Phytochemical composition and in vitro screening of the antimicrobial activity of essential oils on oral pathogenic bacteria

In this study, the activity of essential oils (EOs) against microorganisms involved in oral diseases was evaluated. Fourteen EOs were selected and subjected to gas chromatographic analysis, including Illicium verum, Eucaliptus globulus, Eugenia caryophyllata, Leptospermum scoparium, Mentha arvensis, Mentha piperita, Myrtus communis, Salvia officinalis, Melaleuca alternifolia, Rosmarinus officinalis, Lavandula x intermedia, Thymus capitatus and Thymus vulgaris. These EOs were tested for their antimicrobial activity on Streptococcus mutans and Lactobacillus species clinically isolated from dental surgery patients. The antibacterial activity was evaluated by means of the disc diffusion and the minimum inhibitory concentration (MIC). Five EOs, having shown an interesting antimicrobial activity, were selected for a second screening in combination between them and with chlorhexidine. From the second assays, two EO–EO and three EO-chlorhexidine associations gave interesting results as potential constituents of mouthwashes, especially for the contribution of oxygenated monoterpenes, including menthol, thymol and carvacrol.     

Antimicrobial properties and chemical composition of liquid and gaseous phases of essential oils

The antimicrobial properties of fifteen essential oils (EOs) tested on seventeen microorganisms were determined using the vapour-agar contact method. The most effective EOs (i.e. Lavandula angustifolia, Cymbopogon nardus, Citrus aurantifolia, Juniperus communis, Myrtus communis and Cinnamomum zeylanicum), whose volatile components afforded the best antimicrobial properties, were selected for a detailed study of chemical composition. All these six EOs contained one to three main components that presented 67–91 mass % of total mass of a corresponding essential oil. The amount of other components was much lower (less than 5 mass %). The volatile components of Lavandula angustifolia exhibited the most effective antimicrobial properties because they completely inhibited the tested bacteria and fungi within 3 days and 1 week, respectively. The components of Lavandula angustifolia with the highest concentration in the gaseous phase were linalool (99.0 ppmv), eucalyptol (44.9 ppmv), linalyl acetate (25.9 ppmv), myrcene (22.2 ppmv), β-trans-ocimene (19.7 ppmv), camphor (16.7 ppmv) and limonene (14.9 ppmv).     

Antibacterial Effects of Essential Oils of Seven Medicinal-Aromatic Plants Against the Fish Pathogen Aeromonas veronii bv. sobria: To Blend or Not to Blend?

Despite progress achieved, there is limited available information about the antibacterial activity of constituents of essential oils (EOs) from different medicinal-aromatic plants (MAPs) against fish pathogens and the complex interactions of blended EOs thereof. The present study aimed to investigate possible synergistic antimicrobial effects of EOs from seven Greek MAPs with strong potential against Aeromonas veronii bv. sobria, a fish pathogen associated with aquaculture disease outbreaks. The main objective was to evaluate whether blending of these EOs can lead to increased antimicrobial activity against the specific microorganism. A total of 127 combinations of EOs were prepared and their effect on A. veronii bv. sobria growth was tested in vitro. We examined both the inhibitory and bactericidal activities of the individual EOs and compared them to those of the blended EOs. The vast majority of the investigated combinations exhibited significant synergistic and additive effects, while antagonistic effects were evident only in a few cases, such as the mixtures containing EOs from rosemary, lemon balm and pennyroyal. The combination of EOs from Greek oregano and wild carrot, as well as the combinations of those two with Spanish oregano or savoury were the most promising ones. Overall, Greek oregano, savoury and Spanish oregano EOs were the most effective ones when applied either in pure form or blended with other EOs.     

Chemical composition,cytotoxicity, antimicrobial and antifungal activity of several essential oils

Essential oils (EOs) are known and used for their biological, antibacterial, antifungal and antioxidant properties. Numerous studies have shown that EOs exhibit a large spectrum of biological activities in vitro. The incidence of drug-resistant pathogens and the toxicity of antibiotics have drawn attention to the antimicrobial activity of natural products, encouraging the development of alternative treatments. The aim of this study was to analyse the phytochemical and the cytotoxic characteristic of 36 EOs; we then evaluated the antimicrobial activity of the less-toxic EOs on Gram-positive, Gram-negative and fungi strains. The results showed low cytotoxicity in seven EOs and good activity against Gram-negative and Candida spp. strains. Based on our results, EOs could be proposed as a novel group of therapeutic agents. Further experiments are necessary to confirm their pharmacological effectiveness, and to determine potential toxic effects and the mechanism of their activity in in vivo models.     

Buffalo Yogurt Fortified with Eucalyptus (Eucalyptus camaldulensis) and Myrrh (Commiphora Myrrha) Essential Oils: New Insights into the Functional Properties and Extended Shelf Life

Eucalyptus (Eucalyptus camaldulensis) and Myrrh (Commiphora Myrrha) essential oils (EOs) stand out for their benefits in terms of health and functionality. Buffalo set yogurt enriched with different concentrations of EOs (0.3, 0.6, and 0.9%) were investigated. The effects of addition on sensory, syneresis, antibacterial activity, and bioactive properties (total phenol content and antioxidant activity) of yogurt were studied. The most acceptable organoleptic properties of treated yogurt were those samples treated with Eucalyptus oil. The levels of syneresis were decreased by increasing the concentration of EOs. Moreover, the antioxidant activity, antibacterial activity, and total phenolic content were enhanced by increasing the concentration of EOs. Yogurt with 0.9% Eucalyptus oil showed the highest antioxidant activity and total phenolic content. The same concentration of Eucalyptus oil showed the highest antibacterial activity against S. typhimurium (the inhibition zone was 20.63 mm) then E. coli (the inhibition zone was 19.43 mm). On the other hand, the highest antibacterial effect against L. monocytogene was for Myrrh oil-enriched yogurt by 0.9% and the inhibition zone was 19.21 mm. The obtained results showed that Eucalyptus and Myrrh oils can be applied to yogurt to improve its beneficial properties in terms of physical characteristics and for human health due to their antioxidant activity and phenolic materials.     

Isolation of Volatile Compounds with Repellent Properties against Aedes albopictus (Diptera: Culicidae) Using CPC Technology

The present work describes the use of Centrifugal Partition Chromatography (CPC) for the bio-guided isolation of repellent active volatile compounds from essential oils. Five essential oils (EOs) obtained from three Pinus and two Juniperus species were initially analyzed by gas chromatography–mass spectrometry (GC/MS) and evaluated for their repellent properties against Aedes albopictus. The essential oil from needles of P. pinea (PPI) presented the higher activity, showing 82.4% repellency at a dose of 0.2 μL/cm². The above EO, together with the EO from the fruits of J. oxycedrus subsp. deltoides (JOX), were further analyzed by CPC using the biphasic system n-Heptane/ACN/BuOH in ratio 1.6/1.6/0.2 (v/v/v). The analysis of PPI essential oil resulted in the recovery of (−)-limonene, guaiol and simple mixtures of (−)-limonene/β-pheladrene, while the fractionation of JOX EO led to the recovery of β-myrcene, germacrene-D, and mixtures of α-pinene/β-pinene (ratio 70/30) and α-pinene/germacrene D (ratio 65/45). All isolated compounds and recovered mixtures were tested for their repellent activity. From them, (−)-limonene, guaiol, germacrene-D as well the mixtures of (−)-limonene/β-pheladrene presented significant repellent activity (>97% repellency) against Ae. albopictus. The present methodology could be a valuable tool in the effort to develop potent mosquito repellents which are environmentally friendly.     

Biological Activity of Essential Oils of Four Juniper Species and Their Potential as Biopesticides

The objective of this study was to assess the biological activity of essential oils (EOs) of four Juniperus species obtained via two different distillation methods and their potential as biopesticides. The studied factors were juniper species (Juniperus communis L., J. oxycedrus L., J. pygmaea C. Koch., and J. sibirica Burgsd), plant sex (male (M) and female (F)), and distillation method (hydrodistillation via a standard Clevenger apparatus (ClevA) and semi-commercial (SCom) steam distillation). The hypothesis was that the EO will have differential antioxidant, antimicrobial, and insecticidal activities as a function of plant species, plant sex, and distillation method. The two distillation methods resulted in similar EO composition within a given species. However, there were differences in the EO content (yield) due to the sex of the plant, and also differences in the proportions of some EO components. The concentration of α-pinene, β-caryophyllene, δ-cadinene and δ-cadinol was dissimilar between the EO of M and F plants within all four species. Additionally, M and F plants of J. pygmaea, and J. sibirica had significantly different concentrations of sabinene within the respective species. The EOs obtained via ClevA extraction showed higher antioxidant capacity within a species compared with those from SCom extraction. All of the tested EOs had significant repellent and insecticidal activity against the two aphid species Rhopalosiphum padi (bird cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of the EO in the solution of 1%, 2.5%, and 5%. The tested EOs demonstrated moderate activity against selected pathogens Fusarium spp., Botrytis cinerea, Colletotrichum spp., Rhizoctonia solani and Cylindrocarpon pauciseptatum. The results demonstrate that the standard ClevA would provide comparable EO content and composition in comparison with SCom steam distillation; however, even slight differences in the EO composition may translate into differential bioactivity.     

Feeding deterrents against two grain storage insects from Euphorbia fischeriana

The screening of several Chinese medicinal herbs for insecticidal principles showed that Euphorbia fischeriana roots possessed significant feeding deterrent activity against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From ethanol extract, four feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as jolkinolide B, 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate, 17-hydroxyjolkinolide A and B on the basis of their phytochemical and spectral data. Jolkinolide B and 17-hydroxyjolkinolide B possessed strong feeding deterrent activities against S. zeamais (EC?? = 342.1 and 543.9 ppm, respectively) and T. castaneum adults (E?? = 361.4 and 551.5 ppm, respectively). 17-Hydroxyjolkinolide A and 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate A also exhibited feeding deterrent activity against the two grain storage insects with EC?? values of 631.9 and 884.3 ppm for S. zeamais and 656.5 and 1058.4 ppm for T. castaneum adults.     

Chemical Characterization and Bioactivity of Commercial Essential Oils and Hydrolates Obtained from Portuguese Forest Logging and Thinning

Essential oils (EOs) and hydrolates (Hds) are natural sources of biologically active ingredients with broad applications in the cosmetic industry. In this study, nationally produced (mainland Portugal and Azores archipelago) EOs (11) and Hds (7) obtained from forest logging and thinning of Eucalyptus globulus, Pinus pinaster, Pinus pinea and Cryptomeria japonica, were chemically evaluated, and their bioactivity and sensorial properties were assessed. EOs and Hd volatiles (HdVs) were analyzed by GC-FID and GC-MS. 1,8-Cineole was dominant in E. globulus EOs and HdVs, and α- and β-pinene in P. pinaster EOs. Limonene and α-pinene led in P. pinea and C. japonica EOs, respectively. P. pinaster and C. japonica HVs were dominated by α-terpineol and terpinen-4-ol, respectively. The antioxidant activity was determined by DPPH, ORAC and ROS. C. japonica EO showed the highest antioxidant activity, whereas one of the E. globulus EOs showed the lowest. Antimicrobial activity results revealed different levels of efficacy for Eucalyptus and Pinus EOs while C. japonica EO showed no antimicrobial activity against the selected strains. The perception and applicability of emulsions with 0.5% of EOs were evaluated through an in vivo sensory study. C. japonica emulsion, which has a fresh and earthy odour, was chosen as the most pleasant fragrance (60%), followed by P. pinea emulsion (53%). In summary, some of the studied EOs and Hds showed antioxidant and antimicrobial activities and they are possible candidates to address the consumers demand for more sustainable and responsibly sourced ingredients.     

The Inhibition of Non-albicans Candida Species and Uncommon Yeast Pathogens by Selected Essential Oils and Their Major Compounds

The epidemiology of yeast infections and resistance to available antifungal drugs are rapidly increasing, and non-albicans Candida species and rare yeast species are increasingly emerging as major opportunistic pathogens. In order to identify new strategies to counter the threat of antimicrobial resistant microorganisms, essential oils (EOs) have become an important potential in the treatment of fungal infections. EOs and their bioactive pure compounds have been found to exhibit a wide range of remarkable biological activities. We investigated the in vitro antifungal activity of nine commercial EOs such as Thymus vulgaris (thyme red), Origanum vulgare (oregano), Lavandula vera (lavender), Pinus sylvestris (pine), Foeniculum vulgare (fennel), Melissa officinalis (lemon balm), Salvia officinalis (sage), Eugenia caryophyllata (clove) and Pelargonium asperum (geranium), and some of their main components (α-pinene, carvacrol, citronellal, eugenol, γ-terpinene, linalool, linalylacetate, terpinen-4-ol, thymol) against non-albicans Candida strains and uncommon yeasts. The EOs were analyzed by GC-MS, and their antifungal properties were evaluated by minimum inhibitory concentration and minimum fungicidal concentration parameters, in accordance with CLSI guidelines, with some modifications for EOs. Pine exhibited strong antifungal activity against the selected non-albicans Candida isolates and uncommon yeasts. In addition, lemon balm EOs and α-pinene exhibited strong antifungal activity against the selected non-albicans Candida yeasts. Thymol inhibited the growth of all uncommon yeasts. These data showed a promising potential application of EOs as natural adjuvant for management of infections by emerging non-albicans Candida species and uncommon pathogenic yeasts.     

Identification of metabolomic markers of lavender and lavandin essential oils using mid-infrared spectroscopy

Lavender (Lavandula angustifolia) and lavandin (sterile hybrid of L. angustifolia P. Mill. × Lavandula latifolia (L.f.) Medikus) are widely cultivated in the Mediterranean area for produce essential oils. In this study, 80 lavandin and 55 lavender essential oil samples from various varieties were analyzed. Firstly, a chemometric treatment of mid-infrared spectra was used to evaluate the capacity of Partial Least Squares Discriminant Analysis (PLS-DA) regression to discriminate French lavandin and lavender essential oil (EO) samples and their varieties (Abrial, Fine, Grosso, Maillette, Matherone, Sumian and Super), and secondly, to quantify the main compounds such as linalyl acetate, linalool, eucalyptol and camphor by PLS regression using reference data from gas chromatography. The examination of PLS and PLS-DA regression coefficients allowed the identification of metabolomic markers. The lavender/lavandin EOs and their varieties were very well classified (100% for lavender/lavandin EOs and between 98 and 100% for varieties). The calibration models obtained by PLS regression for the determination of the main compound contents revealed good correlation (≥0.86) between the predicted and reference values. This method can be used to control the authenticity and traceability of lavender/lavandin and their varieties. Finally, mid-infrared and Raman spectroscopy results were compared.     

Chemical composition variations,allelopathic, and antioxidant activities of Symphyotrichum squamatum (Spreng.) Nesom essential oils growing in heterogeneous habitats

The present study aimed to analyze the chemical composition of Symphyotrichum squamatum EOs growing in two different habitats to explore the ecological implication on the EOs production and evaluate their antioxidant and allelopathic potentialities. The EOs from the aerial parts collected from coastal Mediterranean belt and inland abandoned habitats in the Nile Delta of Egypt, were extracted and analyzed using gas chromatography-mass spectrometry. Sixty compounds were characterized as overall constituents of EOs from both samples. Sesquiterpenes were the main component and represented by 69.77% and 88.68% from coastal and inland sample, respectively. The coastal sample attained a relatively high content of monoterpenes compared to the inland sample. Major compounds from the EOs of the coastal habitat sample, were humulene epoxide, (-)-spathulenol, (-)-caryophyllene oxide, germacrene D, and α-humulene representing 59.72%. However, β-pinene, germacrene D, α-humulene, α-muurolene, humulene epoxide, (-)-caryophyllene oxide, and β-cadinene were the major compounds of EOs of the inland habitat sample, representing 63.70%. The correlation analysis revealed more correlation between the Egyptian inland S. squamatum and the Japanese ecospecies. However, the Egyptian coastal S. squamatum and Turkish ecospecies were more correlated to each other. The present data suggested that chemotypes of S. squamatum maintain their typical pattern despite ecological or climatic differences. The EOs of S. squamatum showed moderate antioxidant activity, wherein coastal and inland EOs have an IC₅₀ value of 382.53 and 559.63 μL L⁻¹, respectively. Also, the EOs from both habitats showed moderate allelopathic activity against the noxious weed Bidens pilosa. However, the activity of the coastal sample was more than inland one and could be attributed to the content of the major compounds, especially the oxygenated terpenes.     

Effect of the Distillation Time on the Chemical Composition,Antioxidant Potential and Antimicrobial Activity of Essential Oils from Different Cannabis sativa L. Cultivars

Within the unavoidable variability of various origins in the characteristics of essential oils, the aim of this study was to evaluate the effect of the distillation time on the chemical composition and biological activity of Cannabis sativa essential oils (EOs). The dry inflorescences came from Carmagnola, Kompolti, Futura 75, Gran Sasso Kush and Carmagnola Lemon varieties from Abruzzo region (Central Italy), the last two being new cultivar here described for the first time. EOs were collected at 2 h and 4 h of distillation; GC/MS technique was applied to characterize their volatile fraction. The EOs were evaluated for total polyphenol content (TPC), antioxidant capacity (AOC) and antimicrobial activity against food-borne pathogens and spoilage bacteria. The time of distillation particularly influenced EOs chemical composition, extracting more or less terpenic components, but generally enriching with minor sesquiterpenes and cannabidiol. A logical response in ratio of time was observed for antioxidant potential, being the essential oils at 4 h of distillation more active than those distilled for 2 h, and particularly Futura 75. Conversely, except for Futura 75, the effect of time on the antimicrobial activity was variable and requires further investigations; nevertheless, the inhibitory activity of all EOs against Pseudomonas fluorescens P34 was an interesting result.     

Antimicrobial activity and phytochemical analysis of crude extracts and essential oils from medicinal plants

We aimed to establish a phytochemical analysis of the crude extracts and performed GC-MS of the essential oils (EOs) of Eugenia uniflora L. (Myrtaceae) and Asteraceae species Baccharis dracunculifolia DC, Matricaria chamomilla L. and Vernonia polyanthes Less, as well as determining their antimicrobial activity. Establishment of the minimal inhibitory concentrations of the crude extracts and EOs against 16 Staphylococcus aureus and 16 Escherichia coli strains from human specimens was carried out using the dilution method in Mueller-Hinton agar. Some phenolic compounds with antimicrobial properties were established, and all EOs had a higher antimicrobial activity than the extracts. Matricaria chamomilla extract and E. uniflora EO were efficient against S. aureus strains, while E. uniflora and V. polyanthes extracts and V. polyanthes EO showed the best antimicrobial activity against E. coli strains. Staphylococcus aureus strains were more susceptible to the tested plant products than E. coli, but all natural products promoted antimicrobial growth inhibition.     

In vitro inhibitory activity of essential oil vapors against Ascosphaera apis

This work evaluates the in vitro inhibitory activity of 70 essential oils (EOs) in the vapor phase for the control of Chalkbrood disease caused by Ascosphaera apis Maassen ex Claussen (Olive et Spiltoir). Two wild strains isolated from infected honey bee colonies together with one standard collection strain were tested by the microatmosphere method. From 70 EOs, 39 exhibited an antifungal effect against A. apis standard and wild strains. The greatest antifungal action was observed for EO vapors from Armoracia rusticana, followed by Thymus vulgaris, Cymbopogon flexosus, Origanum vulgare and Allium sativum. An investigation of chemical composition by GC-MS revealed, that the most active EOs contained allyl isothiocyanate, citral, carvacrol and diallyl sulfides as the main constituents. The chemical composition plays a key role, as activities of different EOs from the same botanical species were different according to their composition.     

Composition,Anti-MRSA Activity and Toxicity of Essential Oils from Cymbopogon Species

Many of the essential oils obtained from medicinal plants possess proven antimicrobial activity and are suitable for medicinal purposes and applications in the food industry. The aim of the present work was the chemical analysis of 19 essential oils (EOs) from seven different Cymbopogon species (C. nardus, C. citratus, C winterianus, C. flexuosus, C. schoenanthus, C. martinii, C. giganteus). Five different chemotypes were established by GC/MS and TLC assay. The EOs, as well as some reference compounds, i.e., citronellol, geraniol and citral (neral + geranial), were also tested for their antimicrobial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA) by the microdilution method and direct bioautography. The toxicity of EOs was evaluated by Danio rerio ‘Zebrafish’ model assay. All examined EOs showed moderate to high activity against MRSA, with the highest activity noted for C. flexuosus—lemongrass essential oil, both in microdilution and direct autobiography method. Significant difference in the toxicity of the examined EOs was also detected.     

Chemical composition,and antibacterial and antioxidant activities of essential oils from Laggera tomentosa Sch. Bip. ex Oliv. et Hiern (Asteraceae)

Laggera tomentosa Sch. Bip. ex Oliv. et Hiern (Asteraceae), an endemic Ethiopian medicinal plant, is traditionally used to treat various ailments. Previously, the chemical constituents of the essential oil (EO) of its leaves and inflorescence were documented. However, no data about the chemical compositions of other parts of the EOs of the plant have been reported to date. Moreover, there are no previous biological activity reports on any parts of the EOs of this plant. Thus, in this study, the EOs were isolated from the stem bark and roots of this plant by hydrodistillation and analyzed using gas chromatography-mass spectrometry to identify their components. In addition, antibacterial potentials of the oils were evaluated using the disc diffusion and minimal inhibitory concentration (MIC) methods. 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide methods were also employed to assess their antioxidant properties. Oxygenated monoterpenes (71.82% and 77.51%), of which 2,5-dimethoxy- p -cymene (57.28% and 64.76%) and thymol methyl ether (9.51% and 8.93%) were identified as major components in the EOs of stem bark and roots of L. tomentosa and the oils, were the most potent in the DPPH (IC50, 0.33 ± 1.10 and 0.39 ± 0.97 mg/mL) assay, respectively. Moreover, the EOs demonstrated appreciable activity towards the gram+ ( S. aureus and B. cereus ) bacteria. Among these oils, the oil of the stem bark showed the greatest activity to the gram+ (MIC = 0.625 mg/mL) bacteria. Therefore, the overall results suggested that the EOs of L. tomentosa may be a promising prospect for pharmaceutical, food, and other industrial applications.     

Chemical Composition and Antibacterial Activity of Liquid and Volatile Phase of Essential Oils against Planktonic and Biofilm-Forming Cells of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen causing life-threatening, hard-to-heal infections associated with the presence of a biofilm. Essential oils (EOs) are promising agents to combat pseudomonal infections because of the alleged antimicrobial activity of their volatile fractions and liquid forms. Therefore, the purpose of this paper was to evaluate the antibacterial efficacy of both volatile and liquid phases of seven EOs (thyme, tea tree, basil, rosemary, eucalyptus, menthol mint, lavender) against P. aeruginosa biofilm and planktonic cells with the use of a broad spectrum of analytical in vitro methods. According to the study results, the antibacterial activity of EOs in their liquid forms varied from that of the volatile fractions. Overall, liquid and volatile forms of rosemary EO and tea tree EO displayed significant antibiofilm effectiveness. The outcomes indicate that these particular EOs possess the potential to be used in the therapy of P. aeruginosa infections.     

Nanovesicles Loaded with Origanum onites and Satureja thymbra Essential Oils and Their Activity against Food-Borne Pathogens and Spoilage Microorganisms

Food poisoning is a common cause of illness and death in developing countries. Essential oils (EOs) could be effective and safe natural preservatives to prevent and control bacterial contamination of foods. However, their high sensitivity and strong flavor limit their application and biological effectiveness. The aim of this study was firstly the chemical analysis and the antimicrobial evaluation of the EOs of Origanum onites L. and Satureja thymbra L. obtained from Symi island (Greece), and, secondly, the formulation of propylene glycol-nanovesicles loaded with these EOs to improve their antimicrobial properties. The EOs were analyzed by GC-MS and their chemical contents are presented herein. Different nanovesicles were formulated with small average sizes, high homogeneity, and optimal ζ-potential. Microscopic observation confirmed their small and spherical shape. Antibacterial and antifungal activities of the formulated EOs were evaluated against food-borne pathogens and spoilage microorganisms compared to pure EOs. Propylene glycol-nanovesicles loaded with O. onites EO were found to be the most active formulation against all tested strains. Additionally, in vitro studies on the HaCaT cell line showed that nanovesicles encapsulated with EOs had no toxic effect. The present study revealed that both EOs can be used as alternative sanitizers and preservatives in the food industry, and that their formulation in nanovesicles can provide a suitable approach as food-grade delivery system.     

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

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.