Aspects of the chemistry and origins of terpenes from Australian Myrtaceae

Abstract

A survey to determine the origins of many of the mono- and sesquiterpenoids derived from over 800 species from the Eucalyptus, Leptospermum and Chamelaucium alliances of the family Myrtaceae subfamily Leptospermoideae was undertaken using specially developed small-scale extraction and steam-ditillation techniques (using normal and O-labelled water) coupled with enantioselective gas chromatography. This information was used to indirectly identify potential biosynthetic pathways and accessed how extraction conditions, such as those encountered during a distillation, can alter the oil profiles obtained. Terpenes present in the oils of the Myrtaceae showed a wide range of acid-catalysed solvolysis reactions during distillation and leaf aging thereby altering the biosynthetic history laid down by the plant. Such changes can occur both during leaf aging and distillation. Similarly acid-sensitive sesquiterpenes also undergo acid-solvolysis during leaf aging or distillation. This work identifies the biosynthetic and degradative origins of many of the compounds present in the oils extracted from the Myrtaceae and has found that the composition of an oil, regardless of extractive conditions, should not be considered a true representation of the biosynthetic history of the plant.

Date of Award	1999
Original language	English