Diterpenoids from Acanthopanacis Cortex and Their Anti-Inflammatory Activity Studies.

Acanthopanacis Cortex ( A. -C ) with a long history of more than1000 years, has been used to treat rheumatism effectively. Nineteen diterpenoids have been isolated from A. -C , including six new compounds ( 1 - 6 ). Among them, compounds 7 , 9 - 11 , 13 , and 17 were discovered from A. -C for the first time. The structures of 1 - 6 were determined by analyzing their NMR data and comparing their experimental and calculated electronic circular dichroism spectra. Moreover, the single-crystal X-ray diffraction data of 1 , 2 , 8 , and 14 were provided. The antiinflammatory activity of 1 - 5 and 7 - 18 on neutrophil elastase, cyclooxygenase-1 (COX -1), and cyclooxygenase-2 (COX -2) has been studied in vitro , and the results showed that 15 had almost no inhibitory effects on COX -1 at 200 mu M but a significant activity against COX -2 with an IC 50 of 0.73 +/- 0.006 mu & Mcy;. It indicated that compound 15 can provide valuable information for the design of selective COX -2 inhibitors.