Volatile Constituents of Talauma ovata A.St.-Hil. Fruits

Journal of Essential Oil Research: JEOR, Jul/Aug 2005 by Stefanello, Maria Élida A, de Mello-Silva, Renato

Abstract

The headspace volatiles isolated by aeration from unripe fruits of Talauma ovata A.St.-Hil. (Magnoliaceae) were analyzed by capillary GC/MS. Among the 17 compounds identified, the major components were naphthalene (35.1%), cc-bulnesene (10.1%), germacrene D (7.0%), α-guaiene (6.6%) and δ-cadinene (5.4%).

Key Word Index

Talauma ovata, Magnoliaceae, headspace volatiles.

Introduction

The genus Talauma (Magnoliaceae) comprises ca. 50 species, mainly found in Asia (1). There are four species in Brazil, of which T. ovata A.St.-Hil. is the most abundant (2). It is a large tree that produces woody fruits and seeds with sarcotesta very appreciated by birds. Several studies have been carried out on Talauma species (3-9), but only one concerning volatile compounds (10). Phytochemical investigation of T. ovata has been previously reported (11-14). In this paper, we describe for the first time the chemical composition of the headspace volatiles of the fruit.

Experimental

Plant material: Unripe fruits of T. ovata were collected in April 2001 from a cultived plant in the garden of Universidade de S. Paulo. A voucher specimen (Mello-Silva 1820) was deposited in the University of São Paulo Herbarium (SPF).

Headspace isolation: Fresh unripe fruits were put in an aeration chamber and clean air was pumped in it for 4 h. The volatiles were trapped on SuperQ and eluted with diethyl ether. A system blank was run as control (15).

GCJMS analysis: GC/EIMS (70 eV) analysis was performed on a Varian Saturn 2000 GC/MS spectrometer in a split injector mode. A VA-5 capillary column (30 m x 0.25 mm, 0.25 µm film thickness) was operated at 60°C for 5 min, and then programmed from 60°-240°C at 3°C/min, after which it was kept isothermal at 240°C for 15 min. The carrier gas was helium and the injector temperature was 270°C. The headspace components were identified by comparison of their mass spectra and retention indices (relative to n-alkanes) with data in the literature (16-17). The relative percentage of individual components was calculated from the GC peak areas.

Results and Discussion

Seventeen components were identified, representing 93.1% of the total volatiles from unripe fruits of T. ovata (Table I). The headspace contained only hydrocarbons: 4 monoterpenes (12.1%) and 12 sesquiterpenes (45.9%), with naphthalene (35.1%) as the main constituent. Amongtheterpenes, the majorcomponentswere oc-bulnesene (10.1%), germacrene D (7.0%), oc-guaiene (6.6%) and δ-cadinene (5.4%). These results differ markedly from those of T. giôi fruits, that contain safrole and methyl eugenol as the two major components. Limonene and (E)-β-ocimene were found in both species as minor constituents (10). Although uncommon, naphthalene has been found before as the main constituent of the flowers of other Magnoliaceae species (18).

References

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