Eucalyptus punctata

A very important lactone in wines is the so-called wine lactone," 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone 5, which exists in four enantiomeric pairs. This compound was first identified and isolated from the urine of Koala bears (75TL1885, 97JAFC3027), from their diet of the leaves of the Eucalyptus punctata tree. And this shows that the wine lactone belongs to monoterpenoid flavoring ingredients, which have been converted into oxygenated forms. 

Three new monoterpenoid lactones, (28)—(30), isolated from the urine of koala bears fed on Eucalyptus punctata, appear to have arisen from the cyclization of carboxylic acids formed as hydrolysis products of glucuronide conjugates from the metabolism of a- and /3-pinenes.70 Linalool injected into various plant species has been claimed to be converted into a-terpineol and other monoterpenoids.71 However, direct interconversions cannot be inferred from this type of non-radioactive tracer study. The terpenoids alleged to be produced may well be stress metabolites or be formed b secondary processes that perturb the usual pattern of terpenoid formation. 

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