Cyclonellin, a new cyclic octapeptide from the marine sponge Axinella carteri.

Cyclonellin (1), a new cyclic octapeptide, was isolated from an aqueous extract of the marine sponge Axinella carteri. Its structure was elucidated by interpretation of NMR spectral data of the intact compound and N-terminal Edman sequencing of linear peptide fragments obtained by partial hydrolysis of 1. The absolute configurations of the constituent amino acids were determined by acid hydrolysis, derivitization with FDAA, and LC-MS analyses.