A bis-sesquiterpene and sesquiterpenolides from Inula macrophylla.

Macrophyllidimer C, a novel bis-sesquiterpene, in which the two sesquiterpene units are directly connected by a C-C bond, and eight other sesquiterpenolides were obtained from the bark of Inula macrophylla. Seven of these, macrophyllilactones A-G, are new eudesmanolide- and elemanolide-type sesquiterpenes. Their structures were determined on the basis of spectroscopic evidence and chemical reaction.