Synthesis, binding affinities and metabolic stability of dimeric dermorphin analogs modified withβ3-homo-amino acids

In this study, proteinogenic amino acids residues of dimeric dermorphin pentapeptides were replaced by the corresponding β(3)-homo-amino acids. The potency and selectivity of hybrid α/β dimeric dermorphin pentapeptides were evaluated by competetive receptor binding assay in the rat brain using [3H]DAMGO (a μ ligand) and [3H]DELT (a δ ligand). Tha analog containing β(3)-homo-Tyr in place of Tyr (Tyr-D-Ala-Phe-Gly-β(3)-homo-Tyr-NH-)2 showed good μ receptor affinity and selectivity (IC50 = 0.302, IC50 ratio μ/δ = 68) and enzymatic stability in human plasma.