Dragmacidin G, a Bioactive Bis-Indole Alkaloid from a Deep-Water Sponge of the Genus Spongosorites

A deep-water sponge of the genus has yielded a bis-indole alkaloid which we have named dragmacidin G. Dragmacidin G was first reported by us in the patent literature and has recently been reported by Hitora et al. from a sponge of the genus . Dragmacidin G is the first in this series of compounds to have a pyrazine ring linking the two indole rings. It also has a rare -(2-mercaptoethyl)-guanidine side chain. Dragmacidin G shows a broad spectrum of biological activity including inhibition of methicillin-resistant , , and a panel of pancreatic cancer cell lines.