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Alternifolia

Alternifolia

Alternifolia

Melaleuca alternifolia is a small tree that can grow to about 7 m (20 ft) with a bushy crown and whitish, papery bark. The leaves are arranged alternately, sometimes scattered or whorled. The leaves are smooth, soft, linear in shape, 10–35 mm (0.4–1 in) long and 1 mm (0.04 in) wide. They are also rich in oil with the glands prominent. Flowers occur in white or cream-colored masses of spikes 3–5 cm (1–2 in) long over a short period, mostly spring to early summer, and give the tree an appearance of looking fluffy. The small woody, cup-shaped fruit, 2–3 mm (0.08–0.1 in) in diameter are scattered alongthe branches.32. Carson, C. F., K. A. Hammer, and T. V. Riley. 1995. Broth micro-dilution method for determining the susceptibility of Escherichia coli and Staphylococcus aureus to the essential oil of Melaleuca alternifolia (tea tree oil). Microbios 82:181-185. [PubMed] [Google Scholar].

Alternifolia

Many complementary and alternative medicines have enjoyed increased popularity in recent decades. Efforts to validate their use have seen their putative therapeutic properties come under increasing scrutiny in vitro and, in some cases, in vivo. One such product is tea tree oil (TTO), the volatile essential oil derived mainly from the Australian native plant Melaleuca alternifolia. Employed largely for its antimicrobial properties, TTO is incorporated as the active ingredient in many topical formulations used to treat cutaneous infections. It is widely available over the counter in Australia, Europe, and North America and is marketed as a remedy for various ailments.

Given the scope for batch-to-batch variation, it is fortunate that the composition of oil sold as TTO is regulated by an international standard for “Oil of Melaleuca—terpinen-4-ol type,” which sets maxima and/or minima for 14 components of the oil (89) (Table ​(Table1).1). Notably, the standard does not stipulate the species of Melaleuca from which the TTO must be sourced. Instead, it sets out physical and chemical criteria for the desired chemotype. Six varieties, or chemotypes, of M. alternifolia have been described, each producing oil with a distinct chemical composition. These include a terpinen-4-ol chemotype, a terpinolene chemotype, and four 1,8-cineole chemotypes (83). The terpinen-4-ol chemotype typically contains levels of terpinen-4-ol of between 30 to 40% (83) and is the chemotype used in commercial TTO production. Despite the inherent variability of commercial TTO, no obvious differences in its bioactivity either in vitro or in vivo have been noted so far. The suggestion that oil from a particular M. alternifolia clone possesses enhanced microbicidal activity has been made (106), but the evidence is not compelling. (Source: www.ncbi.nlm.nih.gov)

 

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