Natural products isolation studies of Australian native plants

<p dir="ltr">This thesis reports natural products isolation studies on a range of Australian native plant species. Pressurised hot water extraction (PHWE) utilising an unmodified household espresso machine was employed to facilitate the study of two <i>Nothofagus</i> species, sixteen fern species and three <i>Myoporum </i>species. <br>A review of secondary metabolites present in more than 100 fern species consumed in several countries in Asia was undertaken. <i>Diplazium esculentum</i> and <i>Pteridium</i> <i>aquillinum</i> are most widely consumed. A broad range of secondary metabolites have been isolated from these edible ferns. Several edible ferns have medicinal properties and most feature in traditional medicines. <br>Phytochemical screening of 16 native Australian fern species resulted in the isolation of 14 different natural products from 12 species. This included α- and γ-lactones, flavonoid glycosides, a dihydrobenzofuran neolignan, in addition to hydroxycinnamate/caffeic acid esters.<br>Natural products isolation studies of <i>Nothofagus gunnii</i> and <i>N. cunninghamii </i>were undertaken. The leaves of <i>N. gunnii</i> resulted in the isolation of stilbenes, flavonoids, sesquiterpenoids and chalcones. Four flavonoids were isolated from the leaves of N. cunninghamii. These natural products isolated were consistent with the respective subgenera <i>Fucuspora</i> and <i>Lozophonia</i>. <br>Natural products isolation study was undertaken of <i>Myoporum insulare</i>, <i>M.</i> <i>parvifolium</i> and <i>M. montanum</i>. As a result, two previously unreported furanosesquiterpenes and three γ-lactone-containing analogues, along with nine known furanosesquiterpenes and five other natural products were isolated. Overall, three distinct types of furanosesquiterpene structures were present in these three <i>Myoporum </i>species. <br>Four novel compounds, two prenylated flavonoids bearing unusual malonic acid groups, a prenylated flavonoid and an ent-labdane diterpenoid were isolated from <i>Dodonaea filiformis </i>and flowers of <i>D. viscosa</i> ssp. <i>spatulata</i>. An additional twelve known clerodane diterpenoids, ent-labdane diterpenoids and flavonoids were isolated. This study also revealed that the structure assigned to a compound previously isolated from <i>D. viscosa</i> was incorrect and that this molecule was actually a prenylated flavonoid containing a malonic acid moiety.</p>