Isolation of norsesterterpenes and spongian diterpenes from Dorisprismatica (= Glossodoris) atromarginata

Ten new norscalarane metabolites (1-10) with the mooloolabene skeleton in which the C-8 methyl substituent of a scalarane is replaced by a C-7/C-8 double bond are described from the nudibranch Doriprismatica (= Glossodoris) atromarginata and characterized by extensive 1D and 2D NMR studies, together with MS data. Also isolated was the known scalarane 12-deacetoxy-12-oxo-deoxoscalarin together with 26 furanoterpenes, nine of which (11-19) are reported for the first time. The high diversity of chemical compounds and variation between individuals and locations could reflect a varied sponge diet or an enzymatic detoxification mechanism.