Editor's note: This study focused on the application of essential oils AND grapefruit seed extract for the eradication of three strains of Staphylococcus aureus bacteria, including an MRSA strain. The study modeled both topical application and vapor exposure (as would occur with a diffuser, for example).

Study: The effect of essential oils on methicillin-resistant Staphylococcus aureus using a dressing model.

Edwards-Jones V, Buck R, Shawcross SG, Dawson MM, Dunn K.Department of Biological Sciences, the Manchester Metropolitan University, Chester Street, Manchester, M15GD, UK.

Patchouli, tea tree, geranium, lavender essential oils and Citricidal (grapefruit seed extract) were used singly and in combination to assess their anti-bacterial activity against three strains of Staphylococcus aureus: Oxford S. aureus NCTC 6571 (Oxford strain), Epidemic methicillin-resistant S. aureus (EMRSA 15) and MRSA (untypable). The individual essential oils, extracts and combinations were impregnated into filter paper discs and placed on the surface of agar plates, pre-seeded with the appropriate strain of Staphylococcus. The effects of the vapours of the oils and oil combinations were also assessed using impregnated filter paper discs that were placed on the underside of the Petri dish lid at a distance of 8mm from the bacteria. The most inhibitory combinations of oils for each strain were used in a dressing model constructed using a four layers of dressings: the primary layer consisted of either Jelonet or TelfaClear with or without Flamazine; the second was a layer of gauze, the third a layer of Gamgee and the final layer was Crepe bandage. The oil combinations were placed in either the gauze or the Gamgee layer. This four-layered dressing was placed over the seeded agar plate, incubated for 24h at 37 degrees C and the zones of inhibition measured. All experiments were repeated on three separate occasions. No anti-bacterial effects were observed when Flamazine was smeared on the gauze in the dressing model. When Telfaclear was used as the primary layer in the dressing model compared to Jelonet, greater zones of inhibition were observed. A combination of Citricidal and geranium oil showed the greatest-anti-bacterial effects against MRSA, whilst a combination of geranium and tea tree oil was most active against the methicillin-sensitive S. aureus (Oxford strain). This study demonstrates the potential of essential oils and essential oil vapours as antibacterial agents and for use in the treatment of MRSA infection.

Editor's note: Also, this study specifically evaulated Tea Tree essential oil against MRSA. As with another study, Tea Tree oil was not considered exceptionally effective against nasal infections - as above, however, it may be more than Tea Tree oil alone that will provide the best action against this serious bactierial infection.

Study: A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization.

Dryden MS, Dailly S, Crouch M.Department of Microbiology and Communicable Disease, Royal Hampshire County Hospital, Romsey Road, Winchester, Hampshire SO22 5DG, UK.

Two topical MRSA eradication regimes were compared in hospital patients: a standard treatment included mupirocin 2% nasal ointment, chlorhexidine gluconate 4% soap, silver sulfadiazine 1% cream versus a tea tree oil regimen, which included tea tree 10% cream, tea tree 5% body wash, both given for five days. One hundred and fourteen patients received standard treatment and 56 (49%) were cleared of MRSA carriage. One hundred and ten received tea tree oil regimen and 46 (41%) were cleared. There was no significant difference between treatment regimens (Fisher's exact test; P = 0.0286). Mupirocin was significantly more effective at clearing nasal carriage (78%) than tea tree cream (47%; P = 0.0001) but tea tree treatment was more effective than chlorhexidine or silver sulfadiazine at clearing superficial skin sites and skin lesions. The tea tree preparations were effective, safe and well tolerated and could be considered in regimens for eradication of MRSA carriage.

Editor's note: These are a sampling of the abstracts from published scientific studies regarding the anti-microbial efficacy of Tea Tree essential oil. It is pointed out that terpinen-4-ol is the primary anti-microbial component of the oil; the cineol does not have significant anti-microbial effect. However, cineol is a well-regarded decongestant, a fact which implies the broad range of therapeutic possibilities for tea tree essential oil.

Study: Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes.

Raman A, Weir U, Bloomfield SF.Department of Pharmacy, King's College London, UK.

Major components of two tea-tree oil samples were identified using thin layer and gas-liquid chromatography (TLC and GLC). Using a TLC-bioautographic technique, the tea-tree oils, terpinen-4-ol, alpha-terpineol and alpha-pinene were found to be active against Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes whereas cineole was inactive against these organisms. The MIC values of the three active compounds increased in the order alpha-terpineol < terpinen-4-ol < alpha-pinene for all three micro-organisms. MIC values of the tea-tree oils and terpinen-4-ol were lower for P. acnes than for the two staphylococci. This study supports the use of tea-tree oil in the treatment of acne, and demonstrates that terpinen-4-ol is not the sole active constituent of the oil.

Study: In vivo activity of terpinen-4-ol, the main bioactive component of Melaleuca alternifolia (tea tree oil) against azole-susceptible and -resistant human pathogenic Candida species.

Mondello F, De Bernardis F, Girolamo A, Cassone A, Salvatore G.Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.

BACKGROUND: Recent investigations on the antifungal properties of essential oil of Melaleuca alternifolia Cheel (Tea Tree Oil, TTO) have been performed with reference to the treatment of vaginal candidiasis. However, there is a lack of in vivo data supporting in vitro results, especially regarding the antifungal properties of TTO constituents. Thus, the aim of our study was to investigate the in vitro and the in vivo anti-Candida activity of two critical bioactive constituents of TTO, terpinen-4-ol and 1,8-cineole. METHODS: Oophorectomized, pseudoestrus rats under estrogen treatment were used for experimental vaginal infection with azole (fluconazole, itraconazole) -susceptible or -resistant strains of C. albicans. All these strains were preliminarily tested for in vitro susceptibility to TTO, terpinen-4-ol and 1,8-cineole for their antifungal properties, using a modification of the CLSI (formerly NCCLS) reference M27-A2 broth micro-dilution method. RESULTS: In vitro minimal inhibitory concentrations (MIC90) values were 0.06% (volume/volume) for terpinen-4-ol and 4% (volume/volume) for 1,8-cineole, regardless of susceptibility or resistance of the strains to fluconazole and itraconazole. Fungicidal concentrations of terpinen-4-ol were equivalent to the candidastatic activity. In the rat vaginal infection model, terpinen-4-ol was as active as TTO in accelerating clearance from the vagina of all Candida strains examined. CONCLUSION: Our data suggest that terpinen-4-ol is a likely mediator of the in vitro and in vivo activity of TTO. This is the first in vivo demonstration that terpinen-4-ol could control C. albicans vaginal infections. The purified compound holds promise for the treatment of vaginal candidiasis, and particularly the azole-resistant forms.

Study: In vitro and in vivo activity of tea tree oil against azole-susceptible and -resistant human pathogenic yeasts.

Mondello F, De Bernardis F, Girolamo A, Salvatore G, Cassone A.Laboratory of Bacteriology and Medical Mycology, Istituto Superiore di Sanità, Rome, Italy.

A tea tree oil (TTO) preparation of defined chemical composition was studied, using a microbroth method, for its in vitro activity against 115 isolates of Candida albicans, other Candida species and Cryptococcus neoformans. The fungal strains were from HIV-seropositive subjects, or from an established type collection, including reference and quality control strains. Fourteen strains of C. albicans resistant to fluconazole and/or itraconazole were also assessed. The same preparation was also tested in an experimental vaginal infection using fluconazole-itraconazole-susceptible or -resistant strains of C. albicans. TTO was shown to be active in vitro against all tested strains, with MICs ranging from 0.03% (for C. neoformans) to 0.25% (for some strains of C. albicans and other Candida species). Fluconazole- and/or itraconazole-resistant C. albicans isolates had TTO MIC50s and MIC90s of 0.25% and 0.5%, respectively. TTO was highly efficacious in accelerating C. albicans clearance from experimentally infected rat vagina. Three post-challenge doses of TTO (5%) brought about resolution of infection regardless of whether the infecting C. albicans strain was susceptible or resistant to fluconazole. Overall, the use of a reliable animal model of infection has confirmed and extended our data on the therapeutic effectiveness of TTO (tea tree essential oil) against fungi, in particular against C. albicans.

Study: Antibacterial activity of essential oils on the growth of Staphylococcus aureus and measurement of their binding interaction using optical biosensor.

Chung KH, Yang KS, Kim J, Kim JC, Lee KY.Center for Functional Nano Fine Chemicals, Chonnam National University, Gwangju 500-757, Korea.

Antibacterial activity of essential oils (Tea tree, Chamomile, Eucalyptus) on Staphylococcus aureus growth was evaluated as well as the essential oil-loaded alginate beads. The binding interactions between the cell and the essential oils were measured using an optical biosensor. The antibacterial activity of the essential oils to the cell was evaluated with their binding interaction and affinity. The antibacterial activity appeared in the order of Tea Tree> Chamomile>Eucalyptus, in comparison of the inhibition effects of the cell growth to the essential oils. The association rate constant and affinity of the cell binding on Tea Tree essential oil were 5.0 x 10(-13) ml/(CFU-s) and 5.0 x 10(5) ml/CFU, respectively. The affinity of the cell binding on Tea Tree was about twice higher than those on the other essential oils. It might be possible that an effective antibacterial activity of Tea Tree essential oil was derived from its strong adhesive ability to the cell, more so than those of the other essential oils.

These two studies demonstrate a couple of documented anti-anxiety effects of the simple aromatherapy technique of inhalation of essential oil aromas. The first discusses an anti-anxiety effect of lavender essential oil on gerbils, interestingly particularly the female gerbils! The second uses lemon essential oil, comparing its anti-stress effect to three known anxiolytic chemical agents. The lemon aroma had the most potent effect.

Study: Anxiolytic (anti-anxiety) effects of Lavandula angustifolia odour (Lavender essential oil) on the Mongolian gerbil elevated plus maze.

Bradley BF, Starkey NJ, Brown SL, Lea RW.
Department of Psychology, University of Central Lancashire, Preston, Lancashire, UK.

Lavender (essential oil) is a popular treatment for stress and mild anxiety in Europe and the USA. The present study investigated the effects of (Lavandula angustifolia Mill. (Lamiaceae)) lavender odour inhalation over 2 weeks or 24 h periods, on gerbil behaviour in the elevated plus maze in mature male and female gerbils, and compared results with the effects of diazepam (1 mg/kg) i.p. after 30 min and 2-week administration. Traditional measures of open entries showed an increasing trend over the 2 weeks exposure, whereas ethological measures indicative of anxiety; stretch-attend frequency and percentage protected head-dips, were significantly lower. Exploratory behaviour, total head-dip frequency, increased after 24 h lavender and 2 weeks exposure. These results are comparable with diazepam administration. There were sex differences in protected head-dip an ethological indicator of anxiety: females showed a significant decrease in protected head-dips compared to both males and to female controls. In conclusion exposure to lavender odour (Lavender essential oil) may have an anxiolytic profile in gerbils similar to that of the anxiolytic diazepam. In addition, prolonged, 2-week lavender odour exposure increased exploratory behaviour in females indicating a further decrease in anxiety in this sex.

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

Komiya M, Takeuchi T, Harada E.
Graduate School of Veterinary Science, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.

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.

Study: Positive modulation of mood and cognitive performance following administration of acute doses of Salvia lavandulaefolia essential oil to healthy young volunteers.

Tildesley NT, Kennedy DO, Perry EK, Ballard CG, Wesnes KA, Scholey AB.Human Cognitive Neuroscience Unit, Division of Psychology, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK.

Members of the Sage family, such as Salvia officinalis (sage essential oil) and Salvia lavandulaefolia, have a long history of use as memory-enhancing agents coupled with cholinergic properties that may potentially be relevant to the amelioration of the cognitive deficits associated with Alzheimer's disease. The current study utilised a placebo-controlled, double-blind, balanced, crossover design in order to comprehensively assess any mood and cognition modulation by S. lavandulaefolia. Twenty-four participants received single doses of placebo, 25 microl and 50 microl of a standardised essential oil of S. lavandulaefolia in an order dictated by a Latin square. Doses were separated by a 7-day washout period. Cognitive performance was assessed prior to the day's treatment and at 1, 2.5, 4 and 6 h thereafter using the Cognitive Drug Research (CDR) computerised test battery. Subjective mood ratings were measured using Bond-Lader visual analogue scales. The primary outcome measures were scores on the five cognitive factors that can be derived by factor analysis of the task outcomes from the CDR battery. The results showed that administration of S. lavandulaefolia resulted in a consistent improvement for both the 25- and 50-microl dose on the 'Speed of Memory' factor. There was also an improvement on the 'Secondary Memory' factor for the 25-microl dose. Mood was consistently enhanced, with increases in self-rated 'alertness', 'calmness' and 'contentedness' following the 50-microl dose and elevated 'calmness' following 25 microl. These results represent further evidence that Salvia is capable of acute modulation of mood and cognition in healthy young adults. The data also suggest that previous reports of memory enhancement by Salvia may be due to more efficient retrieval of target material.

Study: Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults.

Moss M, Cook J, Wesnes K, Duckett P.
Human Cognitive Neuroscience Unit, Division of Psychology, Northumberland Building, University of Northumbria, Newcastle upon Tyne, NE1 8ST, UK. mark.moss@unn.ac.uk

This study was designed to assess the olfactory impact of the essential oils of lavender (Lavandula angustifolia) and rosemary (Rosmarlnus officinalis) on cognitive performance and mood in healthy volunteers. One hundred and forty-four participants were randomly assigned to one of three independent groups, and subsequently performed the Cognitive Drug Research (CDR) computerized cognitive assessment battery in a cubicle containing either one of the two odors or no odor (control). Visual analogue mood questionnaires were completed prior to exposure to the odor, and subsequently after completion of the test battery. The participants were deceived as to the genuine aim of the study until the completion of testing to prevent expectancy effects from possibly influencing the data. The outcome variables from the nine tasks that constitute the CDR core battery feed into six factors that represent different aspects of cognitive functioning.

Analysis of performance revealed that lavender produced a significant decrement in performance of working memory, and impaired reaction times for both memory and attention based tasks compared to controls. In contrast, rosemary produced a significant enhancement of performance for overall quality of memory and secondary memory factors, but also produced an impairment of speed of memory compared to controls. With regard to mood, comparisons of the change in ratings from baseline to post-test revealed that following the completion of the cognitive assessment battery, both the control and lavender groups were significantly less alert than the rosemary condition; however, the control group was significantly less content than both rosemary and lavender conditions. These findings indicate that the olfactory properties of these essential oils can produce objective effects on cognitive performance, as well as subjective effects on mood.

These two studies show the efficacy of lavender and melissa essential oils for soothing agitated behavior for patients with dimentia.

Study: The effect of lavender aromatherapy on cognitive function, emotion, and aggressive behavior of elderly with dementia.

Lee SY, Department of Nursing, Kongju National University, Korea.

PURPOSE: This study was to develop an aromatherapy hand massage program, and to evaluate the effects of lavender aromatherapy on cognitive function, emotion, and aggressive behavior of elderly with dementia of the Alzheimer's type. METHOD: The Research design was a nonequivalent control group non-synchronized quasiexperimental study. Lavender aromatherapy was administrated to experimental group I for 2 weeks, jojoba oil massage was administrated to experimental group II for 2 weeks, and no treatment was administrated to the control group for 2 weeks. Data was analyzed using the chi(2)-test, ANOVA, repeated measures of ANCOVA and ANCOVA in the SPSS program package. RESULT: 1. Experimental group I did not show significant differences in cognitive function in relation to the experimental group II and control group. 2. Experimental group I showed significant differences in emotion and aggressive behavior in relation to the experimental group II and control group. CONCLUSION: A Lavender aromatherapy hand massage program is effective on emotions and aggressive behavior of elderly with dementia of the Alzheimer's type.

Study: Aromatherapy as a safe and effective treatment for the management of agitation in severe dementia: the results of a double-blind, placebo-controlled trial with Melissa.

Ballard CG, O'Brien JT, Reichelt K, Perry EK. Wolfson Research Centre, Newcastle General Hospital, Institute for Ageing and Health, Newcastle upon Tyne, United Kingdom.

BACKGROUND: Behavioral and psychological symptoms in dementia are frequent and are a major management problem, especially for patients with severe cognitive impairment. Preliminary reports have indicated positive effects of aromatherapy using select essential oils, but there are no adequately powered placebo-controlled trials. We conducted a placebo-controlled trial to determine the value of aromatherapy with essential oil of Melissa officinalis (lemon balm) for agitation in people with severe dementia. METHOD: Seventy-two people residing in National Health Service (U.K.) care facilities who had clinically significant agitation in the context of severe dementia were randomly assigned to aromatherapy with Melissa essential oil (N = 36) or placebo (sunflower oil) (N = 36). The active treatment or placebo oil was combined with a base lotion and applied to patients' faces and arms twice a day by caregiving staff. Changes in clinically significant agitation (Cohen-Mansfield Agitation Inventory [CMAI]) and quality of life indices (percentage of time spent socially withdrawn and percentage of time engaged in constructive activities, measured with Dementia Care Mapping) were compared between the 2 groups over a 4-week period of treatment. RESULTS: Seventy-one patients completed the trial. No significant side effects were observed. Sixty percent (21/35) of the active treatment group and 14% (5/36) of the placebo-treated group experienced a 30% reduction of CMAI score, with an overall improvement in agitation (mean reduction in CMAI score) of 35% in patients receiving Melissa balm essential oil and 11% in those treated with placebo (Mann-Whitney U test; Z = 4.1, p < .0001). Quality of life indices also improved significantly more in people receiving essential balm oil (Mann-Whitney U test; percentage of time spent socially withdrawn: Z = 2.6, p = .005; percentage of time engaged in constructive activities: Z = 3.5, p = .001). CONCLUSION: The finding that aromatherapy with essential balm oil is a safe and effective treatment for clinically significant agitation in people with severe dementia, with additional benefits for key quality of life parameters, indicates the need for further controlled trials.