Activity Of Thyme Essential Oils Research Articles

Synergistic effects of Thymus vulgaris essential oil in combination with antifungal agents and inhibition of virulence factors of Candida albicans

BackgroundCombination antifungal therapy has become a prominent approach in medical practice as it takes advantage of synergistic interactions by interfering with multiple targets of the pathogen, broadening the spectrum of activity, reducing the development of resistance, and improving treatment outcomes. Therefore, combining conventional antifungal drugs with natural products can increase antifungal activity, reduce side effects, and optimize therapeutic effects. PurposeThe present study aimed to evaluate the antifungal activity of thyme essential oil (ThyEO) in combination with amphotericin B, caspofungin, fluconazole, itraconazole, and posaconazole (PSZ), as well as its inhibitory effect on Candida albicans virulence factors. Materials and MethodsThe microbroth dilution assay was employed to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). Interactions were assessed using the microdilution checkerboard assay. Ergosterol and methylene blue assays were used to detect effects on fungal membrane, while the sorbitol assay was used to detect effects on fungal cell wall. Inhibition of yeast virulence factors (adherence to epithelial cells, germ tube and pseudomycelium formation, secretion of hydrolytic enzymes, and biofilm formation) was assessed with previously reported methods. ResultsAlmost all combinations showed additivism against C. albicans, except ThyEO/PSZ (31.25/0.0039 µg/ml), which showed partial synergism. Furthermore, all mixtures were fungicidal against C. albicans strains. ThyEO/PSZ, its components alone, and thymol were shown to disrupt the fungal cytoplasmic membrane, increasing its permeability. ThyEO/PSZ, at sub-inhibitory concentrations, significantly decreased the ability of C. albicans to adhere to buccal epithelial cells. ThyEO/PSZ, ThyEO, and PSZ were able to reduce the pseudomycelium production of C. albicans while thymol completely inhibited its formation. ThyEO/PSZ, each combination component on its own, and thymol inhibited biofilm formation and preformed biofilm of C. albicans. Notably, ThyEO/PSZ showed synergistic and fungicidal activity against a resistant strain of C. albicans, reducing the PSZ dose by 4-fold. ConclusionThese findings make ThyEO and ThyEO/PSZ mixture valuable candidates for the development of alternative antifungals with a lower incidence of adverse effects.

Thyme essential oil inhibits intracellular replication of CyHV-3 and inactivates extracellular virus. An in vitro study.

Cyprinid herpesvirus 3 (CyHV-3) can induce up to 100% mortality among carp populations. To date, there has been no safe method to prevent the consequences of the activity of CyHV-3. Thyme is widely used in cooking due to its flavour. Both thyme and thyme essential oil (TEO) are used in traditional herbal medicine, mainly to treat respiratory system disorders. In this study, TEO containing predominantly cymene and thymol was applied to explore its antiviral effect. The toxicity of TEO was examined in MTT and crystal violet assays. The anti-CyHV-3 activity of TEO in the intracellular and extracellular stages of the viral replication cycle was explored in a plaque assay and TaqMan qPCR. TEO interfered with the intracellular stages of the CyHV-3 replication cycle with selectivity indexes (SI) of around 5. It also displayed virucidal activity in a dose- and time-dependent manner. Two-hour preincubation of CyHV-3 with TEO generated SI, ranging from 13.37 to 18.47 depending on cell line and method of examination. Preincubation of cells with TEO at a safe concentration did not decrease the intracellular viral DNA copy number, which suggests that TEO does not disturb the attachment of the virus to the cells. Further research regarding the antiviral activity of compounds of TEO is required in order to indicate the most potent molecules that could be considered candidates for application in aquaculture.

ACTIVITY OF THYME ESSENTIAL OILS AGAINST PLANT PATHOGENIC FUNGI AND ITS POTENTIAL USE AS SEED DISINFECTANT

One potential application of essential oils as low-risk biopesticides is as seeds disinfectant. The main goal of this study was to test the activity of thyme essential oil on four strains of seed/soilborne plant pathogenic fungi, Fusarium graminearum, Botrytis allii, Rhizoctonia solani, and Pythium ultimum, and to evaluate the effect of the inhibitory doses on plant seed germination. The direct application of thyme essential oil on seeds demonstrates a lack of selectivity. The main effects were related to radicle architecture and development of the primary and lateral roots, both in monocotyl, sorghum (Sorghum saccharatum), and in the dicotyls garden cress (Lepidium sativum) and white mustard (Sinapis alba). One potential solution to the lack of selectivity of direct application of the essential oils is biofumigation, i.e., application by volatilization in the rhizosphere area. Our paper raises this issue of compatibility between the necessary doses to inhibit the plant pathogenic fungi and the effects on plant seeds. Formulation of essential oils as slow-release nanoformulation could reduce phytotoxicity while maintaining and even enhancing the activity against plant pathogens.

Improvement of the antioxidant activity of thyme essential oil against biosynthesized titanium dioxide nanoparticles-induced oxidative stress, DNA damage, and disturbances in gene expression in vivo

BackgroundTitanium dioxide nanoparticles (TiO2-NPs) are widely utilized in medicine and industry; however, their safety in biological organisms is still unclear. In this study, we determined the bioactive constitutes of thyme essential oil (TEO) and utilized the nanoemulsion technique to improve its protective efficiency against oxidative stress, genotoxicity, and DNA damage of biosynthesized titanium dioxide nanoparticles (TiO2-NPs). MethodsTEO nanoemulsion (TEON) was prepared using whey protein isolate (WPI). Sixty male Sprague-Dawley rats were divided into six groups and treated orally for 21 days including the control group, TEO, or TEON- treated groups (5 mg/kg b.w), TiO2-NPs-treated group (50 mg/kg b.w) and the groups received TiO2-NPs plus TEO or TEON. Blood and tissues samples were collected for different assays. ResultsThe GC-MS analysis identified 17 bioactive compounds in TEO and thymol and carvacrol were the major compounds. TEON was irregular with average particles size of 230 ± 3.7 nm and ζ-potential of −24.17 mV. However, TiO2-NPs showed a polygonal shape with an average size of 50 ± 2.4 nm and ζ-potential of −30.44 mV. Animals that received TiO2-NPs showed severe disturbances in liver and kidney indices, lipid profile, oxidant/antioxidant indices, inflammatory cytokines, gene expressions, increased DNA damage, and pathological changes in hepatic tissue. Both TEO and TEON showed potential protection against these hazards and TEON was more effective than TEO. ConclusionThe nanoemulsion of TEO enhances the oil bioactivity, improves its antioxidant characteristics, and protects against oxidative damage and genotoxicity of TiO2-NPs.

Control of biofilm-producing Aeromonas bacteria in the water tanks and drinkers of broiler poultry farms using chitosan nanoparticle-based coating thyme oil

In a drinking water distribution system, biofilm-producing bacteria are considered an alarm bell for increased emergence of waterborne pathogens. This study aims to monitor the prevalence of biofilm-forming Aeromonas species in the drinking water distribution systems in different broiler chicken farms. The antimicrobial activity of thyme essential oil (TEO), thyme essential oil nano-emulsion (TEO-N), chitosan (CS), chitosan nanoparticles (CS-NPs), and both CS and CS-NP-based coating TEO against the different Aeromonas spp.was evaluated using the broth microdilution and agar well diffusion assay. The overall prevalence rate of Aeromonas spp. was 49.3% (74.0/150). The highest rate of Aeromonas isolates was noted in water drinkers and tanks 75.0% (30/40) and 62.5% (25/40), respectively) followed by feedstuff 40.0% (12/30). In contrast, the highest percentage of biofilm-producing Aeromonas spp. was Aeromonas hydrophila 70.0% (14/20) followed by Aeromonas caviae 30.0% (6/20). The fatal effect of CS-NPs against all isolated Aeromonas spp. was achieved 100% at 1.5 and 2.0 µg/mL. Moreover, chitosan nanoparticles coating thyme essential oil (CS-NPs/TEO) verified the lethal effect 100% on both A. hydrophila and A. caviae at the ratio of 1:1 and 1:0.75 µg/mL. In conclusion, the main source of Aeromonas spp. in the drinking water distribution system was the unhygienic status of water tanks and drinkers that allowed biofilm to produce due to aggregation of Aeromonas bacteria on the inner surface of that equipment. Both CS-NPs and CS-NPs/TEO could be applied as a sanitizer and/or disinfectant for Aeromonas biofilm control.

Assessment of the Biological Activity of Thyme Essential Oil in the Presence of the Classic Antibiotic Tetracycline.

The present study was purported to assess the activities: (i) antibacterial and synergistic against three types of both Gram-positive and Gram-negative bacteria that are susceptible to drug resistance and (ii) cytotoxic and synergistic on colorectal adenocarcinoma cells, of thyme essential oil (TEo) in combination with tetracycline (Tcyc). Chemical composition of thyme essential oil was evaluated by gas chromatography-mass spectrometry (GC-MS) method, antioxidant capacity by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay, antibacterial and synergistic properties were determined by disk diffusion method and cytotoxic activity by quantifying viable cells by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Thyme essential oil has an elevated antioxidant activity, antibacterial potential against both Gram-positive and Gram-negative bacteria, especially on S. aureus and K. pneumoniae at the highest concentration tested (50µL/mL), also having a synergistic effect when combined with tetracycline (50µL/mL TEo with 10µg/mL Tcyc). Essential oil-treated cells showed a dose-dependent reduction in colorectal adenocarcinoma cell viability, while combination with tetracycline leads to a significantly attenuated decrease in viability.

Evaluating the in vitro Cytotoxicity of Thymus vulgaris Essential Oil on MCF-7 and HeLa Cancer Cell Lines

Thyme essential oil (TEO) was extracted from dried leaves of Thymus vulgaris. The air-dried aerial parts of the plant produced 1.0% yield of TEO. The detection of this essential oil’s compounds was performed by GC-MASS. The cytotoxic activity of TEO was evaluated against two human cancer cell lines, namely HeLa (human epithelial cervical cancer) and MCF-7 (human breast carcinoma). Cells grown in 96 multi-well plates were treated with six concentrations of EO (6.25, 12.5, 25, 50, 100, 200 ppm) and incubated at 37 °C for 72 hrs. Cancer cell lines elicited various degrees of sensitivity to the cytotoxic effect of essential oil. The TEO exhibited significant differences (p≤ 0.01) between the effects of all concentrations against these two human cell lines. The results showed the highest toxicity of TEO on HeLa cell line (78.67%) and MCF-7 cell line (83.60%) at 200 ppm concentration. Also the values of half-maximal inhibitory concentration (IC50) of TEO against HeLa and MCF-7 cell lines were 34.63 and 27.66 ppm, respectively. Cells treated with the IC50 of TEO showed a significant difference (p ≤ 0.01) in p53 fold expression between HeLa cell line (4.33±0.41 folds) and MCF-7 cell line (5.10±0.32 folds). In general, a dose-dependent decrease the survival of the two cell lines was observed. In addition, MCF-7 cell line revealed higher sensitivity against TEO than HeLa cell line.

Hydrodistillation extraction, GC-MS analysis and biological activities of Thymus vulgaris and Mentha arvensis essential oil

The purpose of the study was to examine the chemical composition, antibacterial and antioxidant capabilities of Thymus vulgaris and Mentha arvensis essential oils. The essential oils were extracted using the traditional hydrodistillation process and evaluated using GC-MS. Thymus is a genus of valuable medicinal herbs that are highly recommended owing to the therapeutic effects of its essential oils, which are often known as thyme oil. The essential oils of Thymus vulgaris were tested for phytochemical activity and scientific support of traditional usage. Gas chromatography and mass spectrometry (GC-M) were used to examine the hydrodistillated oil produced from wild thyme species. Forty-seven components were identified. Among those thymol (60.55%), terpinene (8.53%), p-cymene (9.48%) and carvacrol (3.35%) were the major constituents. Other components were present in less than 2% of the total. Gas chromatography and mass spectrometry (GC-MS) were used to identify the components in Mentha arvensis essential oil. The essential oil study resulted in the discovery of twenty-eight compounds, accounting for 92.85% of the oil compositions. Menthone (29.42 percent), Menthol (21.35 percent), Isomenthone (10.85 percent), Eucalyptol (6.95 percent), neo-Menthol (4.75 percent), cis-Piperitone oxide (3.63 percent), Linalool (2.22 percent), Thymol (1.64 percent), Dl-Limonene (1.48 percent), and -Phellandrene (3.22 percent) were just the major components. Thymus vulgaris was investigated for antimicrobial activity against seven common food-borne bacteria and fungi: Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Candida albicans using disc diffusion method. Thyme oil showed positive results against each pathogen. Antibacterial activity of Mentha arvensis was analyzed against six bacteria: Using the micro wells approach, Candida albicans (C. albicans), Pseudomonas aeruginosa (Ps. aeruginosa), Proteus mirabilis (P. mirabilis), Enterococcus faecium (E. faecium), Escherichia coli (E. coli), and Staphylococcus aureus (St. aureus) were employed. Essential oil gave positive results against each bacterium. The essential oil of Mentha arvensis was tested for antifungal efficacy against Candida flexuosus. At all concentrations, essential oil proved effective against F. solani. The antioxidant activity of thyme essential oil was determined using the DPPH test. Results showed, antioxidant activity is directly proportional to phenolic content.

Antimicrobial, antibiofilm and biochemichal properties of Thymus vulgaris essential oil against clinical isolates of opportunistic infections

Thyme belongs to a genus encompassing over 215 species of hardy perennial herbaceous plants and sub-shrubs, which are native to Europe, particularly around the Mediterranean. Thymus vulgaris L., or garden thyme, with narrow small leaves and clusters of tubular mauve flowers, is used mainly in cookery. Dried herb yields 1% and more essential oil, which is a pale yellowish-red liquid with a sweet, very aromatic odour. Thyme is widely used in the pharmaceutical industry and is a source of substances of antimicrobial effect upon antibiotic-resistant strains of microorganisms. The purpose of our work was to identify the biochemical and antimicrobial peculiarities of Th. vulgaris essential oil against clinical isolates of opportunistic microorganisms. The analysis of thyme essential oil was carried out using GC/MS analysis. The clinical isolates were isolated with the use of differentially diagnostic nutrient media. The antibiotic susceptibility was identified with the help of the disc-diffusion test. The sensitivity of microorganisms to plant extracts was determined by the agar diffusion test. The antibiofilm activity of the extracts was tested in standard 96-well microtitration plates. The GC/MS results confirm the earlier reports that the major volatile constituents obtained from the aerial parts of thyme species were thymol, γ-terpinene, p-cymene, 3-carene and carvacrol. After subjecting the selected essential oil to effective steam distillation, substantial contents of phenolic monoterpenoids were obtained – thymol (67.7%) and γ-terpinene (8.2%). The European Pharmacopoeia set quality standards for thyme essential oil, which dealt mainly with the % content (w/w) of the volatile phenols (expressed as thymol: 36.0–55.0%). Garden thyme essential oil has been found to show a high antimicrobial activity against antibiotic-resistant microorganism strains. The obtained results proved the wide spectrum of antibiotic activity of thyme essential oil. The highest antimicrobial activity was registered against the typical and clinic strains of S. aureus and microscopic Candida genus fungi. Garden thyme essential oil was ascertained to show high antibiofilm-forming activity against S. aureus. The antimicrobial and antibiofilm-forming activities of thyme essential oil against both bacterial pathogens of opportunistic infections and microscopic fungi have proven the good prospects for development of a broad-spectrum agent against opportunistic microbial associations based on this oil.

Improved activity of thyme essential oil (Thymus vulgaris) against Aedes aegypti larvae using a biodegradable controlled release system

Aedes aegypti mosquito is the major vector of urban arboviruses and the initial phase of its development occurs in containers with water. The use of chemical control agents is more effective in the larval instar than for the adult insects, due to limited mobility of the larvae in water and their higher sensitivity. Besides, acting in the initial phase is preferable because the mosquito is not yet a vector of diseases. Ae. aegypti, however, developed resistance to common synthetic larvicides that furthermore have a negative impact on both the environment and human health. It is, therefore, necessary to search for new and eco-friendly replacements. Essential oils that are used as natural larvicides are often limited in their applicability as they are poorly water-soluble, degrade easily and volatilize when applied as free oil. These limitations can, however, be overcome using microencapsulation. Thyme essential oil (TEO) contains thymol, an active compound that has a range of biological activities (antioxidant, antimicrobial, insecticidal). The objective of this work was to develop a low-cost bio-degradable larvicide system for controlled release of TEO that is to be applied in small containers in and around households. The controlled release system was prepared by thermoplastic extrusion using corn starch as wall material. The TEO was chemically determined by gas-chromatography to contain 53% w/w of thymol, and its larvicidal activity was determined. The release of the thymol from the particles is demonstrated to correlate with the swelling of the matrix when immersed in water. The particles are effective against larvae from susceptible (Rockefeller) and resistant strains, reduce the required lethal concentration by a factor 3 as compared with the non-encapsulated TEO and significantly prolonged the residual effect, maintaining 100% of larvae mortality for 10 days more than non-encapsulated TEO.

Growth/no-growth models of in-vitro growth of Penicillium paneum as a function of thyme essential oil, pH, aw, temperature

The aims of this study were (i) screening of antifungal activity of thyme essential oil on Penicillium paneum; (ii) development of growth/no-growth models (G/NG); and (iii) validation of the G/NG models by performing bread baking trials. The screening method was based on the measurement of fungal growth in a semi-solid medium through optical density. The combined influence of aw (0.88–0.97), pH (4.8–7.0), temperature (22 and 30 °C), time (0–144 h) and varying concentrations of thyme oil (0–2 μL/mL YES) were assessed. Growth of P. paneum at aw 0.88 was significantly reduced compared to aw 0.93–0.97. A slight pH effect was observed at aw 0.93; growth was delayed at pH 6 compared to pH 4.8. The lowest concentration of thyme oil preventing growth during 144 h of incubation was 1 μL/mL medium. According to the results of the shelf-life test of par-baked bread, fungal growth was inhibited for more than 45 days using 0.3 mL thyme oil/100 g dough. To conclude, this study recognized the potential of using G/NG models to develop better product formulations and to facilitate product innovation.

Potential of thyme essential oil on arugula sanitization

ABSTRACT Essential oils from plants are an important alternative source of antimicrobial compounds against important pathogens for food safety. This study aimed to evaluate the in vitro antimicrobial activity of thyme essential oil (Thymus vulgaris) and to apply it in the sanitization of minimally processed arugula (Eruca sativa), aiming to increase the safety and shelf life of arugula. The in vitro antibacterial activity of the essential oil was evaluated by disc diffusion assays and determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against different foodborne pathogens. Thereafter, a “challenge test” was carried out to evaluate the antibacterial activity of the thyme essential oil (0.2%) on the sanitization of arugula inoculated with Escherichia coli (3 log CFU mL-1) compared to sodium hypochlorite (120 ppm of active chlorine). Afterwards, an experiment of applying the thyme essential oil (0.2%) as a sanitizing agent in minimally processed arugula was carried out to evaluate the vegetable shelf life compared to sodium hypochlorite (120 ppm of active chlorine). The arugula was stored at 8 °C for 7 days, and periodically, the number of aerobic mesophilic microorganisms, pH and titratable acidity were determined, and the color of the samples was evaluated. The thyme essential oil had strong antimicrobial activity in vitro against all species of bacteria tested. In the experiments in situ, the thyme essential oil (0.2%) and sodium hypochlorite (120 ppm of active chlorine) were not efficient in eliminating the inoculated E. coli from minimally processed arugula, and they did not result in an extension of the shelf life of the arugula in comparison to the control (p>0.05). However, the growth rate of the E. coli population over time on the arugula samples sanitized with the thyme essential oil (0.2%) was low, which indicates a positive effect of the essential oil, which may be optimized with future adjustments in the concentration and immersion time for the arugula sanitization.

Validation of in-vitro antifungal activity of thyme essential oil on Aspergillus niger and Penicillium paneum through application in par-baked wheat and sourdough bread

The main objectives of this study were to investigate the antifungal activity of thyme essential oil (Thymus zygis) in-vitro and to validate its activity in par-baked wheat and sourdough bread (in-vivo) using the fungal strains Aspergillus niger and Penicillium paneum. The impact of thyme oil was evaluated in-vitro with the macro-dilution method with modified pH (4.8, 5.0, 5.5 & 6.0), aw (0.95 & 0.97) and temperature (22 & 30 °C) to mimic the conditions of wheat and sourdough par-baked bread stored at room temperature. Furthermore, the oil was applied in par-baked bread (0, 15 and 30 g sourdough/100 g dough). Challenge and shelf-life tests were performed to investigate the biopreservative potential of thyme oil in par-baked wheat and sourdough bread. Despite the promising in-vitro potential of thyme oil, no clear shelf-life extension was observed for par-baked bread which could be attributed to the oil. More research on food applications of essential oils is necessary to give the abundance of in-vitro studies industrial relevance. The use of sourdough, on the contrary, resulted in much more promising shelf-life extending properties. In both in-vitro as in-vivo assays, pH and aw showed no significant effect on fungal growth.

Inhibition of Salmonella by thyme essential oil and its effect on microbiological and sensory properties of minced pork meat packaged under vacuum and modified atmosphere

The antibacterial activity of thyme essential oil (TEO) was evaluated against four serovars of Salmonella (S. Enteritidis, S. Typhimurium, S. Montevideo and S. Infantis), experimentally inoculated (106CFU/g) in minced pork, which was treated with different concentrations of the TEO (0.3%, 0.6% and 0.9%) packaged under vacuum or MAP (30%O2/50%CO2/20% N2) and stored at 3±1°C for 15days. GC–MS analysis of the TEO was performed in order to determine composition, and the predominant constituent was thymol (50.48%), followed by p-cymene and linalool. The minimum inhibitory concentration was determined for each Salmonella serovar studied. Among the tested active compounds, thymol and carvacrol exhibited the greatest inhibitory effect followed by TEO, with minimum inhibitory concentrations of 320 to 640μg/ml. S. Enteritidis was the most sensitive serovar. During the storage period, Salmonella counts in pork were reduced by 1.69–4.05logCFU/g. The influence of TEO on Enterobacteriaceae, lactic acid bacteria and total viable count was determined in control mince with no added Salmonella. The most pronounced antibacterial effect was achieved by the combination MAP and 0.9% TEO. Although the antibacterial activities of all studied concentrations of TEO in pork were evident and significant (P<0.05), sensory analysis showed that 0.3% TEO was the most acceptable to trained panellists.

Nanoencapsulation Approach to Improve Antimicrobial and Antioxidant Activity of Thyme Essential Oil in Beef Burgers During Refrigerated Storage

In this study, thyme essential oil (TEO) loaded chitosan nanoparticles (CS-NP-TEO) are prepared by a two-step process including oil/water emulsion and ionic gelation. Five batches of burgers were prepared by following formulation: control (without any TEO), F-0.05-TEO (0.05 % of free TEO), F-0.1-TEO (0.1 % of free TEO), E-0.05-TEO (0.05 % of encapsulated TEO), E-0.1-TEO (0.1 % of encapsulated TEO), and AA-0.05 (0.05 % of ascorbic acid). All samples treated with TEO significantly reduced the population of investigated microbial counts (P < 0.05) compared to the control during 8 days of storage. At the end of storage, E-0.05-TEO and E-0.1-TEO, presented, respectively, 2.2 and 3 log cycles reduction of Enterobacteriaceae, along with 3.1 and 3.7 log cycles reduction of Staphylococcus aureus. Oxymyoglobin content and redness values reduced with the increase of storage time for all samples. However, AA-0.05 and E-0.1-TEO samples were more efficient at inhibiting discoloration in comparison with E-0.05-TEO and burgers treated with free TEO after 6th day of storage. A significant improvement (P < 0.05) in the reduction of thiobarbituric acid reactive substances (TBARS) amount was found for all TEO treated burgers in comparison to control samples after 8 days chilled storage. According to the results of sensory analyses, F-0.1-TEO and AA-0.05 samples at 4 days and F-0.05-TEO sample at 8 days of storage were rejected by assessors and considered as an unacceptable case. On the basis of our results, the encapsulation of TEO in chitosan nanoparticles may be a promising technology for the control of undesirable microbial, chemical, and sensorial changes in meat products.

Influential Cooperation between Zeolite and PGPR on Yield and Antimicrobial Activity of Thyme Essential Oil

Influential Cooperation between Zeolite and PGPR on Yield and Antimicrobial Activity of Thyme Essential Oil

Development of a thyme essential oil formulation and its effect on Monilinia ructigena

Antifungal activity of thyme essential oil against Monilinia fructigena and development of an effective and stable oil formulation for agricultural use were studied in this paper. Bioactivity of the oil itself and its developed formulation, an emulsifiable concentrate (EC), was tested in vitro and in vivo. In vitro experiments, using a slightly modified agar overlay technique, showed that the initially emulsified thyme essential oil, as well as the developed formulation, significantly inhibited mycelial growth of M. fructigena in vitro. Experiments in vivo, performed on inoculated apple fruits, revealed that the formulation successfully decreased oil evaporation from the treated area and provided a significant level of M. fructigena suppression, 64.7-72.1% compared to the control. To our knowledge, an EC formulation of thyme essential oil for agricultural uses had never been developed before. The presented results are initial findings and evaluation of product activity should be continued in the field to determine its efficacy and activity spectrum, and to estimate the economic aspect of its use.

The Antimicrobial Activity of Thyme Essential Oil Against Multidrug Resistant Clinical Bacterial Strains

The aim of this work was to investigate the antimicrobial activity of thyme essential oil against clinical multidrug resistant strains of Staphylococcus, Enterococcus, Escherichia, and Pseudomonas genus. The antibacterial activity of oil was tested against standard strains of bacteria and 120 clinical strains isolated from patients with infections of the oral cavity, abdominal cavity, respiratory and genitourinary tracts, skin, and from the hospital environment. Agar diffusion was used to determine the microbial growth inhibition of bacterial growth at various concentrations of oil from Thymus vulgaris. Susceptibility testing to antibiotics was carried out using disk diffusion. Thyme essential oil strongly inhibited the growth of the clinical strains of bacteria tested. The use of phytopharmaceuticals based on an investigated essential oil from thyme in the prevention and treatment of various human infections may be reasonable.

The activity of thyme essential oil against Acinetobacter spp.

Abstract The aim of this work was to investigate the antimicrobial properties of thyme essential oil against clinical multiresistant strains of Acinetobacter spp. The antibacterial activity of oil was tested against standard and clinical bacterial strains of Acinetobacter genus. The agar diffusion method was used to check the inhibition of microbial growth at various concentrations of the oil from Thymus vulgaris. Susceptibility testing to antibiotics and chemotherapeutics was prepared using the disc-diffusion method. Identification of bacterial strains was carried out with the Vitek system and confirmed by PCR for Acinetobacter baumanii gyrB gene. The results of experiments showed that the oil from T. vulgaris exhibited an extremely strong activity against all of the clinical strains of Acinetobacter. Thyme oil demonstrated a very good efficacy against multiresistant strains of tested bacteria. Essential oils seems to be an excellent alternative for synthetic preparations and that is reason for an extensive assessment of their antimicrobial activity.

Antifungal activity of thyme (Thymus vulgaris L.) essential oil and thymol against moulds from damp dwellings

To characterize antifungal activities of essential oil of thyme (Thymus vulgaris L.) and pure thymol, as comparative substance, on different mould species isolated from damp dwellings. Fifty samples of wall scrapes were collected from damp dwellings in Zagreb, the capital of Croatia. The members of the following mould genera were recovered from the samples: Aspergillus (44%), Penicillium (18%) Alternaria, Ulocladium, Absidia and Mucor (8%) Cladosporium, Trichoderma and Rhizopus (6%), and Chaetomium (2%). Two strains of Stachybotrys chartarum were isolated from damp dwellings in Slovakia. Antifungal activities of the thyme essential oil, which contains p-cymene (36.5%), thymol (33.0%) and 1,8-cineole (11.3%) as main components, and pure thymol were determined by the dilution method and exposure to vaporous phase of the oil. Minimum inhibitory concentrations (MIC) of both thymol and essential oil were bellow 20 microg ml(-1), except for Mucor spp. (50.20 microg ml(-1)). Thymol exhibited approximately three-times stronger inhibition than essential oil of thyme. The vaporous phase of the thyme essential oil (82 microg l(-1)) in glass chambers strongly suppressed the sporulation of moulds during 60 days of exposure. The thyme essential oil possesses a wide range spectrum of fungicidal activity. The vaporous phase of the oil exhibited long-lasting suppressive activity on moulds from damp dwellings. Essential oil of thyme and thymol could be used for disinfection of mouldy walls in the dwellings in low concentration.