The essential oils of two endemic Portuguese thyme species: Thymus capitellatus Hoffmanns. & Link and T. lotocephalus G. López & R. Morales

The composition of the essential oils of Thymus capitellatus Hoffmanns. & Link and T. lotocephalus G. López & R Morales was studied by GC and GC–MS. The essential oils of T. capitellatus, isolated either from flowers or from leaves of the plant during its vegetative phase, showed a more or less similar composition, but the corresponding oil from T. lotocephalus showed marked differences. The oils of both species consisted mainly of oxygen‐containin monoterpenes (55–69% of the total oils). 1,8‐Cineole (50–56%) was the main component of the oils of T. capitellatus both in the oil from its flowers and in that from its leaves. The oil isolated from the flowers of T. lotocephalus was dominated by linalyl acetate (23%); the other major components were linalol (11%) and 1,8‐cineole (10%). However, in the oil from the leaves of this species 1,8‐cineole (24%) was again the major component, while linalyl acetate and linalol amounted to 5% and 6% respectively Although present in relatively small amounts, sesquiterpenes were more important in the oils of T. lotocephalu (15–17%) than in those of T. capitellatus (3–4%). The presence of 1,8‐cineole, in relatively large amounts, in the oil analysed was in agreement with the earlier finding of this compound as major component of other Iberian thyme oils However, the oil isolated from flowers of T. lotocephalus must be considered as being characterized by linalyl acetate, linalol instead of by 1,8‐cineole.