Sinulobatins A similar to D, new amphilectane-type diterpenoids from the Japanese soft coral Sinularia nanolobata

Four new amphilectane-type diterpenoids, sinulobatins A (1), B (2), C(3) and D (4) were isolated from the Japanese soft coral Sinularia nanolobata. Their determined based on spectroscopic evidence and single crystal X-ray analysis. The absolute stereochemistry of 1 was elucidated on the basis of its CD spectrum. These compounds exhibited cytotoxicity against L1210 cells and KB cells in vitro with IC50 values of 3.0 - 7.7 mu g/mL. (C) 1997 Elsevier Science Ltd.