Chemical Composition and Antimicrobial Activity of Essential Oils II

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Phytochemistry".

Deadline for manuscript submissions: closed (20 January 2023) | Viewed by 6838

Special Issue Editor

Special Issue Information

Dear Colleagues,

Essential oils are volatile and colorless liquids representing the finest aromatic extracts obtained by steam distillation from plants. Each oil is characterized by aromatic chemically pure constituents at room temperature and is subjected to restricted standards of purity. The composition is rich and complex and consists of compounds belong to various chemical classes: terpenes, mostly monoterpenes and sesquiterpenes; terpenoids namely oxygenated compounds such as phenols, alcohols, aldehydes, ketones or ethers and aromatic and aliphatic constituents with low molecular weights. In essential oils there are also a series of minor compounds that can modulate the biological action. Each of bioactive component could show several biological activities including antibacterial and bactericidal ones which have shown growing interest in recent years, proving effective even on strains resistant to several drugs used in the medical field. The antibacterial activity of essential oils depends on their chemical composition and the quantity of each individual compound. In this context it is crucial to carry out a chemical characterization of essential oils in order to describe a volatile profile and identify the possibly responsible molecules of the antimicrobial effect.

This Special Issue is designed to collect scientific papers on essential oils antimicrobial activities and their chemical composition. For this aim, wil be appreciated papers dealing with biological essays to test the activity against microorganisms and chemical analysis techniques to characterize essential by the identification and quantification of individual compounds and their mixtures will be appreciated.

Dr. Stefania Garzoli
Guest Editor

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Keywords

  • essential oils
  • antimicrobial agents
  • minimum inhibitory concentration (MIC)
  • minimum bactericidal
  • concentration (MBC)
  • volatile compounds
  • chemical analyses
  • GC-MS
  • HPLC-MS

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Published Papers (4 papers)

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Research

12 pages, 659 KiB  
Article
Study of the Chemical Composition and Biological Activity of the Essential Oil from Congona (Peperomia inaequalifolia Ruiz and Pav.)
by Eduardo Valarezo, Mercedes Herrera-García, Paola Astudillo-Dávila, Isabel Rosales-Demera, Ximena Jaramillo-Fierro, Luis Cartuche, Miguel Angel Meneses and Vladimir Morocho
Plants 2023, 12(7), 1504; https://doi.org/10.3390/plants12071504 - 30 Mar 2023
Cited by 1 | Viewed by 1635
Abstract
The species Peperomia inaequalifolia, commonly known as congona, is a succulent herbaceous plant belonging to the Piperaceae family, which is used for different purposes in traditional medicine. In this study, the chemical composition, enantiomeric distribution, and biological activity of essential oil isolated [...] Read more.
The species Peperomia inaequalifolia, commonly known as congona, is a succulent herbaceous plant belonging to the Piperaceae family, which is used for different purposes in traditional medicine. In this study, the chemical composition, enantiomeric distribution, and biological activity of essential oil isolated from the leaves of this species was determined. Hydrodistillation was used to isolate the essential oil. Gas chromatography coupled to mass spectrometry was used to determine the qualitative composition, a gas chromatograph equipped with a flame ionization detector was used to determine quantitative composition, and gas chromatography on an enantioselective column was used to determine enantiomeric distribution. Antibacterial activity was determined using the broth microdilution method, for which we used three Gram-positive cocci bacteria, a Gram-positive bacilli bacterium, and three Gram-negative bacilli bacteria. 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cations and 2,2-diphenyl-1-picrylhydryl (DPPH) radicals were used as reagents for determining the antioxidant activity of the essential oil. The spectrophotometric method was used to analyze the acetylcholinesterase inhibitory effect of the essential oil. The yield of leaves in essential oil was 0.16 ± 0.01% (v/w). Forty-three chemical compounds were identified in the essential oil, which represent 97.46% of the total composition. Sesquiterpene hydrocarbons were the most representative group, with 24 compounds (21.63%). The principal constituents were found to be elemicin (27.44 ± 1.35%), bisabolol <α-> (17.76 ± 1.38), myristicin (15.45 ± 0.86), methyl eugenol (6.22 ± 0.24), viridiflorene (6.81 ± 0.10), and safrole (6.68 ± 0.23). Three pairs of enantiomers were identified in the essential oil of Peperomia inaequalifolia. Essential oil presented a minimum inhibitory concentration (MIC) of 4000 μg/mL against Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli. The antioxidant activity of the essential oil was strong according to the DPPH and ABTS methods, with a half radical scavenging capacity (SC50) of 293.76 ± 3.12 µg/mL and 226.86 ± 0.05 µg/mL, respectively. Additionally, the essential oil reported moderate anticholinesterase activity, with an IC50 of 43.93 ± 1.05 µg/mL. Full article
(This article belongs to the Special Issue Chemical Composition and Antimicrobial Activity of Essential Oils II)
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15 pages, 319 KiB  
Article
Vapor and Liquid Phase Profiles of Essential Oils from Abies, Picea and Pinus Species and Their Phytotoxic Interactions with Weed Growth in Pre- and Post-Emergence Conditions
by Stefania Garzoli, Valentina Vaglia, Marcello Iriti and Sara Vitalini
Plants 2023, 12(5), 1172; https://doi.org/10.3390/plants12051172 - 3 Mar 2023
Cited by 1 | Viewed by 1213
Abstract
The chemical content of essential oils (EO) obtained from the leaves of four Pinaceae (Abies alba, Picea abies, Pinus cembra and Pinus mugo) was investigated by SPME-GC-MS technique. The vapor phase was characterized by the monoterpenes with values higher [...] Read more.
The chemical content of essential oils (EO) obtained from the leaves of four Pinaceae (Abies alba, Picea abies, Pinus cembra and Pinus mugo) was investigated by SPME-GC-MS technique. The vapor phase was characterized by the monoterpenes with values higher than 95.0%. Among them, α-pinene (24.7–48.5%), limonene (17.2–33.1%) and β-myrcene (9.2–27.8%) were the most abundant. The monoterpenic fraction prevailed over the sesquiterpenic one (≥74.7%) in the EO liquid phase. Limonene was the major compound in A. alba (30.4%), P. abies (20.3%) and P. mugo (78.5%), while α-pinene in P. cembra (36.2%). Regarding the phytotoxic properties, EOs were studied at different doses (2–100 μL) and concentrations (2–20/100 μL/mL). All EOs were found to be significantly active (p-value ˂ 0.05) against the two recipient species in a dose-dependent way. In pre-emergence tests, germination of Lolium multiflorum and Sinapis alba was reduced by up to 62–66% and 65–82%, respectively, as well as their growth by up to 60–74% and 65–67%, due to the effects of compounds in both the vapor and liquid phases. In post-emergence conditions, at the highest concentration, the phytotoxicity of EOs caused heavy symptoms and, in the case of S. alba, A. alba EO completely destroyed (100%) the treated seedlings. Full article
(This article belongs to the Special Issue Chemical Composition and Antimicrobial Activity of Essential Oils II)
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13 pages, 667 KiB  
Article
Study of the Chemical Profile and Anti-Fungal Activity against Candida auris of Cinnamomum cassia Essential Oil and of Its Nano-Formulations Based on Polycaprolactone
by Roberto Rosato, Edoardo Napoli, Giuseppe Granata, Maura Di Vito, Stefania Garzoli, Corrada Geraci, Silvia Rizzo, Riccardo Torelli, Maurizio Sanguinetti and Francesca Bugli
Plants 2023, 12(2), 358; https://doi.org/10.3390/plants12020358 - 12 Jan 2023
Cited by 5 | Viewed by 1954
Abstract
Background: Candida auris represents an emerging pathogen that results in nosocomial infections and is considered a serious global health problem. The aim of this work was to evaluate the in vitro antifungal efficacy of Cinnamomum cassia essential oil (CC-EO) pure or formulated in [...] Read more.
Background: Candida auris represents an emerging pathogen that results in nosocomial infections and is considered a serious global health problem. The aim of this work was to evaluate the in vitro antifungal efficacy of Cinnamomum cassia essential oil (CC-EO) pure or formulated in polycaprolactone (PCL) nanoparticles against ten clinical strains of C. auris. Methods: nanoparticles of PCL were produced using CC-EO (nano-CC-EO) and cinnamaldehyde (CIN) through the nanoprecipitation method. The chemical profile of both CC-EO and nano-CC-EO was evaluated using SPME sampling followed by GC-MS analysis. Micro-broth dilution tests were performed to evaluate both fungistatic and fungicidal effectiveness of CC-EO and CIN, pure and nano-formulated. Furthermore, checkerboard tests to evaluate the synergistic action of CC-EO or nano-CC-EO with micafungin or fluconazole were conducted. Finally, the biofilm disrupting activity of both formulations was evaluated. Results: GC-MS analysis shows a different composition between CC-EO and nano-CC-EO. Moreover, the microbiological analyses do not show any variation in antifungal effectiveness either towards the planktonic form (MICCC-EO = 0.01 ± 0.01 and MICnano-CC-EO = 0.02 ± 0.01) or the biofilm form. No synergistic activity with the antifungal drugs tested was found. Conclusions: both CC-EO and nano-CC-EO show the same antimicrobial effectiveness and are potential assets in the fight against C. auris. Full article
(This article belongs to the Special Issue Chemical Composition and Antimicrobial Activity of Essential Oils II)
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16 pages, 850 KiB  
Article
Chemical Study and Comparison of the Biological Activities of the Essential Oils of Helichrysum petiolare, H. cymosum, and H. odoratissimum
by Selena O. Adewinogo, Rajan Sharma, Charlene W. J. Africa, Jeanine L. Marnewick and Ahmed A. Hussein
Plants 2022, 11(19), 2606; https://doi.org/10.3390/plants11192606 - 3 Oct 2022
Cited by 3 | Viewed by 1566
Abstract
Helichrysum species are prominent South African medicinal plants. From the essential oils (EOs) of three Helichrysum species, H. petiolare, H. odoratissimum, and H. cymosum, sixty-three constituent components were identified, with hydrocarbons and oxygenated monoterpenes and sesquiterpenes as [...] Read more.
Helichrysum species are prominent South African medicinal plants. From the essential oils (EOs) of three Helichrysum species, H. petiolare, H. odoratissimum, and H. cymosum, sixty-three constituent components were identified, with hydrocarbons and oxygenated monoterpenes and sesquiterpenes as major components. The compounds were analyzed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy. In H. petiolare EO, the major components were faurinone (20.66%) and (E)-β-ocimene (17.21%). Faurinone was isolated from this EO for the first time. In H. odoratissimum, 1,8-cineole (17.44%) and α-pinene, and γ-curcumene (15.76%) were the major components whereas, in H. cymosum, α-pinene (29.82%) and (E)-caryophyllene (19.20%) were the major components. In the antibacterial activity study, the EOs were tested against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The EOs were found to possess low antibacterial, anti-tyrosinase, and photoprotection activities and moderate antioxidant capacities, thus establishing these Helichrysum EOs as valuable antioxidant agents. Full article
(This article belongs to the Special Issue Chemical Composition and Antimicrobial Activity of Essential Oils II)
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