Essential Oils from the Leaves of Some Queensland Annonaceae

Journal of Essential Oil Research: JEOR, Mar/Apr 2004 by Brophy, Joseph, Goldsack, Robert, Forster, Paul

Isolation of oils: The leaf oils were obtained by steam distillation with cohobation as outlined in Brophy et al. (31). Analyses of the oils were by gas chromatography and combined gas chromatography/mass spectrometry.

Identification of components: Analytical gas chrornatography (GLC) was carried out on a Shimadzu GC6 AMP gas cliromatograph. A SCOT column of SP100 (85 m x 0.5 min), programmed from 40�-225�C at 3�C/min or a WCOT column of DB-Wax (60 m x 0.53 mm, 1.0 �m film thickness] programmed from 50�-220�C at 3�C/min were used with helium carrier gas. GLC integrations were performed on a SMAD electronic integrator. GC/MS was performed on a VG Quattro mass spectrometer operating at 70 eV ionisation energy. In this case, the column used was DB-Wax (60 m x 0.32 mm, 0.25 �m) programmed from 35�-220�C at 3�C/min, with helium as carrier gas. Compounds were identified by their identical GLC retention times to known compounds and by comparison of their mass spectra with either known compounds or published spectra (32-35).

Results and Discussion

With the exception of M. zippeliana and C. odorata, which contained significant amounts of monoterpenes, the other three species produced oils that were overwhelmingly sesquiterpenic in character. Full details of the compounds identified in the oil of all the species, with the exception of Artabotrys sp. (Claudie River B.Gray 3240), in which the majority of the compounds were not identified, are given in Takle I.

Uvaria concava produced an oil (in 0.1% yield based on fresh leaves) that was almost entirely sesquiterpenoid in character. The principal components were spathulenol (6-33%) and caryophyllene oxide (1-28%). These were accompanied by smaller amounts of the hydrocarbons [alpha]-copaene (2-4%), germacrene D (t-4%), bicyclogermacrene (t-3%), [delta]-cadinene (1-4%) and elemol (0.5%). The only monoterpenoids detected in anything more than trace quantities were pinocarvonc (0.2%), linalool (1.5%) and trans-pinocarveol (0.2%).

The leaf oil obtained from U. rufa was dominated by [alpha]-humulene (50%). There were lesser amounts of bicyclogermacrene (9.4%), [beta]-caryophyllene (3.8%), gerniacrene D (1.6%) and spathulenol (2.8%). Monoterpenes were not prevalent, with the principal components being sabinene (1.7%), myrcene (2.2%), limonene (2.1%) and [beta]-phellandrene (3.0%). Also detected in the oil were benzyl benzoatc (0.7%), benzyl salicylate (0.1%) and a suspected methyl thiophenol (2.9%). The oil yield was 0.01-0.05%, based on fresh leaves.

In common with the leaf oils of U. narum (27) and U. chamae (23,24), those of the Australian species of Uvaria were sesquiterpenoid but did not contain significant amounts of benzoic acid and benzyl benzoate, which have been reported from the other extra-Australian species.

Like the two North Queensland species of Uvaria, C. micranthum also produced an oil that was sesquiterpenoid in character. The oil yield was 0.3%, based on fresh leaves. The principal components were, once again, spathulenol (10.7%) and caryophyllene oxide (25.8%). Other significant sesquiterpenes were aromadendrene (5.6%), [alpha]-muurolene (2.0%), [gamma]-cadinene (1.3%), globulol (5.8%) and viridiflorol (2.6%). Benzyl benzoate was present at 3.6% amount.