Abstract
Fortisterol (1), a novel steroid with a rare seven-membered lactone ring B, has been isolated from the marine sponge Biemna fortis and its structure gas been elucidated on the basis of spectroscopic data.
Acknowledgements
This research is financially supported by the “National Science Foundation for Outstanding Chinese Youth” (No. 30125044), National 863 project (2001AA620403) and the “National Natural Science Foundation” (No. 30170106).