New sesquiterpenoids from the flowers of (L.) D.Gut.Larr.

Five new sesquiterpenoids, (4, 5, 6, 7, 8 )-5,6-dihydroxy-1-acetoxy-10(14)-en-britannilactone (), (4, 5 , 6, 7, 8 )-5,6-dihydroxy-1-acetoxy-10(14)-en-britannilactone (), 6-O-propionyl-britannilactone (), 1-hydroxy-3-acetoxyeudesma-11(13)-en-12,8-olide () and 1,5-dihydroxyeudesma-11(13)-en-12,8-olide (), along with twelve known ones were isolated from the flowers of (L.) D.Gut.Larr. Among them, compounds and were stereoisomers which belong to 1,10-seco-eudesmane sesquiterpenoid with rare double bond between C-10 and C-14. The structures of the isolated compounds were elucidated by various spectroscopic methods, including 1D and 2D NMR experiments.