BIOACTIVE DITERPENOIDS ISOLATED FROM DILOPHUS-LIGULATUS

Nine diterpenoids, acetyldictyolal (1), epoxyoxodolabelladiene (2), di ctyotalide B (3), neodictyolactone (4), pachylactone (5), the acetals 6a and 6b, isoacetoxycrenulatin (7), and dictyolactone (8) were isolat ed from the brown alga Dilophus ligulatus (Kutz.) Feldm. Their structu res have been elucidated by comparison of mass, IR, H-1- and C-13-NMR spectra with reported literature data. Compounds 1, 2, 4, 7, and 8 exh ibited antifungal activity. Cytotoxic activity against several types o f mammalian cells (KB, P-388, P-388/DOX, and NSCLCN6-L16) in culture w as examined for the 8 diterpenoids. Some of them showed stronger cytot oxicity than mercaptopurine which was used as a positive control in th is study.