Tea Tree Oils from Australia and New Zealand

Both Australia and New Zealand have indigenous tea trees in the family Myrtaceae, which were reputedly used for brewing tea by Captain Cook. There is, however, no resemblance between real tea Camellia sinensis, Camelliaceae, and the taste or odor of these species. The Australian tea tree oil from Melaleuca alternifolia and other Melaleuca species has strong antimicrobial potential (see Lis-Balchin et al., 2000, for a review and references). 

There is scant evidence that Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides) have such potential, but as the essential oils are said to have remarkable powers of healing, based on folk medicinal usage. These oils are being used by some aromatherapists, although there have been no safety or toxicological evaluations performed on them. 

Many of the folk-medicinal uses of the New Zealand tea tree oils are related to both species, e.g., the leaves of Manuka and Kanuka were used as vapor baths for colds an infusion was very astringent and various uses were found for concoctions including urinary complaints and as a febrifuge. Kanuka was applied to scalds and bums, used to stop coughing, and as a sedative it was also used against dysentery. The decoction of boiled leaves and bark was used to treat stiff backs, etc. Seed capsules were boiled to yield a decoction to apply externally to treat inflammation or to drink for diarrhea the capsules or leaves were also chewed for dysentery. The water from boiled bark was used for treating inflamed breasts and also to treat mouth, throat, and eye problems. 

The antibacterial effect of honey derived from Kanuka and Manuka blossom against Staphylococcus aureus was shown and, more recently, Manuka honey was shown to be active against Helicobacter pylori. Leptospermum scoparium contains leptospermone, which has antihelminthic properties and is closely related to compounds having similar properties in male ferns leptospermone has insecticidal properties, and is similar in structure to the insecticide valone. 

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