Synthesis and opioid activity of tyrosine sulfate containing dermorphin and deltorphin peptides.

To study the effect of the sulfate ester moiety on the opioid activity, we prepared two tyrosine sulfate-(Tyr(SO3H)-containing dermorphin and deltorphin peptides. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membranes and in two bioassays, using guinea pig ileum and mouse vas deferens. In comparison to original peptides and morphine, the obtained data indicate that whereas H-Tyr(SO3H)-D-Ala-Phe-Gly-NH2 shows very minimal interaction with opioid receptors, H-Tyr(SO3H)-D-Ala-Phe-Asp-Val-Val-Gly-NH2 retains a significant activity.