SYNTHESIS AND BIOLOGICAL-ACTIVITY OF NEW ANALOGS OF BETA-CAZOMORPHINE-5

Four new analogues of beta-cazomorphine-5 modified at the C-end with e thylendiamine- and glycine-containing derivatives were synthesized by the standard method of peptide chemistry (mixed anhydrides, carbodiimi d, activated esters): H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-H (I) H-Tyr-Pro-P he-Pro-Gly-EtDA-Gly-Gly-H (II) H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-Gly-CO-C II3 (III) yr-Pro-Phe-Pro-Gly-EtDA-Gly-Gly-CO-CII2-CII2-COOII (IV) The level of affinity and the degree of selectivity of the peptides toward s the mu-and delta-opioid receptors of the rat brain lyophilized membr anes were studied by the radioreceptor method. All the new peptides di splayed analgetic activity, largely depending upon their structure.