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Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence

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

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 15874

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Dr. Horváth Györgyi

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Department of Pharmacognosy, University of Pécs, Pécs, Hungary
Interests: pharmacognosy; phytotherapy; secondary plant metabolites; essential oil; antibacterial activity; anti-inflammatory effect; biofilm
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Special Issue Information

Dear Colleagues,

Essential oils (EOs) and their compounds are one of the most “popular” and interesting agents among secondary plant metabolites. EOs are a mixture of volatile compounds, mainly mono- and sesquiterpenoids, phenylpropanoids, etc., and contain hundreds of individual chemical constituents, which may have biological activity. They are secreted in special cells in secretion ducts or cavities or in glandular hairs, from which they are extracted by distillation (water–steam or hydro–distillation) or pressing. Because of the spread of multidrug-resistant bacteria and their growing antibiotic-resistance, many research groups have focused their research on investigating the antimicrobial activities of EOs. Not only can nosocomial infections and antibiotic-resistance cause serious health problems, but they can also cause other diseases, such as neurological, cardiovascular, and respiratory diseases as well as cancer, etc., all of which affect a large portion of the world’s population.

The aim of this Special Issue is to collect original research and critical reviews on antibacterial and biological activity and the mode of action of EOs and/or their compounds. Papers offering novel alternatives to antibiotics, new antibacterial therapies to control or prevent infections, or new solutions to treat inflammatory health conditions are welcome. Not only in vitro but also experimental or clinical studies that are focused on the antibacterial and/or biological activity of EOs or their pharmaceutical formulation are greatly encouraged.

Dr. Horváth Györgyi
Guest Editor

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Keywords

essential oil
antibacterial activity
anti-inflammatory effect
mode of action
pharmaceutical formulation
animal experiment
clinical evidence

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Published Papers (6 papers)

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Research

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19 pages, 2710 KiB

Open AccessArticle

Antioxidant, Volatile Compounds; Antimicrobial, Anti-Inflammatory, and Dermatoprotective Properties of Cedrus atlantica (Endl.) Manetti Ex Carriere Essential Oil: In Vitro and In Silico Investigations

by Naoufal El Hachlafi, Hanae Naceiri Mrabti, Samiah Hamad Al-Mijalli, Mohamed Jeddi, Emad M. Abdallah, Nesrine Benkhaira, Hanine Hadni, Hamza Assaggaf, Ahmed Qasem, Khang Wen Goh, Ammar AL-Farga, Abdelhakim Bouyahya and Kawtar Fikri-Benbrahim

Molecules 2023, 28(15), 5913; https://doi.org/10.3390/molecules28155913 - 6 Aug 2023

Cited by 23 | Viewed by 3118

Abstract

Cedrus atlantica (Endl.) Manetti ex Carriere is an endemic tree possessing valuable health benefits which has been widely used since time immemorial in international traditional pharmacopoeia. The aim of this exploratory investigation is to determine the volatile compounds of C. atlantica essential oils (CAEOs) and to examine their in vitro antimicrobial, antioxidant, anti-inflammatory, and dermatoprotective properties. In silico simulations, including molecular docking and pharmacokinetics absorption, distribution, metabolism, excretion, and toxicity (ADMET), and drug-likeness prediction were used to reveal the processes underlying in vitro biological properties. Gas chromatography–mass spectrophotometry (GC-MS) was used for the chemical screening of CAEO. The antioxidant activity of CAEO was investigated using four in vitro complementary techniques, including ABTS and DPPH radicals scavenging activity, ferric reductive power, and inhibition of lipid peroxidation (β-carotene test). Lipoxygenase (5-LOX) inhibition and tyrosinase inhibitory assays were used for testing the anti-inflammatory and dermatoprotective properties. GC-MS analysis indicated that the main components of CAEO are β-himachalene (28.99%), α-himachalene (14.43%), and longifolene (12.2%). An in vitro antimicrobial activity of CAEO was examined against eleven strains of Gram-positive bacteria (three strains), Gram-negative bacteria (four strains), and fungi (four strains). The results demonstrated high antibacterial and antifungal activity against ten of them (>15 mm zone of inhibition) using the disc-diffusion assay. The microdilution test showed that the lowest values of MIC and MBC were recorded with the Gram-positive bacteria in particular, which ranged from 0.0625 to 0.25 % v/v for MIC and from 0.5 to 0.125 % v/v for MBC. The MIC and MFC of the fungal strains ranged from 0.5 to 4.0% (MIC) and 0.5 to 8.0% v/v (MFC). According to the MBC/MIC and MFC/MIC ratios, CAEO has bactericidal and fungicidal activity. The results of the in vitro antioxidant assays revealed that CAEO possesses remarkable antioxidant activity. The inhibitory effects on 5-LOX and tyrosinase enzymes was also significant (p < 0.05). ADMET investigation suggests that the main compounds of CAEO possess favorable pharmacokinetic properties. These findings provide scientific validation of the traditional uses of this plant and suggest its potential application as natural drugs. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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15 pages, 4413 KiB

Open AccessArticle

Microbiological Studies on the Influence of Essential Oils from Several Origanum Species on Respiratory Pathogens

by Bartłomiej Piasecki, Viktória L. Balázs, Anna Kieltyka-Dadasiewicz, Péter Szabó, Béla Kocsis, Györgyi Horváth and Agnieszka Ludwiczuk

Molecules 2023, 28(7), 3044; https://doi.org/10.3390/molecules28073044 - 29 Mar 2023

Cited by 8 | Viewed by 2343

Abstract

Essential oils (EOs) with established and well-known activities against human pathogens might become new therapeutics in multidrug-resistant bacterial infections, including respiratory tract infections. The aim of this study was to evaluate the antimicrobial activity of EOs obtained from several samples of Origanum vulgare, O. syriacum, and O. majorana cultivated in Poland. EOs were analyzed by GC-MS and tested against four bacterial strains: Staphylococcus aureus (MRSA), Haemophilus influenzae, Haemophilus parainfluenzae, and Pseudomonas aeruginosa. Chemical analyses showed that the Eos were characterized by a high diversity in composition. Based on the chemical data, four chemotypes of Origanum EOs were confirmed. These were carvacrol, terpineol/sabinene hydrate, caryophyllene oxide, and thymol chemotypes. Thin-layer chromatography-bioautography confirmed the presence of biologically active antibacterial components in all tested EOs. The highest number of active spots were found among EOs with cis-sabinene hydrate as the major compound. On the other hand, the largest spots of inhibition were characteristic to EOs of the carvacrol chemotype. Minimal inhibitory concentrations (MICs) were evaluated for the most active EOs: O. vulgare ‘Hirtum’, O. vulgare ‘Margarita’, O. vulgare ‘Hot & Spicy’, O. majorana, and O. syriacum (I) and (II); it was shown that both Haemophilus strains were the most sensitive with an MIC value of 0.15 mg/mL for all EOs. O. majorana EO was also the most active in the MIC assay and had the highest inhibitory rate in the anti-biofilm assay against all strains. The most characteristic components present in this EO were the trans-sabinene hydrate and terpinen-4-ol. The strain with the least sensitivity was the MRSA with an MIC of 0.6 mg/mL for all EOs except for O. majorana, where the MIC value reached 0.3 mg/mL. Scanning electron microscopy performed on the Haemophilus influenzae and Haemophilus parainfluenzae biofilms showed a visible decrease in the appearance of bacterial clusters under the influence of O. majorana EO. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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15 pages, 1308 KiB

Open AccessArticle

Inhibitory Effect of Sodium Alginate Nanoemulsion Coating Containing Myrtle Essential Oil (Myrtus communis L.) on Listeria monocytogenes in Kasar Cheese

by Gökçe Polat Yemiş, Elif Sezer and Hatice Sıçramaz

Molecules 2022, 27(21), 7298; https://doi.org/10.3390/molecules27217298 - 27 Oct 2022

Cited by 11 | Viewed by 2240

Abstract

The present study aimed to characterize the physical properties of nanoemulsion-based sodium alginate edible coatings containing myrtle (Myrtus communis L.) essential oil and to determine its inhibitory effects on Listeria monocytogenes in fresh Kasar cheese during the 24-day storage at 4 °C. The GC-MS analysis showed that the main components of myrtle essential oil were 1,8-cineol (38.64%), α-pinene (30.19%), d-limonene (7.51%), and α-ocimene (6.57%). Myrtle essential oil showed an inhibitory effect on all tested L. monocytogenes strains and this effect significantly increased after ultrasonication. Minimum inhibitory and minimum bactericidal concentrations of myrtle essential oil nanoemulsion were found to be 4.00–4.67 mg/mL and 5.00–7.33 mg/mL, respectively. The antibacterial activity of myrtle essential oil nanoemulsion against L. monocytogenes was confirmed by the membrane integrity and FESEM analyses. Nanoemulsion coatings containing myrtle essential oil showed antibacterial activity against L. monocytogenes with no adverse effects on the physicochemical properties of cheese samples. Nanoemulsion coatings containing 1.0% and 2.0% myrtle essential oil reduced the L. monocytogenes population in cheese during the storage by 0.42 and 0.88 log cfu/g, respectively. These results revealed that nanoemulsion-based alginate edible coatings containing myrtle essential oil have the potential to be used as a natural food preservative. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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14 pages, 4524 KiB

Open AccessArticle

Pinus sylvestris L. and Syzygium aromaticum (L.) Merr. & L. M. Perry Essential Oils Inhibit Endotoxin-Induced Airway Hyperreactivity despite Aggravated Inflammatory Mechanisms in Mice

by Eszter Csikós, Kata Csekő, Ágnes Kemény, Lilla Draskóczi, László Kereskai, Béla Kocsis, Andrea Böszörményi, Zsuzsanna Helyes and Györgyi Horváth

Molecules 2022, 27(12), 3868; https://doi.org/10.3390/molecules27123868 - 16 Jun 2022

Cited by 4 | Viewed by 2175

Abstract

Scots pine (SO) and clove (CO) essential oils (EOs) are commonly used by inhalation, and their main components are shown to reduce inflammatory mediator production. The aim of our research was to investigate the chemical composition of commercially available SO and CO by gas chromatography–mass spectrometry and study their effects on airway functions and inflammation in an acute pneumonitis mouse model. Inflammation was evoked by intratracheal endotoxin and EOs were inhaled three times during the 24 h experimental period. Respiratory function was analyzed by unrestrained whole-body plethysmography, lung inflammation by semiquantitative histopathological scoring, myeloperoxidase (MPO) activity and cytokine measurements. α-Pinene (39.4%) was the main component in SO, and eugenol (88.6%) in CO. Both SO and CO significantly reduced airway hyperresponsiveness, and prevented peak expiratory flow, tidal volume increases and perivascular edema formation. Meanwhile, inflammatory cell infiltration was not remarkably affected. In contrast, MPO activity and several inflammatory cytokines (IL-1β, KC, MCP-1, MIP-2, TNF-α) were aggravated by both EOs. This is the first evidence that SO and CO inhalation improve airway function, but enhance certain inflammatory parameters. These results suggest that these EOs should be used with caution in cases of inflammation-associated respiratory diseases. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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18 pages, 5944 KiB

Open AccessArticle

Effective Components and Molecular Mechanism of Agarwood Essential Oil Inhalation and the Sedative and Hypnotic Effects Based on GC-MS-Qtof and Molecular Docking

by Canhong Wang, Yunyun Wang, Bao Gong, Yulan Wu, Xiqin Chen, Yangyang Liu and Jianhe Wei

Molecules 2022, 27(11), 3483; https://doi.org/10.3390/molecules27113483 - 28 May 2022

Cited by 12 | Viewed by 2806

Abstract

Agarwood has been used for the administration of hypnotic therapy. Its aromatic scent induces a relaxed state. However, its aromatic constituents and the underlying molecular effect are still unclear. This study aims to determine the active substance and molecular mechanism of the hypnotic effect of agarwood essential oil (AEO) incense inhalation in insomniac mice. Insomnia models were induced by para-chlorophenylalanine (PCPA, 300 mg/kg) in mice. The sleep-promoting effect was evaluated. Neurotransmitter levels and its receptor were detected to explore the molecular mechanism. The effective components were analyzed by GC-Q/TOF-MS of AEO. The binding mechanisms of the core compounds and core targets were verified by molecular docking. These results showed that AEO inhalation could significantly shorten sleep latency and prolong sleep time, inhibit autonomous activity and exert good sedative and sleep-promoting effects. A mechanistic study showed that AEO inhalation increased the levels of γ-aminobutyric acid (GABA_A), the GABA_A/glutamic acid (Glu) ratio, 5-hydroxytryptamine (5-HT) and adenosine (AD), upregulated the expression levels of GluR1, VGluT1 and 5-HT1A and downregulated 5-HT2A levels. Component analysis showed that the most abundant medicinal compounds were eremophilanes, cadinanes and eudesmanes. Moreover, the docking results showed that the core components stably bind to various receptors. The study demonstrated the bioactive constituents and mechanisms of AEO in its sedative and hypnotic effects and its multicomponent, multitarget and multipathway treatment characteristics in PCPA-induced insomniac mice. These results provide theoretical evidence for insomnia treatment and pharmaceutical product development with AEO. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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17 pages, 718 KiB

Open AccessReview

Beyond the Bark: An Overview of the Chemistry and Biological Activities of Selected Bark Essential Oils

by Melanie Graf and Iris Stappen

Molecules 2022, 27(21), 7295; https://doi.org/10.3390/molecules27217295 - 27 Oct 2022

Cited by 7 | Viewed by 2391

Abstract

Essential oils have been used by indigenous peoples for medicinal purposes since ancient times. Their easy availability played an important role. Even today, essential oils are used in various fields—be it as aromatic substances in the food industry, as an aid in antibiotic therapy, in aromatherapy, in various household products or in cosmetics. The benefits they bring to the body and health are proven by many sources. Due to their complex composition, they offer properties that will be used more and more in the future. Synergistic effects of various components in an essential oil are also part of the reason for their effectiveness. Infectious diseases will always recur, so it is important to find active ingredients for different therapies or new research approaches. Essential oils extracted from the bark of trees have not been researched as extensively as from other plant components. Therefore, this review will focus on bringing together previous research on selected bark oils to provide an overview of barks that are economically, medicinally, and ethnopharmaceutically relevant. The bark oils described are Cinnamomum verum, Cedrelopsis grevei, Drypetes gossweileri, Cryptocarya massoy, Vanillosmopsis arborea and Cedrus deodara. Literature from various databases, such as Scifinder, Scopus, Google Scholar, and PubMed, among others, were used. Full article

(This article belongs to the Special Issue Antibacterial and Biological Activity of Essential Oils: From In Vitro to In Vivo Evidence)

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