The synthesis and biological activity of a new type of enkephalin analogs are reported. A series of branched pentapeptides of the enkephalin sequence with replacement of 2-glycine by D-ornithine and branching of the peptide chain in position 2 by attachment of proline, leucine, asparagine or methionine residues to the δ-amino group of D-ornithine were synthesized by classical solution methodology. Analgesic activity of the new analogs was ...
