Stypolactone, an interesting diterpenoid from the brown alga Stypopodium zonale

A new diterpenoid of mixed biogenesis, stypolactone 8, containing a tricyclic terpenoid moiety which in combination with its spirolactone ring, leads to a novel carbon skeleton, has been isolated from the brown alga Stypopodium zonale. Itʹs structure and relative stereochemistry were established by spectroscopic evidence and biogenetic considerations.