Cytotoxic diterpenoids and sesquiterpenoids from Pteris multifida

Three new ent-kaurane diterpenoids, named pterokaurane M-1-M-3 (1-3) and three new C-14 pterosin-sesquiterpenoids, named multifidoside A-C (4-6), along with 18 known compounds, were isolated from the whole plants of Pteris multifida. The structures of 1-6 were established using spectroscopic methods, including extensive 2D NMR and CD analyses. Compounds 4 and 5 showed cytotoxicity against the HepG2 tumor cell line with IC50 values of less than 10 mu M.