Germacranolides from Artemisia myriantha and their conformation.
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.
Wong
Ho Fai
HF
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.
Brown
Geoffrey D
GD
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
D012717:Sesquiterpenes; D045788:Sesquiterpenes, Germacrane; C432449:germacranolide