Novel enkephalin analogs and process for the preparation thereof

Abstract

The invention relates to novel enkephalin analoge of the general formula I H.sub.2 N-C(NH)-Tyr-A-Gly-Phe-B (I) wherein Tyr, Gly and Phe stand for an L-tyrosine, glycine and L-phenylalanine residue, resp. A stands for a D-amino acid residue having a lower alkyl group or a lower thioalkyl group as side chain, and B stands for an amino group or an L-proline amide moiety, and their pharmaceutically acceptable salts. These compounds can be prepared from peptides containing terminal amino group corresponding in amino acid sequence by transforming the terminal amino group to guanidino group in a known way and, if desired, by forming a salt with a pharmaceutically acceptable acid. The novel compounds of the general formula I possess valuable morphine-like (enkephalin-like) opiate activities.

Dependencies are inferred from the claim text.