VOLATILE COMPOUNDS OF LITHRAEA CAUSTICA (LITRE)
DETERMINATED BY SOLID PHASE MICRO-EXTRACTION (SPME).

JUAN A. GARBARINO^1*, GIUSEPPE SALVATORE², MARISA PIVANOVO¹,
MARÍA CRISTINA CHAMY¹, MARCELLO NICOLETTI³ AND ALFREDO DE IOANNES⁴.

¹ Departamento de Química, Universidad Técnica Federico Santa María,
Casilla 110-V, Valparaíso, Chile. E-mail: juan.garbarino@qui.utfsm.cl
² Laboratorio di Tossicologia Comparata ed Ecotossicologia,
Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome, Italy. E-mail: pino@iss.it
³ Dipto. Biologia Vegetale, Università "La Sapienza",
Ple. Aldo Moro, 5, Rome, Italy. E-mail: marcello.nicoletti@uniroma1.it
⁴Facultad de Ciencias Biológicas, P. Universidad Católica,
Av. Bernardo O’Higgins 340, Santiago. E-mail: aioannes@biosonda.com

(Received: May 16, 2002 - Accepted: August 9, 2002)

ABSTRACT

The head space of the aerial parts of Lithraea caustica was analyzed by Solid Phase Micro-Extraction (SPME) technique, obtaining as main volatile compounds the monoterpenes, myrcene, a -pinene, , p-cymene and limonene, as well as the sesquiterpene caryophylene.

KEY WORDS: Lithraea caustica, Anacardiaceae, Solid Phase Micro-Extraction, head space components, monoterpenes, sesquiterpenes.

RESUMEN

De las partes áereas de Lithraea caustica y usando la técnica de Micro-Extracción en Fase Sólida (MEFS), fueron identificados y cuantificados los principales compuestos volátiles: los monoterpenos, mirceno, a -pineno, p-cimeno y limoneno, y el sesquiterpeno cariofileno.

PALABRAS CLAVES: Lithraea caustica, Anacardiaceae, Micro-Extracción en Fase Sólida, componentes volátiles, monoterpenos, sesquiterpenos.

INTRODUCTION

Lithraea caustica (Anacardiaceae) known as litre is an evergreen tree or shrub endemic in Chile, distributed from Coquimbo (IV Region) to Cautin (IX Region). Due to the hardness, its wood is very appreciated for the construction of small crafts(1,2).

No application is known in popular medicine; on the contrary, and specially during flowering time (September-December), it produces a strong dermatitis in sensitive individuals(3).

In a previous phytochemical study of the constituents of leaves and twigs, a new alkyl catechol was isolated, the litreol (3-[pentadecyl-10-enyl-catechol]) which demostrated to be a powerful allergenic vehicle (4). Nevertheless literature(3) and oral informations, collected by conversations with countrymen and forest rangers who suffered strong dermatitis without physical contacts with the plants, indicate that the disease can be induced not only by contact, but also at distance. Therefore, we studied the composition of the volatile compounds produced by litre in order to verifiy the presence of allergenic substances.

The major components of the head space of litre were established by means of the Solid Phase Micro-Extraction (SPME)(5,6,7). SPME is a clean fast technique, which allows, without the use of solvents, to perform the direct analysis of volatile substances stored in the head space (HS) created in a closed system which contains the plant material.

The aerial parts of Lithraea caustica (Mol.) H. et Arn. were collected in Laguna Verde, Valparaiso (V Region), Chile, in September 2001. One sample was deposited in the herbarium of the Universidad Federico Santa Maria.

Manual SPME holder with fused silica fiber covered with polydimethylsiloxane, 100 m m (Supelco^TM). PE Autosystem Gas Chromatograph with two capillar columns of SBP5 fused silica (60 m x 0.25 mm, film thickness 0.25 mm) paralelly mounted, with flame ionization detector (FID, maintained at 270 ºC); and Turbomass 4.1.1 Mass Spectrometer (70 ev, transfer line 220 ºC); helium as carrier gas (1 ml / min) oxygen and moisture free, using Supelco^TMHigh Capacity Heated Carrier Gas Purifier arranged with OMI-2 Indicating Tube. Inyector temp. 270 ºC. Two different softwares linked to the CG/FID and CG/EM, respectively. Turbochrom and Turbomass Analytical Workstation with NIST/EPA/MSDC Mass Spectral Database.

The clean fresh plant material was stored in paper bags for its quickly translate to Italy. The analysis was carried out in the Istituto Superiore di Sanità in Rome. The sample (81 g) was deposited in a Schott Duran 1 l flask. A Thermoliteâ Shimadzu Plug Septum was inserted in the cover through which the holder was introduced during 30 min. The sample adsorbed in this way was deadsorbed in a CG-mass apparatus. The components of the mixture were identified determining their retention times, Kovat Index (8) and mass spectra, and comparing these data with those of standard samples. The procedure was repetead six times, always resulting the same chromatographic pattern.

The composition of the head space of litre (Table 1) is mainly characterized by the presence of monoterpenes, being myrcene (50%), a -pinene (16%), p-cymene (12%), and limonene (11%) the most abundant ones. Also a sesquiterpene, caryophyllene (6%), and the monoterpenes b -pinene and a -phellandrene are present as minor components.

Table 1. Volatile compounds of Lithraea caustica.

Peak	Retention time (min)	Percent (%)	Compound
1	13.10	16.0	a -pinene
2	15.65	4.1	b -pinene
3	16.36	50.0	Myrcene
4	17.32	1.9	a -phellandrene
5	18.64	11.6	p-cymene
6	18.90	10.7	Limonene
7	49.15	5.7	Caryophyllene

However no one of these substances has known allergenic properties and therefore the idea of considering some of the volatiles as responsible of such allergies is not probable, although the presence of undetectable active compounds can not be excluded.

Research will be continued to obtain informations about possible variations of the volatile content in accordance with the vegative cycle of the plant, as well as its habitats.

ACKNOWLEDGMENTS

The authors thank the CONICYT (Chile) ¾ CNR (Italy) Scientific Cooperation Programme for Financial Support for Academic Interchange (MP and GS), and L. Farina and S. Maurizi (ISS) for their collaboration.

REFERENCES

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2. L .E. Navas. Flora de la Cuenca de Santiago de Chile: Tomo II. Ediciones de la Universidad de Chile, Santiago de Chile, 277 (1976).

3. A. Reyes. El Litre: Enfermedad Anafiláctica, Ed. Zig - Zag S.A., Santiago de Chile, pp. 322 (1942).

4. V. Gambaro, M.C.Chamy, E.von Brand and J.A. Garbarino. Planta Medica, 20, 20-22 (1986).

5. Z. Zhang, and J.Pawliszyn. Analytical Chemistry. 65, 1843-1852 (1993).

6. G.Salvatore and M.Nicoletti. VI Congreso Italo-Latinoamericano de Etnomedicina, Antigua, Guatemala, 6-10 October, T L 11.1 (1997).

7. G. Salvatore. Atti 1º Convegno Estratti Vegetali in Cosmetica, Istituto Superiore di Sanità, Rome, 14-15 December, 223-228 (1998).

8. R. Adams. Identification of essenzial oil components by gas chromatography mass spectroscopy. Allured Publishing Corporation, Carol Strea, Illinois, USA p. 17-43 (1995).

To whom correspondence shoulkd b e addressed.