The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.

Tea tree oil components suppress the production of superoxide by monocytes, but not neutrophils, suggesting the potential for selective regulation of cell types by these components during inflammation.

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A series of four isomeric 3,9-dihydroxymegastigma-4,6,7-trienes, 8, has been prepared. The (3S,6R,9S) isomer of 8 proved to be identical to an isomer of this compound tentatively identified as an intermediate in the formation of damascenone from an allene triol. Each of the four isomers, when hydrolyzed independently of each other at pH 3.0 and 25 degrees C, produced product mixtures in which the major product was damascenone (1). Contrary to expectation, 3-hydroxydamascone (5) was not observed in any of the hydrolyses. Consequently, the mechanism of formation of damascenone proposed earlier requires modification. In each hydrolysis, the product mixtures showed the presence of a second isomer of 8, produced by epimerization during hydrolysis. Chiral analysis on a Cyclosil B column revealed that this epimerization was occurring at C(3) in each of the hydrolyses.

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The structure (III) proposed for the hexacyclic alkaloid, himgaline, on the basis of chemical and spectroscopic characterization was confirmed by several partial syntheses of himgaline derivatives from de-N-methylhimbadine (alkaloid G.B. 13). The biogenesis of the Galbulimima alkaloids is discussed.