Bibenzyls and dihydroisocoumarins from white salsify (Tragopogon porrifolius subsp. porrifolius).
A phytochemical investigation of three accessions of Tragopogon porrifolius L. subsp. porrifolius (Asteraceae, Lactuceae) yielded three new bibenzyl derivatives, 5,4'-dihydroxy-3-alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyloxybibenzyl, 2-carboxyl-3,4'-dihydroxy-5-beta-d-xylopyranosyloxybibenzyl, tragopogonic acid (2'carboxyl-3',5',4''-trihydroxyphenylethanone) and three dihydroisocoumarin derivatives, including the new natural product 6-O-methylscorzocreticoside I. One of the isolated bibenzyl derivatives is considered to be a precursor to the biosynthesis of dihydroisocoumarins. Structures of new compounds were established by HR mass spectrometry, extensive 1D and 2D NMR spectroscopy, and CD spectroscopy. Moreover, radical scavenging activities of the polyphenolic compounds were measured using the 2,2-diphenyl-1-picrylhydrazyl assay; two of the bibenzyls showed moderate and two of the dihydroisocoumarins showed weak radical scavenging activities. The chemosystematic impact of bibenzyls and dihydroisocoumarins is discussed briefly.
Zidorn
Christian
C
Institut für Pharmazie der Universität Innsbruck, Josef-Moeller-Haus, Innrain 52, A-6020 Innsbruck, Austria. Christian.H.Zidorn@uibk.ac.at
Lohwasser
Ulrike
U
Pschorr
Susanne
S
Salvenmoser
Daniela
D
Ongania
Karl-Hans
KH
Ellmerer
Ernst P
EP
Börner
Andreas
A
Stuppner
Hermann
H
D001632:Bibenzyls / Q000737:chemistry* / Q000302:isolation & purification; D003374:Coumarins / Q000737:chemistry* / Q000302:isolation & purification; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification; D015394:Molecular Structure; D031188:Tragopogon / Q000737:chemistry*
D001632:Bibenzyls; D003374:Coumarins; D016166:Free Radical Scavengers