]]> The composition of the essential oil from leaves of Siparuna thecaphora (Poepp. et Endl.) A. DC. collected in Turrialba, Costa Rica, was determined by capillary GC/MS. Seventy-six compounds were identified corresponding to ca. 95% of the oil. The major components were germacrene D (32.7%),  -pinene (16.3%),  - pinene (13.8%) and  -caryophyllene (4.1%). Thirty-one minor compounds were identified for the first time in this genus of plants.

The family Siparunaceae comprases two genera, the monotypic West African genus Glossocalyx and the Neotropical genus Siparuna (formerly placed in the family Monimiaceae), which contains about 72 species of shirubs, straggling shrubs, and trees ( Renner et al. 1997 ). Up lo now, six species of Siparuna from Costa Rica have been describes.

Siparuna thecaphora (Poepp. et Endl.) A. DC. is an aromatic shrub or small tree (3-5 m tall), with opposite, simple leaves, and unisexual flowers. The fruits are fleshy and reddish when ripe, with arilate seeds. Due lo its highly variable morphology, a great number of synonyms are found in the literatura (e.g., S. nicaraguensis, S. ansia, S. gilgiana). This plant is a widespread species in Costa Rica. lt can be found in both Pacific and Caribbean sides of the Country, from near sea level up lo close lo 2000 m elevation. lt is distributed from southern Mexico throughout Central America lo Brazil and Bolivia. lt is called colloquially "limoncillo" (little lemon) probably because of the strong lemon-scented fruits.

]]> In Panama, the infusion of crushed leaves is used lo treat colds and rheumatism (Duke 1972 ). In Guatemala, the fresh leaves are placed on the forehead lo relieve headaches (Morton 1980 ).

To the best of our knowledge, no reports have been made regarding the essential oil composition from this genus of plants in Costa Rica.

Early phytochemical studies of the genus Siparuna revealed the presence of aporphine, oxoaporphine and morphinandienone alkaloids (Braz et al. 1976 , Chiu et al. 1982 , Gerard et al. 1986 , Lopez et al. 1988 , 1990 , 1993 ); cadinane sesquiterpenes (El-Seedi et al. 1994 ) and kaempherol glycosides (Leitão et al. 2000 ). Reports of the leaf essential oils constituents obtained from the Panamanian and Brazilian S. guianensis were varied. They range from those containing as main constituents curzerenone and curzerenone derivatives ( Antonio et al. 1976 ), epi- -bisabolol, spathulenol, selin-11-en-4 -ol, elemol,  -eudesmol, atractylone and germacrone (Zoghbi et al. 1998 ) or (E)-nerolidol (Fernandez-Machado et al. 1998 ).

Some chemical studies of S. thecaphora have been done previously. The oxoaporphine alkaloid liriodenine was isolated from the twigs (under the synonym S. nicaraguensis) (Gerard et al. 1986 ). The alkaloids liriodenine and oxonantenine, reported for the first time in the genus, were isolated from the roots (under the synonym S. gilgiana) (Chiu et al. 1982 ). The volatile oil of the fruits (under the synonym S. nicaraguensis) was studied previously (Manjarrez and Mendoza 1967 ). The main constituents of the oil were  -elemene, citral and  -ionone.

Plant Material: Leaves of Siparuna thecaphora from Costa Rica, were collected in Santa Cruz, Turrialba, province of Cartago, in 1998. A voucher specimen was depositad in the Herbarium of the University of Costa Rica at the School of Biology (USJ 68612).

Essential Oil Isolation: Fresh leaves were subjected to hydrodistillation for 3 hr using a modified Clevenger-type apparatus. The distilled oil was collected as a colorless liquid, dried over anhydrous sodium sulfate, and stored at -10ºC [ 0.2% (v/w) yield].

]]> General Analytical Procedures: The oil was analyzed by gas chromatography/mass spectrometry (GC/MS). The mass spectra were obtained using a Hewlett-Packard G1800A GCMSD System, employing a fused silica (30 m x 0.25 mm) column coated with a 5% phenyl methyl silicone (film thickness 0.25 m). Operation conditions were: carrier gas: He (1.0 mL/min); oven temperature program: 75ºC (4 min), 750-200ºC at 3ºC/min, 200ºC (8 min); sample injection port temperature: 250ºC; detector temperatura: 260ºC; ionization voltage: 7OeV; scanning over 38-400 amu range; split injection 1:20. Integration of the total ion chromatogram, expressed as area percent, has been used to obtain quantitative compositional data.
 
Identification: Identification of the components of the oil was performed using the retention indices on a phenyl methyl silicone column, and by comparison of their mass spectra with those published in the literature (Stenhagen et al. 1974 , Swigar and Silverstein 1981 , McLafferty 1993 , Adams 1995 , 2001 ) or those of our own database.
 
 
Results

The oil is constituted mainly by hydrocarbons (89.0%) whereas the oxygenated compounds accounts only for 6.4% ( Table 1 ). Among the 76 compounds identified, sesquiterpenoids representad 56.7% and monoterpenoids 38.7%.
 
Germacrene D (32.7%),  -pinene (16.3%),  -pinene (13.8%) followed by the widespread sesquiterpene  -caryophyllene (4.1%) were identified as the main constituents of the oil. Among the oxygenated compounds  -cadinol (1.6%), epi- -muurolol (1.0%) and 1,8-cincole (0.8%) were the major ones. The other constituents were 69 compounds found in minor or trace amounts. Of these ones, thirtyone are newly identified compounds in the genus Siparuna (see Table 1 ).
 

]]>   TABLE 1 Percentage composition of the Siparuna thecaphora leaf oil from Costa Rica  

These results differ markedly from those obtained with oils isolated from S. guianensis.  Antonio et al. (1976) reported that the leaf oil of plants collected in Panama, contains as major constituents curzerenone and curzerenone type compounds or products decomposing to curzerenone.  Zoghbi et al. (1998) reported the composition of three types of oils from S. guianensis collected at different locations of the Amazon, Brazil: type A, with epi- -bisabolol and spathulenol as main constituents; type B, with spathulenol, selin-11en-4 -ol,  -eudesmol and elemol; and type C, with gertnacrone, germacrene D, bicyclogermacrene, germacrene B and atractylone as major constituents.  Fernandez-Machado et al. (1998) reported that (E)-nerolidol was the main component of the leaf oil of S. guianensis, during flowering.  They observed a arde seasonal variation of nerolidol.
 
Our results also differ from those obtained by Manjarrez and Mendoza (1967) from the fruits of S. thecaphora from Mexico (under the synonym S. nicaraguensis).  The oil was characterized by the presence of  -elemene, citral and  -ionone.

In the current study of S. thecaphora, Germacrene D (32.7%),  -pinene (16.3%) and  -pinene (13.8%) were identified as the main constituents of the oil. Preliminary studies (still in progress) concerning the composition of the oil of S. thecaphora from three locations in Costa Rica also revealed chemical differences (Chavarría 2002 ). This chemical differences could be attributed to the effect of geographical location and microenvironment or to the effect of interspecific and infraspecific differences or to the phenological stage of the plant.

The authors are grateful to Vicerrectoría de Investigación UCR (Project 809-99-264) for financial support. To M. Segnini and Centro de Investigación en Contaminación Ambiental (International Atomic Energy Agency, project. 802-96-550) for GC/MS facilities. To N. R. Farnsworth (College of Pharmacy, University of Illinois at Chicago, USA) for his help to access the NAPRALERT database. ]]>

La composición química del aceite esencial de las hojas de Siparuna thecaphora (Poepp. et Endl.) A. DC., recolectada en Turrialba, Costa Rica, se estudió mediante la técnica de cromatografía capilar gaseoso-líquida, acoplada a un espectrómetro de masas (GC/MS). Se identificaron 76 compuestos que correspondieron a cerca del 95% del aceite. Los componentes mayoritarios fueron germacreno D (32.7%)  -pineno (16.3%),  -pineno (13.8%) y  -cariofileno (4.1%). Dentro de los compuestos minoritarios, treinta y uno se describen por primera vez como constituyentes de este género de plantas.

Adams, R.R 1995. Identification of Essential Oil Components by Gas Chromatography/ Mass Spectroscopy. Allured, Carol Stream, IL. 468 p.         [ Links ]

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Adams, R.R 2001. Identification of Essential Oil Components by Gas Chromatography/ Quadrupole Mass Spectroscopy. Allured, Carol Stream IL. 456 p.         [ Links ]

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Braz, R., S.J. Gabriel, C.M.R. Gomes, O.R. Gottlieb, M.D.G.A. Bichara & J.G.S. Maia. 1976. Oxoaporphine Alkaloids from Fusea lonGIFolia and Siparuna guianensis. Phytochemistry 15: 1187-1188.         [ Links ]

Chavarría, A. 2002. Variación morfológica, química y molecular de Siparuna thecaphora (Siparunaceae) en tres zonas de Costa Rica. Tesis de licenciatura, Universidad de los Andes, Bogotá, 170 p.         [ Links ]

Chiu, S.Y.C., R.H. Dobberstein, H.H.S. Fong & N.R. Farnsworth. 1982. Oxoaporphine Alkaloids from Siparuna gilgiana. J. Nat. Prod. 45: 229-230.         [ Links ]

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Duke, J.A. 1972. Isthmian Ethnobotanical Dictionary. Fulton, Maryland. pp. 96.         [ Links ]

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Fernandes-Machado, S.M., V.A.F. Adauto-Ribeiro, J.S.L.T. Militão, S. Maia de Morais & M.I. Lacerda-Machado. 1998. Seasonal Variation of (E)-Nerolidol in Siparuna guianensis Aublet and ¹³ C-NMR Spectral Assignments of (E)- and (Z)-Nerolidol. J. Essent. Oil Res. 10: 708-710.         [ Links ]

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1    Centro de Investigaciones en Productos Naturales (CIPRONA) and Escuela de Química, Universidad de Costa Rica, 2060 San José, Costa Rica. Fax: (506) 225 9866; jfciccio@equi.ucr.ac.cr

2   Centro de Investigaciones en Productos Naturales (CIPRONA) and Escuela de Biología, Universidad
de Costa Rica, 2060 San José, Costa Rica.

* Corresponding author.