4 NEW DIMERIC PEPTIDE ALKALOIDS, ANCHINOPEPTOLIDES-B-D, AND CYCLOANCHINOPEPTOLIDE-C, CONGENERS OF ANCHINOPEPTOLIDE-A, FROM THE MEDITERRANEAN MARINE SPONGE ANCHINOE-TENACIOR

Following the characterization of anchinopeptolide A [1], three new conge netic dimeric peptide alkaloids, named anchinopeptolides B [2], C [3], and D [4], have been isolated from the Mediterranean sponge Anchinoe tenacior. A fourth compound, cycloanchinopeptolide C [5], which is related to anchinopeptolide C [5] by a head-to-head intramolecular [2+2] cycle-addition reaction, has also been isolated. The structures of these peptide alkaloids have been elucidated on the basis of spectral evidence. Anchinopeptolides bind to the somatostatin, human B2 bradykinin, and neuropeptide Y receptors.