Artemisia magellanica. Chemical Composition of the Essential Oil from an Unexplored Endemic Species of Patagonia

: The essential oil composition of the aerial parts of Artemisia magellanica Sch. Bip. (Asteraceae), native to Patagonia, was analyzed by GC-FID-MS. This is the first report on the essential oil composition of A. magellanica. A total of 113 components were identified accounting for 95.6-95.7 % of the oil. The essential oil was characterized by a high percentage of γ-costol (21.0-43.5 %), selina-4,11-diene, (Z)-β-ocimene, (E)-β-farnesene, (Z)-en-yn-dicycloether and 23 different esters (28.7 %). In turn, Artemisia biennis, a species native to North America, which is considered by some authors to be conspecific with A. magellanica, yielded an essential oil that was rich in (Z)-β-ocimene (34.7 %), (E)-β-farnesene (40.0 %) and the acetylenes (Z)- and (E)-en-yn-dicycloethers (11.0 %). Thus, as A. biennis lacks the three main components present in A. magellanica, namely γ-costol, 2-methylbutyl 2-methylbutyrate and selina-4,11-diene, these compounds could be considered as potential chemical markers for A. magellanica since they are absent or only found as minor constituents in other members of the genus. The data presented herein is also useful for genus taxonomy.