Tragoponol, a dimeric dihydroisocoumarin from Tragopogon porrifolius L.

A phytochemical re-investigation of Tragopogon porrifolius L. (Asteraceae) yielded (7S,15S)-2,4,12-trihydroxy-7-(4-hydroxyphenyl)-10-methoxy-15-(4-methoxyphenyl)-7,8,15,16-tetrahydrodibenzo[c,i][1,7]dioxacyclododecine-5,13-dione, named tragoponol, a dimeric dihydroisocoumarin.The compound, which represents the first of its kind, is comprised of the open-chained forms of two different mono-methoxylated dihydroisocoumarin moieties, scorzocreticin and hongkongenin, which are connected via two ester bonds to form a macrolide with two lactone moieties featuring a 12-membered ring. The structure of the nearly symmetrical compound was established by HR mass spectrometry, CD measurements, and extensive 1D and 2D NMR experiments.