Table 3.

Opioid receptor affinities and efficacy of [NMePhe¹]arodyn analogs where position 3 was substituted with other aromatic and non-aromatic amino acids

X-NMePhe-Phe-R-Arg-Leu-Arg-Arg-D-Ala-Arg-Pro-Lys-NH₂

Peptide	X	R	Ki ± SEM (nM)		Ki ratio (μ/κ)	AC % control @ 10 μMa
			κ	μ
5	CH3OCO	Phe	4.93 ± 0.15	1750 ± 100	355	74 ± 13
9	CH3OCO	Trp	9.52 ± 1.73	1280 ± 280	134	98 ± 13
13	CH3OCO	Tyr	5.80 ± 1.27	1300 ± 340	224	58 ± 10
14	CH3OCO	Nal(2′)	24.4 ± 7.2	53.8 ± 13.1	2	109 ± 10
15	CH3OCO	Cha	3.60 ± 0.21	818 ± 253	227	55 ± 18
2 b	Ac	Phe	4.56 ± 0.45	5056 ± 790	1100	86 ± 1
3	Ac	Trp	13.0 ± 2.6	2990 ± 700	230	105 ± 16
16	Ac	Tyr	37.3 ± 16.0	3370 ± 570	90	52 ± 11
17	Ac	Nal(2′)	27.0 ± 7.3	121 ± 35	4.5	101 ± 11
18	Ac	Cha	7.85 ± 2.74	5930 ±1920	755	52 ± 6

^aRelative to the full agonist Dyn A (1-13)NH₂ (0% control, 100% inhibition).

^bFrom reference ³⁰.