Biosynthesis of Drimane Terpenoids in Dorid Molluscs: Pivotal Role of 7-Deacetoxyolepupuane in Two Species of Dendrodoris Nudibranchs

Described in this paper is the biosynthesis of defensive drimanes in dorid nudibranchs. Two geographically distinct populations of molluscs belonging to the genus Dendrodoris have been studied. The de novo synthesis of 7-deacetoxyolepupuane (2) has been demonstrated by radiolabelled precursors in both species. The results of the studies are consistent with the pivotal role of 2 in the formation of the other drimanes both in the mantle and in the egg masses of the molluscs. The new drimane 6-[3-acetoxypolygodial (7) is reported from the skin extract of the pacific Dendrodoris arborescens. Its structure elucidation was accomplished by NMR spectroscopy.