Phthalide dimers from Angelica sinensis and their COX-2 inhibition activity

Four new dimeric phthalides, angesinenolides C - F (1 - 4), along with three known ones, were isolated from the roots of Angelica sinensis. Their structures were determined by means of FIRMS and NMR experiments. The structures of compounds 1 and 3 were confirmed using X-ray crystallographic data. All isolated compounds were tested for activities on the inhibition of COX-2 enzyme in vitro. Compounds 1-6 exhibited inhibitory activity against COX-2 with IC50 values ranging from 29.32 +/- 0.07 to 137.91 +/- 0.24 mu M.