New insights into aromatic medicinal plant use by Australian Aboriginal People

Medicinal plants used by Australian Aboriginal people include many essential oil yielding species. In many cases desired therapeutic effects may be directly mediated by volatiles. In addition, volatile components may act indirectly as carriers of fixed components or even as aromatic markers guiding harvest selection by the designated healer or shaman in species with extensive widespread chemovariation. Here we review our recent research concerning the chemistry and bioactivity of volatile and fixed components of native Australian plants selected on an ethnopharmacological basis, particularly concerning members of the genus Eremophila (Scrophulariaceae). Therapeutic usage modalities often involved ritualistic smoking ceremonies (smudging), or alternatively, topical treatments using lipophilic volatile and fixed components extracted into animal fats. We have developed several techniques for laboratory 'smudging' simulation producing greatly enhanced activity in smoke condensates by comparison with volatiles produced by hydrodistillation alone. Other medicinal plants including Pittosporum spp. (Pittosporaceae), Callitris spp. (Cupressaceae) or Geijera spp. (Rutaceae), were similarly employed and are further explored herein. Comprehensive investigation into the pharmacology, chemistry and clinical value of endemic medicinal Australian plants has hitherto involved only a small number of species of known commercial value including Eucalyptus and Melaleuca species. Informed by an ethnopharmacological approach, our research extends the range of species with potential therapeutic and commercial value and casts light on the importance of traditional custom usage modalities, providing the basis for longer term government and private investment in partnership with Aboriginal communities in an emerging health care industry addressing the imperatives of a globalised market while providing employment opportunities for Aboriginal people in marginalised regional communities.