Composition of the leaf oils of the Australian and Lord Howe Island species of Zanthoxylum (Rutaceae)

The leaf oils of the seven Australian and Lord Howe Island species of Zanth oxylum have been investigated by GC and GC/MS. Apart from Z. ovalfolium, wh ich had an oil yield of 1.1-1.9%, the remaining species had yields in the r ange trace-0.1%. The oil of Z. brachyacanthum was found to be rich in alpha -pinene (46.0%), beta-caryophyllene (14.0%) and bicyclogermacrene (12.5%). Z. nitidum, which was sesquiterpenoid in nature, contained beta-caryophylle ne (11.0%) and alpha-humulene (7.2%) as principal components along with 2-t ridecanone (7.7%) and an unidentified 2-alkanone (10.7%). One chemotype of Z. ovalifolium contained alpha-pinene (31.6%) and myrcene (19.8%) as major components, while the other was rich in alpha-humulene (11.3%) and spathule nol (14.8%). In 2. parviflorum, the principal components were alpha-pinene (11.9%), alpha-elemene (8.6%), beta-caryophyllene (23.4%) and caryophyllene oxide (11.7%). In Z. pinnatum from Lord Howe Island, 2-undecanone (54.3%) and 2-tridecanone (31.7%) were by far the major constituents. Unlike Indian oils from Z. rhetsa, the Australian material was sesquiterpenoid in nature with beta-caryophyllene (27.5%) and germacrene D (18.4%) being major compo nents. Z. veneficum oil was also sesquiterpenic in nature with beta-caryoph yllene (36.3%), germacrene D (10.9%) and bicyclogermacrene (25.4%) being th e principal components.