Transdisciplinary implications from contemporary Australian natural product discoveries: Essential oils and saponins in phytochemistry, ethnopharmacology, and systematics

Abstract

<p>Over the last few years, in the course of natural product isolation, our research has enjoyed a 'cross-pollination' of chemistry, taxonomic botany, microbiology, pharmacology and ethnobotany. This search for interesting new metabolites from Australian members of Cupressaceae, Lamiaceae, Pittosporaceae, Rutaceae and Scrophulariaceae has generated a number of taxonomic queries leading to redeterminations and revision of species complexes (completed or underway). Also, phytochemical and ethnobotanical studies have discovered unique pleasant essential oils and therapeutic products respectively, which are now being focused on in the development of indigenous owned cottage industries that provide new fragrances and a treatment for atopic dermatitis (eczema) that utilises pittangretoside saponins and a traditional therapy of Aboriginal Australians [1]. Specific examples include: the genera <i>Phebalium</i> (Rutaceae) and <i>Prostanthera</i> (Lamiaceae), which yield secondary metabolites (sesquiterpenes and coumarins) correlating with morphological traits in heterogeneous species aggregates requiring revision; the two species <i>Eremophila mitchellii</i> (Scrophulariaceae) and E. sturtii have a history of being incorrectly determined and now we know that previous phytochemical studies [2, 3] reported novel metabolites from the wrong taxa; ethnobotanical and phytochemical studies in <i>Eremophila</i> have demonstrated several new natural products (genifuranal [4], myodesert-1-ene and others not yet named), some of which have significant antimicrobial or insecticidal activities; the isolation of the active components from a crude extract of <i>Callitris glaucophylla</i> (Cupressaceae) which inhibited methicillin resistant <i>Staphylococcus aureus</i> below 50 µg/ml; lastly, the development of a HPLC quantitation protocol for pittangretosides A – I [1] from aqueous extracts from <i>Pittosporum angustifolium</i> (Pittosporaceae) and the progress of negotiations with indigenous intellectual property rights owners.</p>