Stilbenoids from Tragopogon orientalis

A phytochemical investigation of Tragopogon orientalis L. (Asteraceae, Cichorieae) yielded the natural products 6'-O-(7,8-dihydrocaffeoyl)-alpha,beta-dihydrorhaponticin, 3'-O-methyl-alpha,beta-dihydrorhaponticin, and (S)-3-(4-beta-glucopyranosyloxybenzyl)-7-hydroxy-5-methoxyphtalide as well as known compounds alpha,beta-dihydrorhaponticin, 3-(4-methoxybenzyl)-5,7-dimethoxyphthalide, p-dihydrocoumaric acid methyl ester, and 1-hydroxypinoresinol-1-O-beta-glucopyranoside. The structures were established by HR mass spectrometry, extensive 1D and 2D NMR spectroscopy, and CD spectroscopy. Moreover, the radical scavenging activities of the major compounds were measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The chemosystematic impact of the occurrence of stilbene derivatives in T. orientalis is discussed.