YOU ARE NOW CONNECTED TO THE TOXLINE (1981 FORWARD, NON-ROYALTY) FILE. ==MELALEUCA OIL== 5 AUTHOR Carson CF AUTHOR Riley TV TITLE Antimicrobial activity of the major components of the essential oil of Melaleuca alternifolia. SOURCE J Appl Bacteriol; VOL 78, ISS 3, 1995, P264-9 ABSTRACT Tea tree oil, or the essential oil of Melaleuca alternifolia, is becoming increasingly popular as a naturally occurring antimicrobial agent. The 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 micro-organisms to 1,8-cineole, 1-terpinen-4-ol, rho-cymene, linalool, alpha-terpinene, gamma-terpinene, alpha-terpineol and terpinolene. While the disc diffusion method lacked reproducibility, it was considered useful as a procedure for screening for antimicrobial activity. Terpinen-4-ol was active against all the test organisms while rho-cymene demonstrated no antimicrobial activity. Linalool and alpha-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. 1 AUTHOR Nenoff P AUTHOR Haustein UF AUTHOR Brandt W TITLE Antifungal activity of the essential oil of Melaleuca alternifolia (tea tree oil) against pathogenic fungi in vitro. SOURCE Skin Pharmacol; VOL 9, ISS 6, 1996, P388-94 ABSTRACT The in vitro antifungal activity of tea oil, the essential oil of Melaleuca alternifolia, has been evaluated against 26 strains of various dermatophyte species, 54 yeasts, among them 32 strains of Candida albicans and other Candida sp. as well as 22 different Malassezia furfur strains. Minimum inhibitory concentrations (MIC) of tea tree oil were measured by agar dilution technique. Tea tree oil was found to be able to inhibit growth of all clinical fungal isolates. For the investigated dermatophytes MIC values from 1,112.5 to 4,450.0 micrograms/ml with a geometric mean of 1,431.5 micrograms/ml were demonstrated. Both C. albicans strains and the other strains belonging to the genus Candida and Trichosporon appeared to be slightly less susceptible to tea tree oil in vitro. However, their MIC values, which varied from 2,225.0 to 4,450.0 micrograms/ml (geometric mean 4,080 micrograms/ml), indicated moderate susceptibility to the essential oil of M. alternifolia. The lipophilic yeast M. furfur seemed to be most susceptible to tea tree oil. MIC values between 556.2 and 4,450.0 micrograms/ml (geometric mean 1,261.5 micrograms/ml) were found against the tested M. furfur strains. However, when calculated as percentage tea tree oil of the agar, the above-mentioned concentrations correspond to 0.5-0.44% tea tree oil content. These values are far below the usual relatively high therapeutic concentrations of the agent; approximately 5-10% solution or even the concentrated essential oil are used for external treatment. In comparison with tea tree oil, in vitro susceptibility against miconazole, an established topical antifungal, was tested. As expected, very low MIC values for miconazole were found for dermatophytes (geometric mean 0.2 microgram/ml), yeasts (geometric mean 1.0 microgram/ml), and M. furfur (geometric mean 2.34 micrograms/ml). It is suggested that the in vivo effect of tea tree oil ointment in the therapy of fungal infections of the skin and mucous membranes as well as in the treatment of dandruff, a mild form of seborrheic dermatitis, may be at least partly due to an antifungal activity of tea tree oil. 8 AUTHOR Villar D AUTHOR Knight MJ AUTHOR Hansen SR AUTHOR Buck WB TITLE Toxicity of melaleuca oil and related essential oils applied topically on dogs and cats. SOURCE Vet Hum Toxicol; VOL 36, ISS 2, 1994, P139-42 (REF: 30) ABSTRACT Cases of melaleuca oil toxicosis have been reported by veterinarians to the National Animal Poison Control Center when the oil was applied dermally to dogs and cats. In most cases, the oil was used to treat dermatologic conditions at inappropriate high doses. The typical signs observed were depression, weakness, incoordination and muscle tremors. The active ingredients of commercial melaleuca oil are predominantly cyclic terpenes. Treatment of clinical signs and supportive care has been sufficient to achieve recovery without sequelae within 2-3 d. 12 AUTHOR JACOBS MR AUTHOR HORNFELDT CS TITLE Melaleuca oil poisoning. SOURCE JOURNAL OF TOXICOLOGY CLINICAL TOXICOLOGY; 32 (4). 1994. 461-464. ABSTRACT BIOSIS COPYRIGHT: BIOL ABS. A 23-month-old boy became confused and was unable to walk thirty minutes after ingesting less than 10 mL of T36-C7, a commercial product containing 100% melaleuca oil. The child was referred to a nearby hospital. His condition improved and he was asymptomatic within 5 hours of ingestion. He was discharged to home the following day. Melaleuca oil, extracted from the Melaleuca alternifolia, contains 50-60% terpenes and related alcohols. Clinical experience with products containing melaleuca oil is limited. This case report suggests that ingestion of a modest amount of a concentrated form of this oil may produce signs of toxicity.