Volatile Leaf Oils of Some South-Western and Southern Australian Species of the Genus Eucalyptus. Part VII. Subgenus Symphyomyrtus, Section Exsertaria
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FLAVOUR AND FRAGRANCE JOURNAL, VOL. 11,35-41(1996) Volatile Leaf Oils of some South-western and Southern Australian Species of the Genus Eucalyptus. Part VII. Subgenus Symphyomyrtus, Section Exsertaria C. M. Bignell and P. J. Dunlop Department of Chemistry, University of Adelaide, South Australia, SM5, Australia J. J. Brophy Department of Organic Chemistry, University of New South Wales, Sydney, NSW, 20S2, Australia J. F. Jackson Department of Viticulture, Oenology and Horticulture, Waite Agricultural Research Institute, University of Adelaide, South Australia, 5005, Australia The volatile leaf oils of Eucalyptus seeana Maiden, E. bancrofrii (Maiden) Maiden, E. parramattensis C. Hall, E. amplifolia Naudin, E. tereticornis J. Smith, E. blakelyi Maiden, E. dealbata A. Cunn. ex. Schauer, E. dwyeri Maiden & Blakely, E. vicina L. A. S. Johnson & K. D. Hill, E. flindersii Boomsma, E. camaldulensis Dehnh. var camaldulensis, E. camaldulensis Dehnh. var. obtusa Blakely, E. rudis Endl., E. exserta F. Muell. and E. gillenii Ewart & L. R. Kerr, isolated by vacuum distillation, were analysed by GC-MS. Most species contained a-pinene (1.5-14%), 1,&cineole (0-81%), p-cymene (O.6-28%) and aromadendrene/terpinen-4-01 (0.6-24%) as principal leaf oil components. KEY WORDS Eucalyptus seeana Maiden; Eucalyptus bancrofrii (Maiden) Maiden; Eucalyptus parramattensis C. Hall; Eucalyptus amplifolia Naudin; Eucalyptus tereticornis J. Smith; Eucalyptus blakelyi Maiden; Eucalyptus dealbata A. Cunn. ex. Schauer; Eucalyptus dwyeri Maiden & Blakely; Eucalyptus vicina L. A. S. Johnson & K. D. Hill; Eucalyptusflindersii Boomsma; Eucalyptus camaldulensis Dehnh. var. camaldulensis; Eucalyptus camaldulensis Dehnh. var. obtusa Blakely; Eucalyptus rudis Endl.; Eucalyptus exserta F. Muell.; Eucalyptus gillenii Ewart & L. R. Kerr; Myrtaceae; leaf essential oil composition; torquatone; mono-and sesquiterpenoids; GC-MS INTRODUCTION vicina L. A. S. Johnson & K. D. Hill, E. dealbata A. Cunn. ex. Schauer, E. amplijolia Naudin and Continuing our investigation of the volatile leaf E. parramattensis C. Hall, occur mainly in New oils of indigenous Australian eucalypts'-6 we South Wales while four others, E. blakelyi have examined the oils of 15 of the species Maiden, E. rereticornis J. Smith, E. bancroftii belonging to section Exsertaria of the Eucalyptus (Maiden) Maiden and E. seeana Maiden, occur in subgenus Symphyomyrtus (see system M. I. H. New South Wales and Queensland. Finally two Brooker and D. A. Kleinig).' Locations of indi- species, E. camaldulensis Dehnh. var. camaldu- vidual species are listed in Table 1. lensis and E. camaldulensis Dehnh. var. obtusa Two of these, E. flindersii Boomsma and E. Blakely, are widespread along the water courses gillenii Ewart & L. R. Kerr, are native to South in most parts of eastern (var. camaldulensis), Australia, while E. rudis Endl. occurs only in central and Western Australia (var. obrusa). South-westem Australia with E. exserra F. Muell. More detailed descriptions of the occurrence of being a native of South-eastem Queensland. Five these eucalypts have been given elsewhere.7*8 other species, E. dwyeri Maiden & Blakely, E. To our knowledge the oils of E. see an^,^ E. CCC 0882-5734/%/010035-U7 Received 21 February I995 0 1996 by John Wiley & Sons, Ltd. Accepted 18 April 1995 36 C. M. BIGNELL ETAL. Table 1. Oil yields from Eucalyprus species, Section Exsertaria" Oil yield Species and locality wt% (dry weight) Eucalyptus seeana Maiden 0.37 Waite arboretum, South Australia E. bancroftii (Maiden) Maiden 0.92 Waite arboretum, South Australia E. parramattensis C. Hall 1.02 Waite arboretum, South Australia E. amplifolia Naudin 0.39 Waite arboretum, South Australia E. tereticornis J. Smith 0.62 Waite arboretum, South Australia E. blakelyi Maiden 1.13 Black Mountain, Canberra E dealbura A. Cunn. ex. Schauer 1.77 Wittunga arboretum, South Australia E. dwyeri Maiden & Blakely 2.34 Waite arboretum, South Australia E. vicina L.A.S. Johnson & K.D. Hill 1.19 Manara Hill. New South Wales E. flindersii Boomsma 0.78 Waite arboretum, South Australia E. camaldulensis Dehnh. var. camaldulensis 0.30 Waite arboretum, South Australia E. camaldulensis Dehnh. var. obtusa Blakely 1.50 Ormiston Gorge, Northern Territory E. rudis Endl. 0.73 Waite arboretum, South Australia E. exserra F. Muell. 0.35 Waite arboretum, South Australia E. gillenii Ewert & L.R. Kerr 0.64 Waite arboretum, South Australia The specimens for these species were authenticated by Mr M.I.H. Brooker, Australian National Herbarium or Dean Nicolle, Valley Orchids, South Australia. bancroftii,' E. parramattensis,' E. am lijolia, lo The dry powder was then vacuum distilled so that E. tereticornis,'* '-' E. blakelyi, g-14 E. the leaf oil condensed on to a gold-plated copper dealbata,9"3 E. dwyeri,I2 E. camaldulensis var. rod maintained at approximately -75°C. camaldulen~is,'~~'~*'~E. camaldulensis var. Complete details of this procedure have been obtusa,'* E. rudis' and E. e~serta'"~"~have been published previously.l7 All oils obtained were investigated previously. colourless to pale yellow liquids which floated on water. Table 1 lists the oil yields (wt%, dry weight) for the fifteen species studied. EXPERIMENTAL Analytical gas chromatography (GC) was car- ried out on a Shimadzu GC6 AMP gas chromato- For each species samples of clean, mature leaves graph. A glass SCOT column of SPlOOO (85 m X were picked from over ten positions on a single 0.5 mm) which was programmed from 65°C to tree and, after drying and freezing with liquid 225°C at 3"C/min was used with helium carrier nitrogen, were reduced to a fine powder using a gas. The GC integrations of the peaks were per- stainless steel Waring blender (Model no. SS110). formed on a SMAD electronic integrator. GC VOLATILE LEAF OILS OF EUCALYPTUS SPECIES 37 analyses were also performed with a HP5890 cineole and 997 s for torquatone. Torquatone was Series I1 unit operated in conjunction with a found to be present in almost all oil samples; HP3396 Series I1 integrator. The 'on-column' in- when this was not the case a sufficient amount was jection technique was used with a SGE BP20 added to the oil solution to obtain that reference capillary column of (25 m X 0.33 mm i.d., and point. (A sample of pure torquatone was kindly film thickness 0.5 pm). The carrier gas was hydro- supplied by Dr Emilio Ghisalberti, Chemistry gen with an inlet pressure of 25 kPa: the flow rate Department, University of Western Australia.) was 2.0 cm3/min. The oven was programmed to The normalized retention times of the column rise from 80°C to 220°C at 5"/min, and the inlet were identified with oil components analysed pre- temperature set to 83°C and increased at the same viously by GC-MS for over 75 eucalyptus species: rate as the column. Using these conditions and a many of these results have been published.'-6 2.0 p1 sample of a 0.2% solution of oil in purified All GC analyses were performed in duplicate dry ether essentially all the components were re- and the retention times and percentage composi- corded by the integrator in 31 minutes. GC-MS tions of each component averaged. Duplicate was performed on a VG Quattro mass spec- times were discarded if they differed by more trometer operating at 70 eV ionization energy. than one second. Components which contributed The GC column in this case was a DB-Wax (60 less than 0.06% to the final analyses were not m X 0.32 mm). Compounds were identified by considered (an arbitrary but practical decision). comparison of their GC retention indices to Figure 1 is a typical chromatogram (average areas known compounds and by comparison of their (log scale) versus normalized times) obtained mass spectra either with known compounds or from the oil of an E. camaldulensis var. camaldu- published lensis tree estimated to be over 100 years in age. Only three of the species (E. parrumaftensis,E. rereticornis and E. dwyeri) were analysed with GC-MS. The oil components of the rest were RESULTS AND DISCUSSION identified using normalized retention times. For this purpose the column was calibrated by assum- Freshly isolated oils obtained by vacuum distilla- ing times for three markers, l,&cineole, octa- tion of powdered leaves from single trees were decane (OD added to the ether) and torquatone. analysed by GC-MS and GC. It was necessary to The raw retention times were first normalized to powder the leaves to rupture the oil glands. If 525 s for OD, and times before and after OD unpowdered leaves are used absolutely no oil adjusted by assuming linearity and using 99 s for is obtained. It appears that the membranes 50 I I I I I I] 5c I 0.5 0.05 <v) 0.005 Y 50 K d5 W 0.5 - $ 0.05 - a 300.0 350.0 400.0 450.0 500.0 < 501 1 I 1 I I I( 51 i 0.5 0.05 I I I I I 5- - 0.5 - 0.05 - NORMALISED RETENTION TIMES Fig. 1 Normalized chromatogram (see text) for Eucalyptus curnaldulensis Dehnh. var. camaldulensis: areas (log scale) versus normalized retention times in seconds Table 2. Compounds identified and their percentage occurrence (10.05%) in the leaf oils of Eucalyprus species, Section Exsertaria" mW .-e -u u 2 2 -,-A5 $-.9 Ek5 5X P No. Compound di) d 3.99 14.72 0.59 4.76 8.01 1 a-Pinene 4.08 3.98 1.44 4.61 1.51 1.78 2.19 8.74 1.78 12.10 - - 2 a-Fenchene - - - - - - 0.06 - - - - 0.08 - 3 Camphene - 0.10 - - - - - 0.11 - - - 0.08 - 0.22 0.07 4 p-Pinene 0.08 - 0.08 0.16 0.12 0.07 - 3.54 0.20 0.53 0.15 0.21 - 0.77 6.29 5 Sabinene - - - - 0.83 - - - - - - - 0.11 - 6 Myrcene 0.20 - - 0.27 0.28 - - 0.08 - 0.20 0.06 - 0.08 - - - - - - - - 3.40 - 7 a-Phellandrene