Stilbenoids from Tragopogon orientalis

Tragopogon orientalis L. (Asteraceae, Cichorieae) yielded the natural products 6″-O-(7,8-dihydrocaffeoyl)-α,β-dihydrorhaponticin, 3′-O-methyl-α,β-dihydrorhaponticin, and (S)-3-(4-β-glucopyranosyloxybenzyl)-7-hydroxy-5-methoxyphtalide as well as known compounds α,β-dihydrorhaponticin, 3-(4-methoxybenzyl)-5,7-dimethoxyphthalide, p-dihydrocoumaric acid methyl ester, and 1-hydroxypinoresinol-1-O-β-glucopyranoside. The structures were established by HR mass spectrometry, extensive 1D and 2D NMR spectroscopy, and CD spectroscopy. The radical scavenging activities of the major compounds were measured using the DPPH assay. The chemosystematic impact of the occurrence of stilbene derivatives in T. orientalis is discussed.