Nonribosomal Peptides from Marine Sponges

Marine sponges are shown to be abundant sources of bioactive peptides. Structurally they include linear peptides, peptide lactones, cyclic peptides, and depsipeptides, with number of residues ranging from two to 48. Some of them have highly modified structural features with nonproteinogenic amino acid or hydroxy acid residues, while others have those with minimal alterations from the common ribosomal peptides. The structural characteristics, biogenesis, biological activity, and the issue of producing symbiotic organisms of nonribosomal peptides reported since 1993 are described in the order of structural types.