Isolation and structural determination of polyphenols in Tasmanian eucalypts

Chapter 1 contains a brief review of chemotaxonomy as it relates to the classification of eucalypts. Particular reference is made to a chromatographic survey by Hillis of the low molecular weight polyphenols on eucalypt leaves. That survey provisionally identified a number of polyphenols of known structure but labelled other compounds \Unknowns\" because of the lack of evidence for the identification of their structure. The present work recounts the isolation and examination of the polyphenols in the leaves of three Eucalypt species important to Tasmania: E. delegatensis E. sieberiand E. coccifera. Chapter 2 gives experimental details of the isolation of polyphenols from these species especially the isolation of some of Hillis' unknowns. Chapter 3 describes the experimental techniques by which evidence for the identity of the isolated polyphenols has been gathered. Chapter 4 then discusses the identity of these polyphenols. First to be identified are a number of known polyphenols: gallic gentisic and protocatechuic acids; quercetin myricetin kaempferol; the flavonol glycosides afzelin rutin quercitrin isoquercitrin hyperin and cannabiscitrin; ellagic acid and (+)-catechin. Secondly some of Hillis' unknowns have been isolated and identified. Unknown D has been isolated (1) from E. sieberi and is identified as a mixture of flavanones: pinocembrin alpinetin and a new natural product00-.dimethylpinocembrin; (2) from E. coccifera and is identified as a mixture of flavones: apigenin and two C-methylflavones sideroxylin and 4' 5-dihydroxy-7-methoxy-6- methylflavone the last identified provisionally. Unknown A is identified as 4-0-methylellagic acid a new ellagic acid ether. Unknown B is provisionally identified as a new lignan15-dimethy1-2 6-bis (trihydroxyphenyl) furo - [15-c] furan. Unknown F is tentatively given the structure of a tetrahydroxydibenzofuran-dicarboxylic acid isomer. Throughout the discussion the use of chromatography of mixtures to provide evidence for chemotaxonomy is critically considered."