New 4,5-Seco-20(10→5)-abeo-abietane Diterpenoids with Anti-inflammatory Activity from Isodon lophanthoides var. Graciliflorus.

Three new 4,5-seco-20(10 -> 5)-abeo-abietane diterpenoids, 16-hydroxysalvilenone (1), 15-hydroxysalprionin (2), and 11 beta,15-dihydroxysalprionin-12-one (3), and nine known abietane diterpenoids, 4-12, along with one known sempervirane diterpenoid, hispidanol A (13), were isolated from the aerial parts of Isodon lophanthoides var. graciliflorus. The structures of compounds 1-3 were determined on the basis of spectroscopic methods including extensive analysis of NMR and mass spectroscopic data. All diterpenoids were tested for their TNF-alpha inhibitory effects on LPS-induced RAW264.7 cells. Compound 9 (16-acetoxyhorminone) was the most potent with an IC50 value of 3.97 +/- 0.70 mu m.