Leaf Essential Oils of Drummondita calida (Rutaceae: Boronieae), The

Journal of Essential Oil Research: JEOR, Nov/Dec 2006 by Brophy, Joseph J, Goldsack, Robert J, Forster, Paul I

Abstract

The leaf oil of Drummondita calida, isolated in 0.8% yield, was subjected to analysis by GC and GCVMS. The oil was dominated by monoterpenes, with α-pinene (79-86%) being the principal component.

Key Word Index

Drummondita calida, Rutaceae, essential oil composition, α-pinene.

Introduction

The genus Drummondita Harvey is endemic to Australia with seven species (1,2). Orummondita was considered by Wilson (3) to be closely allied to Philotheca Rudge but the two genera differ in the former having glumaceous petals, only the antipetalous stamens with anthers that are dorsifixed, and the ovary and fruit rounded at the apex, whereas the latter has soft petals, stamens that are all fertile and with versatile anthers, and the carpels with a terminal sterile portion that is produced in the fruit as a short beak (3). Drummondita was not included by Wilson (4) in the group of genera he considered most closely allied morphologically to Philotheca (i.e. Crowea Sm., Eriostemon Sm.). A molecular phylogeny for Phebalium Vent, that included the genera Asterolasia F. Muell., Chorilaena Endl., Crowea, Drummondita, Leionema (F. Muell.) Paul G. Wilson, Microcybe Turcz., Muriantha C. A. Gardner, Nematolepis Turcz., and Rhadinothamnus Paul G. Wilson in an analysis, based on nrDNA regions ITS 1 2 found that Drummondita was most closely allied to species of Asterolasia and Munantha (5). Apart from Drummondita calida (F.Muell.) Paul G. Wilson, all of the other species in the genus are restricted to south-western and central Western Australia (2,3).

Drummondita calida has a highly disjunct distribution. In Queensland it is known from three localities (Gregory Range, North Head, Bulleringa National Park), but is also found in the Northern Territory in Kakadu National Park in Arnhem Land. Drummondita calida is a small shrub to 2 m high and in Queensland grows in lancewood thickets dominated by Acacia shirleyi on highly laterized sandstone jump-ups (ridges). The foliage of D. calida is heavily gland-dotted and crushed foliage has a scent reminiscent of 'cough-mixture' (Forster, pers. obs.).

Previous chemical exploration of this species has been limited to two reports by Watennan et al. who isolated spathulenol from the foliage of D. calida (yield not given) collected in the Northern Territory (6) and the flavonols 5-hydrozy auranetin, araneosol, auranetin-5 methyl ether and flindulatin-5 methyl ether, several dihydrocinnamic acid derivatives, and the alkaloids γ-fagarine, evolitrine, pteleine, maasculosidine, skimmianine and 2-quinolone (7). Watennan et al. speculated, on the basis of the presence of flavonols in the two species of Drumondita that they investigated that the genus was closely related to Eriostemon in which flavonols also occur, this being a rare occurrence in the tribe Boronieae.

We present here an investigation of the leaf oils of the only eastern Australian member of the genus Drummondita.

Materials and Methods

Plant material: Leaf material was collected from the following location from two individual plants with a bulk sample from a furtherthree plants. PIF22556: Bulleringa National Park, 80 km NW of Mt Surprise, 17° 31'S, 143° 44'E. The voucher is deposited at the Queensland Herbarium (BRI).

Isolation of oils: The leaf oils were isolated by hydrodistillation with cohobation as previously outlined in (8). Analyses of the oils were carried out by gas chromatography and combined gas chromatography/mass spectrometry. The oil yields quoted below are weight/weight, based on fresh material.

Identification of components: Analytical gas chromatography (GC) was carried out on a Shimadzu GC17 gas chromatograph. Either a SCOT column coated with FFAP or a WCOT DB-Wax [60 m x 0.5 mm, film thickness 1.0 µm] was used. In both cases the column was programmed from 50°0 -225°C at 3°C/min with He at 3.5 mIVmin as carrier gas. GC integrations were performed on a SMAD electronic integrator without the use of correction factors. GC/MS was performed on a VG Quattro mass spectrometer operating at 70 eVionization energy; the column used was DB-Wax [60 m x 0.32 mm, film thickness 0.25 µm] programmed from 35°0 -220°C at 3°C/min, with helium at 35 cm/s as carrier gas. Compounds were identified by their identical GC retention times to known compounds and by comparison of their mass spectra with either known compounds or published spectra (9-13).

Results and Discussion

The leaf oil of D. calida, obtained in 0.8% yield w/w, fresh leaf, was overwhelmingly monoterpenoid in character, with sesquiterpenes representing less than 2% of the oil (Table I). By far, the major component of the oil was a-pinene (79-86%). This was accompanied by small amounts (

The preponderance of α-pinene in the oils is similar to the oils of Australian Philotheca species which have been investigated in this laboratory (Brophy et al., unpublished), though there are differences with some oils in the genera Crowea (14), Phebalium (15), Eriostenwn (16) and Leionema (17), which contain more complicated, and in some cases, aromatic oils.