Chemical and biological characterisation of solvent extracts and essential oils from leaves and fruit of two Australian species of Pittosporum (Pittosporaceae) used in Aboriginal medicinal practice
Journal of ethnopharmacology | 1 Jan 2013
NJ Sadgrove and GL Jones
ETHNOPHARMACOLOGICAL SIGNIFICANCE: Although no known medicinal use for Pittosporum undulatum Vent. (Pittosporaceae) has been recorded, anecdotal evidence suggests that Australian Aboriginal people used P. angustifolium Lodd., G.Lodd. & W.Lodd. topically for eczema, pruritis or to induce lactation in mothers following child-birth and internally for coughs, colds or cramps. AIMS OF THE STUDY: Essential oil composition and bioactivity as well as differential solvent extract antimicrobial activity from P. angustifolium is investigated here firstly, to partially describe the composition of volatiles released in traditional applications of P. angustifolium for colds or as a lactagogue, and secondly to investigate antibacterial activity related to topical applications. Essential oils were also investigated from P. undulatum Vent., firstly to enhance essential oil data produced in previous studies, and secondly as a comparison to P. angustifolium. MATERIALS AND METHODS: Essential oils were hydrodistilled from fruit and leaves of both species using a modified approach to lessen the negative (frothing) effect of saponins. This was achieved by floating pumice or pearlite obsidian over the mixture to crush the suds formed while boiling. Essential oil extracts were analysed using GC-MS, quantified using GC-FID then screened for antimicrobial activity using a micro-titre plate broth dilution assay (MIC). Using dichloromethane, methanol, hexane and H(2)O as solvents, extracts were produced from leaves and fruit of P. angustifolium and screened for antimicrobial activity and qualitative phytochemical character. RESULTS: Although the essential oil from leaves and fruit of P. undulatum demonstrated some component variation, the essential oil from fruits of P. angustifolium had major constituents that strongly varied according to the geographical location of collection, suggesting the existence of at least two chemotypes; one with high abundance of acetic acid decyl ester. This chemotype had high antimicrobial activity whilst the other chemotype had only moderate antimicrobial activity against the three microbial species investigated here. This result may support the occurrence of geographical specificity with regard to ethnopharmacological use. Antimicrobial activity screening of the solvent extracts from P. angustifolium revealed the leaves to be superior to fruit, with water being the most suitable extraction solvent. CONCLUSION: To the best of our knowledge, this study constitutes the first time essential oils, and solvent extracts from the fruits of P. angustifolium, have been examined employing comprehensive chemical and biological analysis. The essential oil composition presented in this paper, includes components with structural similarity as chemosemiotic compounds involved in mother-infant identification, which may have significance with regard to traditional applications as a lactagogue.
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