Structure-activity relationships for dermorphin-related tetrapeptides.

The opiate-like activity of six newly synthesized dermorphin-related tetrapeptides was determined in guinea pig ileum, mouse vas deferens and mouse tail-flick tests. Naloxone was a powerful antagonist of all compounds. Moreover, the biological activities of the compounds under examination were correlated in a statistically significant way to the lipophilic character of the C-terminal substituents and to an indicator variable taking into account the presence of an amidic group at the C-terminus.