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Mouse skin tumor promoting activity of orange peel oil and d-limonene: a re-evaluation.
Orange peel oil has previously been shown to be a promoter of mouse skin tumors. It has been assumed that this activity is due to its major (95%) constituent, d-limonene. We have tested both orange peel oil and purified d-limonene as skin tumor promoters in a two-stage skin carcinogenesis model in which tumors were initiated with 7,12-dimethylbenz[a]-anthracene. We confirmed that topically applied orange peel oil is a very weak promoter of both skin papillomas and carcinomas. However, this promotional activity could not be accounted for by topically applied d-limonene. We thus feel that one or more minor components of orange peel oil has promotional activity. Neither orange peel oil nor d-limonene had promotional activity when given via the diet.
Inhibition of listeriolysin O and phosphatidylcholine-specific production in Listeria monocytogenes by subinhibitory concentrations of plant essential oils.
Successful infection by Listeria monocytogenes is dependent upon a range of bacterial extracellular proteins including a cytolysin termed listeriolysin O and phosphatidylcholine-specific phospholipase C. Five plant essential oils--bay, clove, cinnamon, nutmeg and thyme--significantly reduced the production of listeriolysin O by L. monocytogenes. The greatest change was observed after culture with oil of thyme, which reduced haemolysis to 52.1 haemolytic units (HU)/ml compared with 99.8 HU/ml observed with the control. Oil of clove was the only oil that also significantly reduced phosphatidylcholine-specific phospholipase C activity. These changes were observed despite the oils causing no change to the final bacterial concentration or total extracellular protein concentration.
Efficiency of Calamintha officinalis essential oil as preservative in two topical product types.
AIMS: To verify the efficiency of Calamintha officinalis essential oil as natural preservative in two current formulations. METHODS AND RESULTS: The 1.0 and 2.0% (v/v) C. officinalis essential oil was assayed for its preservative activity in two product types (cream and shampoo). The microbial challenge test was performed following the standards proposed by the European Pharmacopoeia Commission (E.P.) concerning topical preparations using standard micro-organisms and in addition wild strains, either in single or mixed cultures were used. The results clearly demonstrated that the C. officinalis essential oil at 2.0% concentration reduced the microbial inoculum satisfying the criterion A of the E.P. in the cream formulation and the criterion B in the shampoo formulation. Standard and wild strains showed a behaviour similar, both in cream and in shampoo formulation, with no significant difference (gerarchic variance, P > 0.05). CONCLUSION: C. officinalis essential oil confirmed its preservative properties but at higher concentration than that shown in previous studies on cetomacrogol cream. SIGNIFICANCE AND IMPACT OF THE STUDY: The nature of the formulation in which an essential oil is incorporated as preservative could have considerable effect on its efficacy.
Antifungal effects of herbal essential oils alone and in combination with ketoconazole against Trichophyton spp.
AIMS: To determine the effects of herbal essential oils on Trichophyton spp. growth and to evaluate the effects of Pelargonium graveolens oil and its main components citronellol and geraniol combined with ketoconazole against Trichophyton spp. METHODS AND RESULTS: Growth inhibition of six Trichophyton spp. by herbal essential oils was accessed and the combined effects of P. graveolens oil and its main components citronellol and geraniol were evaluated using a checkerboard microtitre assay against T. schoenleinii, T. erinacei and T. soudanense. The essential oil fraction of P. graveolens and its main components, geraniol and citronellol, exhibited strong synergism with ketoconazole against T. schoenleinii and T. soudanense, with fractional inhibitory concentration (FIC) indices in the range of 0.18-0.38. CONCLUSIONS: The antifungal effects of ketoconazole against Trichophyton spp. are enhanced significantly by administering it in combination with the essential oil fraction of P. graveolens or its main components, because of strong synergism, especially against T. soudanense and T. schoenleinii. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of ketoconazole and the essential oil fraction from P. graveolens or its main components for treatment of infections caused by Trichophyton species may reduce the minimum effective dose of ketoconazole, and thus minimize the side-effects of ketoconazole.
Tea tree oil in the treatment of tinea pedis.
Tea tree oil (an essential oil derived primarily from the Australian native Melaleuca alternifolia) has been used as a topical antiseptic agent since the early part of this century for a wide variety of skin infections; however, to date, the evidence for its efficacy in fungal infections is still largely anecdotal. One hundred and four patients completed a randomized, double-blind trial to evaluate the efficacy of 10% w/w tea tree oil cream compared with 1% tolnaftate and placebo creams in the treatment of tinea pedis. Significantly more tolnaftate-treated patients (85%) than tea tree oil (30%) and placebo-treated patients (21%) showed conversion to negative culture at the end of therapy (p < 0.001); there was no statistically significant difference between tea tree oil and placebo groups. All three groups demonstrated improvement in clinical condition based on the four clinical parameters of scaling, inflammation, itching and burning. The tea tree oil group (24/37) and the tolnaftate group (19/33) showed significant improvement in clinical condition when compared to the placebo group (14/34; p = 0.022 and p = 0.018 respectively). Tea tree oil cream (10% w/w) appears to reduce the symptomatology of tinea pedis as effectively as tolnaftate 1% but is no more effective than placebo in achieving a mycological cure. This may be the basis for the popular use of tea tree oil in the treatment of tinea pedis.
Peppermint oil for irritable bowel syndrome: a critical review and metaanalysis.
OBJECTIVE: Peppermint oil is the major constituent of several over-the-counter remedies for symptoms of irritable bowel syndrome (IBS). As the etiology of IBS is not known and treatment is symptomatic, there is a ready market for such products. However, evidence to support their use is sparse. The aim of this study was to review the clinical trials of extracts of peppermint (Mentha X piperita L.) as a symptomatic treatment for IBS. METHODS: Computerized literature searches were performed to identify all randomized controlled trials of peppermint oil for IBS. Databases included Medline, Embase, Biosis, CISCOM, and the Cochrane Library. There were no restrictions on the language of publication. Data were extracted in a standardized, predefined fashion, independently by both authors. Five double blind, randomized, controlled trials were entered into a metaanalysis. RESULTS: Eight randomized, controlled trials were located. Collectively they indicate that peppermint oil could be efficacious for symptom relief in IBS. A metaanalysis of five placebo-controlled, double blind trials seems to support this notion. In view of the methodological flaws associated with most studies, no definitive judgment about efficacy can be given. CONCLUSION: The role of peppermint oil in the symptomatic treatment of IBS has so far not been established beyond reasonable doubt. Well designed and carefully executed studies are needed to clarify the issue.
A nmte on the analysis of oil of peppermint by an aluminum oxide-silicic acid double column.
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DETERMINATION OF O-METHOXYCINNAMALDEHYDE IN CASSIA OIL BY INFRA-RED SPECTROPHOTOMETRY.
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An investigation of the actions of the essential oils of Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides), Myrtaceae on guinea-pig smooth muscle.
The two New Zealand tea-tree oils, Manuka (Leptospermum scoparium J.R. et G. Forst) and Kanuka (Kunzea ericoides (A. Rich) J. Thompson), Myrtaceae have been used as folk medicines for treating diarrhoea, colds and inflammation but their pharmacological action has not been investigated. Their mode of action was therefore studied on the field-stimulated guinea-pig ileum. Both Manuka and Kanuka oils induced a spasmolytic effect but Kanuka produced an initial contraction. The spasmolytic action of both oils was the result of a post-synaptic mechanism. Action involving adrenoceptors or cGMP was not considered likely, neither did the oils behave like calcium- or potassium-channel openers. There is some evidence that Manuka acts through cAMP whereas the mode of action of Kanuka is as yet undetermined. The results indicate that the use of these oils as relaxants in aromatherapy might be valid, although their mode of action is not identical.
In vitro antibacterial activity of some plant essential oils.
BACKGROUND: To evaluate the antibacterial activity of 21 plant essential oils against six bacterial species. METHODS: The selected essential oils were screened against four gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris) and two gram-positive bacteria Bacillus subtilis and Staphylococcus aureus at four different concentrations (1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The MIC of the active essential oils were tested using two fold agar dilution method at concentrations ranging from 0.2 to 25.6 mg/ml. RESULTS: Out of 21 essential oils tested, 19 oils showed antibacterial activity against one or more strains. Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. CONCLUSION: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents.
Inhalation aromatherapy during radiotherapy: results of a placebo-controlled double-blind randomized trial.
PURPOSE: To determine whether the inhalation of aromatherapy during radiotherapy reduces anxiety. PATIENTS AND METHODS: Three hundred thirteen patients undergoing radiotherapy were randomly assigned to receive either carrier oil with fractionated oils, carrier oil only, or pure essential oils of lavender, bergamot, and cedarwood administered by inhalation concurrently with radiation treatment. Patients underwent assessment by the Hospital Anxiety and Depression Scale (HADS) and the Somatic and Psychological Health Report (SPHERE) at baseline and at treatment completion. RESULTS: There were no significant differences in HADS depression or SPHERE scores between the randomly assigned groups. However, HADS anxiety scores were significantly lower at treatment completion in the carrier oil only group compared with either of the fragrant arms (P =.04). CONCLUSION: Aromatherapy, as administered in this study, is not beneficial.
[STUDIES ON THE FOLIUM PERILLAE. II. ON ISOEGOMAKETONE].
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Repellency and toxicity of oil from Artemisia annua to certain stored-product beetles.
The essential oil of Artemisia annua L. was tested for its toxic repellent and development inhibitory activities against 2 economically important stored product insects: Tribolium castaneum (Herbst) and Callosobruchus maculatus (L.). Adult beetles of T. castaneum were repelled significantly by oil of A. annua at 1% concentration (vol:vol) and above in filter paper arena test. Dose-response relationship of A. annua oil revealed a significant negative correlation between larval survival; pupal survival and adult emergence of T. castaneum (i.e., increase in dose caused decrease in survival and adult emergence). Effective concentration (EC50) to reduce F1 progeny by 50% was calculated to be 2.6 and 4.1 microl/ml solvent against both the insect species, C. maculatus and T. castaneum, respectively. The relationship between bioactivity of oil from A. annua and responses of T. castaneum and C. maculatus is discussed. We found that oil from A. annua was largely responsible for both repellent (behavioral) and toxic (physiological) actions on 2 species of insect tested.
Toxic effects of six plant oils alone and in combination with controlled atmosphere on Liposcelis bostrychophila (Psocoptera: Liposcelididae).
Six plant essential oils alone as repellent and fumigant, and in combination with the controlled atmosphere against Liposcelis bostrychophila Badonnel were assessed in the laboratory. These essential oils were extracted from the leaves of six source plants: Citrus tangerina Tanaka, Citrus aurantium L., Citrus bergamia Risso et Poiteau, Pinus sylvestris L., Cupressus funebris End]., and Eucalyptus citriodora Hook. The repellency test indicated that L. bostrychophila adults were repelled by filter paper strips treated with six essential oils. Of these essential oils, the C. funebris oil was most effective followed by that of F. sylvestris, C. tangerina, C. bergamia, and E. citriodora. The average repellency of the C. aurantium oil against L. bostrychophila adults was significantly lower than other five test oils by day 14. These essential oils had a high level of toxicity in the fumigation assay against L. bostrychophila adults at both 10 and 20 ppm. When combined with two controlled atmosphere treatments (12% CO2 + 9% O2, and 10% CO2 + 5% O2, balanced N2), the toxicity of plant oils was enhanced significantly.
Toxicity of plant essential oils to Trialeurodes vaporariorum (Homoptera: Aleyrodidae).
A total of 53 plant essential oils were tested for their insecticidal activities against eggs, nymphs, and adults of Trialeurodes vaporariorum Westwood, using an impregnated filter paper bioassays without allowing direct contact. Responses varied according to oil type and dose, and developmental stage of the insect. Bay, caraway seed, clove leaf, lemon eucalyptus, lime dis 5 F, pennyroyal, peppermint, rosewood, spearmint, and tea tree oils were highly effective against T. vaporariorum adults, nymphs, and eggs at 0.0023, 0.0093, and 0.0047 microl/ml air, respectively. These results indicate that the mode of delivery of these essential oils was largely a result of action in the vapor phase. Significant correlations among adulticidal, nymphicidal, and ovicidal activities of the test oils were observed. The essential oils described herein merit further study as potential fumigants for T. vaporariorum control.
A study of the larvicidal activity of Origanum (Labiatae) species from southwest Turkey.
The insecticidal activity of essential oils isolated from two species of Origanum (Origanum onites L. and Origanum minutiflorum (O. Schwarz and P.H. Davis) (Labiate)) was investigated against 3rd and 4th instar larvae of the mosquito, Culex pipiens L. (Diptera: Culicidae). The LC50 and LC90 values were 24.8 and 61.3 ppm, and 73.8 and 118.9 ppm, respectively. This activity was attributed to the carvacrol, the major constituent of these oils.
Antifungal activity of Mexican oregano (Lippia berlandieri Shauer).
Antifungal and sensorial properties of spices have been recognized for years. The antifungal compounds are products of the plant's secondary metabolism, and the action of those compounds could be used to inhibit the growth of spoilage and pathogenic microorganisms in food. Mexican oregano (Lippia berlandieri) grows wildly in the desert zone of Mexico and is usually added to regional foods. The goal of this study was to evaluate the antifungal activity of Mexican oregano versus food-contaminant fungi. Fungi were isolated from spoiled fruit and vegetables and identified according to morphological characteristics. The antifungal activity of oregano was evaluated by radial growth measurement on potato dextrose agar added with dried oregano (0.25 to 4.0%). The essential oil antifungal activity of oregano was also evaluated by the diffusion well test. Twenty-one fungal strains were isolated, which included Penicillium, Geotrichum, Aspergillus, and Bipolaris. In seven of the 21 strains, no inhibitory effect was observed at either concentration of oregano. An increase in growth at the lower or higher concentrations of oregano, when compared to the control, was observed in two fungal strains; in 12 strains, a strong inhibitory effect of oregano was evident. The oregano essential oil was inhibitory to all fungal strains, but there were differences in the extent of the effect. Although the antifungal effect of oregano is strongly established, there was a differential effect with the fungal strains studied. Besides pathogenic fungi and bacteria, microbial spoilage flora should be considered when the addition of spices for food preservation is proposed.