Cephalodiscus gilchristi alkaloids

Pettit et al. (24), working on the marine worm Cephalodiscus gilchristi (order Cephalodisicida, phyla Hemichordata, class Pterobranchia) collected from the Indian Ocean off Southeast Africa, have isolated a number of bioactive bis-steroidal pyrazine alkaloids, the cephalostatins 1-15 (11-25). 

Pettit et al., have proposed a biogenetic pathway for the dimeric pyrazine-containing steroidal alkaloids, the cephalostatins isolated from the marine worm Cephalodiscus gilchristi and the tunicate Ritterella tokioka. These alkaloids contain at least 13 fused rings, which constitutes the largest such system known in marine animals. 

---