Influence of nitrogen fertilizers on the yield and composition of thyme (Thymus vulgaris)

The influence of nitrogen fertilizers on the yield of crop, as well as on the production and composition of the essential oil and some other chemical characteristics of thyme, was investigated. Different levels of fertilizers (N = 0, 45, 90, and 135 kg x ha(-)(1)) were applied. It was found that fertilizers increase thyme crop, but differences in the yield of essential oil were not remarkable. However, the use of certain amounts of nitrogen fertilizers resulted in higher yields of essential oil obtainable from the cultivation area unit (dm(3) ha(-)(1)). Totally, 61 constituents were identified in thyme essential oil by capillary GC and GC-MS. Thymol was the dominating compound in the all analyzed oils (44.4-58.1%), followed by p-cymene (9.1-18.5%), gamma-terpinene (6.9-18.9%), and carvacrol (2.4-4.2%). Differences in the percentage of these and other compounds in thyme herb cultivated under different fertilization doses were not significant; very slight changes in the percentage composition were detected after drying. Some variations in the amount of individual constituents expressed in arbitrary units per kilogram of herb (which is almost equivalent to mg x kg(-)(1)) were observed. The highest amounts of sugars and sucrose, in particular, were determined in the second year of thyme cultivation. Differences in the content of dry soluble substances were not meaningful, and there was no effect of nitrogen fertilizers on this chemical characteristic. Some effect of fertilization on the content of vitamin C and carotenes was observed in the first year of thyme cultivation. It was determined that nitrogen fertilizers influence the amount of nitrates, which was highest in the second-year-first-harvest.     

Thymus zygis subsp. Gracilis: watering level effect on phytomass production and essential oil quality

Thymus zygis subsp. gracilis (chemotype thymol) was evaluated on the basis of its phytomass production and essential oil quality. Three different watering levels were assayed to achieve 63, 44, and 30% of the local potential evapotranspiration (Eto). According to the statistical analysis, a water supplement equivalent to 44% Eto in this cultivation area was optimal for maximum plant dry matter production and essential oil yield. Capillary GC-MS analysis of the essential oil allowed the identification of 86 volatile components. Among them, 30 are described for the first time as volatile constituents of the essential oil in this thyme subspecies and chemotype. The watering level effect on essential oil composition was noticeable, because the application of a water supplement equivalent to the 63% Eto favored the production of an essential oil richer in low molecular weight components. However, the greatest thymol concentrations were obtained under the 30 and 44% Eto watering levels.     

Essential oils from Mediterranean lamiaceae as weed germination inhibitors

The essential oils obtained from rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and savory (Satureja montana L.) and the four monoterpenes that are their major constituents have been analyzed by GC and GC-MS and tested for their allelopathic properties on the seeds of three different annual weeds (Chenopodium album, Portulaca oleracea, and Echinochloa crus-galli) and three crops (Raphanus sativus, Capsicum annuum, and Lactuca sativa), with the aim to evaluate in vitro their potential as germination inhibitors. The essential oil composition varied with the species, thymol being the main constituent (44%) of thyme and carvacrol (57%) that of savory oil. Differences in essential oil composition were observed within two different rosemary ecotypes, type A, with alpha-pinene (37%) and 1,8-cineole (23%), and type B, characterized by a 2-fold content of 1,8-cineole (47%). This latest essential oil inhibited completely the germination of weeds while concurrently displaying little effect on pepper. The other two oils showed less selective action. S. montana essential oil, with 57% carvacrol, is the most active compound, completely inhibiting germination both of crops and weeds. Borneol, one of the main constituents of the oil of rosemary type B, showed an activity comparable to that of the whole oil. Crop and weed seeds treated with 1,8-cineole showed germination values that were not significantly different from controls, even if a slowing of the germination process expressed in terms of a significant increase in mean germination time was observed. Monoterpene compounds also present in the essential oils mainly represented the volatile fraction released from the crops and their residues into the soil.     

Volatile components and key odorants of fennel (Foeniculum vulgare Mill.) and thyme (Thymus vulgaris L.) oil extracts obtained by simultaneous distillation-extraction and supercritical fluid extraction

Volatile oil extracts of fennel seeds (Foeniculum vulgare Mill.) and thyme leaves (Thymus vulgaris L.) were obtained by simultaneous distillation-extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). In general, fennel oil extracted by SDE and SFE showed similar compositions, with trans-anethole, estragole, and fenchone as the main components. In contrast, thymol and p-cymene, the most abundant compounds in thyme leaves, showed big differences, with generally higher amounts of monoterpenes obtained by SDE. However, in this case, the differences between the extracts were higher. Key odorants of fennel seeds determined by gas chromatography-olfactometry (GC-O) showed similar patterns when applying SDE and SFE. trans-Anethole (anise, licorice), estragole (anise, licorice, sweet), fenchone (mint, camphor, warm), and 1-octen-3-ol (mushroom) were the most intense odor compounds detected in fennel extracts. Thymol and carvacrol, with oregano, thyme, and spicy notes, were identified as key compounds contributing to the aroma of thyme leaves.     

Watering level effect on Thymus hyemalis Lange essential oil yield and composition

Thymus hyemalis Lange (chemotype thymol) was cultivated as an experimental crop under different watering level conditions in order to achieve 80, 60, 40, and 20% of the local potential evapotranspiration (Eto). Two harvesting periods were considered, winter and spring. As a consequence of the great variability among plants, essential oil yield percentages did not show statistically significant differences among seasons and different levels of water supply. Capillary GC-MS analysis of the essential oils permitted the detection of 84 volatile components. Among them, 54 are described for the first time as volatile constituents of the chromatographic profile of this Thymus species. Winter harvesting showed high concentrations in thymol percentage (25.92 +/- 4.39), the 40% Eto watering level being the best with respect to obtaining the optimum quality of this essential oil. However, in spring this thyme species needs a greater water supply (80% Eto) to achieve the same amount of thymol in the essential oil (29.20 +/- 2.83). From this, it was concluded that winter harvesting could be used for the extraction of the essential oil, with a low level of water supply, whereas spring harvesting could be employed for collection of leaves as a food condiment.     

Composition of the essential oils of Thymus and Origanum species from Algeria and their antioxidant and antimicrobial activities

The composition of the essential oils of Origanum and Thymus species restricted to Algeria and the North Africa region was determined. Antioxidant and antibacterial activities of the isolated essential oils were also determined. The oils of oregano plants were strongly characterized by p-cymene (16.8-24.9%), gamma-terpinene (16.8-24.9%), thymol (8.4-36.0%), and carvacrol (1.1-29.7%), a thymol chemotype for Origanum floribundum and a alpha-terpineol chemotype for Thymus numidicus being described for the first time. The strains of Listeria monocytogenes tested were relatively resistant to the action of essential oils of either Origanum or Thymus species. All essential oils possessed antioxidant activity, but this was dependent on the specific chemical composition and the method employed to determine such activity.     

Correlation between the chemical and genetic relationships among commercial thyme cultivars

The essential oil composition and genetic variability of six commercial cultivars of thyme (Thymus vulgaris L.), a Mediterranean medicinal and aromatic plant, were analyzed by GC-MS and randomly amplified polymorphic DNA (RAPD), respectively. All evaluated cultivars belong to the thymol chemotype, with differences in the concentrations of thymol, gamma-terpinene, p-cymene, and other minor components. The comparison of the oil components concentration by multivariate analysis allowed separation of the cultivars into two groups. All of the cultivars exhibited characteristic RAPD patterns that allowed their identification. On the basis of the RAPD patterns, the cultivars could be divided into two clusters, which coincides with results obtained by oil GS-MS analysis, with a correlation coefficient of -0.779.     

GC-MS analysis of essential oils from some Greek aromatic plants and their fungitoxicity on Penicillium digitatum

The isolated essential oils from seven air-dried plant species were analyzed by gas chromatography-mass spectrometry (GC-MS). Thymus vulgaris (thyme), Origanum vulgare (oregano), and Origanumdictamus (dictamus) essential oils were found to be rich in phenolic compounds representing 65.8, 71.1, and 78.0% of the total oil, respectively. Origanum majorana (marjoram) oil was constituted of hydrocarbons (42.1%), alcohols (24.3%), and phenols (14.2%). The essential oil from Lavandula angustifolia Mill. (lavender) was characterized by the presence of alcohols (58.8%) and esters (32.7%). Ethers predominated in Rosmarinus officinalis (rosemary) and Salvia fruticosa (sage) essential oils, constituting 88.9 and 78.0%, respectively. The radial growth, conidial germination, and production of Penicillium digitatum were inhibited completely by oregano, thyme, dictamus, and marjoram essential oils at relatively low concentrations (250-400 microg/mL). Lavender, rosemary, and sage essential oils presented less inhibitory effect on the radial growth and conidial germination of P. digitatum. Conidial production of P. digitatum was not affected by the above oils at concentrations up to 1000 microg/mL. Apart from oregano oil, all essential oils were more effective in the inhibition of conidial germination than of radial growth. The monoterpene components, which participate in essential oils in different compositions, seem to have more than an additive effect in fungal inhibition.     

Yield and oil composition of 38 basil (Ocimum basilicum L.) accessions grown in Mississippi

A field experiment was conducted to assess yield, oil content, and composition of 38 genotypes of sweet basil ( Ocimum basilicum L.). Overall, biomass yields were high and comparable to those reported in the literature. However, basil genotypes differed significantly with respect to oil content and composition. Oil content of the tested accessions varied from 0.07% to 1.92% in dry herbage. On the basis of the oil composition, basil accessions were divided into seven groups: (1) high-linalool chemotype [19-73% (-)-linalool], (2) linalool-eugenol chemotype [six chemotypes with 28-66% (-)-linalool and 5-29% eugenol], (3) methyl chavicol chemotype [six accessions with 20-72% methyl chavicol and no (-)-linalool], (4) methyl chavicol-linalool chemotype [six accessions with 8-29% methyl chavicol and 8-53% (-)-linalool], (5) methyl eugenol-linalool chemotype [two accessions with 37% and 91% methyl eugenol and 60% and 15% (-)-linalool], (6) methyl cinnamate-linalool chemotype [one accession with 9.7% methyl cinnamate and 31% (-)-linalool], and (7) bergamotene chemotype [one accession with bergamotene as major constituent, 5% eucalyptol, and <1% (-)-linalool]. Our results demonstrated that basil could be a viable essential oil crop in Mississippi. The availability of various chemotypes offers the opportunity for production of basil to meet the market requirements of specific basil oils or individual compounds such as (-)-linalool, eugenol, methyl chavicol, methyl cinnamate, or methyl eugenol.     

Antibacterial and antioxidant activities of essential oils isolated from Thymbra capitata L. (Cav.) andOriganum vulgare L

Antilisterial activities of Thymbra capitata and Origanum vulgare essential oils were tested against 41 strains of Listeria monocytogenes. The oil of T. capitata was mainly constituted by one component, carvacrol (79%), whereas for O. vulgare three components constituted 70% of the oil, namely, thymol (33%), gamma-terpinene (26%), and p-cymene (11%). T. capitata essential oil had a significantly higher antilisterial activity in comparison to O. vulgare oil and chloramphenicol. No significant differences in L. monocytogenes susceptibilities to the essential oils tested were registered. The minimum inhibitory concentration values of T. capitata essential oil and of carvacrol were quite similar, ranging between 0.05 and 0.2 microL/mL. Antioxidant activity was also tested, the essential oil of T. capitata showing significantly higher antioxidant activity than that of O. vulgare. Use of T. capitata and O. vulgare essential oils can constitute a powerful tool in the control of L. monocytogenes in food and other industries.     

Effect of maturation on the composition and biological activity of the essential oil of a commercially important Satureja species from Turkey: Satureja cuneifolia Ten. (Lamiaceae)

The essential oil obtained by hydrodistillation from aerial parts of Satureja cuneifolia Ten., collected in three different maturation stages such as preflowering, flowering, and postflowering, were analyzed simultaneously by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Thymol (42.5-45.2%), p-cymene (19.4-24.3%), and carvacrol (8.5-13.2%) were identified as the main constituent in all stages. At the same time, the essential oils and main components were evaluated for their antimicrobial activity using a microdilution assay resulting in the inhibition of a number of common human pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and the yeasts Candida albicans and Candida tropicalis. The minimum inhibitory concentrations (MIC) varied between 62.5 and 250 microg/mL within a moderate antimicrobial activity range. Furthermore, the antioxidant capacity of the essential oils and major components thymol and carvacrol were examined in vitro. The essential oils obtained from S. cuneifolia in three different stages and its main components were interacted with 1,1-diphenyl-2-picrylhydrazyl (DPPH (*)) as a nitrogen-centered stable radical, resulting in IC 50 = 1.6-2.1 mg/mL. In addition, the effects on inhibition of lipid peroxidation of the essential oils were assayed using the beta-carotene bleaching method. All of the tested oils inhibited the linoleic acid peroxidation at almost the same level as butylated hydroxytoluene (BHT) (93.54-94.65%). BHT and ascorbic acid were used as positive controls in the antioxidant assays.     

Antioxidative properties of Thymus vulgaris leaves: comparison of different extracts and essential oil chemotypes

Thyme (Thymus vulgaris L., Lamiaceae) is a subshrub from the Lamiaceae family with plants that are rich in essential oils and antioxidative phenolic substances. Twelve accessions originating from southern France and the variety 'Deutscher Winter' were grown in an experimental field in eastern Austria. Leaf samples from these plants as well as from a commercial thyme rich in thymol were analyzed for their essential oil and the antioxidative potential in various extracts. The assays for antioxidative activity were the total phenolics according to the Folin-Ciocalteu method, DPPH decoloration, and Fe(3+) reduction (FRAP). Both extraction techniques used, in the water bath at 40 degrees C and in the ultrasonic bath at room temperature, proved to be efficient. The best results were obtained with 60% ethanol as extractant. In the comparison of the different accessions the less active and the most active of these extracts differed by factors of 2.1 and 2.6 in the total phenolics and FRAP assay, respectively, and by factors 1.5-2.0 in the DPPH assay. Rosmarinic acid accounted for 22-55% of the antioxidant activity in the ethanolic extracts. Essential oils with high proportions of the phenolic components thymol and/or carvacrol showed the highest antioxidant activity. Ethanolic extracts from the residues after distillation were considerably lower in antioxidant activity than the respective extracts from the dried leaves. Extracts with CH2Cl2 in the ultrasonic bath contained volatiles in proportions close to the essential oil but displayed very low antioxidant activity.     

Effect of thyme essential oils (Thymus hyemalis and Thymus zygis) and monensin on in vitro ruminal degradation and volatile fatty acid production

The effect of the essential oils of thyme on the in vitro ruminal degradability of a barley seed/alfalfa hay substrate was studied. Two essential oils were used, one from Thymus hyemalis (TH), rich in carvacrol, and the other from Thymus zygis (TZ), rich in thymol. Four experimental treatments of in vitro degradability, using the Daisy II(200/220) incubator, were conducted including a negative control (CO), a positive control at 7.5 microg/mL of monensin (MO), and two treatments with essential oils (TH or TZ) at 1.35 microL/mL. The material was incubated at 39.5 degrees C for various lengths of time. At each time, the disappearance of dry matter, crude protein, and neutral detergent fiber was measured. Volatile fatty acids (VFAs) were determined after 48 h of incubation. CO and MO provided (p < 0.01) higher values of potential degradability (a + b) of DM than the TH and TZ treatments (72.6 and 70.8 vs 53.2 and 48.2%, respectively). Also, crude protein degradability was lowest in the essential oil treatments. The CO treatment showed the highest potential degradability of NDF. The values of VFA production obtained (p < 0.001) with CO and MO treatments were higher than those obtained with TH and TZ treatments (21.0 and 19.1 vs 11.2 and 10.1 mM). The essential oils decreased the molar proportion of propionate, increasing the acetate/propionate ratio. In conclusion, the effects of essential oils at assayed doses would not be nutritionally beneficial to the ruminal energetic metabolism.     

Vasomodulating potential of mediterranean wild plant extracts

The incidence of cardiovascular disease and endothelial dysfunction is low in the Mediterranean area, where the major proportion of daily calories comes from plant food, high in antioxidant polyphenols. It has been shown that a reduced production or enhanced inactivation of endothelium-derived nitric oxide (NO) is involved in the onset of endothelial dysfunction. We investigated the effects of Mediterranean wild plant, that is, wild artichoke and thyme, phenolic-rich extracts on NO release by porcine aortic endothelial cells (PAECs; by using indirect methods) and by cerebral cell membrane homogenates (by using direct NO detection). NO release by PAECs was significantly potentiated by 234% and 135% by wild artichoke and thyme extracts (10(-6) mol/L), respectively. Direct detection of NO release by brain membranes also showed significantly increased NO production after wild artichoke addition (+35.4%). Further, the release of another vasorelaxant factor by PAECs, that is, prostacyclin, was significantly increased by wild artichoke and thyme (10(-6) mol/L) (+269% and +190%, respectively). Investigation of the mechanism(s) of action of wild artichoke and thyme suggests maintenance of an intracellular reduced environment, as previously shown for ascorbate. Even though these data require in vivo confirmation, they suggest that regular intake of bioactive compounds from Mediterranean wild plants contributes to maintenance of proper vasomotion and to the low incidence of atherosclerosis and endothelial dysfunction recorded in the Mediterranean area.     

固封精油熏蒸对油桃采后保鲜效果的影响

为开发一种新的植物精油保鲜方法,本试验用琼脂平板固封百里香精油和薄荷精油,制成精油香膏,使精油缓慢释放,用于熏蒸油桃,并采用固相微萃取-气质联用(SPME-GCMS)分析精油香膏熏蒸时盒内空气中精油活性成分的变化,同时比较不同精油香膏熏蒸对油桃果实腐烂指数、失重率、硬度、抑菌能力以及可溶性固形物、可滴定酸、抗坏血酸和类...     

Characterization of volatile constituents of Haplopappus greenei and studies on the antifungal activity against phytopathogens

Essential oil of Haplopappus greenei A. Gray was obtained by hydrodistillation of aerial parts, which were subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. Major components were identified as carvacrol (8.7%), beta-pinene (7.6%), trans-pinocarveol (6.2%), and caryophyllene oxide (5.8%), respectively. In total, 104 components representing 84.9% of the investigated essential oil were characterized. Furthermore, the essential oil was evaluated for antimalarial, antimicrobial, and antifungal activities. However, only antifungal activity was observed against the strawberry anthracnose-causing fungal plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides using the direct overlay bioautography assay. Major essential oil components were also evaluated for antifungal activity; the carvacrol standard demonstrated nonselective activity against the three Colletotrichum species and the other compounds were inactive.     

Antibacterial activities of plant essential oils and their components against Escherichia coli O157:H7 and Salmonella enterica in apple juice

We evaluated 17 plant essential oils and nine oil compounds for antibacterial activity against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica in apple juices in a bactericidal assay in terms of % of the sample that resulted in a 50% decrease in the number of bacteria (BA(50)). The 10 compounds most active against E. coli (60 min BA(50) range in clear juice, 0.018-0.093%) were carvacrol, oregano oil, geraniol, eugenol, cinnamon leaf oil, citral, clove bud oil, lemongrass oil, cinnamon bark oil, and lemon oil. The corresponding compounds against S. enterica (BA(50) range, 0.0044-0.011%) were Melissa oil, carvacrol, oregano oil, terpeineol, geraniol, lemon oil, citral, lemongrass oil, cinnamon leaf oil, and linalool. The activity (i) was greater for S. enterica than for E. coli, (ii) increased with incubation temperature and storage time, and (iii) was not affected by the acidity of the juices. The antibacterial agents could be divided into two classes: fast-acting and slow-acting. High-performance liquid chromatography analysis showed that the bactericidal results are related to the composition of the oils. These studies provide information about new ways to protect apple juice and other foods against human pathogens.     

Evaluation of 28 balm and lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) accessions for content and composition of essential oil and content of rosmarinic acid

Lemon balm (Melissa officinalis L.) is a well-known aromatic and medicinal plant. Because of its proven sedative, spasmolytic and antiviral effects, it is often used in watery or alcoholic extracts for self-medication or pharmaceutical purposes. Its therapeutic effect is due to the content of essential oil and rosmarinic acid. A set of 28 balm accessions was evaluated for the variability of essential oil content and composition and the content of rosmarinic acid. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil in the first cut of the years 2009 and 2010 varied in this study in a range between 0.02 and 0.48% and in the second cut between 0.01 and 0.72%. The rosmarinic acid content of the collection ranged in the year 2009 for the first cut from 3.99 to 8.78% and in the second cut from 2.45 to 6.78%. Ploidy was determined for all accessions and two cytotypes were found: diploid 2n = 2x = 32 (15 accessions), tetraploid 2n = 4x = 64 (13 accessions). Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype germacrene D.     

Antimicrobial and antioxidant activity of the essential oil and methanol extracts of Thymus pectinatus Fisch. et Mey. Var. pectinatus (Lamiaceae)

The essential oil, obtained by using a Clevenger distillation apparatus, and water-soluble (polar) and water-insoluble (nonpolar) subfractions of the methanol extract of Thymus pectinatus Fisch. et Mey. var. pectinatus were assayed for their antimicrobial and antioxidant properties. No (or slight) antimicrobial activity was observed when the subfractions were tested, whereas the essential oil showed strong antimicrobial activity against all microorganisms tested. Antioxidant activities of the polar subfraction and the essential oil were evaluated using 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide radical scavenging, and lipid peroxidation assays. The essential oil, in particular, and the polar subfraction of the methanol extract showed antioxidant activity. The essential oil was analyzed by GC/MS, and 24 compounds, representing 99.6% of the essential oil, were identified: thymol, gamma-terpinene, p-cymene, carvacrol, and borneol were the main components. An antimicrobial activity test carried out with fractions of the essential oil showed that the activity was mainly observed in those fractions containing thymol, in particular, and carvacrol. The activity was, therefore, attributed to the presence of these compounds. Other constituents of the essential oil, such as borneol, gamma-terpinene, and p-cymene, could be also taken into account for their possible synergistic or antagonistic effects. On the other hand, thymol and carvacrol were individually found to possess weaker antioxidant activity than the crude oil itself, indicating that other constituents of the essential oil may contribute to the antioxidant activity observed. In conclusion, the results presented here show that T. pectinatus essential oil could be considered as a natural antimicrobial and antioxidant source.     

Content and composition of essential oil and content of rosmarinic acid in lemon balm and balm genotypes (<Emphasis Type="Italic">Melissa officinalis</Emphasis>)

Lemon balm (Melissa officinalis L.) is used since ancient times because of its sedative, spasmolytic and antiviral effects. Its therapeutic impact is due to the content of essential oil and rosmarinic acid. A set of 68 M. officinalis genotypes was evaluated for content and composition of essential oil and the content of rosmarinic acid. For all genotypes the level of ploidy was determined. The 68 genotypes were clone plants grown and evaluated for two years at Quedlinburg. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil varied in this study in ranges from 0.03 to 0.33% for the second cut 2010 and 0.01–0.35% for the second cut 2011. The rosmarinic acid content ranged in the year 2010 from 3.67 to 7.55% and in the year 2011 from 4.92 to 8.07%. Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype β-caryophyllene oxide. Ploidy was determined for all genotypes and two cytotypes were found: diploid 2n = 2x = 32 (62 of 68 genotypes) and triploid 2n = 3x = 48 (6 of 68 genotypes).