title: Germacrenes from fresh costus roots.
abstract: Four germacrenes, previously shown to be intermediates in sesquiterpene lactone biosynthesis, were isolated from fresh costus roots (Saussurea lappa). The structures of (+)-germacrene A, germacra-1(10),4,11(13)-trien-12-ol, germacra-1(10),4,11(13)-trien-12-al, and germacra-1(10),4,11(13)-trien-12-oic acid were deduced by a combination of spectral data and chemical transformations. Heating of these compounds yields (-)-beta-elemene, (-)-elema-1,3,11(13)-trien-12-ol, (-)-elema-1,3,11(13)-trien-12-al, and elema-1,3,11(13)-trien-12-oic acid respectively, in addition to small amounts of their diastereomers. Acid induced cyclisation of the germacrenes yields selinene, costol, costal, and costic acid respectively. It is highly probable that the elemenes reported in literature for costus root oil are artefacts.
authors.affiliation: Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB, The, Wageningen, Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: de Kraker
authors.forename: M C
authors.initials: MC
authors.lastname: Franssen
authors.forename: A
authors.initials: A
authors.lastname: de Groot
authors.forename: T
authors.initials: T
authors.lastname: Shibata
authors.forename: H J
authors.initials: HJ
authors.lastname: Bouwmeester
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D018517:Plant Roots / Q000737:chemistry*; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D012717:Sesquiterpenes