Search Results (27)

Background/Objectives: The rapid emergence of antibiotic-resistant Escherichia coli in food and clinical environments necessitates new, clean-label antimicrobials. This study assessed eight Greek native essential oils—oregano, thyme, dittany, rosemary, peppermint, lavender, cistus and helichrysum—for activity against six genetically and phenotypically diverse E. coli strains (reference, pNorm, mecA, mcr-1, blaOXA and O157:H7). We aimed to identify oils with broad-spectrum efficacy and clarify the chemical constituents responsible. Methods: Disk-diffusion assays measured inhibition zones at dilutions from 50% to 1.56% (v/v). MIC and MBC values were determined by broth microdilution. GC–MS profiling identified dominant components, and Spearman rank-order correlations (ρ) linked composition to activity. Shapiro–Wilk tests (W = 0.706–0.913, p ≤ 0.002) indicated non-normal data, so strain comparisons used Kruskal–Wallis one-way ANOVA with Dunn’s post hoc and Bonferroni correction. Results: Oregano, thyme and dittany oils—rich in carvacrol and thymol—exhibited the strongest activity, with MIC/MBC ≤ 0.0625% (v/v) against all strains and inhibition zones > 25 mm at 50%. No strain-specific differences were detected (H = 0.30–3.85; p = 0.998–0.571; p_adj = 1.000). Spearman correlations confirmed that carvacrol and thymol content strongly predicted efficacy (ρ = 0.527–0.881, p < 0.001). Oils dominated by non-phenolic terpenes (rosemary, peppermint, lavender, cistus, helichrysum) showed minimal or no activity. Conclusions: Phenolic-rich EOs maintain potent, strain-independent antimicrobial effects—including against multidrug-resistant and O157:H7 strains—via a multi-target mode that overcomes classical resistance. Their low-dose efficacy and GRAS status support their use as clean-label food preservatives or adjuncts to antibiotics or bacteriophages to combat antimicrobial resistance. Full article

Ruminant livestock contribute significantly to methane emissions, necessitating sustainable mitigation strategies. Essential oils (EOs) show promise for modulating ruminal fermentation, but their synergistic effects remain underexplored. Two 24 h in vitro experiments evaluated the synergistic effects of EO blends on rumen microbial fermentation. Exp. 1 screened five oils using two triad combinations. Triad 1 tested 10 combinations of thyme (THY), peppermint (PPM), and cinnamon leaf (CIN) oils. Triad 2 tested 10 combinations of anise (ANI), clove leaf (CLO), and peppermint (PPM) oils. Each blend was tested at 400 mg/L, using batch culture methods measuring: pH, ammonia-N (NH₃-N), and volatile fatty acids (VFAs). The two most effective blends, designated as T1 and T2, were selected for Exp. 2 to assess total gas and methane (CH₄) production using pressure transducer methods. All treatments were incubated in a rumen fluid–buffer mix with a 50:50 forage-to-concentrate substrate (pH 6.6). In Exp. 1, data were analyzed according to the Simplex Centroid Design using R-Studio. In Exp. 2, an analysis was conducted using the MIXED procedure in SAS. Mean comparisons were assessed through Tukey’s test. The results from Exp. 1 identified CIN+PPM (80:20) and ANI+CLO (80:20) as optimal combinations, both increasing total VFAs while reducing acetate/propionate ratios and NH₃-N concentrations. In Exp. 2, both combinations significantly reduced total gas and CH₄ productions compared to the control, with CIN+PPM achieving the greatest methane reduction (similar to monensin, the positive control). Specific essential oil combinations demonstrated synergistic effects in modulating rumen fermentation and reducing methane emissions, offering potential for sustainable livestock production. Further in vivo validation is required to optimize dosing and assess long-term effects on animal performance. Full article

The antifungal effectiveness of essential oils (EOs) and their predominant components were tested on 14 phytopathogenic fungi isolated from olive trees. Commercial EOs from holy basil (Ocimum tenuiflorum L.), Chinese cinnamon (Cinnamomum aromaticum Ness), lemon (Citrus × limon), peppermint (Mentha × piperita L.), oregano (Origanum compactum Benth), and thyme (Thymus vulgaris L.) and components eugenol, e-cinnamaldehyde, limonene, menthol, carvacrol, and thymol were used. Antifungal efficacy was tested on six species from the Botryosphaeriaceae family: Botryosphaeria dothidea (Moug. ex Fr.) Ces. & De Not.; Diplodia mutila (Fr.) Fr.; D. seriata De Not.; Dothiorella iberica A.J.L. Phillips, J. Luque & A. Alves; Do. sarmentorum (Fr.) A.J.L. Phillips, Alves & Luque; and Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips. Other tested species included Biscogniauxia mediterranea (De Not.) Kuntze, B. nummularia (Bull.) Kuntze; Cytospora pruinosa Défago; Nigrospora gorlenkoana Novobr.; N. osmanthi Mei Wang & L. Cai; N. philosophiae-doctoris M. Raza, Qian Chen & L. Cai; Phaeoacremonium iranianum L. Mostert, Grafenhan, W. Gams & Crous; and Sordaria fimicola (Roberge ex Desm.) Ces. & De Not. The results show that Chinese cinnamon and oregano EOs, along with their components, completely inhibited the growth of all tested fungi, indicating their potential as biological control agents in sustainable agriculture. In contrast, the least effective treatments were the EOs derived from lemon and peppermint, as well as the components limonene, menthol, and thymol. Notably, the fungi Do. iberica and N. gorlenkoana were among the most sensitive to all the treatments applied. Full article

Eggs are considered a nutritionally complete food and an excellent source of protein. However, they are prone to bacterial contamination, which can affect their internal quality and safety. This study aimed to evaluate the effectiveness of essential oils (EOs) as natural sanitizers for eggshells to reduce the bacterial load and improve shelf life. Ten EOs—cinnamon, clove, lavender, peppermint, thyme, rosemary, green tea, mustard, basil, and marjoram—were tested for antibacterial activity against three Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis, and Listeria monocytogenes) and three Gram-negative bacteria (Salmonella Enteritidis, Pseudomonas aeruginosa, and Escherichia coli) using the well diffusion method. The most effective EOs were assessed in vapor form using a disc volatilization technique. A total of 288 eggs from a local farm in South Lebanon were treated with selected EOs and stored at room temperature for three weeks to evaluate microbial load and quality. The eggs were grouped into six categories: dry control, ultraviolet (UV) treated, and eggs sprayed with EOs, based on the recorded minimum inhibitory concentration (MIC) values. At each time point, 12 eggs from each group were analyzed for microbiological testing and external and internal quality. Results indicated that nine of the ten EOs showed antibacterial activity, with the highest inhibition zones recorded for cinnamon against S. Enteritidis (14 mm) and E. coli (9 mm), peppermint against P. aeruginosa (10 mm), and rosemary against L. monocytogenes (22 mm), S. aureus (19 mm), and E. faecalis (12 mm). Vapor phase testing showed that rosemary, thyme, clove, and cinnamon EOs had average inhibition zones ranging from 21 to 33 mm against the tested bacteria, and peppermint EO achieved complete inhibition of P. aeruginosa. Clove EO consistently reduced the bacterial load as a sanitizer on eggs, initially achieving complete inhibition. While egg quality parameters such as weight, shell thickness, Haugh unit, and yolk color declined over time, EOs helped maintain better quality compared to dry controls. GC-MS analysis of the tested EOs revealed that monoterpene alcohols are the major constituents of most oils. This study concludes that EOs are effective natural sanitizers for eggs, enhancing safety and preserving quality during storage. Full article

Food contamination with Listeria monocytogenes can cause health problems of increasing global concern. The resistance of L. monocytogenes to antibiotics requires finding alternative solutions to protect human health. This mini study was designed to evaluate the effects of antibiotics and some particular essential oils on L. monocytogenes isolates from food of animal origin and isolates from food-producing surfaces. This aim was to investigate the effects of seven antibiotics (amikacin, gentamicin, penicillin, cephalexin, ceftriaxone, tetracycline, and nalidixic acid) on L. monocytogenes isolated from food and surface samples. Also, the antibacterial activity of four essential oils (thyme, oregano, peppermint, and rosemary) against the growth of L. monocytogenes isolates was investigated. Listeria monocytogenes isolates were from food of an animal origin and food-producing surfaces. The isolation and determination of L. monocytogenes from food samples followed ISO 11290-1. Surface samplings were performed in compliance with ISO 18593, followed by the isolation and determination of L. monocytogenes. A disc diffusion method was used, and the tests were performed in triplicate. The results of this study confirmed the pronounced antibacterial activity of essential oils compared to antimicrobial drugs. The essential oil of Thymus vulgaris showed a bactericidal effect against all tested L. monocytogenes isolates. Full article

Aeromonas spp. is a major pathogen in aquaculture with a great negative economic impact. Essential oils (EOs) are compounds of the secondary metabolism of plants known for their antibacterial and antibiofilm activities. In this study, in vitro antibacterial activity of eight EOs: tea tree (extracted from Melaleuca alternifolia), eucalyptus (extracted from Eucalyptus globulus LABILL.), knee timber (extracted from Pini mungo L.), peppermint (extracted from Mentha piperita L.), oregano (extracted from Origanum vulgare L.), rosemary (extracted from Rosmarinus officinalis L.), thyme (extracted from Thymus vulgaris L.) and pine EO (extracted from Pinus silvestris L.), obtained from Calendula a.s., was evaluated. Their antibacterial activity was demonstrated against Aeromonas spp. isolates. Oregano and thyme EOs showed the strongest activity against all tested isolates at low concentrations, followed by tea tree and peppermint EOs. The MIC value ranged from 0.06 µL/mL to 1.0 µL/mL. The tested EOs showed a significant antibiofilm activity against biofilm-forming isolates with MBIC₅₀ ranging from 0.015 µL/mL to 0.25 µL/mL. All tested isolates were obtained from rainbow trout free of clinical signs of infection. Twelve isolates of Aeromonas salmonicida subsp. masoucida, four Aeromonas hydrophila, and four isolates of Aeromonas veronii were identified. The results of the in vitro study showed a significant effect of EOs against Aeromonas spp., which confirmed their potential for use in aquaculture as a prevention against bacterial diseases and a way of reducing the use of antibiotics. Full article

Presently, there is an increasing shift towards the utilization of natural antioxidants and compounds with protective attributes for fatty acids in order to replace synthetic counterparts that may pose health risks. This transition aligns with the growing emphasis on promoting healthy and organic food choices. Essential oils stand out in this context due to scientific validations of their antioxidant properties. There are few published research results concerning changes in the fatty acid composition in model systems with the addition of essential oils. This study aims to investigate the impact of incorporating peppermint and thyme oils on inhibiting changes in the fatty acid profile of sunflower oil stored at both room temperature with exposure to daylight and in a thermostat set at 40 °C. The experimental procedure involved the addition of peppermint and thyme oils, along with butylated hydroxyanisole (BHA), to batches of sunflower oil. The samples were then stored for 11 months. The study observed a detrimental influence of storage conditions on the quantitative changes in the fatty acid profile of the sunflower oil. The addition of BHA stabilized the content of linoleic acid in the sunflower oil (approximately 53 g/100 g of linoleic acid compared to approximately 58 g/100 g in the control sample). Meanwhile, the model system of sunflower oil with the addition of peppermint and thyme oils (40 °C) exhibited a statistically significant decrease in the concentration of linoleic acid to approximately 8 g/100 g after eleven months of thermostating. Similar trends to those observed for linoleic acid were noted for the total fatty acid content in the sunflower oil. Notably, the efficacy of the selected substances in inhibiting adverse transformations in fats was contingent upon their concentration and the storage temperature. Full article

Traditional Chinese medicines (TCM) have been considered an important source of curative remedy for many years due to their potential chemical components which can promote health and prevent diseases. According to TCM, influenza is differentiated into two kinds, namely, wind-cold syndrome and wind-heat syndrome. Many traditional Chinese medicinal plants have been found to exert impacts against both cold and influenza viruses. This article included randomized control experiments, observational and analytical designs, and review articles which have been searched in Scopus, PubMed, and Google Scholar. The most important antiviral herbs for cold and flu are honey-suckle flowers (Lonicera periclymenum L.), thyme leaf (Thymus vulgaris L.), green chireta (Andrographis paniculata (Burm.f.) Wall. Ex Nees), Calendula (Calendua officinalis L.), and peppermints leaf and oil (Mentha piperita L.). The most notable expectorant herbs for cold and flu are snake root (Ageratina altissima (L.) R.King & H.Rob), tulsi (Ocimum tenuiflorum L.), licorice root (Glycyrrhiza glabra L.), slippery elm (Ulmus rubra Muhl) and marshmallow osha root (Althea officinalis L.), clove (Syzygium aromaticum (L.) Merr. & L.M.Perry), and sage leaf (Salvia officinalis L.). Immunostimulant herbs for cold and flu are eucalyptus (Eucalyptus globuls Labill), Echinacea root (Echinacea purpurea (L.) Moench), ginseng (Panax ginseng C.A. Mey), garlic (Allium sativum L.), marshmallow (Althaea officinalis L.), Isatis root (Isatis tinctoria L.), ginger root (Zingiber officinale Rosc), and myrrh resin (Commiphora myrrha (T.Nees) Engl.). The most famous and practical herbal prescriptions from China are Jinchai, Rorrico, Ge Gen Decoction, Gegen Qinlian Decoction, Xin-Jia-Xiang-Ru-Yin, Yi-Zhi-Hao pellet, IMOD, and Arbidol combinations. Traditional Chinese medicinal plants and herbs with antiviral activities and prescriptions which are common in China can be considered for prevention and treatment of influenza and cold. Full article

Antioxidant activities of five essential oils (cinnamon, thyme, clove, lavender and peppermint oils) and their major components (eugenol, thymol, linalool, and menthol) were evaluated on scavenging DPPH (2,2-diphenyl-1 picrylhydrazyl) free radicals, inhibiting polyunsaturated fatty acid oxidation in fish oil emulsion (FOE), and reducing oxidative stress in human red blood cells (RBC). The essential oils from cinnamon, thyme, clove and their main components, eugenol and thymol, exhibited the highest antioxidant activity in the FOE and RBC systems. It was found that the antioxidant activity of essential oils was positively correlated to the content of eugenol and thymol, while lavender and peppermint oils and their main components, linalool and menthol, had very low antioxidant activity. Compared with scavenging DPPH free radical activity, the antioxidant activity in FOE and RBC systems could better reflect the actual antioxidant potential of essential oil in preventing lipid oxidation and reducing oxidative stress in biological system. Full article

Increased antibiotic resistance presents a health problem worldwide. The World Health Organization published a list of pathogens considered a priority for designing new treatments. Klebsiella pneumoniae (Kp) is a top-priority microorganism, highlighting the strains that produce carbapenemases. Developing new efficient therapies or complementing existing treatments is a priority, and essential oils (EOs) provide an alternative. EOs could act as antibiotic adjuvants and enhance antibiotic activity. Employing standard methodologies, the antibacterial activity of the EOs and their synergic effect with antibiotics were detected. A string test was used to identify the impact of the EOs over the hypermucoviscosity phenotype presented by Kp strains, and Gas Chromatography–Mass Spectrometry analysis identified EOs and the composition of EOs. The potential of EOs for designing synergistic therapies with antibiotics to combat the infection of KPC diseases was demonstrated. In addition, the alteration of the hypermucoviscosity phenotype was shown as the principal mechanism of a synergic action between EOs and antibiotics. The differential composition of the EOs lets us identify some molecules that will be analyzed. Synergic activity of EOs and antibiotics can provide a solid platform for combating multiresistant pathogens that represent a severe health sector problem, such as Kp infections. Full article

Essential oils (EOs) and Plant extracts (PEs) are gaining attention as eco-friendly alternatives to synthetic fungicides for the management of soil-borne fungi related to root rot and the wilt of marigolds. Here, EOs of Cinnamomum zeylanicum (cinnamon), Mentha piperita (peppermint), Syzygium aromaticum (clove), Thymus vulgaris (thyme), PEs of Cymbopogon citratus (lemongrass), Lantana camara (lantana), Ocimum basilicum (basil), and Zingiber officinales (ginger) were first evaluated in vitro for their inhibitory activity against the mycelium growth of the root rot and wilt fungi of marigold: Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium oxysporum, and F. solani, and in vivo for their activity in reducing disease progression. The results show that all EOs had a strong inhibitory activity on the mycelium growth of pathogens. Maximum inhibition of mycelium growth was achieved at a concentration of 1 mL/Lof S. aromaticum, C. zeylanicum, and M. piperita. The inhibition values were 100, 80.9, and 72.4% for F. solani, 100, 81.1, and 70% for S. sclerotiorum, 90.2, 79.4, and 69.1% for F. oxysporum, and 85.4, 78.2, and 68.7% for R. solani, respectively. Regarding plant extracts, the highest inhibition of mycelium growth was attained at a concentration of 20% of Z. officinales, C. citratus, and L. camara. The inhibition values were 77.4, 69.1, and 60.6% for F. solani, 76.5, 67.2, and 58% for S. sclerotiorum, 73.5, 68.2, and 56.3% for F. oxysporum, and 72, 64.8, and 55.2% for R. solani, respectively. In pot experiments, the application of EOs and PEs showed high efficiency in suppressing root rot and wilt of marigold at all concentrations used, especially at 3 mL/L for seed soaking (along with 1.5 mL/L for foliar spraying) for S. aromaticum, C. zeylanicum, and M. piperita EOs, and (40% for seed soaking along with 20% for foliar spraying) for Z. officinales, C. citratus, and L. camara PEs. All the treatments applied in the field greatly reduced the diseases in both seasons, especially S. aromaticum EO, C. zeylanicum EO, Z. officinales PE, and carbendazim treatments. This was accompanied by a significant improvement in morphological, yield, and phytochemical parameters of marigold as well as a significant increase in the activity of defense-related antioxidant enzymes. Overall, essential oils and plant extracts can be used effectively to control root rot and wilt in marigold as sustainable and eco-friendly botanical biofungicides. Full article

Essential oils (EOs) are mixtures of volatile molecules endowed with health-promoting biological activities that go beyond their role as aromas and natural preservatives and can be exploited to develop functional foods and diet supplements. Their composition is briefly addressed along with regulatory aspects. The potential health benefit of human diet supplementation with EOs is outlined through a review of the recent literature on available clinical trials and preclinical research concerning EOs activity towards: (1) irritable bowel syndrome; (2) inflammatory bowel disease; (3) regulation of microbiota; (4) gastroprotection; (5) hepatoprotection; (6) protection of the urinary tract and diuresis; (7) management of metabolic disorders including hyperglycemia and hyperlipidemia; (8) anti-inflammatory and pain control; (9) immunomodulation and protection from influenza; and (10) neuroprotection and modulation of mood and cognitive performance. The emerging potential in such activities of selected EOs is given focus, particularly green and black cumin, bergamot, orange, myrtle, peppermint, sage, eucalyptus, lavender, thyme, lemon balm, ginger, and garlic. Full article

The purpose of the study was to describe the antimicrobial activity of 16 common essential oils (EOs) on multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates, including the determination of the effects on mex efflux pumps gene expression. Seventy-two clinical isolates of P. aeruginosa collected between 2020–2022 were screened for susceptibility to EOs using Kirby–Bauer disk diffusion to identify potential candidates for future alternative therapies. The minimal inhibitory concentration (MIC) was further determined for the EO that proved antibacterial activity following the disk diffusion screening. Positive and negative controls were also used for method validation. Since cinnamon EO exhibited the best antimicrobial activity, it was further used to evaluate its influence on mex A, B, C, E, and X efflux pumps gene expression using real-time RT-PCR. Cinnamon EO inhibited all P. aeruginosa strains, followed by thyme EO (37.5%, n = 27) and lavender EO (12.5%, n = 9). The other EOs were less efficient. The MIC detection showed that cinnamon at a concentration of 0.05% v/v inhibited all MDR P. aeruginosa isolates. Thyme, turmeric, peppermint, basil, clove, and lavender EOs presented various results, most of them having activity at concentrations higher than 12.5% v/v. By studying the activity of cinnamon EO on mex efflux pumps, it was found that mexA and mexB (66.5%) were generally under-expressed. The remarkable results produced using the very low concentrations of cinnamon EO, with 100% antimicrobial activity against multi-, extended-, and pan- drug-resistant (MDR, XDR, PDR) P. aeruginosa clinical isolates, completed with the severe alteration of the RNA messaging system, supports its potential to be used as adjuvant treatment, with impact on therapeutic results. Full article

Mosquitoes are one of the most important disease vectors from a medical viewpoint in that they transmit several diseases such as malaria, filariasis, yellow and Dengue fever. Mosquito vector control and personal protection from mosquito bites are currently the most efficient ways to prevent these diseases. Several synthetic repellents such as DEET, ethyl butylacetylaminopropionate (IR3535) and 1-(1-methylpropoxycarbonyl)-2-(2-hydroxyethyl)piperidine) (Picaridin), have been widely used to prevent humans from receiving mosquito bites. However, the use of synthetic repellents has raised several environment and health concerns. Therefore, essential oils (EOs) as natural alternatives receive our attention. In order to discover highly effective mosquito repellents from natural sources, the repellent activity of 60 commercial EOs against Ae. albopictus was screened in this study. Eight EOs including cinnamon, marjoram, lemongrass, bay, chamomile, jasmine, peppermint2, and thyme, showed a suitable repellent rate (>40%) at the tested dose of 10 μg/cm². Then, their main constituents were analyzed by GC-MS, and the active constituents were identified. The most active compounds including cinnamaldehyde, citral and terpinen-4-ol, exhibited an 82%, 65% and 60% repellent rate, respectively. Moreover, the nanoemulsions of the three active compounds were prepared and characterized. In the arm-in-cage assay, the protection times of the nanoemulsions of cinnamaldehyde and citral were significantly extended compared with their normal solutions. This study provides several lead compounds to develop new mosquito repellents, and it suggests that nanoemulsification is an effective method for improving the duration of the activity of natural repellents. Full article

Wound dressings for skin lesions, such as bedsores or pressure ulcers, are widely used for many patients, both during hospitalization and in subsequent treatment at home. To improve the treatment and shorten the healing time and, therefore, the cost, numerous types of wound dressings have been developed by manufacturers. Considering certain inconveniences related to the intolerance of some patients to antibiotics and the antimicrobial, antioxidant, and curative properties of certain essential oils, we conducted research by incorporating these oils, based on polyvinyl alcohol/ polyvinyl pyrrolidone (PVA/PVP) biopolymers, into dressings. The objective of this study was to study the potential of a polymeric matrix for wound healing, with polyvinyl alcohol as the main material and polyvinyl pyrrolidone and hydroxypropyl methylcellulose (HPMC) as secondary materials, together with additives (plasticizers poly(ethylene glycol) (PEG) and glycerol), stabilizers (Zn stearate), antioxidants (vitamin A and vitamin E), and four types of essential oils (fennel, peppermint, pine, and thyme essential oils). For all the studied samples, the combining compatibility, antimicrobial, and cytotoxicity properties were investigated. The obtained results demonstrated a uniform morphology for almost all the samples and adequate barrier properties for contact with suppurating wounds. The results show that the obtained samples containing essential oils have a good inhibitory effect on, or antimicrobial properties against, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The MTT assay showed that the tested samples were not toxic and did not lead to cell death. The results showed that the essential oils used provide an effective solution as active substances in wound dressings. Full article