English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Eucalyptus papuana F. Muell. (syn. E . papuana var. aparrerinja Blakely), which grows commonly in central Australia and sparsely in northern Australia and Papua, is known as the "ghost gum" because of the intense whiteness of its trunk, branches, and twigs. This whiteness is due to a powder which comes off when rubbed and is used by the aborig' ' O H ines as a pigment.l Bark scraped from the surface of the trunk yields about 20% by weight of crystalline triterpenes, and it appears to be this material which is responsible for the unusual appearance of the tree. The triterpenes consist largely of (1) morolic acid2 (3-hydroxyolean-18-en-28-oic acid, I) which has previously been isolated only from a saponin found in the heartwood of Mora excelsa Benth.3 and from Agauria salicifolia When the crude triterpenes from E . papuana bark are esterified with diazomethane and the esters chromatographed on alumina as much as 70% of the total is recovered as methyl morolate. The bark is therefore a very convenient source of morolic acid. In chromatographing the methyl esters no methyl morolate acetate was detected in the early fractions from the column, showing that morolic acid acetate is not present in the original triterpene acids. According to Blakely's classification1 E . papuana belongs to the series Corymbosae, and like other members of this group its leaf wax does not contain long-chain /3-diketones of the type found in the leaf waxes of many Eucalyptus specie^.^ It was previously noted6 that the fruits of E . polycarpa (Corymbosae peltatae) are coated with triterpenes; these have not been fully examined but they do not contain any appreciable quantity of morolic acid, and the major component is probably ursolic acid. The isolation of morolic acid from E . papuana and of 11,12-dehydroursolic lactone acetate from several Eucalyptus species7 suggests considerable variation in the triterpenes occurring in this genus. * Manuscript received August 11, 1964. t Division of Organic Chemistry, CSIRO, Chemical Research Laboratories, Melbourne. 1 Blakely, W. F., "A Key to the Eucalypts." 2nd Ed. (Forestry and Timber Bureau: Canberra 1955.) Barton, D. H. R., and Brooks, C. J. W., J. Chern. Soc. 1951, 257. Barton, D. H. R., and Brooks, C. J. W., J. Amer. Chem. Soc., 1950, 72, 3314. Sosa, A. and Dussy, J., C . r . hebd. Slunc. Acud. P r . , 1951, 232, 2249. DUSSY, J. and Sosa, A,, Bull . Soc. Chim. Biol., 1951, 33, 1672, 1697. Horn, D. H. S., Kranz, 2. H., and Lamberton, J. A., Aus t . J. Chem., 1964, 17, 464. Horn, D. H. S., and Lamberton, J. A,, Aus t . J. Chern., 1964, 17, 477.

Morolic acid (3-Hydroxyolean-18-en-28-oic acid) from the bark of Eucalyptus papuana F. Muell