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PubMed2006

Comparison of effects of octopamine and insecticidal essential oils on activity in the nerve cord, foregut, and dorsal unpaired median neurons of cockroaches.

Essential oil constituents were tested for their neurophysiological effects in Periplaneta americana and Blaberus discoidalis. Eugenol depressed spontaneous and stimulus-evoked impulses recorded extracellularly in the abdominal nerve cord, with an almost complete block of spikes at 2 x 10(-3) M. Geraniol and citral had similar depressive effects but increased spontaneous firing at lower doses (threshold 2.5 x 10(-4) M). Similar effects occurred in dorsal unpaired median (DUM) neurons, recorded intracellularly in the isolated terminal abdominal ganglion of P. americana. Spontaneous firing was progressively reduced by increasing concentrations of eugenol, whereas geraniol and citral produced biphasic effects (excitation at 10(-4) M, depression at 2 x 10(-3) M). All three oils decreased excitability of silent DUM neurons that were depolarised by applied current, but eugenol (at 10(-3) M) also changed the firing pattern from single spikes to bursts driven by plateau potentials. All oils reduced spike undershoot. Low doses of citral and geraniol (threshold ca. 10(-4) M) reversibly increased the frequency of spontaneous foregut contractions and abolished them at 2 x 10(-3) M (together with response to electrical stimulation). Eugenol reversibly reduced spontaneous activity at 10(-4) M and above. Eugenol has been reported to exert its insecticidal properties via a low-dose activation of octopamine receptors. In our studies, however, octopamine was found to have opposing effects to eugenol on DUM neurons and foregut activity (excitatory in both). Furthermore, eugenol did not affect the response to octopamine in DUM neurons. These results suggest that reported effects of eugenol were on a different sub-type of octopamine receptor.

Acyclic Monoterpenes↗
PubMed2004

Antinociceptive and gastroprotective effects of inhaled and orally administered Lavandula hybrida Reverchon "Grosso" essential oil.

In this study the antinociceptive and the gastroprotective effects of orally administered or inhaled Lavandula hybrida Reverchon "Grosso" essential oil, and its principal constituents linalool and linalyl acetate were evaluated in rodents. Either when orally administered (100 mg/kg) or inhaled for 60 min lavender essential oil significantly reduced the acetic acid-writhing response in a naloxone-sensitive manner. In the hot plate test, analgesic activity observed after oil inhalation was inhibited by naloxone, atropine, mecamylamine pretreatment suggesting the involvement of opioidergic as well as cholinergic pathways. Regardless of the administration route and the experimental model used both linalool and linalyl acetate did not produce significant analgesic response. Oral or inhalatory treatment with analgesic doses of essential oil did not affect mice spontaneous locomotor activity. Concerning the gastric effects, lavender oil, linalool and linalyl acetate oral administration protected against acute ethanol-induced gastric ulcers but did not prevent indomethacin-induced lesions indicating no interference with arachidonic acid metabolic cascade. In conclusion, besides this gastroprotection, lavender oil reveals an interesting analgesic activity mainly relevant after inhalation, at doses devoid of sedative side effect, suggesting the interest for potential application of this oil in aromatherapy.

Acetic Acid↗
PubMed2005

Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity.

Essential oils extracted from different plants (Anthemis nobilis L., Artemisia dracunculus L., Cannabis sativa L., Cupressus sempervirens L., Cymbopogon citratus (DC.) Stapf., Curcuma longa L., Foeniculum vulgare L., Hypericum perforatum L., Hyssopus officinalis L., Mentha spicata L., Monarda didyma L., Ocimum basilicum L., Ocotea quixos Kosterm., Origanum vulgare L., Pinus nigra J.F. Arnold, Pinus silvestris L., Piper crassinervium Kunth., Rosmarinus officinalis L., Salvia officinalis L., Salvia sclarea L., Santolina chamaecyparissus L., Thymus vulgaris L., Zingiber officinaie L.) were screened in guinea pig and rat plasma in order to assess antiplatelet activity and inhibition of clot retraction. The oils were chemically analysed and a relationship between components and ability to affect hemostasis was evidenced. O. quixos, F. vulgaris, and A. dracunculus showed the highest antiplatelet activity against ADP, Arachidonic Acid and the Thromboxane A2 agonist U46619 (IC50, 4-132 microg ml(-1)), and a good ability to destabilize clot retraction (IC50, 19-180 microg ml(-1)). For these oils a significant correlation between antiplatelet potency and phenylpropanoids content (54-86%) was evidenced thus suggesting a key role for this moiety in the prevention of clot formation. These findings provide the rationale to take in account the antiplatelet activity in the pharmacological screening of natural products containing phenylpropanoids.

Animals↗
PubMed2005

How rainfall, relative humidity and temperature influence volatile emissions from apple trees in situ.

Headspace volatiles from apple-bearing twigs were collected in the field with a Radiello sampler during three different diurnal periods over the complete fruit growing season. Analyses by thermal desorption-GC-MS identified a total of 62 compounds in changing quantities, including the terpenoids alpha-pinene, camphene, beta-pinene, limonene, beta-caryophyllene and (E,E)-alpha-farnesene, the aldehydes (E)-2-hexenal, benzaldehyde and nonanal, and the alcohol (Z)-3-hexen-1-ol. The variations in emission of these plant odours were statistically related to temperature, humidity and rainfall in the field. Remarkably, rainfall had a significant positive influence on changes in volatile release during all three diurnal periods, and further factors of significance were temperature and relative humidity around noon, relative humidity in the late afternoon, and temperature and relative humidity during the night. Rainfall was associated consistently with an increase in the late afternoon in terpene and aldehyde volatiles with a known repellent effect on the codling moth, one of the key pests of apple fruit. During the summer of 2003, a season characterized by below-average rainfall, some postulated effects of drought on trees were tested by establishing correlations with rainfall. Emissions of the wood terpenes alpha-pinene, beta-pinene and limonene were negatively correlated with rainfall. Another monoterpene, camphene, was only detected in this summer but not in the previous years, and its emissions were negatively correlated with rainfall, further supporting the theory that drought can result in higher formation of secondary metabolites. Finally, the two green leaf volatiles (E)-2-hexenal and (Z)-3-hexen-1-ol were negatively correlated with rainfall, coinciding well with the expectation that water deficit stress increases activity of lipoxygenase. To our knowledge, this work represents the first empirical study concerning the influence of abiotic factors on volatile emissions from apple trees in situ.

Climate↗
PubMedDate not supplied

Ambulation-promoting effect of peppermint oil and identification of its active constituents.

Various plant-derived essential oils (EOs) have traditionally been used in the treatment of mental disorders, despite a lack of scientific evidence. In a previous study, we demonstrated that certain EOs possess behavioral effects, a finding that supports our original hypotheses that EOs possess psychoactive actions. The present study was conducted in order to obtain further evidence to support our hypothesis. Peppermint oil, a type of EO, is believed to be effective for treating mental fatigue. When the oil was administered intraperitoneally to ICR mice, the ambulatory activity of mice increased dramatically. We identified alpha-pinene, beta-pinene, (R)-(+)-limonene, 1,8-cineol, isomenthone, menthone, menthol, (R)-(+)-pulegone, menthyl acetate and caryophyllene as constituent elements of peppermint oil by GC-MS analysis. We then examined the effect of each constituent element of peppermint oil on ambulatory activity in mice. Intraperitoneal administration of 1,8-cineol, menthone, isomenthone, menthol, (R)-(+)-pulegone, menthyl acetate and caryophyllene significantly increased ambulatory activity in mice, suggesting that these chemicals are the behaviorally active elements of peppermint oil. Intravenous administration of these substances to mice induced a significant increase in ambulatory activity at much lower doses. The present study provides further evidence demonstrating that EOs possess pharmacological actions on behavior. In addition, our finding revealed that the action of peppermint oil comes from its constituent elements.

Animals↗
PubMed2003

Inhibitory effect of cinnamon, clove, lemongrass, oregano and palmarose essential oils on growth and fumonisin B1 production by Fusarium proliferatum in maize grain.

The effect of cinnamon, clove, oregano, palmarose and lemongrass oils on growth and FB1 production by three different isolates of F. proliferatum in irradiated maize grain at 0.995 and 0.950 aw and at 20 and 30 degrees C was evaluated. The five essential oils inhibited growth of F. proliferatum isolates at 0.995 aw at both temperatures, while at 0.950 aw only cinnamon, clove and oregano oils were effective in inhibiting growth of F. proliferatum at 20 degrees C and none of them at 30 degrees C. Cinnamon, oregano and palmarose oils had significant inhibitory effect on FB1 production by the three strains of F. proliferatum at 0.995 aw and both temperatures, while clove and lemongrass oils had only significant inhibitory effect at 30 degrees C. No differences were found using 500 or 1000 microg essential oil g(-1). At 0.950 aw, none of the essential oils had any significant effect on FB1 production. The results suggest that mainly cinnamon and oregano oils could be effective in controlling growth and FB1 production by F. proliferatum in maize under preharvest conditions.

Cinnamomum zeylanicum↗
PubMed2002

Effect of oil extracted from some medicinal plants on different mycotoxigenic fungi.

Essential oils of 12 medicinal plants were tested for inhibitory activity against Aspergillus flavus, A. parasiticus, A. ochraceus and Fusarium moniliforme. The oils of thyme and cinnamon (< or = 500 ppm), marigold (< or = 2000 ppm), spearmint, basil, quyssum (3000 ppm) completely inhibit all the test fungi. Caraway was inhibitory at 2000 ppm against A. flavus, A. parasiticus and 3000 ppm against A. ochraceaus and F. moniliforme. A. flavus, A. ochraceus, A. parasiticus and F. moniliforme were completely inhibited by anise at< or = 500 ppm. However, chamomile and hazanbul at all concentrations were partially effective against the test toxigenic fungi. The results indicate that the test toxigenic fungi are sensitive to the 12 essential oils, and particularly sensitive to thyme and cinnamon. The results also showed that the essential oils of thyme, cinnamon, anise and spearmint have more effect on fungal development and subsequent mycotoxin production in wheat grains. The extent of inhibition of fungal growth and mycotoxin production was dependent on the concentration of essential oils used.

Antifungal Agents↗
PubMed2002

Water soluble fractions of rose-scented geranium (Pelargonium species) essential oil.

The essential oil of rose-scented geranium (Pelargonium species, family: Geraniaceae) obtained through steam or water plus steam distillation of shoot biomass is extensively used in the fragrance industry and in aromatherapy. During distillation, a part of the essential oil becomes dissolved in the distillation water (hydrosol) and is lost as this hydrosol is discarded. In this investigation, hydrosol was shaken for 30 min with hexane (10:1 proportion) and the hexane was distilled to yield 'secondary' or 'recovered' essential oil. The chemical composition of secondary oil was compared with that of 'primary' oil (obtained directly by distilling shoot biomass of the crop). Primary oil accounted for 93.0% and secondary oil 7.0% of the total oil yield (100.2 ml from 100 kg green shoot biomass). Fifty-two compounds making up 95.0-98.5% of the primary and the secondary oils were characterized through gas chromatography (GC) and gas chromatography-mass spectroscopy (GC--MS). Primary oil was richer in hydrocarbons (8.5-9.4%), citronellyl formate (6.2-7.5%), geranyl formate (4.1-4.7%), citronellyl propionate (1.0-1.2%), alpha-selinene (1.8-2.2%), citronellyl butyrate (1.4-1.7%), 10-epi-gamma-eudesmol (4.9-5.5%) and geranyl tiglate (1.8-2.1%). Recovered oil was richer in organoleptically important oxygenated compounds (88.9-93.9%), commercial rhodinol fraction (74.3-81.2%), sabinene (0.4-6.2%), cis-linool oxide (furanoid) (0.7-1.2%), linalool (14.7-19.6%), alpha-terpineol (3.3-4.8%) and geraniol (21.3-38.4%). Blending of recovered oil with primary oil is recommended to enhance the olfactory value of the primary oil of rose-scented geranium. Distillation water stripped of essential oil through hexane extraction can be recycled for distilling the next batch of rose-scented geranium.

Biotechnology↗
PubMed2002

Acaricidal activity of pine essential oils and their main components against Tyrophagus putrescentiae, a stored food mite.

Some essential oils obtained from the branches of four Pinus species (P. pinea L., P. halepensis Mill., P. pinaster Soil in Ait., and P. nigra Arnold) have been evaluated for their acaricidal activity by aerial diffusion against the stored food mite Tyrophagus putrescentiae (L.). All the essential oils showed a good efficacy, but P. pinea oil and its two constituents 1,8-cineole and limonene were the most effective compounds, showing 100% acaricidal activity at 8 microL; 1,8-cineole showed the same activity at 6 microL.

Acyclic Monoterpenes↗
PubMed2003

Antioxidant activity of dietary oregano essential oil and alpha-tocopheryl acetate supplementation in long-term frozen stored turkey meat.

The effects of dietary oregano essential oil and alpha-tocopheryl acetate supplementation on the oxidative stability of long-term frozen stored turkey meat were investigated. Thirty 12-week-old turkeys, randomly divided into five groups, were given a basal diet or a basal diet supplemented with 200 mg of alpha-tocopheryl acetate kg(-1), or 100 or 200 mg of oregano oil kg(-1), or 100 mg of oregano oil plus 100 mg of alpha-tocopheryl acetate kg(-1) for 4 weeks prior to slaughter. Lipid oxidation in breast and thigh meat was assessed after 1, 3, 6, and 9 months of frozen storage at -20 degrees C prior to or following 7 days of refrigerated storage at 4 degrees C. Results showed that oregano oil increased the oxidative stability of breast and thigh meat during the frozen storage. Dietary oregano oil at the inclusion level of 200 mg kg(-1) feed was significantly (p < 0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg(-1), but equivalent to dietary alpha-tocopheryl acetate supplementation at 200 mg kg(-1), which in turn was inferior to dietary supplementation of 100 mg kg(-1) oregano essential oil plus 100 mg kg(-1) alpha-tocopheryl acetate that was significantly (p < 0.05) superior to all other treatments. Thigh meat was more susceptible to oxidation than breast meat, although the former contained alpha-tocopherol at markedly higher levels. Mean alpha-tocopherol levels in breast and thigh meat from all treatments decreased during the frozen storage, the decrease being sharper between 1 and 3 months of frozen storage for breast and between 3 and 6 months for thigh meat. Oregano oil supplementation increased (p < 0.05) the retention of alpha-tocopherol in meat, the increase being positively correlated with the supplementation level. However, the retention of alpha-tocopherol in meat could only partly elucidate the antioxidant activity exhibited by dietary oregano oil supplementation.

Animals↗
PubMed2006

Quality control of commercially available essential oils by means of Raman spectroscopy.

The essential oils of different spices and aroma plants were investigated fast and nondestructively by means of Raman spectroscopy. The main ingredients of these oils, mostly monoterpenes and phenylpropane derivatives, were identified. A hierarchical cluster analysis shows that the oils of the investigated plants cluster chemotaxonomically, which means according to their chemical composition and not according to their botanical degree of relationship. In addition, cross-sections of anise seeds were analyzed applying the Raman mapping technique to localize and investigate the distribution of the oil in situ.

Monoterpenes↗
PubMed2001

In-vitro and in-vivo anti-Trichophyton activity of essential oils by vapour contact.

The minimum inhibitory doses (MIDs) of essential oils by vapour contact to inhibit the growth of Trichophyton mentagrophytes and Trichophyton rubrum on agar medium were determined using airtight boxes. Among seven essential oils examined, cinnamon bark oil showed the least MID, followed by lemongrass, thyme and perilla oils. Lavender and tea tree oils showed moderate MID, and citron oil showed the highest MID, being 320 times higher than that of cinnamon bark oil. The MID values were less than the minimum inhibitory concentration (MIC) values determined by agar dilution assay. Furthermore, the minimum agar concentration (MAC) of essential oils absorbed from vapour was determined at the time of MID determination as the second antifungal measure. The MAC value by vapour contact was 1.4 to 4.7 times less than the MAC remaining in the agar at the time of MIC determination by agar dilution assay. Using selected essential oils, the anti-Trichophyton activity by vapour contact was examined in more detail. Lemongrass, thyme and perilla oils killed the conidia, inhibited germination and hyphal elongation at 1-4 micrograms ml-1 air, whereas lavender oil was effective at 40-160 micrograms ml-1 air. The in-vivo efficacy of thyme and perilla oils by vapour contact was shown against an experimental tinea pedis in guinea pigs infected with T. mentagrophytes. These results indicated potent anti-Trichophyton action of essential oils by vapour contact.

Agar↗
PubMed2003

Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7.

AIMS: To quantify the antibacterial properties of five essential oils (EO) on a non-toxigenic strain of Escherichia coli O157:H7 in the presence and absence of a stabilizer and an emulsifier and at three different temperatures. METHODS AND RESULTS: Five EOs known to exhibit antibacterial properties were screened by disc diffusion assay and the most active were selected for further study in microdilution colorimetric assays. Oregano (Origanum vulgare) and thyme (Thymus vulgaris; light and red varieties) EO had the strongest bacteriostatic and bactericidal properties, followed by bay (Pimenta racemosa) and clove bud (Eugenia caryophyllata synonym: Syzygium aromaticum) EO. Oregano oil was colicidal at 625 microl l(-1) at 10, 20 and 37 degrees C. The addition of 0.05% (w/v) agar as stabilizer reinforced the antibacterial properties, particularly at 10 degrees C, whereas 0.25% (w/v) lecithin reduced antibacterial activity. Scanning electron micrographs showed extensive morphological changes to treated cells. CONCLUSIONS: Oregano and thyme EO possess significant in vitro colicidal and colistatic properties, which are exhibited in a broad temperature range and substantially improved by the addition of agar as stabilizer. Bay and clove bud EO are less active. Lecithin diminished antibacterial properties. The bactericidal concentration of oregano EO irreversibly damaged E. coli O157:H7 cells within 1 min. SIGNIFICANCE AND IMPACT OF THE STUDY: Oregano and light thyme EO, particularly when enhanced by agar stabilizer, may be effective in reducing the number or preventing the growth of E. coli O157:H7 in foods.

Agar↗
PubMed2003

Antimicrobial activity of essential oils against Helicobacter pylori.

BACKGROUND: Helicobacter pylori is an important pathogen responsible for gastroduodenal diseases in humans. Although the eradication of H. pylori using antibiotics often improves gastroduodenal diseases, resistance to the antibiotics is emerging. MATERIALS AND METHODS: The antimicrobial effect of essential oils and the development of resistance to the essential oils were evaluated in vitro and in vivo. RESULTS: Thirteen essential oils used in this study completely inhibited the growth of H. pylori in vitro at a concentration of 0.1% (v/v). Cymbopogon citratus (lemongrass) and Lippia citriodora (lemon verbena) were bactericidal against H. pylori at 0.01% at pH 4.0 and 5.0. Resistance to lemongrass did not develop even after 10 sequential passages, whereas resistance to clarithromycin developed under the same conditions. In in vivo studies, the density of H. pylori in the stomach of mice treated with lemongrass was significantly reduced compared with untreated mice. CONCLUSIONS: These results demonstrate that the essential oils are bactericidal against H. pylori without the development of acquired resistance, suggesting that essential oils may have potential as new and safe agents for inclusion in anti-H. pylori regimens.

Animals↗
PubMed2001

In vitro evaluation of the antibacterial activity of beta-triketones admixed to Melaleuca oils.

The in vitro antibacterial properties of mixtures of Australian tea tree oil and niaouli oil after adding the beta-triketone complex isolated from manuka oil were tested. MIC and MBC values for four different bacteria were determined applying the broth dilution method. Both Melaleuca oil mixtures showed good antimicrobial effects against Staphylococcus aureus and Moraxella catarrhalis, exceeding the effectiveness of myrtol, which is well established in the treatment of acute and chronic bronchitis and sinusitis. The death kinetics of S. aureus were determined to draw subtle comparisons between the mixtures. The kill rate data indicated that both Melaleuca oil mixtures achieved a complete kill within 240 min.

Anti-Infective Agents, Local↗
PubMed2001

Metabolic engineering of essential oil yield and composition in mint by altering expression of deoxyxylulose phosphate reductoisomerase and menthofuran synthase.

Peppermint (Mentha x piperita L.) was independently transformed with a homologous sense version of the 1-deoxy-d-xylulose-5-phosphate reductoisomerase cDNA and with a homologous antisense version of the menthofuran synthase cDNA, both driven by the CaMV 35S promoter. Two groups of transgenic plants were regenerated in the reductoisomerase experiments, one of which remained normal in appearance and development; another was deficient in chlorophyll production and grew slowly. Transgenic plants of normal appearance and growth habit expressed the reductoisomerase transgene strongly and constitutively, as determined by RNA blot analysis and direct enzyme assay, and these plants accumulated substantially more essential oil (about 50% yield increase) without change in monoterpene composition compared with wild-type. Chlorophyll-deficient plants did not afford detectable reductoisomerase mRNA or enzyme activity and yielded less essential oil than did wild-type plants, indicating cosuppression of the reductoisomerase gene. Plants transformed with the antisense version of the menthofuran synthase cDNA were normal in appearance but produced less than half of this undesirable monoterpene oil component than did wild-type mint grown under unstressed or stressed conditions. These experiments demonstrate that essential oil quantity and quality can be regulated by metabolic engineering. Thus, alteration of the committed step of the mevalonate-independent pathway for supply of terpenoid precursors improves flux through the pathway that leads to increased monoterpene production, and antisense manipulation of a selected downstream monoterpene biosynthetic step leads to improved oil composition.

Aldose-Ketose Isomerases↗
PubMed2006

A combination of peppermint oil and caraway oil attenuates the post-inflammatory visceral hyperalgesia in a rat model.

OBJECTIVE: Visceral hyperalgesia plays a pivotal role in manifestation of symptoms in patients with functional gastrointestinal disorders. In clinical studies combined treatment of peppermint- and caraway oil significantly reduced symptoms. Thus, the aim of this study was to characterize the effects of peppermint- and caraway oil, individually and in combination, on visceral nociception in a rat model of post-inflammatory visceral hyperalgesia. MATERIAL AND METHODS: On day 28, male Lewis rats (n=80) were randomized to treatment with a rectal administration of trinitrobenzene sulphonic acid (TNBS)/ethanol or physiological saline solution. To quantify the visceromotor response to a standardized colorectal distension, bipolar electrodes were implanted into the external oblique musculature, just superior to the inguinal ligament for electromyographic recordings on day 3. On day 0, baseline measurement was performed. Thereafter, oral treatment with peppermint- or caraway oil or combination treatment was started and continued for 14 consecutive days. After 7 and 14 days of treatment a colorectal distension was performed. Colonic tissue samples were obtained on days 0, 7 and 14 to assess histological alterations due to the different treatment groups and the influence of different compounds. RESULTS: After a single instillation of TNBS/ethanol persistent elevation of the visceromotor response at all different time-points was observed, although colonic mucosa was completely normal. After 14 days of combined treatment with peppermint- and caraway oil, a reduced visceromotor response of up to 50% compared to placebo was detected in TNBS/ethanol pretreated animals. In contrast, neither peppermint- nor caraway oil had a significant effect on post-inflammatory visceral hyperalgesia. In saline-treated controls there was no significant difference in the visceromotor response. CONCLUSIONS: These data show that combined treatment with peppermint- and caraway oil modulates post-inflammatory visceral hyperalgesia synergistically. The exact mechanisms have to be further investigated.

Administration, Rectal↗