Tea tree oil Research Papers (original) (raw)

ABSTRACTThis study examined the effect of subinhibitoryMelaleuca alternifolia(tea tree) essential oil on the development of antibiotic resistance inStaphylococcus aureusandEscherichia coli. Frequencies of single-step antibiotic-resistant mutants were determined by inoculating bacteria cultured with or without subinhibitory tea tree oil onto agar containing 2 to 8 times the MIC of each antibiotic and with or without tea tree oil. Whereas most differences in resistance frequencies were relatively minor, the combination of kanamycin and tea tree oil yielded approximately 10-fold fewer resistantE. colimutants than kanamycin alone. The development of multistep antibiotic resistance in the presence of tea tree oil or terpinen-4-ol was examined by culturingS. aureusandE. coliisolates daily with antibiotic alone, antibiotic with tea tree oil, and antibiotic with terpinen-4-ol for 6 days. Median MICs for each antibiotic alone increased 4- to 16-fold by day 6. Subinhibitory tea tree oil or te...

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- Microbiology, Medical Microbiology, Biology, Medicine

This in vitro study assessed the antifungal activity of a well-known and widely used essential oil, Melaleuca alternifolia (Australian tea tree oil), against the ubiquitous dermatophyte Trichophyton rubrum. The literature has reported the antifungal properties of M. alternifolia citing the minimum inhibitory concentration needed to secure this effect.

Lavender essential oil is popular as a complementary medicine in its own right and as an additive to many over the counter complementary medicine and cosmetic products ' \ Indeed, products derived from the popular garden herb Lavender (Lavandula spp.) have been used for centuries as a therapeutic agent, with the more 'recent ' addition, the essential oils derived from these plants, being widely used as an antibacterial in World War I],! The oil is traditionally believed to have sedative, carminative, anti-depressive and antiinflammatory properties, in addition to its recognised antimicrobial effects.

- by Heather Cavanagh
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- Nursing, Essential Oil, Tea tree oil, Infectious Disease

Aims: To investigate the in vitro antiviral activity of Melaleuca alternifolia essential oil (TTO) and its main components, terpinen-4-ol, a-terpinene, c-terpinene, p-cymene, terpinolene and a-terpineol. Methods and Results: The antiviral activity of tested compounds was evaluated against polio type 1, ECHO 9, Coxsackie B1, adeno type 2, herpes simplex (HSV) type 1 and 2 viruses by 50% plaque reduction assay. The anti-influenza virus assay was based on the inhibition of the virus-induced cytopathogenicity.

- by Pio Maria Furneri
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- Multidisciplinary, Applied Economics Letters, Essential Oil, Tea tree oil

In latest years, the importance of the Melaleuca alternifolia essential oil (EO) has been greatly empathised due to its anti-microbial and anti-inflammatory effects, as well as to its toxic properties towards many arthropods of great medical and veterinary importance. In this research, the EO extracted from aerial parts of M. alternifolia was evaluated for its toxicity against larvae of the most invasive mosquito worldwide, Aedes albopictus (Diptera: Culicidae), and towards adults of the water flea, Daphnia magna (Cladocera: Crustacea), a non-target aquatic organism that share the same ecological niche of A . albopictus. The chemical composition of M. alternifolia EO was investigated by GC-MS analysis. Tea tree EO was mainly composed by oxygenated monoterpenes, with 1,8-cineole as the major constituent. M. alternifolia EO exerted toxic activity against A. albopictus larvae, with a LC 50 =267.130 ppm. However, this EO had a remarkable acute toxicity also towards adults of the non-target arthropod D . magna, with a LC 50 =80.636 ppm. This research provide useful information for the development of newer and safer mosquito control tools, highlighting that the non-target effects against aquatic organisms that share the same ecological niche of A . albopictus larvae are crucial in the development of ecofriendly mosquito control strategies.

- by Guido Flamini
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- Microbiology, Parasitology, Entomology, Medical Microbiology
- by Christine Carson
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- Hospital Infection, Medicinal Plants, Phytotherapy, Tea tree oil

Plants belonging to Melaleuca genus (Myrtaceae family) are native to Oceania, where they have been used for ages by Aborigine people in Australian traditional medicine, mainly because of their broad-spectrum antimicrobial activity. Although, M. linariifolia, M. dissitiflora, and other species of Melaleuca can also be used, the tea tree oil, an essential oil obtained from M. alternifolia shows the longest history of medicinal uses. Tea tree oil contains for the 80-90% several monoterpenes (terpinen-4-ol, α-terpinene, 1,8-cineol, p-cymene, α-terpineol, α-pinene, terpinolene, limonene, and sabinene). Sesquiterpenes and aromatic compounds further compose this oil. The essential oil of Melaleuca spp. has been reported to possess effective antibacterial and antifungal properties in vitro. In particular, data show that 1,8-cineol, terpinen-4-ol and methyl eugenol play the key role in mediating this oil's antimicrobial activity. Copyright © 2017 John Wiley & Sons, Ltd.

- by Dr. Bahare Salehi
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- Biological Sciences, Phytotherapy, Tea tree oil, Melaleuca

Objectives: The essential oil of Melaleuca alternifolia (tea tree oil) and its components have antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, fungi and viruses. The mechanism(s) by which Pseudomonas aeruginosa NCTC 10662 maintains a decreased susceptibility to tea tree oil and components was investigated. Results: Ethylene diamine tetraacetic acid enhanced the antimicrobial activity of tea tree oil and terpinen-4-ol against stationary phase P. aeruginosa while polymyxin B nonapeptide enhanced the activity of tea tree oil and g-terpinene. Pre-treatment with the protonophore carbonyl cyanide m-chlorophenylhydrazone increased the susceptibility of exponential phase cells to sub-inhibitory concentrations of tea tree oil, terpinen-4-ol and g-terpinene, indicating that intrinsic tolerance to tea tree oil and components is substantially energy dependent. Conclusions: Increased tolerance to tea tree oil in P. aeruginosa is directly related to the barrier and energy functions of the outer membrane, and may involve efflux systems.

- by Christine Carson
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- Microbiology, Electron Microscopy, Medical Microbiology, Biology

Food safety is a fundamental concern of both consumers and the food industry. The increasing incidence of foodborne diseases increases the demand of using antimicrobials in foods. Spices and plants are rich in essential oils and show inhibition activity against microorganisms, which are composed of many compounds. In this research, effects of garlic, bay, black pepper, origanum, orange, thyme, tea tree, mint, clove, and cumin essential oils on Listeria monocytogenes AUFE 39237, Escherichia coli ATCC 25922, Salmonella enteritidis ATCC 13076, Proteus mirabilis AUFE 43566, Bacillus cereus AUFE 81154, Saccharomyces uvarum UUFE 16732, Kloeckera apiculata UUFE 10628, Candida albicans ATCC 10231, Candida oleophila UUPP 94365, and Metschnikowia fructicola UUPP 23067 and effects of thyme oil at a concentration of 0.5% on L. monocytogenes and C. albicans in apple-carrot juice during þ48C storage (first to fifth day) were investigated. Strong antibacterial and antifungal activities of some essential oils were found. Thyme, origanum, clove, and orange essential oils were the most inhibitory against bacteria and yeasts. Cumin, tea tree, and mint oils inhibited the yeasts actively. It is concluded that some essential oils could be used as potential biopreservatives capable of controlling foodborne pathogens and food spoilage yeasts.

- by Reyhan Irkin
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- Engineering, Biological Sciences, Tea tree oil, Listeria monocytogenes

The activity of tea tree oil (TTO) and TTO-containing products was investigated according to the EN 1276 and EN 12054 European suspension methods. The activity of different concentrations of TTO, a hygienic skin wash (HSW), an alcoholic hygienic skin wash (AHSW) and an alcoholic hand rub (AHR) was investigated. These formulations were assessed in perfect conditions with the EN 12054 test, and in perfect conditions as well as in the presence of interfering substances with the EN 1276 test, against Staphylococcus aureus, Acinetobacter baumannii, Escherichia coli and Pseudomonas aeruginosa. With the latter test, the activity of the same formulations without TTO was also assessed as a control. With the EN 1276 test, the AHR achieved a O10 5 -fold reduction against all four test organisms within a 1-min contact time. The AHSW achieved a R10 5 -fold reduction against A. baumannii after a 1-min contact time and against S. aureus, E. coli and P. aeruginosa after a 5-min contact time. The efficacy of TTO appeared to be dependent on the formulation and the concentration tested, the concentration of interfering substances and, lastly, the organism tested. Nevertheless, 5% TTO achieved a O10 4 -fold reduction in P. aeruginosa cell numbers after a 5-min contact time in perfect conditions. TTO (5%) in 0.001% Tween 80 was significantly more active against E. coli and P. aeruginosa than against S. aureus and A. baumannii. With the EN 12054 test, after a 1-min contact time, 5% TTO in 0.001% Tween 80 and the AHSW achieved a O10 4 -fold reduction in E. coli and A. baumannii cell numbers, respectively, and the AHR achieved a O4 log 10 reduction Journal of Hospital Infection (xxxx) xx, 1-13 www.elsevierhealth.com/journals/jhin 0195-6701/$ -see front matter Q

- by Katherine Hammer
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- Hospital Infection, Tea tree oil, Bacteria, Staphylococcus aureus
- by Greg Swords
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- Engineering, Tea tree oil, Agricultural food, CHEMICAL SCIENCES
- by Christine Carson
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- Fungi, Tea tree oil, Bacteria, Melaleuca

Background: Colonization with Methicillin-Resistant Staphylococcus Aureus (MRSA) is independently is associated with mortality in critically ill adults. Tea tree has broad bactericidal activity. Clinical evidence supports its efficacy in eradicating MRSA, but there are no published data on its role in preventing MRSA colonization. The aim of the study: To determine whether the daily use of 5% tea tree oil compared with standard care (soap and water) had a lower incidence of Methicillin-Resistant Staphylococcus Aureus colonization.

Our previous study demonstrated that Melaleuca alternifolia (tea tree) oil (TTO) had an interesting antiviral activity against Influenza A in MDCK cells. In fact, when we tested TTO and some of its components, we found that TTO had an inhibitory effect on influenza virus replication at doses below the cytotoxic dose; terpinen-4-ol, terpinolene, and alfa-terpineol were the main active components.

- by A. Stivala
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- Medical Microbiology, Influenza virus, Essential Oil, Dogs

Resistance of Sarcoptes scabiei to various topical therapies has been described, but clinical assessment of treatment failure is problematic and in-vitro assays are generally not available. We describe a simple in-vitro analysis used to evaluate the relative efficacy of a range of topical, oral, and herbal treatments available in Australia for the treatment of scabies. S. scabiei var. hominis mites were collected from skin scrapings obtained from 7 crusted scabies patients over a period of 2 years (1997 and 1998). Larvae, nymphal instars, and adult mites were tested within 3 h of collection and continuously exposed to selected commercially available treatment products until death, with the elapsed time recorded. Neem was the only product to show little acaricidal activity. Survival curves indicated that, of the other agents, 5% permethrin (Lyclear) had the slowest killing time, with 35% of mites still alive after 3 h, and 4% still alive after 18-22 h of constant exposure. In contras...

- by Shelley Walton
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- Microbiology, Medical Microbiology, Tea tree oil, Insecticides
- by Katherine Hammer
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- Nursing, Essential Oil, Tea tree oil, Skin

The natural-like assessment of essential oils is a demanding task due to the growing trend toward adulterations. Usually chiral chromatography was used for this purpose due to the capability of assessing stereospecificity which is directly related to the enzymatic pathways of each plant species. On the other hand, the quality of an essential oil involves also the evaluation of its oxidative state, mainly connected with the age and storage conditions. In fact, some modifications in the chemical profile of the oil can occur if not properly preserved. Alterations of the components due to oxidative reactions lead to the formation of peroxides, endoperoxides and epoxides, such as ascaridole and 1,2,4-trihydroxymenthane, usually present in very low amount, formed by the oxidation of terpinen-4-ol and ␣-terpinene, respectively. Therefore, in the present research, the quality of Australian Tea Tree oil (Melaleuca alternifolia (Maiden & Betche) Cheel, Myrtaceae) was investigated by means of a multi heart-cut multidimensional gas chromatographic system coupled to a mass spectrometer detector and by conventional enantio-GC. The MDGC system allowed the complete separation of the compounds of interest transferred from the first column to a second dimension based on a different separation mechanism. The MS detector at the end of the second column provided the identification of the peaks with high similarity values because of their high purities after the multidimensional separation. Method validation was carried out, in order to use this procedure for routine application, monitoring the repeatability of 1D retention times and 2D peak areas, LoD and LoQ. Finally, enantiomeric ratios for chiral compounds were established to support quality data obtained.

- by Danilo Sciarrone
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- Engineering, Technology, Mass Spectrometry, Essential Oil

Nama dan harga obat kurap tradisional di apotik terdekat - - Wa/Tlp/Sms – 081390026844 / 087714496126 = Gejala kurap pada kulit bagian tubuih yang sangat mengganggu sekali bisa Anda coba atasi dengan menggunakan obat kurap alami di apotik resmi seperti berikut ini obat eximtas, bersih darah, pipeca, salep exclear, Lidah buaya, Cuka apel, Tea tree oil, Minyak kelapa, Minyak atau teh sereh, Kunyit, Bawang putih, Grapefruit seed extract. obat kurap paling ampuh, obat kurap sangat manjur, obat kurap terbukti mujarab, obat kurap paling tradisional, obat kadas, obat kudis, ciri ciri kurap akan sembuh, perbedaan kadas dan kurap, obat kurap membandel, obat kurap kering, obat kurap paling manjur sedunia, makanan penyebab kurap, perbedaan kadas dan kurap, obat kurap membandel, bahaya kurap, gambar kurap yang sudah sembuh, obat kurap paling manjur sedunia, kurap di wajah, cara mengobati jamur kulit yang membandel, ciri ciri kurap akan sembuh

- by obat G A T A L selangkangan ampuh
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- Tea tree oil, Kunyit, Bawang Putih, Lidah Buaya

Wound care has come through various trials and errors with primitive cultures applying old age techniques and knowledge. Recent research has shown that the moist environment promotes wound healing than the dry. In the present research, hydrogel membranes were fabricated by esterification of polyvinyl alcohol (PVA) with starch and glutaraldehyde as a cross-linker. The essential oils (clove oil, Oregano oil and tea tree oil) have been incorporated in PVA/Starch based hydrogel membranes. The aim was to achieve optimized anti-bacterial activity and mechanical strength. The anti-bacterial testing was performed using the disc diffusion method. The maximum antibacterial activity for fabricated hydrogels was attained by addition of 0.1 mL clove oil in PVA/Starch hydrogel was 39 ± 0.57 mm and 37 ± 0.29 mm for MRSA and E. coli, respectively. The FTIR results presented the occurrence of –OH group in hydrogel membrane. The SEM results showed around dense nature of membranes with having an antibacterial agent in it or not. Mechanical examination of hydrogel membranes presented suitable tensile strength of 19.36 MPa for 0.1 mL Clove oil. Furthermore, water vapour transmission rate (WVTR) and moisture retention capability (MRC) for 0.1 mL clove oil was 36.22 g/m2h and 95.50%, respectively. The experimental conclusion nominated that fabricated hydrogel articulates good antibacterial, mechanical and physical properties that it could be used in wound dressing applications. The best results were obtained for clove oil using 0.1 mL as an antibacterial agent.

- by Farooq Sher
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- Starch, Hydrogels, Tea tree oil, Antibacterial activity

Are you an acne sufferer and have tried all the skin care products that exist with absolutely no success? Do you often wonder if there is a better alternative like using a natural remedy for acne? If you answered yes to both, we have a... more

- by Usman Raza
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- Tea tree oil
- by Ares Tea
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- Tea tree oil, Light, Immunization, Terpenes

When applied 20 min after injection of histamine into human forearm skin, tea tree oil (TTO) reduces the developing cutaneous vascular response. In this study, the effect of TTO on inflammatory microvascular changes was dissected at the base of an experimental blister on rat skin. 1,8-Cineole, representing 2% of TTO, reduced vascular changes induced by sensory neuropeptides released when the distal portion of a cut sciatic nerve was electrically stimulated. The pre-terminal modulatory effect of 1,8-Cineole was confirmed in tests in sensory-denervated rats. Terpinen-4-ol (approximately 40% TTO) reduced substance P-induced microvascular changes and protein extravasation by a direct nitric oxide-mediated effect on the microvasculature, without sensory nerve involvement. a-Terpineol (3% of TTO) regulated both pre-and post-sensory nerve terminals. In human skin, terpinen-4-ol applied 10 min after histamine injection, but not a-terpineol or 1,8-cineole, regulated the developing wheal and flare suggesting that the histamine-induced responses in humans (at the dose used in this study, 50 lL of 330 lM histamine) are in large part determined by histamine directly affecting the vasculature via post-terminal-mediated events. The underlying strength of these studies is the use of a well-established rat physiologic model to differentiate the mechanism of regulation of microvascular changes by modulatory agents.

- by narmatha narmatha
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- Histamine, Tea tree oil, Nitric oxide, Physiological Models

Nevertheless, the main outcome of the European handwashing method is for the formulation tested to be significantly more active than the SS; both 5% TTO in Tween 80 and the AHSW achieved this both in-vivo and ex-vivo. TTO in Tween 80 and... more

- by Katherine Hammer
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- Hospital Infection, Pharmaceutical Chemistry, Phytotherapy, Tea tree oil

In recent decades, Melaleuca alternifolia has been grown in plantations for the commercial production of tea tree oil extracted from harvested leaf and stem material by steam distillation. Plantations are grown from seedlings raised from seeds collected from wild populations of this endemic Australian species. Considerable variation in morphology and leaf oil composition and yield has been observed and studies have demonstrated genetic and phenotypic heterozygosity between populations.

- by Lyndon Brooks
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- Genetics, Technology, Genetic Diversity, Biological Sciences

Chitosan coatings, containing or not essential oils (bergamot, thyme and tea tree oil), were applied to oranges (cv. Navel Powell). Antifungal effect was evaluated by applying coatings before and after inoculating the fruit with Penicillium italicum CECT 2294 (10 5 spores/mL), preventive and curative treatments, respectively. The effect of coatings on the quality parameters (acidity, pH, soluble solids, juice percentage, weight loss, firmness, color parameters, and respiration rate) was controlled for the different oranges samples throughout the cold storage time. Preventive antimicrobial treatments with coatings containing tea tree oil were the most effective with a reduction of the microbial growth (expressed as the percentage of infected samples) of 50%, as compared to the uncoated samples. The coatings did not lead to any relevant changes in the development of the sample quality parameters throughout the cold storage, except for a slightly reduced loss of both weight and firmness when the coatings contained bergamot oil.

- by Amparo Chiralt
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- Chemical Engineering, Food Science, Chitosan, Food Microbiology

. Tea tree oil, or the essential oil of Melaleuca alternfoolia, is becoming increasingly popular as a naturally occurring antimicrobial agent. T h e antimicrobial activity of eight components of tea tree oil was evaluated using disc diffusion and broth microdilution methods. Attempts were also made to overcome methodological problems encountered with testing compounds which have limited solubility in aqueous media. After assessing media with and without solubilizing agents, the disc diffusion method was used to determine the susceptibility of a range of microorganisms to 1,8-cineole, 1-terpinen-4-ol, p-cymene, linalool, a-terpinene, y-terpinene, a-terpineol and terpinolene. While the disc diffusion method lacked reproducibility, it was considered useful as a procedure for screening for antimicrobial activity. Terpinen-4-01 was active against all the test organisms while p-cymene demonstrated no antimicrobial activity. Linalool and a-terpineol were active against all organisms with the exception of Pseudomonas aeruginosa. Minimum inhibitory and minimum cidal concentrations of each component against Candida albicans, Escherichia coli and Staphylococcus aureus were determined using a broth microdilution method. Modifications to this method overcame solubility and turbidity problems associated with the oil components and allowed the antimicrobial activity of each of the components to be quantified reproducibly. There was reasonable agreement between minimum inhibitory concentrations and zones of inhibition. These results may have significant implications for the future development of tea tree oil as an antimicrobial agent.

- by Christine Carson
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- Pharmacognosy, Medicinal Plants, Applied microbiology, Multidisciplinary
- by Christine Carson
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- Tea tree oil, Reproductive toxicology, Puberty, Gynecomastia

Objective and Design: To evaluate potential antiinflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia. Material and Methods: The ability of tea tree oil to reduce the production in vitro of tumour necrosis factor-a (TNFa), interleukin (IL)-1b, IL-8, IL-10 and prostaglandin E 2 (PGE 2 ) by lipopolysaccharide (LPS)-activated human peripheral blood monocytes was examined. Results: Tea tree oil emulsified by sonication in a glass tube into culture medium containing 10% fetal calf serum (FCS) was toxic for monocytes at a concentration of 0.016% v/v. However, the water soluble components of tea tree oil at concentrations equivalent to 0.125% significantly suppressed LPS-induced production of TNFa, IL-1b and IL-10 (by approximately 50%) and PGE 2 (by approximately 30%) after 40 h. Gas chromatography/ mass spectrometry identified terpinen-4-ol (42%), a-terpineol (3%) and 1,8-cineole (2%, respectively, of tea tree oil) as the water soluble components of tea tree oil. When these components were examined individually, only terpinen-4-ol suppressed the production after 40 h of TNFa, IL-1b, IL-8, IL-10 and PGE 2 by LPS-activated monocytes. Conclusion: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.

- by Christine Carson
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- Mass Spectrometry, Cytokines, Inflammation, Medicinal Plants

The safety of topical application of Australian tea tree Oil (TTO) is confounded by a lack of transdermal penetration data, which adequately informs opinions and recommendations. In this study we applied TTO in its pure form and as a 20% solution in ethanol in vitro to human epidermal membranes from three different donors, mounted in horizontal Franz-type diffusion cells, using normal 'in use' dosing conditions (10 mg/cm 2 ). In addition, we examined the effect of partially occluding the application site on the penetration of TTO components. Our data showed that only a small quantity of TTO components, 1.1-1.9% and 2-4% of the applied amount following application of a 20% TTO solution and pure TTO, respectively, penetrated into or through human epidermis. The largest TTO component penetrating the skin was terpinen-4-ol. Following partial occlusion of the application site, the penetration of terpinen-4-ol increased to approximately 7% of the applied TTO. Measurement of the rate of evaporation of tea tree oil from filter paper (7.4 mg/ cm 2 ) showed that 98% of the oil evaporated in 4 hours. Overall, it is apparent that the penetration of TTO components through human skin is limited.

- by Ian A Southwell
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- Evaluation, Risk assessment, Tea tree oil, In Vitro

The threat posed by drug-resistant pathogens has resulted in the increasing momentum in research and development for effective alternative medications. The antioxidant and antibacterial properties of phytochemical extracts makes them attractive alternative complementary medicines. Therefore, this study evaluated the phytochemical constituents of Melaleuca cajuputi flower and leaf (GF and GL, respectively) extracts and their antioxidant and antibacterial activities. Radical scavenging capacity of the extracts was estimated using 2,2-diphenyl-2-picrylhydrazyl and Fe(2+)-chelating activity. Total antioxidant activity was determined using ferric reducing antioxidant power assay. Well diffusion, minimum inhibitory concentration, and minimum bactericidal concentration assays were used to determine antibacterial activity against eight pathogens, namely Staphylococcus aureus, Escherichia coli, Bacillus cereus, Staphylococcus epidermidis, Salmonella typhimurium, Klebsiella pneumonia, Strepto...

- by Mustafa Kassim
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- Chemistry, Free Radicals, Complementary and Alternative Medicine, Medicine
- by Katherine Hammer and +1
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- Essential Oil, Tea tree oil, Cell line, Anti-inflammatory agents
- by Katherine Hammer
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- Fungi, Tea tree oil, Bacteria, Melaleuca
- by Matheus Baldissera and +1
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- Microbiology, Veterinary Parasitology, Tea tree oil, Experimental parasitology

... of Melaleuca alternifolia (tea tree) oil Xia Liu · Yuangang Zu · Yujie Fu · Liping Yao · ChengboGu · Wei Wang · Thomas EVerth Received: 15 January 2009 / Revised: 26 February 2009 / Accepted: 9 March 2009 / Published online: 25 March... more

- by Thomas Efferth
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- Kinetics, Cell Cycle, Prostate Cancer, Industrial Biotechnology

The monoterpene α-terpinene is used as a fragrance compound and is present in different essential oils. It is one of the components responsible for the antioxidant activity of tea tree oil. α-Terpinene is structurally similar to other monoterpenes, e.g., limonene, known to autoxidize on air exposure and form allergenic compounds. The aim of the present study was to investigate the possible autoxidation of α-terpinene at room temperature. To investigate the sensitization potency of air-exposed α-terpinene and the oxidation products formed, the murine local lymph node assay was used. Chemical analysis showed that α-terpinene degrades rapidly, forming allylic epoxides and p-cymene as the major oxidation products and also hydrogen peroxide. Thus, the oxidation pathway differs compared to that of, e.g., limonene, which forms highly allergenic hydroperoxides as the primary oxidation products on autoxidation. The sensitization potency of α-terpinene was increased after air-exposure. The allylic epoxides and a fraction, in which only an α,β-unsaturated aldehyde could be identified, were shown to be strong sensitizers in the local lymph node assay. Thus, we consider them to be the major contributors to the increased sensitization potency of the autoxidized mixture. We also investigated the presence of α-terpinene and its oxidation products in four different tea tree oil samples of various ages. α-Terpinene and its oxidation products were identified in all of the tea tree oil samples. Thus, from a technical perspective, α-terpinene is a true antioxidant since it autoxidizes rapidly compared with many other compounds, preventing these from degradation. However, as it easily autoxidizes to form allergens, its suitability can be questioned when used in products for topical applications, e.g., in tea tree oil but also in cosmetics and skin care products.

- by Ann-therese Karlberg
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- Analytical Chemistry, Inorganic Chemistry, Organic Chemistry, Antioxidants

An investigation of the in vitro mutagenic potential of a variety of commercially available and widely used tea tree essential oils was performed. The mutagenic potential of tea tree oil (Melaleuca alternifolia) was examined using the Histidine Reversion Assay (Ames Test). One of the major components, the monoterpenoid terpinen-4-ol, was also examined to determine if it demonstrated any mutagenic potential. Salmonella typhimurium (TA102, TA100 and TA98) was utilised in the Ames test. Commercially available tea tree oils were tested. Despite a previous report demonstrating a possible mutagenic trend in a single commercially available tea tree product, no mutagenic effect was determined in any of the brands of tea tree oil on any of the strains of Salmonella examined with or without metabolic activation. The same negative results were obtained for the terpinen-4-ol component examined. There was a clear evidence of toxicity of tea tree oil on all Salmonella strains and also by terpinen-4-ol at higher dose levels. It is suggested that terpinen-4-ol may contribute significantly to the widely reported antibacterial activity of tea tree oil.

- by John Cassella
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- Complementary and Alternative Medicine, United Kingdom, Essential Oil, Tea tree oil

Globally, scabies affects more than 130 million people at any time. In the developed world, outbreaks in health institutions and vulnerable communities result in a significant economic burden. A review of the literature demonstrates the emergence of resistance toward classical scabicidal treatments and the lack of effectiveness of currently available scabicides in reducing the inflammatory skin reactions and pyodermal progression that occurs in predisposed patient cohorts. Tea tree oil (TTO) has demonstrated promising acaricidal effects against scabies mites in vitro and has also been successfully used as an adjuvant topical medication for the treatment of crusted scabies, including cases that did not respond to standard treatments. Emerging acaricide resistance threatens the future usefulness of currently used gold standard treatments (oral ivermectin and topical permethrin) for scabies. The imminent development of new chemical entities is doubtful. The cumulative acaricidal, antib...

- by Pascale Dettwiller
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- Tea tree oil, Scabies, Acaricides, Medical and Health Sciences

Background: Melaleuca alternifolia (tea tree) oil (TTO) applied topically in a dilute (10%) dimethyl sulphoxide (DMSO) formulation exerts a rapid anti-cancer effect after a short treatment protocol. Tumour clearance is associated with skin irritation mediated by neutrophils which quickly and completely resolves upon treatment cessation. Objective: To examine the mechanism of action underlying the anti-cancer activity of TTO. Methods: Immune cell changes in subcutaneous tumour bearing mice in response to topically applied TTO treatments were assessed by flow cytometry and immunohistochemistry. Direct cytotoxicity of TTO on tumour cells in vivo was assessed by transmission electron microscopy. Results: Neutrophils accumulate in the skin following topical 10% TTO/DMSO treatment but are not required for tumour clearance as neutrophil depletion did not abrogate the anti-cancer effect. Topically applied 10% TTO/DMSO, but not neat TTO, induces an accumulation and activation of dendritic cells and an accumulation of T cells. Although topical application of 10% TTO/DMSO appears to activate an immune response, anti-tumour efficacy is mediated by a direct effect on tumour cells in vivo. The direct cytotoxicity of TTO in vivo appears to be associated with TTO penetration. Conclusion: Future studies should focus on enhancing the direct cytotoxicity of TTO by increasing penetration through skin to achieve a higher in situ terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours. ß

- by Pierre Filion
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- Immune response, Cancer, Flow Cytometry, Immunohistochemistry
- by Katherine Hammer
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- Medicinal Plants, Tea tree oil, In Vitro, Escherichia coli

Terbutaline sulfate (TBS) was assayed in biological samples by validated HPTLC method. Densitometric analysis of TBS was carried out at 366 nm on precoated TLC aluminum plates with silica gel 60F 254 as a stationary phase and chloroform-methanol (9.0:1.0, v/v) as a mobile phase. TBS was well resolved at R F 0.34 ± 0.02. In all matrices, the calibration curve appeared linear (r 2 P 0.9943) in the tested range of 100-1000 ng spot À1 with a limit of quantification of 18.35 ng spot À1 . Drug recovery from biological fluids averaged P95.92%. In both matrices, rapid degradation of drug favored and the T 0.5 of drug ranged from 9.92 to 12.41 h at 4°C and

- by Roop Khar and +1
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- Analytical Chemistry, Drug Delivery System, Tea tree oil, Pharmaceutical

- by Annette Pearce and +1
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- Histamine, Tea tree oil, Nitric oxide, Physiological Models

Objective and Design: Whilst the anti-microbial properties of tea tree oil (TTO) are established, the antiinflammatory effects of TTO in human skin remain largely anecdotal and require evaluation. This study examined the effect of topically applied TTO on nickel-induced contact hypersensitivity reactions in human dorsal skin. Treatment: TTO (100 %), a 5 % TTO lotion, a placebo lotion (no TTO), or 100 % macadamia oil were applied at days 3 and 5 after nickel exposure. Methods: The flare area and erythema index were measured on days 3, 5 and 7. The regulatory effects of TTO were also investigated on the proliferative response to nickel or polyclonal mitogens by peripheral blood mononuclear cells from nickel-sensitive and control subjects. Results: TTO (100 %) significantly reduced the flare area and erythema index when compared to the nickel-only sites. With respect to the erythema index, the anti-inflammatory effects were predominantly, but not exclusively, seen in a subgroup of nickel-sensitive subjects with a prolonged development phase of nickel-induced contact hypersensitivity response. The 5 % TTO lotion, the placebo lotion and the 100 % macadamia oil were all without significant effect. TTO significantly inhibited proliferation to nickel but not to non-specific polyclonal mitogens by peripheral blood mononuclear cells from nickel-sensitive subjects. Conclusions: Topical application of 100 % TTO may have therapeutic benefit in nickel-induced contact hypersensitivity in human skin. The mode of action of TTO requires further investigation, but may be an effect on the antigen presenting cells or the antigen presenting process in nickel-induced contact hypersensitivity, as well as vascular changes associated with this response.

- by Annette Pearce and +1
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- Inflammation, Phytotherapy, Tea tree oil, Antigen Presentation

Tea tree oil (TTO) is known for its antimicrobial activity. In this study, we determined whether TTO is effective against Staphylococcus aureus in biofilms and how TTO activity is affected by the S. aureus growth phase. All clinical strains tested were killed by TTO both as planktonic cells and as biofilms. The minimum biofilm eradication concentration was usually two times higher than the minimum bactericidal concentration, yet it was never higher than 1% v/v. The fastest killing of biofilm occurred during the first 15min of contact with TTO and was not influenced by increasing TTO concentration above 1% v/v. Planktonic stationary phase cells exhibited decreased susceptibility to TTO compared with exponential phase cells. The killing rate for stationary phase cells was also less affected by increasing TTO concentration than that for exponential phase cells. These data show that TTO efficiently kills S. aureus in the stationary growth phase and within biofilms and is therefore a promising tool for S. aureus eradication.

- by Jakub M Kwiecinski and +1
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- Biofilms, Tea tree oil, Staphylococcus aureus

A broth micro-dilution method was used to examine the susceptibility of Escherichia coli (n = 110) and Staphylococcus aureus (n = 105) to the essential oil of Melaleuca alternifolia (tea tree oil). The detergent Tween 80 was used successfully to enhance the solubility of tea tree oil in the test medium. The MIC90 of tea tree oil for E. coli was 0.25% while for S. aureus it was 0.50%.

- by Christine Carson
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- Medicinal Plants, Tea tree oil, In Vitro, Escherichia coli

The in vitro activity of Melaleuca alternifolia (tea tree) oil against 161 isolates of oral bacteria from 15 genera was determined. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranged from 0.003 to 2.0% (v/v). MIC 90 values were 1.0% (v/v) for Actinomyces spp., Lactobacillus spp., Streptococcus mitis and Streptococcus sanguis, and 0.1% (v/v) for Prevotella spp. Isolates of Porphyromonas, Prevotella and Veillonella had the lowest MICs and MBCs, and isolates of Streptococcus, Fusobacterium and Lactobacillus had the highest. Time kill studies with Streptococcus mutans and Lactobacillus rhamnosus showed that treatment with !0.5% tea tree oil caused decreases in viability of >3 log colony forming units/ml after only 30 s, and viable organisms were not detected after 5 min. These studies indicate that a range of oral bacteria are susceptible to tea tree oil, suggesting that tea tree oil may be of use in oral healthcare products and in the maintenance of oral hygiene.

- by Katherine Hammer and +1
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- Dentistry, Immunology, Oral Microbiology, Medical Microbiology

This study examined the effect of subinhibitory Melaleuca alternifolia (tea tree) essential oil on the development of antibiotic resistance in Staphylococcus aureus and Escherichia coli. Frequencies of single-step antibiotic-resistant mutants were determined by inoculating bacteria cultured with or without subinhibitory tea tree oil onto agar containing 2 to 8 times the MIC of each antibiotic and with or without tea tree oil. Whereas most differences in resistance frequencies were relatively minor, the combination of kanamycin and tea tree oil yielded approximately 10-fold fewer resistant E. coli mutants than kanamycin alone. The development of multistep antibiotic resistance in the presence of tea tree oil or terpinen-4-ol was examined by culturing S. aureus and E. coli isolates daily with antibiotic alone, antibiotic with tea tree oil, and antibiotic with terpinen-4-ol for 6 days. Median MICs for each antibiotic alone increased 4-to 16-fold by day 6. Subinhibitory tea tree oil or terpinen-4-ol did not greatly alter results, with day 6 median MICs being either the same as or one concentration different from those for antibiotic alone.

- by Katherine Hammer
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- Microbiology, Medical Microbiology, Tea tree oil, Escherichia coli