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PubMed2004

Chemical constituents, antifungal and antioxidative effects of ajwain essential oil and its acetone extract.

GC and GC-MS analysis of ajwain essential oil showed the presence of 26 identified components which account for 96.3% of the total amount. Thymol (39.1%) was found as a major component along with p-cymene (30.8%), gamma-terpinene (23.2%), beta-pinene (1.7%), terpinene-4-ol (0.8%) whereas acetone extract of ajwain showed the presence of 18 identified components which account for 68.8% of the total amount. The major component was thymol (39.1%) followed by oleic acid (10.4%), linoleic acid (9.6%), gamma-terpinene (2.6%), p-cymene (1.6%), palmitic acid (1.6%), and xylene (0.1%). Moreover, the oil exhibited a broad spectrum of fungitoxic behavior against all tested fungi such as Aspergillus niger, Aspergillus flavus, Aspergillus oryzae, Aspergillus ochraceus, Fusarium monoliforme, Fusarium graminearum, Pencillium citrium, Penicillium viridicatum, Pencillium madriti, and Curvularia lunata as absolute mycelial zone inhibition was obtained at a 6-microL dose of the oil. However, the acetone extract showed better antioxidative activity for linseed oil as compared with synthetic antioxidants such as butylated hydroxyl toluene and butylated hydroxyl anisole.

Acetone↗
PubMed2004

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.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

Acaricidal activity of constituents identified in Foeniculum vulgare fruit oil against Dermatophagoides spp. (Acari: Pyroglyphidae).

Acaricidal activities of components derived from Foeniculum vulgare fruit oil against Dermatophagoides farinae and Dermatophagoides pteronyssinus were examined using direct contact application and compared with that of the commercial repellent benzyl benzoate. The major biologically active constituent of Foeniculum fruit oil was characterized as (+)-fenchone by spectroscopic analyses. On the basis of LD(50) values, the compound most toxic to D. farinae was p-anisaldehyde (11.3 mg/m(2)) followed by (+)-fenchone (38.9 mg/m(2)), (-)-fenchone (41.8 mg/m(2)), benzyl benzoate (89.2 mg/m(2)), thymol (90.3 mg/m(2)), and estragol (413.3 mg/m(2)). Against D. pteronyssinus, p-anisaldehyde (10.1 mg/m(2)) was much more effective than benzyl benzoate (67.5 mg/m(2)), thymol (68.5 mg/m(2)), and estragol (389.9 mg/m(2)). These results indicate that the acaricidal activity of F. vulgare fruit oil likely results from (+)-fenchone and p-anisaldehyde. (+)-Fenchone was 20.3 times more abundant in the oil than p-anisaldehyde. (+)-Fenchone and p-anisaldehyde merit further study as potential house dust mite control agents or as lead compounds.

Acari↗
PubMed2005

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.

Chromatography, Gas↗
PubMed2005

Vapor phase toxicity of marjoram oil compounds and their related monoterpenoids to Blattella germanica (Orthoptera: Blattellidae).

The toxicity of marjoram, Origanum majorana L., oil, 41 monoterpenoids, and 2 sesquiterpenoids against adult females of the German cockroach, Blattella germanica L., was examined using direct contact and vapor phase toxicity bioassays and compared with those of deltamethrin, dichlorvos, permethrin, and propoxur, four commonly used insecticides. In a filter-paper contact toxicity bioassay, the adulticidal activities of pulegone (0.06 mg/cm2), (+/-)-camphor (0.07 mg/cm2), and verbenone (0.07 mg/cm2) were comparable to that of permethrin (0.05 mg/cm2) but more pronounced than that of propoxur (0.18 mg/cm2), as judged by the 24-h LC50 values. These compounds were less effective than either deltamethrin (0.013 mg/cm2) or dichlorvos (0.007 mg/cm2). The toxicity of marjoram oil, thymol, alpha-terpineol, (-)-alpha-thujone, linalool, 1,8-cineole, (-)-camphor, and (+)-carvone, ranging from 0.08 to 0.18 mg/cm2, was higher than that of propoxur. In vapor phase toxicity tests, verbenone (11.48 mg/L air) was the most toxic compound followed by (-)-alpha-thujone (18.43 mg/L of air), thymol (18.76 mg/L of air), alpha-terpineol (21.89 mg/L of air), (+/-)-camphor (24.59 mg/L of air), linalool (26.20 mg/L of air), and marjoram oil (38.28 mg/L of air) on the basis of the 24-h LC50 values. Dichlorvos (0.07 mg/L of air) was the most potent fumigant. Structure-activity relationships indicate that structural characteristics, such as degrees of saturation and types of functional groups rather than types of carbon skeleton, and hydrophobicity and vapor pressure parameters appear to play a role in determining the monoterpenoid toxicities to adult B. germanica. Marjoram oil and the monoterpenoids described merit further study as potential fumigants or leads for the control of B. germanica.

Animals↗
PubMed2000

Inhibition of oxidation of human low-density lipoproteins by phenolic substances in different essential oils varieties.

Phenolics antioxidant phytochemicals have been recently implicated for the lower rates of cardiac disease mortality among people consuming a Mediterranean diet. Essential oils are natural products extracted from vegetable materials, which can be used as antibacterial, antifungal, antioxidants, and anti-carcinogenic agents or to preserve and give specific flavors to foods. The activities of 23 selected essential oils in inhibiting the copper-catalyzed oxidation of human-low-density lipoproteins (LDL) were determined in vitro. LDL oxidation was inhibited between 6, 2, and 83% by 2 microM (GAE) total phenolics. The relative inhibition of LDL oxidation was used to categorize the essential oils into four groups below 2% when they contained methylchavicol, anethol, p-cymen, apiole, cinnamic ether; 6-10% if they possessed a majority of carvacrol, thymol, p-cymene, or vanillin; 10-50% for moderate amounts of thymol, carvacrol, cuminol, or eugenol; and 50-100% when eugenol is the major component. Total phenol content of essential oils gave a correlation with LDL antioxidant activity of r = 0.75. The Activity of each phenolics compound could play a role in protecting LDL against oxidation if the substance is absorbed by the body.

Humans↗
PubMed2002

Silphinene sesquiterpenes as model insect antifeedants.

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11beta-acetoxy-5alpha-angeloyloxysilphinen-3-one (1), 11beta-acetoxy-5alpha-tigloyloxysilphinen-3-one (2), 11beta-acetoxy-5alpha-isobutyryloxysilphinen-3-one (3), 11beta-hydroxy-5alpha-angeloyloxysilphinen-3-one (4), 11beta,5alpha-dihydroxysilphinen-3-one (5), 11beta,5alpha-diacetoxysilphinen-3-one (6), 5alpha,11beta-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.

Animals↗
PubMed2003

Qualitative and quantitative variation in monoterpene co-occurrence and composition in the essential oil of Thymus vulgaris chemotypes.

Thymus vulgaris has a chemical polymorphism with six different chemotypes that show marked spatial segregation in nature. Although some populations have a single chemotype in majority, many have two or three chemotypes. In this study we analyze the quantitative variation among T. vulgaris populations in the percentage of oil composed of the dominant monoterpene(s) for each chemotype. In general, phenolic chemotypes (thymol and carvacrol), which occur at the end of the biosynthetic chain, have a significantly lower proportion of their oil composed of their dominant monoterpene than nonphenolic chemotypes (geraniol, alpha-terpineol, and linalool). This is due to the presence of high amounts of precursors (gamma-terpinene and paracymene) in the oil of phenolic chemotypes. The essential oil of the nonphenolic thuyanol chemotype has four characteristic monoterpenes that together make up a lower proportion of the oil than the single dominant monoterpene of the other nonphenolic chemotypes. For all chemotypes, the percentage composition of the dominant monoterpene decreased significantly at sites where the chemotype is not the majority type. This decrease is correlated with a significant increase in either the proportion of the two precursors for the thymol chemotype or the monoterpenes characteristic of the other chemotypes at the site. The latter result suggests that a plant with dominant genes is responsible for the production of different monoterpenes can produce several molecules.

Adaptation, Physiological↗
PubMed2003

Antimicrobial activity and chemical composition of the essential oil of Lippia graveolens from Guatemala.

The composition and the antimicrobial activity of the essential oil of Lippia graveolens H.B.K. collected in Guatemala were studied. Two samples of essential oils were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC and GC-MS. The oils were characterized by their high content of monoterpenes (70.0-87.2 %). Important differences between the major constituents were found, particularly for carvacrol (0.2 vs. 44.8 %), thymol (18.1 vs. 7.4 %) and p-cymene (6.8 vs. 21.8 %). Both oils showed significant activity against all tested Gram-positive and Gram-negative bacteria, as well as against fungi. Nevertheless, the oil with the higher carvacrol content was found to be more active than the thymol type, with MICs ranging from 0.25 to 0.83 microL/mL and 0.12 to 0.27 microL/mL for bacteria and fungi, respectively.

Anti-Bacterial Agents↗
PubMed1989

Toxicological properties of thio- and alkylphenols causing flavor tainting in fish from the upper Wisconsin River.

EC50 Microtox (5 min, 25 degrees C) assay values for 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2,4-diisopropylphenol, 2,5-diisopropylphenol 2,6-diisopropylphenol, 3,5-diisopropylphenol, carvacrol, thymol, thiophenol, and thiocresol ranged from 2 x 10(-2) mM for thymol (least toxic) to 2 x 10(-4) mM for 2,4-diisopropylphenol and 4-isopropylphenol (most toxic).

Alkylation↗
PubMed2003

Chemical composition and in vitro evaluation of antioxidant effect of free volatile compounds from Satureja montana L.

As a part of an investigation of natural antioxidants from Dalmatian aromatic plants, in this paper we report a study of the antioxidant activity related to the chemical composition of savory free volatile compounds. Twenty-one compounds were identified in the essential oil without fractionation, representing 97.4% of the total oil. The major compound was phenolic monoterpene thymol (45.2%). Other important compounds were monoterpenic hydrocarbons p-cymene (6.4%) a nd gamma-terpinene (5.9%)and oxygen-containing compounds carvacrol methyl ether (5.8%), thymol methyl ether (5.1%), carvacrol (5.3%), geraniol (5.0%) and borneol (3.9%). The evaluation of antioxidant power was performed in vitro by the beta-carotene bleaching and thiobarbituric acid (TBA) methods. As determined with both methods, the total savory essential oil as well as different fractions or pure constituents containing hydroxyl group exhibited relatively strong antioxidant effect. The hydrocarbons, when isolated as CH fraction, showed the poorest effectiveness in spite the fact that this fraction contained gamma-terpinene, alpha-terpinene, p-cymene and terpinolene which previously were identified as potential antioxidants.

Antioxidants↗
PubMed1997

Insecticidal activity of monoterpenoids to western corn rootworm (Coleoptera: Chrysomelidae), twospotted spider mite (Acari: Tetranychidae), and house fly (Diptera: Muscidae).

Acute toxicities of 34 naturally occurring monoterpenoids were evaluated against 3 important arthropod pest species; the larva of the western corn rootworm, Diabrotica virgifera virgifera LeConte; the adult of the twospotted spider mite. Tetranychus urticae Koch; and the adult house fly. Musca domestica L. Potential larvicidal or acaricidal activities of each monoterpenoid were determined by topical application, leaf-dip method, soil bioassay, and greenhouse pot tests. Phytotoxicity was also tested on a corn plant. Citronellic acid and thymol were the most topically toxic against the house fly, and citronellol and thujone were the most effective on the western corn rootworm. Most of the monoterpenoids were lethal to the twospotted spider mite at high concentrations; carvomenthenol and terpinen-4-ol were especially effective. A wide range of monoterpenoids showed some larvicidal activity against the western corn rootworm in the soil bioassay. Perillaldehyde, the most toxic (LC50 = 3 micrograms/g) in soil, was only 1/3 as toxic as carbofuran, a commercial soil insecticide (LC50 = 1 microgram/g). Selected monoterpenoids also effectively protected corn roots from attack by the western corn rootworm larvae under greenhouse conditions. alpha-Terpineol was the best monoterpenoid in the greenhouse pot test. The acute toxicity of monoterpenoids was low relative to conventional insecticides. Some monoterpenoids were phytotoxic to corn roots and leaves. l-Carvone was the most phytotoxic, whereas pulegone was the safest. The results with thymyl ethyl ether, one of the synthetic derivatives of thymol, showed a potential of derivatization to reduce monoterpenoid phytotoxicity.

Animals↗
PubMed1987

Contact allergy to a reaction product in Hirudoid cream: an example of compound allergy.

We have investigated patients with a contact allergy to Hirudoid cream. The hypersensitivity reactions appeared to be due to an allergy to the cream base, but the separate ingredients did not give rise to positive patch test reactions. The hypersensitivity proved to be due to an allergy to a reaction product, and the simultaneous presence of the preservatives 1,3,5-trihydroxyethylhexahydrotriazine and thymol was found to be necessary for the occurrence of a positive patch test reaction. A new allergen was found to be formed by the reaction between thymol and the degradation products of the triazine derivative. This allergen was identified by nuclear magnetic resonance spectroscopy and infrared spectroscopy as 3-(hydroxyethyl)-5-methyl-8-(2-methylethyl)-3,4-dihydro-2H-1,3-benzoxazi ne.

Aged↗
PubMed1994

Antifungal action and antiaflatoxigenic properties of some essential oil constituents.

The effect of 20 essential oil constituents on Aspergillus flavus growth and aflatoxin production was tested at the level of 1000 ppm. Some of the tested oils exhibited inhibitory effects on fungal growth and toxin formation. Five oils, namely geraniol, nerol and citronellol (aliphatic oils), cinnamaldehyde (aromatic aldehyde) and thymol (phenolic ketone), completely suppressed growth and aflatoxin synthesis. Trials for determining the minimum inhibitory concentration (MIC) of these oils revealed that geraniol, nerol and citronellol were effective at 500 ppm, while thymol and cinnamaldehyde were highly effective at doses as low as 250 and 200 ppm, respectively. It was observed that citral, citronellol and eugenol prevented fungal growth and toxin formation for up to 8 d. However, after 15 d of incubation, toxin production was greater than the controls.

Aflatoxins↗
PubMed1991

Studies of the development of optical fiber sensors for biochemical analysis.

An optical fiber sensor utilizing Thymol blue and an ion-exchange resin complex in a cellulose acetate membrane was developed. By monitoring several different chromophores of Thymol blue, the sensor could measure the pH of the solution from 1.0 to 12.0 with good reproducibility. An optical fiber glucose sensor utilizing a cellulose acetate membrane containing glucose oxidase, 2,7-diaminofluorene dihydrochloride, and sodium N-(3-sulfopropyl)-3,3',5,5'-tetramethylbenzidine was developed. Reflectance changes at 580 nm were large enough to trace changes in glucose concentration in physiological saline solution.

Biosensing Techniques↗
PubMed2003

Depigmenting activity and low cytotoxicity of alkoxy benzoates or alkoxy cinnamte in cultured melanocytes.

To obtain effective and safe topical depigmenting agents, we synthesized hydroxybenzoates, alkoxybenzoates, and 3,4,5-trimethoxycinnamate containing a thymol moiety and screened then for high-level inhibitory activity against melanin synthesis in cultured melanocytes. Eight compounds were tested for their depigmenting effect and cytotoxicity using a murine melanocyte cell line. We found that 3,4,5-trialkoxybenzoates and 3,4,5-trimethoxycinnamate, synthesized by conjugating 3,4,5-trialkoxybenzoic acids and 3,4,5-trimethoxycinnmic acid with thymol, showed a potent depigmenting effect and low cytotoxicity. Compound 4h, 5-methyl-2-(methylethyl)phenyl (2E)-3-(3,4,5-trimethoxyphenyl)prop-2-enoate, showed the most potent depigmenting effect (IC50=10 microM) with low cytotoxicity (IC50=200 microM).

Animals↗
PubMed2005

Ability of fourteen chemical agents used in dental practice to induce chromosome aberrations in Syrian hamster embryo cells.

To assess the genotoxicity of 14 chemical agents used in dental practice, the ability of these agents to induce chromosome aberrations was examined using Syrian hamster embryo (SHE) cells. Statistically significant increases in the frequencies of chromosome aberrations were induced in SHE cells treated with 7 of 10 chemical agents used as endodontic medicaments, that is, carbol camphor, m-cresol, eugenol, guaiacol, zinc oxide, hydrogen peroxide, and formaldehyde. The other 3 chemical agents, that is, thymol, glutaraldehyde, and iodoform, did not increase the levels of chromosome aberrations. Of the 4 chemical agents that are used as an antiseptic on the oral mucosa, chromosome aberrations were induced by iodine, but not by the other 3 antiseptics, benzalkonium chloride, benzethonium chloride, and chlorhexidine. Among the 6 chemical agents exhibiting a negative response in the assay, only thymol induced chromosome aberrations in the presence of exogenous metabolic activation. Our results indicate that chemical agents having a positive response in the present study are potentially genotoxic to mammalian cells and need to be studied further in detail.

Animals↗
PubMedDate not supplied

Analysis of essential oil of Coridothymus capitatus (L.) and its antibacterial and antifungal activity.

The water-distilled essential oil the leaves of Coridothymus capitatus were analyzed by GC/MS and also analyzed by direct thermal desorption GC/MS. Comparison was made between two analyses techniques. The essential oil consisted mainly of monoterpenes 98.9%, while oxygenated hydrocarbons were identified as 55.6 % and non-oxygenated hydrocarbons as 43.6%. As major components were found carvacrol (35.6%), p-cymene (21.0%), thymol (18.6%), gamma-terpinene (12.3%), alpha-terpinene (3.2%), beta-myrcene (3.0%) and alpha-thujene (1.3%) by hydrodistillation and by the GC/MS method. The direct thermal desorption GC/MS analysis also showed the same major components, namely carvacrol (51.6%), thymol (21.7%), p-cymene (9.7%) gamma-terpinene (8.2%), alpha-terpinene (1.64%). The essential oil of C. capitatus showed strong activity against S. aureus, P. vulgaris, P. aeruginosa, E. coli, K. pneumonia, B.

Anti-Bacterial Agents↗