Essential oil composition of three Grindelia species

The essential oil of Grindelia humilis Hook ct Am (G.H.), G. robusta Nutt ( G.R.) and G. squarrosa Dun F. (G.S.), were analyzed by GC/MS. Sixty-nine co mponents were identified in the oil of G. humilis, representing 89.9% of th e oil, while 56 components in the oil of G. robusta, and 68 components in t he oil of G. squarrosa were identified representing 78.9% and 81.9% of the oils, respectively. The study revealed that the major components of the oil of G. humilis were polyacetylenes (46.2%) and germacrene D (11.9%). In con trast, the major components of G, robusta were oxygenated terpenoids (57.4% ), of which borneol (14.8%) was the largest constituent. The oil of G. squa rrosa was characterized by monoterpene hydrocarbons (47.7%), of which limon ene (16.8%), alpha-pinene (16.1%) were the major components.