Para-substituted Phe3 deltorphin analogues: Enhanced selectivity of halogenated derivatives for δ opioid receptor sites

Article abstract of DOI:10.1021/jm00103a001

The δ-selective opioid peptide deltorphin C(H-Tyr-D-Ala-Phe-Asp-Val-Val- Gly-NH₂) (DEL C) was modified by para-substitution of Phe³ with halogens (F, Cl, Br, I), amino, or nitro groups. The bioactive potencies in peripheral tissues a