title: Germacranolides from Artemisia myriantha and their conformation.
abstract: The CH(2)Cl(2) extract of the aerial parts of Artemisia myriantha afforded three germacranolides derived from 13-acetoxy-3beta-hydroxy-germacra-1(10)E,4E,7(11)-trien-12,6alpha-olide, whose structures were elucidated by 2D-NMR spectroscopic analyses. Some conclusions are drawn about the possible conformations of the ten-membered germacranolide ring system from the exchange peaks seen in the NOESY spectra, and an estimate is made of the energy barrier to ring-flipping from variable-temperature NOESY experiments. The conclusions reached were supported by molecular modeling studies and an NMR spectroscopic investigation of the commercially available germacranolide, parthenolide.
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Ho Fai
authors.initials: HF
authors.lastname: Wong
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Brown
mesh_terms: D019306:Artemisia / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification*; D045788:Sesquiterpenes, Germacrane; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D012717:Sesquiterpenes; D045788:Sesquiterpenes, Germacrane; C432449:germacranolide