Penasterol, a novel antileukemic sterol from the okinawan marine sponge Penares sp.

A novel lanosterol-derived metabolite, penasterol (1), with potent antileukemic activity has been isolated from the Okinawan marine sponge Penares sp. and the structure elucidated on the basis of evidence provided by spectroscopy and chemical transformations. This is the first isolation of a marine sterol with a 14-carboxy group potentially important within the framework of sterol biosynthesis.