Antimicrobial activity of the essential oil of Melaleuca alternifolia

Melaleuca alternifolia has been used for medical purposes since Australia was colonized in 1788. Melaleuca alternifolia is commonly called tea tree, although this vernacular name is also given to many other species in the Leptospermum and Melaleuca genera. A small tree, it grows up to 5 m in height, has papery bark and narrow, tapered leaves up to 20 mm in length and flowers in summer. Melaleuca alternifolia is unique to Australia and its natural habitat is a relatively small area around the Clarence and Richmond rivers in the north-east coastal area of New South Wales where the terrain is generally low lying and swampy. The essential oil of M. alternifolia, or tea tree oil, has enjoyed increased medicinal use in recent years. It is a pale yellow viscous liquid with a distinctive pungent odour and is composed of a complex mixture of monoterpenes, 1-terpinen-4-ol, cineole and other hydrocarbons (Pena 1962).