[Comparison of the opioid activity of a number of enkephalin and dermorphin analogs]

In search of selective ligands of opioid receptors there was synthetized a number of shortened dermorphin analogues containing nucleic amino acid substituents in positions 4 and 5 and also nucleic amino acid analogues of enkephalins. All synthetized analogues of enkephalins and dermorphin possess opioid activity revealed on preparations of the guinea pig ileum and the mouse vas deferens. Among the obtained analogues there were detected analogues exhibiting a high delta-agonistic (Tyr-D-Ala-Phe-Gly-DL-Tal-OH) or mu-agonistic (Tyr-D-Phe-Gly-Tal-Leu-OH) activity comparable with that for standard preparations DADLE and DAGO.