone (BP) and 1-(3-hydroxybenzo[b]thiophen-2-yl) propan-1-one hydrate (EP), might possess antiproliferative activity against cancer cells. Hydroxyl-containing BP and EP show selectivity towards laryngeal cancer cells (HEp2), with IC50 values of 27.02 ± [...] Read more.
In this study, we speculate that the hydroxyl-containing benzo[b]thiophene analogs, 1-(3-hydroxybenzo[b]thiophen-2-yl) ethanone (BP) and 1-(3-hydroxybenzo[b]thiophen-2-yl) propan-1-one hydrate (EP), might possess antiproliferative activity against cancer cells. Hydroxyl-containing BP and EP show selectivity towards laryngeal cancer cells (HEp2), with IC50 values of 27.02 ± 1.23 and 35.26 ± 2.15 µM, respectively. The hydroxyl group present in the third position is responsible for the anticancer activity and is completely abrogated when the hydroxyl group is masked. BP and EP enhance the antioxidant enzyme activity and reduce the ROS production, which are correlated with the antiproliferative effect in HEp-2 cells. An increase in the BAX/BCL-2 ratio occurs during the BP and EP treatment and activates the caspase cascade, resulting in apoptosis stimulation. It also arrests the cells in the Sub-G1 phase, indicating the induction of apoptosis. The molecular docking and simulation studies predicted a strong interaction between BP and the CYP1A2 protein, which could aid in combinational therapy by enhancing the bioavailability of the drugs. BP and EP possess an antioxidant property with low antiproliferative effects (~5.18 µg/mL and ~7.8 µg/mL) as a standalone drug, therefore, they can be combined with other drugs for effective chemotherapy that might trigger the effect of pro-oxidant drug on healthy cells. Full article
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11 pages, 800 KiB  
Article
Optimization of Lipid Extraction from Spirulina spp. by Ultrasound Application and Mechanical Stirring Using the Taguchi Method of Experimental Design
by Emilia Neag, Zamfira Stupar, Cerasel Varaticeanu, Marin Senila and Cecilia Roman
Molecules 2022, 27(20), 6794; https://doi.org/10.3390/molecules27206794 - 11 Oct 2022
Cited by 4 | Viewed by 1282
Abstract
The present study uses the Taguchi method of experimental design to optimize lipid extraction from Spirulina spp. by ultrasound application and mechanical stirring. A Taguchi L9 orthogonal array was used to optimize various parameters, such as methanol: chloroform (M:C) ratio, biomass: solvent [...] Read more.
The present study uses the Taguchi method of experimental design to optimize lipid extraction from Spirulina spp. by ultrasound application and mechanical stirring. A Taguchi L9 orthogonal array was used to optimize various parameters, such as methanol: chloroform (M:C) ratio, biomass: solvent ratio, and extraction time for lipid extraction. The results were analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). The biomass: solvent ratio significantly influenced lipid content (p < 0.05) with 92.1% and 92.3% contributions to the lipid and S/N ratio data, respectively. The extraction time presented a contribution value of 5.0%, while the M:C ratio presented the most negligible contribution of 0.4% for S/N data. The optimum extraction conditions were: M:C ratio of 1:1, biomass: solvent ratio of 1:60, and extraction time of 30 min. The predominant fatty acids were palmitic acid (44.5%), linoleic acid (14.9%), and gamma-linolenic acid (13.4%). The confirmation experiments indicated a lipid content of 8.7%, within a 95% confidence interval, proving the Taguchi method’s effectiveness in optimizing the process parameters for lipid extraction. Full article
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26 pages, 2003 KiB  
Article
Biologically Active Preparations from the Leaves of Wild Plant Species of the Genus Rubus
by Łukasz Kucharski, Krystyna Cybulska, Edyta Kucharska, Anna Nowak, Robert Pełech and Adam Klimowicz
Molecules 2022, 27(17), 5486; https://doi.org/10.3390/molecules27175486 - 26 Aug 2022
Cited by 2 | Viewed by 1463
Abstract
The plants of the genus Rubus (R.) are applied as antiseptic agents in the treatment of skin diseases. Despite the great interest in plants of this genus, there are few reports on the antioxidant and biological activities of preparations obtained from [...] Read more.
The plants of the genus Rubus (R.) are applied as antiseptic agents in the treatment of skin diseases. Despite the great interest in plants of this genus, there are few reports on the antioxidant and biological activities of preparations obtained from the leaves of these plants. Therefore, we decided to evaluate the antioxidant activity of preparations from leaves of wild plant species of the genus Rubus using the frequently applied DPPH, ABTS, and FRAP methods, as well as to determine the total polyphenol content using the Folin–Ciocalteau method and perform qualitative evaluation by gas chromatography–mass spectrometry (GC-MS). The bactericidal and fungicidal activities of the obtained preparations were evaluated by applying laboratory tests: using the disc and the well methods based on the standards EN 13697:2019, EN 13697:2015, and EN 1500:2013. Microbiological tests of the plant preparations against bacteria, fungi, and yeasts isolated from the environment and against reference strains were performed. Moreover, antimicrobial testing of antibiotics against the tested strains was performed for comparison. The n-octanol/water partition coefficient of the obtained preparations was determined by the shake-flask method to determine their lipophilicity. According to the results, a high content of polyphenols and other antioxidant and biologically active compounds can be thought of as the parameter responsible for the effective activity of plant preparations obtained from wild plant species of the genus Rubus. The methods for determining bactericidal and fungicidal activity clearly demonstrates that preparations with reduced ethanol content exhibit bactericidal and fungicidal activity on surfaces. Testing of hand disinfection by means of rubbing with the preparations confirmed their antimicrobial activity against Escherichia coli K12 NCTC 10538. The obtained results show that the tested preparations exhibit on average two times lower activity against the reference bacterial strains than comparable antibiotics. The preparations obtained from the leaves of R. idaeus L. and R. fruticosus L. could complement classical antibiotics. While environmental bacteria showed a similar response to the preparations and antibiotics, their sensitivity was about one-third less than that of the reference strains. Our studies have shown that the obtained preparations are highly hydrophilic (logP < 0). Thus, these preparations can only be used in lipid bilayers in the aqueous core of liposomes, not in the lipid envelope. Full article
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13 pages, 1756 KiB  
Article
Inhibition of Bacterial Adhesion and Biofilm Formation by Seed-Derived Ethanol Extracts from Persea americana Mill
by Silvia del Carmen Molina Bertrán, Lianet Monzote, Davie Cappoen, Julio Cesar Escalona Arranz, Mario Juan Gordillo Pérez, Annarli O. Rodríguez-Ferreiro, Idelsy Chill Nuñez, Claudina Pérez Novo, Daniel Méndez, Paul Cos and Gabriel Llauradó Maury
Molecules 2022, 27(15), 5009; https://doi.org/10.3390/molecules27155009 - 06 Aug 2022
Cited by 5 | Viewed by 2017
Abstract
The increase in antibiotic resistance demands innovative strategies to combat microorganisms. The current study evaluated the antibacterial and antivirulence effects of ethanol extracts from Persea americana seeds obtained by the Soxhlet (SE) and maceration (MaE) methods. The UHPLC-DAD-QTOF analysis showed mainly the presence [...] Read more.
The increase in antibiotic resistance demands innovative strategies to combat microorganisms. The current study evaluated the antibacterial and antivirulence effects of ethanol extracts from Persea americana seeds obtained by the Soxhlet (SE) and maceration (MaE) methods. The UHPLC-DAD-QTOF analysis showed mainly the presence of polyphenols and neolignan. Ethanol extracts were not cytotoxic to mammalian cells (CC50 > 500 µg/mL) and displayed a moderate antibacterial activity against Pseudomonas aeruginosa (IC50 = 87 and 187 µg/mL) and Staphylococcus aureus (IC50 = 144 and 159 µg/mL). Interestingly, no antibacterial activity was found against Escherichia coli. SE and MaE extracts were also able to significantly reduce the bacterial adhesion to A549 lung epithelial cells. Additionally, both extracts inhibited the biofilm growth at 24 h and facilitated the release of internal cell components in P. aeruginosa, which might be associated with cell membrane destabilization. Real-time PCR and agarose electrophoresis gel analysis indicated that avocado seed ethanol extracts (64 µg/mL) downregulated virulence-related factors such as mexT and lasA genes. Our results support the potential of bioproducts from P. americana seeds as anti-adhesive and anti-biofilm agents. Full article
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20 pages, 5364 KiB  
Article
The Effect of Copper Salts on Bioactive Compounds and Ultrastructure of Wheat Plants
by Otilia Culicov, Adina Stegarescu, Maria-Loredana Soran, Ildiko Lung, Ocsana Opriș, Alexandra Ciorîță and Pavel Nekhoroshkov
Molecules 2022, 27(15), 4835; https://doi.org/10.3390/molecules27154835 - 28 Jul 2022
Viewed by 1236
Abstract
Abiotic stress agents, among them metal stress, can cause oxidative damage to plant cells. In defense, plants can increase the production of secondary metabolites in order to mitigate the harmful effects caused by them. The purpose of this work was to evaluate the [...] Read more.
Abiotic stress agents, among them metal stress, can cause oxidative damage to plant cells. In defense, plants can increase the production of secondary metabolites in order to mitigate the harmful effects caused by them. The purpose of this work was to evaluate the effect of two types of copper salts (CuSO4 and Cu(NO3)2), added in two different amounts in soil (150 mg/kg, respectively 300 mg/kg), on assimilating pigments, total polyphenols, antioxidant activity and the elemental composition of wheat. The obtained results were compared with those from control plants grown in the same conditions but without copper salts. The amount of assimilating pigments, total polyphenols, and antioxidant activity respectively increases or decreases in the plants treated with copper salts compared to the control depending on the stage of development of the plant. No significant damage induced in the leaves of the wheat plants treated with the selected salts was observed following the TEM analysis. In six-week-old plants it was observed by EDX analysis that the salts are transformed into nanoparticles. The bioactive compounds, elemental composition and their interaction is influenced by concentration of metal’s salt, type of salt and exposure period. Full article
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18 pages, 1140 KiB  
Article
Chemometric Optimization of Biologically Active Compounds Extraction from Grape Marc: Composition and Antimicrobial Activity
by Aliona Ghendov-Mosanu, Daniela Cojocari, Greta Balan, Antoanela Patras, Ildiko Lung, Maria-Loredana Soran, Ocsana Opriş, Elena Cristea and Rodica Sturza
Molecules 2022, 27(5), 1610; https://doi.org/10.3390/molecules27051610 - 28 Feb 2022
Cited by 18 | Viewed by 2711
Abstract
The article focuses on the optimization of the extraction process of biologically active compounds (BAC) from grape marc—a by-product of the wine industry. The influence of temperature, specifically 30 °C, 45 °C and 65 °C, and ethanol concentration in solutions, specifically 0–96% ( [...] Read more.
The article focuses on the optimization of the extraction process of biologically active compounds (BAC) from grape marc—a by-product of the wine industry. The influence of temperature, specifically 30 °C, 45 °C and 65 °C, and ethanol concentration in solutions, specifically 0–96% (v/v) on the extraction yield of polyphenols, flavonoids, tannins and anthocyanins, were investigated. The composition of individual polyphenols, anthocyanins and organic acids, antioxidant activity (DPPH and ABTS) and CIELab chromatic characteristics of the grape marc extracts (GME), were characterized. The microbiostatic and microbicidal effects in direct contact of GME with pathogenic microorganisms, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, were determined in vitro. The influence of extraction parameters on the total polyphenol content (TPC), total flavonoid content (TFC), tannin content (TC), total anthocyanin content (TAC) and their interdependencies were studied using information analysis. A mathematical model was developed on cubic spline functions. The analysis of individual compounds showed the presence of a wide range of flavonoids (procyanidin B2, procyanidin B1, hyperoside and quercetin), flavones (catechin), hydroxybenzoic acid derivatives (gallic, protocatechuic, p-hydroxybenzoic acids, m-hydroxybenzoic acid, syringic acid), hydroxycinic acid derivatives and ferulic acid methyl ester. The malvidol-3-glucoside was the main anthocyanin identified in the extract. A high amount of tartaric acid was also found. GME showed significant antimicrobial activity against Gram-positive bacteria and lower activity against Gram-negative bacteria. Full article
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Review

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31 pages, 1575 KiB  
Review
Biosynthesis of Nanoparticles Using Plant Extracts and Essential Oils
by Sérgio Antunes Filho, Mayara Santana dos Santos, Otávio Augusto L. dos Santos, Bianca Pizzorno Backx, Maria-Loredana Soran, Ocsana Opriş, Ildiko Lung, Adina Stegarescu and Mohamed Bououdina
Molecules 2023, 28(7), 3060; https://doi.org/10.3390/molecules28073060 - 29 Mar 2023
Cited by 10 | Viewed by 5647
Abstract
Plant extracts and essential oils have a wide variety of molecules with potential application in different fields such as medicine, the food industry, and cosmetics. Furthermore, these plant derivatives are widely interested in human and animal health, including potent antitumor, antifungal, anti-inflammatory, and [...] Read more.
Plant extracts and essential oils have a wide variety of molecules with potential application in different fields such as medicine, the food industry, and cosmetics. Furthermore, these plant derivatives are widely interested in human and animal health, including potent antitumor, antifungal, anti-inflammatory, and bactericidal activity. Given this diversity, different methodologies were needed to optimize the extraction, purification, and characterization of each class of biomolecules. In addition, these plant products can still be used in the synthesis of nanomaterials to reduce the undesirable effects of conventional synthesis routes based on hazardous/toxic chemical reagents and associate the properties of nanomaterials with those present in extracts and essential oils. Vegetable oils and extracts are chemically complex, and although they are already used in the synthesis of nanomaterials, limited studies have examined which molecules are effectively acting in the synthesis and stabilization of these nanostructures. Similarly, few studies have investigated whether the molecules coating the nanomaterials derived from these extracts and essential oils would bring benefits or somehow reduce their potential activity. This synergistic effect presents a promising field to be further explored. Thus, in this review article, we conducted a comprehensive review addressing the main groups of molecules present in plant extracts and essential oils, their extraction capacity, and available methodologies for their characterization. Moreover, we highlighted the potential of these plant products in the synthesis of different metallic nanomaterials and their antimicrobial capacity. Furthermore, we correlated the extract’s role in antimicrobial activity, considering the potential synergy between molecules from the plant product and the different metallic forms associated with nanomaterials. Full article
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23 pages, 2036 KiB  
Review
Artemisia vestita: A Folk Medicine with Hidden Herbal Fortune
by Shivani Dogra, Joginder Singh, Bhupendra Koul and Dhananjay Yadav
Molecules 2023, 28(6), 2788; https://doi.org/10.3390/molecules28062788 - 20 Mar 2023
Cited by 2 | Viewed by 2348
Abstract
Traditional medicines are nature’s gift and our native heritage, which play a vital role in maintaining a disease-free life. Artemisia vestita Wall. ex Besser (family: Asteraceae), popularly known as “Kubsha” or “Russian wormwood”, is a highly enriched folklore medicine with wound- healing, [...] Read more.
Traditional medicines are nature’s gift and our native heritage, which play a vital role in maintaining a disease-free life. Artemisia vestita Wall. ex Besser (family: Asteraceae), popularly known as “Kubsha” or “Russian wormwood”, is a highly enriched folklore medicine with wound- healing, antiphlogistic, antifebrile, antifeedant, anti-helminthic, antimicrobial, antiviral, antitumor, and antiproliferative potential attributed to the presence of various volatile and non-volatile secondary metabolites. A systematic and extensive review of the literature on A. vestita was carried out via the Web of Science, PubMed, INMEDPLAN, EMBASE, Google Scholar, and NCBI, as well as from several websites. The highly relevant literature contained in 109 references was selected for further inclusion in this review. A total of 202 bioactive compounds belonging to different chemical classes such as terpenoids, coumarins, flavonoids, alkaloids, acetylenes, tannins, carotenoids, and sterols have been reported in A. vestita, which are responsible for different pharmacological activities. The chemical structures obtained from the PubChem and Chem Spider databases were redrawn using the software Chem Draw® version 8.0. This review paper summarizes the distribution, botanical description, phytochemistry, pharmacological activities, and conservation of A. vestita, which will assist scientists for further investigation. Extensive studies on the active constituents, pharmaceutical standardization, mode of action, and sustainable conservation of A. vestita are needed to further explore its wound-healing and allied medicinal properties. Full article
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