Isolation of the Cembranoid Preverecynarmin Alongside Some Briaranes,the Verecynarmins,from Both the Nudibranch Mollusc Armina maculata and the Octocoral Veretillum cynomorium of the East Pyrenean Mediterranean Sea

It is shown that the nudibranch mollusc Armina maculata and its prey, the pennatulacean octocoral Veretillum cynomorium, of east Pyrenean waters contain a novel cembranoid, preverecynarmin ((+)- 8 ), besides the known cembranoid cembrene C ( 9 ) and three further briarane diterpenoids (verecynarmin E ((?)- 5 ), F ((?)- 6 ), and G ((?)- 7 )). A biogenetic scheme is proposed.