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PubMed2006

Essential oils as potential adulticides against two populations of Aedes aegypti, the laboratory and natural field strains, in Chiang Mai province, northern Thailand.

Essential oils derived from five plant species, celery (Apium graveolens), caraway (Carum carvi), zedoary (Curcuma zedoaria), long pepper (Piper longum), and Chinese star anise (Illicium verum), were subjected to investigation of adulticidal activity against mosquito vectors. Two populations of Aedes aegypti, the laboratory and natural field strains, collected in Chiang Mai province, northern Thailand were tested in pyrethroid-susceptibility bioassays. The results revealed that the natural field strain of A. aegypti was resistant to permethrin, with mortality rates ranging from 51 to 66%. A mild susceptibility, with mortality rates ranging from 82 to 88%, was observed in the natural field strain of A. aegypti exposed to lambdacyhalothrin, which suggested that this strain was tolerant and might be resistant to this insecticide. However, laboratory-reared A. aegypti exposed to discriminating dosages of permethrin and lambdacyhalothrin induced 100% mortality in all cases, thus indicating complete susceptibility of this strain to these insecticides. The adulticidal activity determined by topical application revealed that all five essential oils exerted a promising adulticidal efficacy against both laboratory and natural field strains of A. aegypti. Although the laboratory strain was slightly more susceptible to these essential oils than the natural field strain, no statistically significant difference was observed. Moreover, comparison of the adulticidal activity indicated that the performance of these essential oils against the two strains of A. aegypti was similar. The highest potential was established from caraway, followed by zedoary, celery, long pepper, and Chinese star anise, with an LC(50) in the laboratory strain of 5.44, 5.94, 5.96, 6.21, and 8.52 microg/mg female, respectively, and 5.54, 6.02, 6.14, 6.35, and 8.83 microg/mg female, respectively, in the field strain. These promising essential oils are, therefore, an alternative in developing and producing mosquito adulticides as an effective measure used in controlling and eradicating mosquito vectors.

Aedes↗
PubMed2006

Antiparasitic activity of two Lavandula essential oils against Giardia duodenalis, Trichomonas vaginalis and Hexamita inflata.

Two essential oils derived from Lavandula angustifolia and Lavandula x intermedia were investigated for any antiparasitic activity against the human protozoal pathogens Giardia duodenalis and Trichomonas vaginalis and the fish pathogen Hexamita inflata: all of which have significant infection and economic impacts. The study has demonstrated that low (< or = 1%) concentrations of L. angustifolia and L. x intermedia oil can completely eliminate T. vaginalis, G. duodenalis and H. inflata in vitro. At 0.1% concentration, L. angustifolia oil was found to be slightly more effective than L x intermedia oil against G. duodenalis and H. inflata. The potential applications are discussed.

Animals↗
PubMed2006

Effectiveness of Zanthoxylum piperitum-derived essential oil as an alternative repellent under laboratory and field applications.

Recently, there were considerable efforts made to promote the use of environmentally friendly and biodegradable natural insecticides and repellents, particularly from botanical sources. In this study, Zanthoxylum piperitum-derived essential oil isolated by steam distillation was investigated and compared to the standard synthetic repellent, N,N-diethyl-3-methylbenzamide (DEET), for repellency against mosquitoes under laboratory and field conditions. The oil of Z. piperitum alone and also with 5% vanillin added repelled laboratory-reared female Aedes aegypti with the median protection times of 1.5 and 2.5 h, respectively. These repellency times were proven to be significantly lower than those of DEET-based products: 25% DEET and 25% DEET + 5% vanillin demonstrating 3.5 and 5.5 h, respectively. However, when applied under field conditions, Z. piperitum oil + 5% vanillin was found to provide better protection against a wide range of natural mosquito populations than 25% DEET + 5% vanillin. While the product of DEET was effective in reducing bites with 99.7% protection, the protective effect of Z. piperitum oil product appeared complete (100%). It had a protective effect against Aedes gardnerii, Anopheles barbirostris, Armigeres subalbatus, Culex tritaeniorhynchus, Culex gelidus, Culex vishnui group, and Mansonia uniformis. The better repellency against a wide range of field mosquitoes derived from Z. piperitum oil products suggested an advantage of efficacy by providing a broad spectrum of activity. Therefore, Z. piperitum could have potential for use in the development of combined repellents as a natural active ingredient, synergist, or additive to conventional synthetic chemicals, particularly in situations when DEET is ineffective and impractical.

Animals↗
PubMed1999

Microbiological safety of essential oils used in complementary therapies and the activity of these compounds against bacterial and fungal pathogens.

To determine the safety of plant essential oils we determined the sterility of eight of these products obtained from retail outlets. In addition, the ability of oils to support the growth of fungal and bacterial pathogens was examined. The antimicrobial activity of these products against seven bacterial species and Candida albicans was also investigated. All oils and their respective carriers were sterile. Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa were unable to survive in oils for longer than 6 h, whereas C. albicans was able to survive, but not multiply, in ylang ylang oil for at least 48 h.

Bacteria↗
PubMed1991

The mechanism of action of peppermint oil on gastrointestinal smooth muscle. An analysis using patch clamp electrophysiology and isolated tissue pharmacology in rabbit and guinea pig.

An investigation of the mechanism of peppermint oil action was performed using isolated pharmacological preparations from guinea pig large intestine and patch clamp electrophysiology techniques on rabbit jejunum. Peppermint oil relaxed carbachol-contracted guinea pig taenia coli (IC50, 22.1 micrograms/mL) and inhibited spontaneous activity in the guinea pig colon (IC50, 25.9 micrograms/mL) and rabbit jejunum (IC50, 15.2 micrograms/mL). Peppermint oil markedly attenuated contractile responses in the guinea pig taenia coli to acetylcholine, histamine, 5-hydroxytryptamine, and substance P. Peppermint oil reduced contractions evoked by potassium depolarization and calcium contractions evoked in depolarizing Krebs solutions in taenia coli. Potential-dependent calcium currents recorded using the whole cell clamp configuration in rabbit jejunum smooth muscle cells were inhibited by peppermint oil in a concentration-dependent manner. Peppermint oil both reduced peak current amplitude and increased the rate of current decay. The effect of peppermint oil resembled that of the dihydropyridine calcium antagonists. It is concluded that peppermint oil relaxes gastrointestinal smooth muscle by reducing calcium influx.

Animals↗
PubMed1990

Effect of almond and anis oils on mouse liver alcohol dehydrogenase, aldehyde dehydrogenase and heart lactate dehydrogenase isoenzymes.

The effects of short-term intraperitoneal injection of diluted almond or anis oil on heart lactate dehydrogenase isoenzymes, liver alcohol dehydrogenase and subcellular aldehyde dehydrogenase were studied in the female mouse. Hepatic alcohol dehydrogenase was induced from control by administration of almond oil 3.2 g/kg/d for 7 days, or anis oil 1.6 g/kg/d for 7 days. Treatment with almond but not anis oil inhibited both cytoplasmic and mitochondrial liver aldehyde dehydrogenase. The mitochondrial isoenzyme with an apparently low Km was also inhibited by the almond oil trial. No significant changes occurred in heart lactate dehydrogenase isoenzymes by the treatments used. The enzymatic inhibition kinetics were found to be non-competitive. The apparent Km for almond-treated mouse aldehyde dehydrogenase was greater than the controls. This indicates lower substrate affinity for almond oil than for acetaldehyde. The results suggest adverse hepatic metabolic interaction between almond oil and alcohol.

Alcohol Dehydrogenase↗
PubMed1992

Essential oils and antimicrobial activity of two varieties of Cedronella canariensis (L.) W. et B.

The qualitative and quantitative determination of the essential oils of the aerial part of two varieties of Cedronella canariensis (L.) W. et B., namely, C. canariensis var. canariensis and C. canariensis var. anisata have been performed, together with the study of the antimicrobial activity of both oils. The noteworthy inhibition exhibited against Bordetella bronchiseptica and Cryptococcus albidus may justify the popular use of the these plants in the treatment of certain diseases of the respiratory tract.

Bacteria↗
PubMed2006

Lemon oil vapor causes an anti-stress effect via modulating the 5-HT and DA activities in mice.

We examined the anti-stress action of the essential oils of lavender, rose, and lemon using an elevated plus-maze task (EPM), a forced swimming task (FST), and an open field task (OFT) in mice. Lemon oil had the strongest anti-stress effect in all three behavioral tasks. We further investigated a regulatory mechanism of the lemon oil by pre-treatments with agonists or antagonists to benzodiazepine, 5-HT, DA, and adrenaline receptors by the EPM and the FST. The anti-stress effect of lemon oil was significantly blocked by pre-treatment with frumazenil, benzodiazepine receptor antagonist, or apomorphine, a nonselective DA receptor agonist. In contrast, agonists or antagonists to the 5-HT receptor and the alpha-2 adrenaline receptor did not affect the anti-stress effect of lemon oil. Buspirone, DOI, and mianserine blocked the antidepressant-like effect of lemon oil in the FST, but WAY100,635 did not. These findings suggest that the antidepressant-like effect of lemon oil is closely related with the 5-HTnergic pathway, especially via 5-HT(1A) receptor. Moreover, the lemon oil significantly accelerated the metabolic turnover of DA in the hippocampus and of 5-HT in the prefrontal cortex and striatum. These results suggest that lemon oil possesses anxiolytic, antidepressant-like effects via the suppression of DA activity related to enhanced 5-HTnergic neurons.

Administration, Inhalation↗
PubMed2004

Geraniol, a component of plant essential oils, modulates DNA synthesis and potentiates 5-fluorouracil efficacy on human colon tumor xenografts.

We investigated on colon cancer cells the effect of geraniol on thymidylate synthase and thymidine kinase expression, two enzymes related to 5-fluorouracil cytotoxicity. The anti-tumoral efficacy of geraniol and 5-fluorouracil were also evaluated on TC-118 human tumors transplanted in Swiss nu/nu mice. Geraniol (150 microM) but not 5-fluorouracil caused a 2-fold reduction of thymidylate synthase and thymidine kinase expression in cancer cells. In nude mice, the combined administration of 5-fluorouracil (20 mg/kg) and geraniol (150 mg/kg) caused a 53% reduction of the tumor volume, whereas a 26% reduction was obtained with geraniol alone, 5-fluorouracil alone showed no effect.

Acyclic Monoterpenes↗
PubMed2006

Characterization of essential oil components of Iranian geranium oil using gas chromatography-mass spectrometry combined with chemometric resolution techniques.

The essential oil components of geranium oil cultivated in center of Iran were identified and determined using gas chromatography-mass spectrometry data combined with the chemometric resolution techniques. A total of 61 components accounting for 91.51% were identified using similarity searches between the mass spectra and MS database. This number was extended to 85 components using chemometric techniques. Various chemometric methods such as morphological scores, simplified Borgen method (SBM) and fixed size moving window evolving factor analysis (FSMWEFA) were used for determining the number of components, pure variables, zero concentration and selective regions. Then the overlapping peak clusters were resolved into pure chromatograms and pure mass spectra using heuristic evolving latent projections (HELP) method. A characteristic feature of the Iranian geranium oil is the absence of 10-epi-gamma-eudesmol in its constituents compared with the oil from northern and southern parts of India. The results of this work show that combination of hyphenated chromatographic methods and resolution techniques provide a complementary method for accurate analysis of essential oils.

Gas Chromatography-Mass Spectrometry↗
PubMed2005

Compositions and antimicrobial activities of the essential oils of two Hypericum species from Turkey.

The chemical compositions of essential oils obtained from Hypericum hyssopifolium var. microcalycinum and Hypericum lysimachioides var. lysimachioides were analysed by using GC and GC-MS. Caryophyllene oxide was found to be the major component. The essential oils of both Hypericum species showed antimicrobial activity against nine microorganism at a concentration of 60 to 80 microg/ml.

Anti-Infective Agents↗
PubMed2004

Inactivation of Colletotrichum gloeosporioides spores by high hydrostatic pressure combined with citral or lemongrass essential oil.

Anthracnose, caused by the fungus Colletotrichum gloeosporioides, is the main post-harvest disease of the papaya. Inactivation of the spores of C. gloeosporioides in saline solution by the use of high hydrostatic pressure, citral oil and lemongrass oil, alone and in combination, was studied. C. gloeosporioides spores were efficiently inhibited after a pressure treatment of 350 MPa for 30 min. When C. gloeosporioides was treated with 0.75 mg ml(-1) of citral or lemongrass oil, the pressure needed to achieve the same spore inhibition was 150 MPa. This work suggests the use of high hydrostatic pressure and plant essential oils as an alternative control for fruit diseases.

Acyclic Monoterpenes↗
PubMed2004

Evaluation of five essential oils from aromatic plants of Cameroon for controlling food spoilage and mycotoxin producing fungi.

Five essential oils (EO) extracted from Cymbopogon citratus, Monodora myristica, Ocimum gratissimum, Thymus vulgaris and Zingiber officinale were investigated for their inhibitory effect against three food spoilage and mycotoxin producing fungi, Fusarium moniliforme, Aspergillus flavus and Aspergillus fumigatus. Five strains of each fungus were tested. The agar dilution technique was used to determine the inhibitory effect of each EO on the radial growth of the fungus, and a dose response was recorded. The EO from O. gratissimum, T. vulgaris and C. citratus were the most effective and prevented conidial germination and the growth of all three fungi on corn meal agar at 800, 1000 and 1200 ppm, respectively. Moderate activity was observed for the EO from Z. officinale between 800 and 2500 ppm, while the EO from M. myristica was less inhibitory. These effects against food spoilage and mycotoxin producing fungi indicated the possible ability of each essential oil as a food preservative. A comparative test on the preservative ability of the EO from O. gratissimum and potassium sorbate against A. flavus at pH 3.0 and 4.5 showed that the EO remained stable at both pH, whereas the efficacy of potassium sorbate was reduced at higher pH. We concluded that the EO from O. gratissimum is a potential food preservative with a pH dependent superiority against potassium sorbate, and these are novel scientific information.

Antifungal Agents↗
PubMed2006

Ultrastructural studies on antimicrobial efficacy of thyme essential oils on Listeria monocytogenes.

OBJECTIVES: Listeria monocytogenes has gained increasing attention as a pathogen of public health importance owing to large numbers of food-borne outbreaks of listeriosis. Because of negative consumer perception of chemical preservatives, attention is shifting towards natural alternatives. Particular interest has been focused on the potential application of plant essential oils. The objective of the present study was to determine ultrastructural changes brought about by essential oils from two types of thyme, Thymus eriocalyx and Thymus x-porlock, on Listeria monocytogenes. MATERIALS AND METHODS: Minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations and bactericidal kinetics of the oils were determined. Listeria monocytogenes were treated with essential oils from two thyme species and observed under a transmission electron microscope. RESULTS: The oils from the above plants were found to be strongly antimicrobial. Analysis of the oils by gas chromatography and gas chromatography/mass spectrometry lead to the identification of 18 and 19 components in T. eriocalyx and T. x-porlock oils, respectively. Listeria monocytogenes treated with essential oils from the two thyme species exhibited a thickened or disrupted cell wall with increased roughness and lack of cytoplasm. CONCLUSION: The antilisterial effects of thyme oil are stronger than the action of electric shocks in combination with nisin reported in the literature. It is concluded that essential oils such as thyme oil, which inhibited the growth of L. monocytogenes at low concentrations, could be considered as preservative materials for some kinds of foods; they could find an application as additives to foodstuffs in storage to protect them from listerial contamination.

Anti-Bacterial Agents↗
PubMed2005

Preliminary investigation of the effect of peppermint oil on an objective measure of daytime sleepiness.

The assertion, often quoted in the popular literature, that peppermint has invigorating properties has been investigated through objective assessment of daytime sleepiness. Pupillary fatigue oscillations have been used to give an index of pupillary unrest that can be used as a reliable measure of daytime sleepiness. When compared with a no-odour condition, the presence of peppermint oil limited the increase in sleepiness during 11 min spent in a darkened room. This significant difference in sleepiness between the peppermint oil and the no-odour conditions was shown not to be related to differences in subjective ratings of initial sleepiness, from the Stanford Sleepiness Scale (SSS). Neither was it related to differences in initial pupillary unrest or mean pupil size. It seems that in conditions that favour an increase in daytime sleepiness, peppermint oil can indeed reduce sleepiness. However, the mechanisms by which peppermint oil has its effect and the applicability of these findings to situations in everyday life will require further empirical investigation.

Adult↗
PubMed2006

Ethnopharmacological study of two Lippia species from Oriximiná, Brazil.

Lippia alba (Miller) N.E. Brown is an aromatic herb that occurs in practically all regions of Brazil and has a large importance in Brazilian folk medicine. This species is characterized by a variability in morphology and in the chemical composition of the essential oil. The present work focused on the ethnopharmacological investigation of Lippia alba, locally known as "erva-cidreira" and Lippia alba f. intermedia, known as "carmelitana". In addition, the chemical composition and antimicrobial activity of their essential oils was investigated in order to correlate to their traditional uses. The ethnopharmacological study showed a good agreement of the major use (MUA) of Lippia alba (MUA=92.0%) and to a lesser extent, for Lippia alba f. intermedia (MUA=66.7%), as sedatives. The analyses of the essential oils allowed the identification of Lippia alba as a myrcene-citral chemotype (15% and 37.1%, respectively) and Lippia alba f. intermedia as a citral chemotype (22.1%). The essential oils of both species were active against all microorganisms assayed (bacteria and fungi) by the drop test, with inhibition halos ranging from 1.1 to 5.0 cm, probably due to the high content of oxygenated monoterpenes (51.0% and 40.1%, respectively), specially represented by aldehydes and alcohols. The chemical and pharmacological data of Lippia alba are in agreement with the ethnobotanical survey.

Anti-Bacterial Agents↗