The heliangolide dihydrohirsutolide from Arctotis fastuosa and dichloromethyldihydrohirsutolide.

Three of ten sesquiterpene lactones isolated from the herb of Arctotis fastuosa (Asteraceae) belong to the heliangolide series. The first was identified as hirsutolide, the second is new and named dihydrohirsutolide, and the third, dichloromethyldihydrohirsutolide, is an artifact. The known degraded carotenoid loliolide was also isolated. Structures were established by spectroscopic methods including IR, 1D-/2D-1H-NMR, 13C-NMR, GHSQC, GHMBC, HREIMS and CD.