Marine alkaloids, 15. Two alkaloids, flustramine E and debromoflustramine B, from the marine bryozoan Flustra foliacea.

A new alkaloid, flustramine E [1], with inhibitory activity towards Rhizotonia solani and Botrytis cinerea was isolated by gas-phase extraction from the marine bryozoan Flustra foliacea. The structure was determined as 3a,8a-cis-1-methyl-3a-(3-methyl-2- butenyl)-6-bromo-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole, based on spectroscopic investigations. Another alkaloid, debromoflustramine B [2a], was detected in trace amounts and identified by comparison of the mass spectrum with that of a synthetic sample. The extract also contained the previously reported alkaloids flustramine A and B in the ratio 1:7.