The chemical composition of essential oils and lipophilic extracts of Silphium integrifolium Michx. and Silphium trifoliatum L. rhizomes

An anatomical evaluation of the secretory structures of Silphium integrifolium and S. trifoliatum rhizomes as well as GC-FID and GC/MS of the essential oil compositions and lipophilic extracts from organs of both species collected in 1999-2001. It was found that sesquiterpene compounds such as alpha-isocomene, modhephene, 7 beta-H-silphiperfol-5-ene, beta-caryophyllene, beta-isocomene, germacrene D, 7 alpha-H-silphiperfol-5-ene, silphiperfol-6-ene and beta-bisabolene were the main components of the tested oils and extracts from S. integrifolium and S. trifoliatum. Among the oils and extracts analyzed, significant amounts of allo-aromadendr-9-ene as well as alpha- and beta-himachalene were found only in S. integrifolium rhizome oil. The main constituent of lipophilic extracts that was absent in the oils was 16-acetoxycarterochaetol at average content of 39.7 +/- 1.0% and 40.5 +/- 5.9% in tested extracts.