Analogs of the δ opioid receptor selective cyclic peptide [2-D- penicillamine,5-D-penicillamine]-enkephalin: 2',6'-Dimethyltyrosine and Gly3-Phe4 amide bond isostere substitutions

Article abstract of DOI:10.1021/jm00094a002

In order to develop systemically-active opioid peptides, the δ-selective, opioid pentapeptide [D-Pen²,D-Pen⁵]-enkephalin (DPDPE) was modified by esterification and by substitution of 2',6'-dimethyltyrosine for tyrosine to yield 4. Co