VARIABILITY OF ESSENTIAL OILS OF THYMUS-CAESPITITIUS FROM PORTUGAL

The composition and variability of the essential oils of several popul ations of Thymus caespititius from Portugal were investigated by GC, G C-mass spectrometry and C-13 NMR. All samples from NW Portugal were ch aracterized by their high alpha-terpineol content, while the main comp onents in the oil sample from Pico island (Azores archipelago) were ca rvacrol and thymol. The analytical data of individual samples from NW Portugal showed no chemical polymorphism in this area. The different a reas of distribution (NW Portugal and Azores) that show great climatic and soil variation conditions may be the origin of the alpha-terpineo l-type oil from NW Portugal and the carvacrol/thymol-type oil from the Azores. C-13 NMR spectra of the essential oil, previously fractionate d by column chromatography, led to the identification of trans-dihydro agarofuran, a new oxygenated sesquiterpene for the genus Thymus and a characteristic compound of T. caespititius. (C) 1997 Elsevier Science Ltd.