7alpha-hydroxytheonellasterol, a cytotoxic 4-methylene sterol from the Philippines sponge Theonella swinhoei.

A new 4-methylene sterol, 7alpha-hydroxytheonellasterol (3), was isolated from the Philippines sponge Theonella swinhoei, along with the known compounds theonellasterol (1) and bistheonellide A. The structure of 3 was elucidated by interpretation of its spectroscopic data, which were compared with those of 1.