Conformational analysis of the biflavanoid GB2 and a polyhydroxylated flavanone-chromone of Cratoxylum neriifolium.
Three compounds, namely the interesting biflavanonol GB-2(naringenin 1-3, 11-8-dihydroquercetin, 1), 1-4',1-5,11-5,1-7,11-7-pentahydroxyflavanone(l-3,11-8)chromone [naringenin-(3 -8) 5,7-dihydroxychromone, 21 and stigmasterol, have been isolated from the leaves of Cratoxylum neriifolium Kurz. Compounds 1 and 2 show rotameric behavior due to the presence of a single bond between the highly substituted flavanone and flavanonol part and the flavanone and chromone part, respectively. Complete NMR spectral assignments of 1 and 2 have been done at 27 C and 90 C for the first time followed by a study of conformational behavior at room temperature by ROESY.
Department of Pharmaceutical Chemistry, Albertstrasse 25, 79104 Freiburg, Germany.
Vineet
V
Kumar
Volker
V
Brecht
August Wilhelm
AW
Frahm
D028084:Clusiaceae; D005419:Flavonoids / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves
D005419:Flavonoids; D010936:Plant Extracts