Bisabolane-Type Sesquiterpenoids with a Tetrahydrofuran or Tetrahydropyran Ring from Vernonia solanifolia .

Phytochemical investigation of the aerial parts of resulted in the isolation of 23 new highly oxidized bisabolane-type sesquiterpenoids (-). Structures were determined by interpretation of spectroscopic data, single-crystal X-ray diffraction analysis, and time-dependent density functional theory electronic circular dichroism calculations. Most compounds possess a rare tetrahydrofuran (-) or tetrahydropyran ring (-). Compounds / and / are pairs of epimers isomerized at C-10, while compounds / and / are isomerized at C-11 and C-2, respectively. The anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages was evaluated for pure compounds. Compound inhibited LPS-stimulated NO production at the concentration of 80 M. It showed an anti-inflammatory effect by suppressing the activation of the NF-κB signaling pathway.