Essential Oils from Australian Medicinal Plants - An Ethnopharmacological Perspective (BA 25)

Abstract

In this presentation we will review research into the chemistry, bioactivity and possible pharmacological and therapeutic uses of essential oils from native Australian plants used in traditional medicinal practices of Aboriginal peoples with specific mention of recent research in our laboratory. Australia has more endemic flora and an unusually higher proportion of total endemic species than any other region in the world. In this context the endemic genus 'Eremophila' (Myoporaceae), is of particular interest to us owing to its distinctive phytochemical characteristics as well as the high degree of representation in literature detailing indigenous medical ethnobotanical practices. Members of the 'Rutaceae' also yield significant levels of essential oils and are cited as sources of indigenous 'materia medica'. With respect to the putative role of essential oils in achieving the intended therapeutic effects, consideration must be given to traditional useage modalities. This is of particular importance in the therapeutic application of ritualistic smoking. We have attempted to reproduce in the laboratory conditions likely to occur during the production of smoke from smouldering leaves and collected and characterised modified partially pyrolysed oils. Comprehensive investigation into the pharmacology, clinical value and related phytochemistry of native Australian plants with supposed therapeutic activity, has largely been restricted to a small number of species of known commercial value. In particular, efforts have concentrated on steam distilled essential oils of myrtaceaeous genera with reputed antiseptic properties, the most well known and researched examples being those derived from various species of 'Eucalyptus' and 'Melaleuca' and more recently, citral rich oils of 'Backhousia cariodora' ("lemon myrtle"). In these instances, a pre-existing markep, based on popular demand, for over the counter therapeutic and cosmetic products is well established, and this has served to promote and direct research into the therapeutic value of these products. Notwithstanding the successes which have occurred in Australian native medicinal plant research, a vast number of endemic species with rare and sometimes unique phytochemical constituents still remain to be thoroughly examined. This is particularly evident in terms of the bioactivity and pharmacological potential of essential oils and we will be presenting some of our recent research in this regard.