Chemical Constituents of the Bark Oil of Goniothalamus macrophyllus Hook. f. from Malaysia

Journal of Essential Oil Research: JEOR, Mar/Apr 2005 by Jantan, Ibrahim bin, Ahmad, Fasihuddin bin, Din, Laily bin

Abstract

The bark oils of Goniothalamus macrophyllus Hook, f., obtained from two different sites, were investigated by capillary GC and GC/MS. The oils were found to possess little differences in the chemical composition but considerable variation in the levels of the individual components. The oils were rich in monoterpenoids (91.8-94.0%), with terpinen-4-ol at 38.8% and 42.7%, respectively, as the dominant component. The major differences between the oils were the presence of appreciable amounts of 1,8-cineole (18.1%), geranyl acetate (11.1%) andgeraniol (9.7%) in one sample and relatively low amounts of these compounds in the other sample. However, the latter sample contained significantly higher concentrations of (Z)-β-ocimene (25.4%) and α-terpineol (10.0%).

Keyword Index

Goniothalamus macrophyllus, Annonaceae, essential oil composition, terpinen-4-ol, 1,8-cineole, geranyl acetate, (Z)-β-ocimene, β-terpineol.

Introduction

Goniothalamus macrophyllus Hook. f. belonging to the family Annonaceae is a bush or tree commonly found in Malaysia especially in the peninsular (1). The wood is aromatic but has no commercial use. Decoctions of the roots and leaves are used in traditional medicine to treat colds, fever, malaria, cholera and are administered after childbirth. The root has been reported to be used in attempts to procure abortion (1,2).

Phytochemical and biological screenings of several Goniothalamus species have resulted in the isolation of a large number of cytotoxic compounds, notably styryl-lactone derivatives, acetogenins, aporphine alkaloids and related alkaloids (3-8). Some of these compounds have also been found to possess strong antimicrobial, larvicidal and antimalarial activities (9-11 ). E mbryotoxic compounds namely goniothalamin and gomothalamin oxide, have been isolated from G. macrophyllus(12). However, no systematic chemical study on the essential oil of G. macnyhyttus has yet been carried out. The present paper reports on the chemical composition of the bark oils of G. macrophyllus collected from two different sites in Malaysia.

Experimental

Plant material: The fresh bark samples of Goniothalamus nuicrophyllus were collected from the following sites in Malaysia: Sample 1 from Fraser Hill, Pahang, September 2000; Sample 2 from Merapok, Lawas, Sarawak, July, 2000. Voucher specimens of sample 1 and sample 2 were deposited at the Herbarium of Universiti Kebangsaan Malaysia and the Herbarium of Universiti Malaysia Sarawak, respectively.

Oil isolation: The plant materials were subjected to water distillation in a Clevenger-type apparatus for 8 h. The oily layers obtained we re separated and dried over anhydrous magnesium sulfate. The yields were averaged over three experiments and calculated based on dry weight of the plant materials.

Analysis of the oils: The oils were analyzed on a Shimadzu GC 14A chromatograph equipped with an FID detector using a DB-5 capillary column (25 m x 0.25 mm, 0.25 µm film thickness). The operation parameters were: nitrogen as carrier gas at 50 cm/s, injector and detector temperatures were maintained at 250°C. The column was programmed initially at 75°C for 10 min, then at 3°C/min to 210°C and held for 1 min. The oils were also examined using a DB-I stationary phase column (25 m x 0.25 mm, 0.25 µm film thickness) programmed from 60°C for 10 min, then at 3°C/min to 180°C and held for 10 min. Peak areas and retention times were measured by electronic integration. The relative amounts of individual components are based on peak areas obtained, without FID response factor correction. Temperature program linear retention indices of the compounds were also determined relative to n-alkanes.

The oils were also analyzed by GC/M S with a Hewlett Packard GC-MSD 5890 series 2 mass spectrometer (70 eV direct inlet) on a SE-30 column (25 m x 0.25 mm, 0.25 µm film thickness) initially at 60°C for 10 min, then at 3°C/min to 180°C for 10 min with helium as carrier gas. The constituents were identified by comparison of their retention indices with literature values and their mass spectral data with those from the Wiley mass spectral database, and in some cases by co-chromatography on the different columns with authentic samples (13-15).

Results and Discussion

Water distillation of the fresh barks of Goniothalamus macrophyllus gave the followingyields (calculated based on dry weight basis): Sample 1 (150g, 0.8%); Sample 2 (150g, 0.7%). The composition of the bark oils collected from the two sites showed little qualitative differences but there was a marked variation in the quantity of some components (Table I). The gas chromatograms of the oils revealed the presence of at least 54 components. Forty-six compounds had been identified in the oil representing more than 96% of the oil. The unidentified compounds showed mass fragmentation patterns indicative of sesquiterpene hydrocarbons and their oxygenated derivatives. The oils were made up predominantly of monoterpenoids, constituting 91.8% and 94.0% of the oils, respectively. The characteristic spicy-herbaceous odor of the oil was contributed chiefly by the main components terpinen-4-ol, 1,8-cineole, (Z)-β-ocimene, α-terpineol, geraniol and geranyl acetate.