Five New Diterpenoids from an Okinawan Soft Coral, Cespitularia sp.

Five new diterpenoids 1-5 were isolated from an Okinawan soft coral, Cespitularia sp., together with the known diterpenoid, alcyonolide (6). New diterpenoid structures were elucidated by spectroscopic methods and by comparison of their NMR data with those of related compounds. Alcyonolide (6) was cytotoxic against HCT 116 cells (IC50 5.85 mu M), while these new diterpenoids 1-5 were much less active (IC50 28.2-91.4 mu M).