Search Results (117)

Thymus, Satureja, and Monarda are three plant genera, belonging to the Lamiaceae family, that are particularly valued for their essential oils (EOs) abundant in phenolic terpenoids. In this study, a botanical characterization of the following eight Eastern European cultivars (some of them newly bred) grown in Ukraine is distinguished: Thymus vulgaris (‘Yalos’, ‘101’), Thymus richardii (‘Fantasia’), Satureja montana (‘Krymsky smaragd’, ‘Lunata’, ‘4-18’), Monarda fistulosa (‘Premiera’), and Monarda × hybrida hort., which is a Monarda didyma × Monarda fistulosa hybrid (‘Tonya’). The EO of those cultivars was obtained and characterized in detail using GC-MS and GC-FID. Additionally, some biological activities of these oils were tested. Antimicrobial activity was verified against Escherichia coli, Staphylococcus aureus, and Candida albicans using disk diffusion and microdilution methods. Furthermore, some preliminary tests were performed on the motility of bull sperm using the CASA system. All the Thymus cultivars were very rich in thymol (57.99–67.62%), and all the S. montana cultivars were very abundant in carvacrol (62.22–75.53%). M. fistulosa cv. ‘Premiera’ contained mainly thymol (49.87%), and M. × hybrida cv. ‘Tonya’ contained both thymol (46.70%) and carvacrol (10.37%). All the tested EOs, as well as thymol and carvacrol, exhibited strong antibacterial and antifungal action with minimal inhibitory concentrations ranging from <0.25–0.5 mg/mL for Satureja, through <0.25–0.5 mg/mL for Monarda, to 0.5–4 mg/mL for Thymus. The EOs, at a concentration of 0.4 µL/mL, exhibited cytotoxicity towards bull spermatozoa when compared to the control sample. Full article

Background: Antimicrobial resistance in oral pathogens drives interest in natural alternatives such as essential oils (EOs). Methods: The chemical composition and in vitro antimicrobial activity of Origanum vulgare, Thymus vulgaris, and Lavandula angustifolia EOs were investigated. Oils were profiled by gas chromatography–mass spectrometry (GC-MS) and tested against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231 using the disc diffusion method (triplicate, 1 µL/disc, ~850–950 µg). Results: O. vulgare oil produced the strongest inhibition against C. albicans (18.4 ± 0.5 mm), T. vulgaris was most active E. coli (13.0 ± 0.5 mm), while L. angustifolia showed negligible activity (6–7 mm). All EO inhibition zones were smaller than those of antibiotics. Conclusions: At clinically relevant doses, Oregano and Thyme oils showed modest antimicrobial effects, whereas Lavender was inactive. However, these findings are limited by the use of ATCC strains, small sample size, and reliance on the disc diffusion method, which provides only qualitative data and does not capture biofilm or host interactions. Future studies should include minimum inhibitory concentrations (MIC)/minimum bactericidal concentrations (MBC) assays, biofilm models, and cytotoxicity testing. AI-assisted GC-MS analysis and automated inhibition zone measurement should be considered as future perspectives to improve reproducibility and translational potential. Full article

The COVID-19 pandemic has reignited interest in traditional medicinal plants as potential therapeutic agents. This study examined the chemical composition, cytotoxicity, and antimicrobial activity of essential oils from six Moroccan medicinal plants, namely, Eucalyptus globulus, Artemisia absinthium, Syzygium aromaticum, Thymus vulgaris, Artemisia alba, and Santolina chamaecyparissus, which are commonly used by the Moroccan population for COVID-19 prevention. The chemical composition of each essential oil was determined using gas chromatography–mass spectrometry (GC–MS) to identify key compounds. Cytotoxicity was evaluated in the Vero E6 cell line, which is frequently used in SARS-CoV-2 research, using the neutral red assay, with oil concentrations ranging from 25 to 100 µg/mL. Antimicrobial activity was tested against standard reference strains, including Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Candida albicans (ATCC 10231), and Bacillus subtilis (ATCC 6633), using the disc diffusion method. GC–MS analysis revealed significant components such as spathulenol (15%) and caryophyllene oxide (7.67%) in Eucalyptus globulus and eugenol (54.96%) in Syzygium aromaticum. Cytotoxicity assays indicated that higher concentrations of essential oils significantly reduced cell viability, with Thymus vulgaris showing the highest IC₅₀ (8.324 µM) and Artemisia absinthium the lowest (18.49 µM). In terms of antimicrobial activity, Eucalyptus globulus had the strongest effect, with a 20 ± 0.00 mm inhibition zone against Bacillus subtilis, whereas both Syzygium aromaticum and Artemisia herba-alba had a 12.25 ± 0.1 mm inhibition zone against the same strain. These findings suggest that these essential oils have significant therapeutic potential, particularly in combating antimicrobial resistance and exerting cytotoxic effects on viral cell lines. Further research is necessary to explore their mechanisms of action and ensure their safety for therapeutic use. Full article

This study, conducted in Southern Italy in 2023, investigated the effects of a dynamic agrivoltaics (AV) system on microclimate, water consumption, plant growth, and essential oil yield in six medicinal species: lavender (Lavandula angustifolia L. ‘Royal purple’), lemmon thyme (Thymus citriodorus (Pers.) Schreb. ar. ‘Aureus’), common thyme (Thymus vulgaris L.), rosemary (Salvia rosmarinus Spenn. ‘Severn seas’), mint (Mentha spicata L. ‘Moroccan’), and sage (Salvia officinalis L. subsp. Officinalis). Due to the rotating solar panels, two distinct ground zones were identified: a consistently shaded area under the panels (UP), and a partially shaded area between the panels (BP). These were compared to an adjacent full-sun control area (T). Microclimate parameters, including solar radiation, air and leaf infrared temperature, and soil temperature, were recorded throughout the cultivation season. Reference evapotranspiration (ET_O) was calculated using Turc’s method, and crop evapotranspiration (ET_C) was estimated with species-specific crop coefficients (K_C). Results showed significantly lower microclimatic values in the UP plot compared to both BP and especially T, resulting in ET_C reductions of 81.1% in UP and 13.1% in BP relative to T, an advantage in water-scarce environments. Growth and yield responses varied among species and treatment plots. Except for mint, all species showed a significant reduction in fresh biomass (40.1% to 48.8%) under the high shading of UP compared to T. However, no biomass reductions were observed in BP. Notably, essential oil yields were higher in both UP and BP plots (0.60–2.63%) compared to the T plot (0.51–1.90%). These findings demonstrate that dynamic AV systems can enhance water use efficiency and essential oil yield, offering promising opportunities for sustainable, high-quality medicinal crop production in arid and semi-arid regions. Full article

In the present work, the antimicrobial efficacy of Thymus vulgaris essential oil (EO) was investigated on Alternaria alternata strain BNR; a paper biodeteriogen was used as a model for a contaminated library. The influence of EO volume and diffusion modality, treatment duration, and inoculum age was evaluated in the vapor phase. In Petri dish screening, the influence of different EO volumes (5, 7.5, and 10 μL) on the microbial growth lag phase was investigated, and the growth inhibition period was established. The most effective treatment (10 μL EO) was then scaled up in a glass airtight container of 2650 cm³; a cold diffusion method was applied in order to quickly reach the maximum concentration of active compounds in the vapor phase. These tests demonstrated that EO efficacy is affected by the inoculum age and the contact time, and that the treatment should be performed as early as is feasible. A mycostatic effect was confirmed to be proportional to the utilized EO volume and independent from the treatment method. The information obtained in the present work will be applied to the set-up of an EO treatment in a library characterized by different levels of air contamination. Full article

Overexploitation has led to a rise in pathogenic bacteria within aquaculture, increasing reliance on antibiotics, and developing microorganism resistance. This situation underscores the need to explore alternatives with a reduced ecological impact. Metabolites derived from essential oils have demonstrated antimicrobial properties that can inhibit or diminish the activity of various microorganisms. In this study, the antimicrobial efficacy of cinnamon (Cinnamomum zeylanicum), tea tree (Melaleuca alternifolia), and thyme (Thymus vulgaris) essential oils against pathogenic bacteria (Aeromonas, Pseudomonas, Shewanella, Comamonas, Vibrio, Acinetobacter, and Empedobacter) isolated from tilapia (Oreochromis spp.) brooded in Hidalgo State, Mexico, were investigated. Diffusion tests were conducted using discs infused with 12 different antibiotics and discs infused with essential oils at concentrations of 15, 10, and 5 μL each. Minimal inhibitory concentration tests were performed using a 96-well microplate format. All bacterial strains exhibited multi-resistance to various antibiotics; however, thyme and cinnamon effectively inhibited the tested bacteria at the lowest concentrations, while tea tree oil was the least effective. The findings suggest the potential incorporation of thyme and cinnamon as an alternative prevention to decrease the use of antibiotic treatment. Full article

Staphylococcus aureus and coagulase-negative staphylococci (CNS) are the main causative agents of mastitis in sheep. Their ability to form biofilms in vivo is considered an important virulence factor underlying mastitis outbreaks refractory to antibiotic treatments. Furthermore, pre- and postdipping immersion during milking in iodine substances could determine the presence of residues in milk and therefore represent a health risk factor for consumers. The aim of this study was to evaluate the antibacterial and biofilm inhibitory activity of Thymus vulgaris L. essential oil (TEO) against staphylococci strains isolated from ovine clinical mastitis. In particular, 3 reference strains (S. aureus 25923 and 11623 and S. epidermidis 12228) and 12 clinical isolates (6 S. aureus and 6 CNS) were used. TEO solutions, from a concentration of 1% (v/v) to 1.25% (v/v), corresponding to 9.28–2.32 mg/mL, were obtained after solubilization in 10% dimethyl sulfoxide (DMSO) and used to evaluate the bacterial time-kill compared to that of an iodine-based solution. Antibacterial efficacy was then assessed by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), while biofilm inhibition was assessed by minimum biofilm inhibitory concentration (MBIC) using a spectrophotometer at a wavelength of 570 nm. Additionally, biofilm-associated genes (icaA and icaD) were evaluated in all tested strains by PCR. The tested TEO concentrations were able to significantly and prominently reduce bacterial growth compared to controls, as demonstrated by bacterial time-kills. The MIC value was obtained at a concentration of 0.50% (v/v) for a single coagulation-positive isolate (S. aureus (f)) and at a concentration of 0.25% (v/v) for all other isolates. TEO showed effective bactericidal action with a 99.9% reduction in CFU/mL of all isolates in the MBC test at a concentration of 0.25% (v/v) for most of the tested strains. Furthermore, a marked inhibition in biofilm formation at all tested concentrations was observed, with MBIC value of 0.25%. All S. aureus tested were biofilm-producing strains and positive for icaA and icaD genes, while two CNS biofilm-producing strains were negative for both genes. These preliminary results suggest that TEO could be a promising alternative as an udder disinfectant during milking practices. Although in vivo studies are needed to confirm the efficacy and safety of TEO as an adjuvant in the prevention and treatment of udder infections, TEO could help counteract the emergence of antimicrobial resistance and reduce the potential risk of iodine residues in milk. Full article

Plant biostimulants are used to promote plant growth by increasing tolerance to abiotic stressors and improving the efficiency of natural resource use. In the present two-year research (2022–2023 and 2023–2024), the effects of biostimulant foliar applications on the morphological parameters, fresh and dry yields, antioxidant capacity, total phenolic content, and chemical composition of the essential oil of thyme (Thymus vulgaris L.) were studied. For this purpose, four commercial biostimulants, Biostimol Plus + Peptamin-V Plus^®, Acadian MPE^®, Megafol^®, and BlueN^®, were evaluated on thyme cultivated in field conditions. The experiment was laid out in a randomized block design with five treatments and with three replications. During the second growing season, the plants treated with BlueN^®, composed of the bacteria Methylobacterium symbioticum SB23, showed the highest plant weight (152.1 g plant⁻¹), fresh biomass yield (501.9 g m⁻²), and dry yield (172.2 g m⁻²). BlueN^® was the biostimulant that also obtained the highest essential oil yield in both years (0.47 and 0.53%), and for all biostimulants, the amount of thymol and carvacrol increased in the second year, especially with Megafol^® (63.75 and 3.16%). The antioxidant capacity was enhanced in the second year by all biostimulants, according to the ABTS assay, but in particular, by BlueN^® and BPPVP (26.97 μmol/g and 25.01 μmol/g), while the phenolic content was higher in the first year, especially with BlueN^® (65.98 mg GAE/g Extract). The other biostimulants had less intense effects. In conclusion, the biostimulants influenced some characteristics of the essential oil, but the greatest influencers were BlueN^®, Megafol^®, and BPPVP. 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

Sperm cryopreservation provides patients undergoing oncological, surgical, or infertility treatments the opportunity to conceive their own children, using assisted reproductive technologies. However, the freezing-thawing process can negatively influence both the quantity and the quality of spermatozoa, mainly due to an excessive production of reactive oxygen species and/or an impaired antioxidant defense system in sperm. Aromatic and medicinal plants synthesize essential oils with antioxidant proprieties as a part of their ecological adaptation to environmental stress, thanks to their rich bioactive phytochemical components. This study aimed to assess sperm progressive motility, viability, plasma membrane functionality, and lipid peroxidation levels of human cryopreserved normozoospermic (n = 51) and asthenozoospermic (n = 51) samples without or with the addition of Thymus satureoides (TSEO) (20 µg/mL), Artemisia vulgaris (AVEO) (48 µg/mL), and Rosmarinus officinalis (ROEO) (13 µg/mL) essential oils. Sperm parameters were significantly better preserved with ROEO in both normozoospermic (p < 0.05) and asthenozoospermic samples (p < 0.01). In contrast, TSEO had a negative impact for both groups (p < 0.05). Meanwhile, no significant effects were observed with AVEO. In summary, the study revealed that in vitro addition of essential oils as antioxidant agents during cryopreservation can be either beneficial, which helps preserve sperm parameters and fertilizing potential, or detrimental as spermicidal agents. 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

Garden thyme (Thymus vulgaris L.) is an annual herbaceous plant of the family Lamiaceae. It can be found both in the wild and as a cultivated plant in Bulgaria. This study is aimed at assessing the garden thyme essential oil composition and antioxidant activities, which were collected from three different areas in Bulgaria. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC-MS). The main compounds in the garden thyme essential oils (over 2%) were as follows: thymol (42.88–53.55%), p-cymene (14.25–25.51%), γ-terpinene (6.58–15.51%), borneol (2.75–3.57%), carvacrol (2.00–3.02%), β-linalool (2.07–2.31%), cis-sabinene hydrate (4.05%), eucalyptol (1.08–3.65%), α-terpinene (1.01–3.24%), carvacrol methyl ether (1.18–3.02%), and thymol methyl ether (2.26–3.16%). The oils were mainly composed of oxygenated phenyl propanoids, and all the essential oils belonged to the chemotype thymol. Antioxidant activities were measured by DPPH (2,2-diphenyl-1-picrylhydrazyl radical) and ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] assays. All the samples exhibited antioxidant activity relative to the DPPH radical (from 143.20 mM TE/mL to 165.91 mM TE/mL) and by the ABTS method (from 121.67 mM TE/mL to 127.62 mM TE/mL). These garden thyme essential oils could be used as natural antioxidants for food and as nutraceuticals. Full article

The aim of this study was to determine the activity of common thyme (Thymus vulgare L.), Greek oregano (Origanum vulgare L. ssp. hirtum), and common oregano (Origanum vulgare L. ssp. vulgare) essential oils (EOs) against selected phytopathogenic microorganisms in relation to their chemical profile. The EOs were obtained from the herbs of 2-year-old plants cultivated in the organic farming system in a temperate climate in Central Europe. The EOs’ composition was determined by GC/MS and GC/FID. The investigated species were represented by the following three chemotypes: ‘thymol’ for common thyme, ‘carvacrol’ for Greek oregano, and mixed ‘caryophyllene oxide + β-caryophyllene’ for common oregano. The antimicrobial activity of the EOs was assessed based on minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) values. The plant pathogenic bacteria Pseudomonas syringae, Xanthomonas hortorum, Erwinia carotovora, and fungi: Fusarium culmorum, Alternaria alternata, Botrytis cinerea, Epicoccum purpurascens, Cladosporium cladosporioides, Phoma strasseri, and Pythium debaryanum were tested. The EOs revealed a stronger inhibitory effect against fungal growth in comparison to bacterial growth (MIC: 0.016–2 µL/mL for fungi and 0.125–4 µL/mL for bacteria). Common thyme and Greek oregano EOs indicated stronger antimicrobial power than common oregano EO. These results were associated with the chemical profile of the analysed EOs. The growth of examined bacteria and fungi strains (in particular, X. hortorum, F. culmorum, and P. debaryanum) were negatively correlated with the content of phenolic monoterpenes and monoterpene hydrocarbons. Among the tested strains, P. strasseri turned out to be the most sensitive (MIC 0.016 µL/mL) and E. carotovora the most resistant (MIC 0.250–4 µL/mL) to all investigated EOs. Full article

This study focused on the evaluation of the phytotoxic activity of four essential oils (EOs) from the Mediterranean species of Thymus sp. pl., namely Thymus algeriensis Boiss. et Reut., T. ciliatus Desf. subspecies coloratus (Boiss. et Reut.) Batt., T. vulgaris L. ecotype Fasano and T. vulgaris cultivar L. Varico 3, to identify new biomolecules with herbicide potential. The chemical characterization of EOs was performed by GC-MS. The evaluation of the phytotoxicity of the EOs was conducted under in vitro conditions, and the inhibition of germination and seedling growth of Lolium perenne L. and Amaranthus retroflexus L. were assessed. Five concentrations (100, 250, 500, 750 and 1000 µL/100 mL) were considered. Phytochemical analysis revealed a great diversity of compounds. T. algeriensis and T. ciliatus EOs were characterized by the absence of carvacrol and a low content of thymol in T. ciliatus. On the contrary, T. vulgaris ecotype Fasano and T. vulgaris cultivar Varico 3 were characterized by an important content of p-cymene, thymol and carvacrol. All the EOs expressed a potent phytotoxic activity against the tested species. The total inhibition of seed germination and seedling growth were recorded for the highest concentrations of all the EOs. T. vulgaris ecotype Fasano expressed the most effective activity. Full article