Sesquiterpenes from the east African sandalwood Osyris tenuifolia
The essential oil of East African sandalwood Osyris tenuifolia was investigated by NMR, Mass spectrometry and chemical correlations. Four new sesquiterpenes including 15 and 17 with a new skeleton were identified.
Introduction
Osyris tenuifolia (East African sandalwood) belongs taxonomically to the Santalaceae. The small tree occurs in the equatorial region of Africa, where the extract of its small shoots is used as antipyretic agent by the Massai for cattle (Thanner, 1908). The essential oil of O. tenuifolia was investigated for the first time by Naves and Ardizio (1954), who could already identify the main constituent lanceol.
In the present work the essential oil of O. tenuifolia was analyzed by GC–MS. Four new sesquiterpenes – ar-tenuifolene (15), tenuifolene (17), 2,(7Z,10Z)-bisabolatrien-13-ol (23) and lanceoloxide (21) – could be isolated by preparative GC. The structures of the compounds were investigated by mass spectroscopy and NMR (1H, 13C, 1H–1H COSY, HMQC, HMBC and NOESY). Compounds 17 and 21 show a sesquiterpene backbone which is reported for the first time.
Section snippets
Results and discussion
The commercially available essential oil of O. tenuifolia shows a complex fraction of sesquiterpenoids. Most of the known compounds (1–14, 16 and 20) were identified by comparing their mass spectra and retention indices to a spectral library established under identical experimental conditions (Joulain and König, 1998). The already known sesquiterpenes epi-cyclosantalal (18) (Brunke and Vollhardt, 1995), (−)-epi-α-bisabolol (19) (Isaak et al., 1968; Kergomard and Veschambre, 1977), the main
Gas chromatography
Orion Micromat 412 double column instrument with 25 m fused silica capillaries with polysiloxane CPSil-5 and polysiloxane CPSil-19 (Chrompack); Carlo Erba Fractovap 2150 or 4160 gas chromatographs with 25 m fused silica capillaries with octakis(2,6-di-O-methyl-3-O-pentyl)-γ-cyclodextrin, heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin or heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV 1701 (50%, w/w), split injection; split ratio approx. 1:30; FID; carrier gas 0.5
Acknowledgements
We gratefully acknowledge financial support of “Fonds der Chemischen Industrie”. We although thank Dr. V. Sinnwell, University of Hamburg, for his support in recording the NMR spectra and Mrs. A. Meiners and Mr. M. Preusse for GC–MS measurements.
References (9)
- et al.
The role of germacrene D as a precursor in sesquiterpene biosynthesis: investigation of acid catalyzed, photochemically and thermally induced rearrangements
Phytochemistry
(2000) - et al.
Preparative enantiomer separation with modified cyclodextrins as chiral stationary phases
Journal of Chromatography A
(1994) - et al.
Synthése et configuration absolute de terpénes naturels: (+)-uroterpenol, (+)- et (−)-α-bisabolols, (−)-α-bisabololone
Tetrahedron
(1977) - et al.
Cyclosantalal and epicyclosantalal – new sesquiterpene aldehydes from East Indian sandalwood oil
Flavour and Fragrance Journal
(1995)
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