Chemotaxonomic study on Thymus villosus from Portugal

The composition of the essential oils of four populations of Thymus villosu s subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and CC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision w ith the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents i n these two taxa were found. Linalool, geranyl acetate, geraniol and terpin en-4-ol were the main components of the essential oils of T. villosus subsp . lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterize d in each one: linalool; linalool/ terpinen-4-olltrans-sabinene hydrate; li nalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8- cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p- cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/ myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. vill osus can be easely differenciated by the composition of their essential oil s. (C) 2000 Elsevier Science Ltd. All rights reserved.