Developmental Potential for Endomorphin Opioidmimetic Drugs

Table 1

Opioid receptor affinities of opioid ligands 1–50.

Nos.	Compounds		Kiμ (nM)	Kiδ (nM)	Kiδ/Kiμ	Reference
1	H-Tyr-Pro-Trp-Phe-NH2	(EM-1)	0.36	1,510	4,190	[4]
2	H-Tyr-Pro-Phe-Phe-NH2	(EM-2)	0.69	9,230	13,380	[4]
3	D-D-D-D	(EM-2)	1,041	16,579	98	[5]
4	L-L-D-D	(EM-2)	24.3	1,249	51	[5]
5	D-D-L-L	(EM-2)	2,755	19,459	7	[5]
6	D-L-L-L	(EM-2)	32.1	4,121	128	[5]
7	L-D-D-D	(EM-2)	2,013	13,278	6.6	[5]
8	L-L-L-D	(EM-2)	45.9	8,159	177	[5]
9	D-D-D-L	(EM-2)	107.9	7,203	67	[5]
10	L-L-D-L	(EM-2)	203.2	4,230	21	[5]
11	D-D-L-D	(EM-2)	7,051	18,624	2.6	[5]
12	L-D-L-L	(EM-2)	512.4	30,641	60	[5]
13	D-L-D-D	(EM-2)	363.5	21,264	58	[5]
14	D-L-L-D	(EM-2)	557.3	4,187	7.5	[5]
15	L-D-D-L	(EM-2)	4,707	16,662	3.5	[5]
16	D-L-D-L	(EM-2)	651.6	14,584	22	[5]
17	L-D-L-D	(EM-2)	1,311	26,211	20	[5]
18	H-Tyr-Pro-Phe-NH2		46.1	15,900	344	[9]
19	H-Dmt-Pro-Trp-Phe-NH2		0.054	5.6	104	[10]
20	H-Dmt-Pro-Phe-Phe-NH2		0.15	28.2	188	[9]
21	H-Dmt-Pro-Phe-NH2		0.12	53.2	443	[9]
22	H-Dmt-Pro-Phe-NH-C2H4-Ph		0.51	18	35	[9]
23	H-Dmt-Pro-Phe-NH-Bzl		0.52	13.8	27	[11]
24	H-Dmt-Pro-Phe-NH-Ph		1.11	20.6	19	[11]
25	H-Dmt-Pro-Phe-NH-4-Pyr		0.36	52.6	146	[11]
26	H-Dmt-Pro-Phe-NH-3-Pyr		0.17	287	1,690	[11]
27	H-Dmt-Pro-Phe-NH-2-Pyr		0.13	157	1,210	[11]
28	H-Dmt-Pro-Phe-NH-1-Nph		0.29	19.9	68	[11]
29	H-Dmt-Pro-Phe-NH-3-Qln		0.33	190	575	[11]
30	H-Dmt-Pro-Phe-NH-5-Qln		0.11	30	272	[11]
31	H-Dmt-Pro-Phe-NH-6-Qln		0.22	46.6	212	[11]
32	H-Dmt-Pro-Phe-NH-8-Qln		0.49	33.1	68	[11]
33	H-Dmt-Pro-Phe-NH-5-Isq		0.19	98.3	517	[11]
34	H-Mmt-Pro-Phe-Phe-NH2		0.132	528.6	4,005	[12]
35	H-Emt-Pro-Phe-Phe-NH2		0.063	55.7	884	[12]
36	H-Imt-Pro-Phe-Phe-NH2		0.15	190	1,226	[12]
37	H-Det-Pro-Phe-Phe-NH2		0.084	69.7	830	[12]
38	H-Dit-Pro-Phe-Phe-NH2		2.29	105	46	[12]
39	H-Tmt-Pro-Phe-Phe-NH2		0.111	593.5	5,347	[12]
40	H-Dmt-Pro-Mmp-Phe-NH2		0.18	4.61	26	[13]
41	H-Dmt-Pro-^3,5Dmp-Phe-NH2		0.11	11.6	105	[13]
42	H-Dmt-Pro-Dmp-Phe-NH2		0.069	2.27	33	[13]
43	H-Dmt-Pro-Dmt-Phe-NH2		0.092	80.8	878	[13]
44	H-Dmt-Pro-Tmp-Phe-NH2		0.18	1.83	10	[13]
45	H-Dmt-Pro-Emp-Phe-NH2		0.21	3.03	14	[13]
46	H-Dmt-Pro-Imp-Phe-NH2		0.32	4.61	14	[13]
47	[N-allyl-Dmt^1]EM-1		0.26	10.3	40	[10]
48	[N-allyl-Dmt^1]EM-2		0.45	560	1,244	[10]
49	1,6-bis[N-allyl-Dmt-NH]hexane		12.4	51.5	4	[10]
50	3,6-bis[N-allyl-Dmt-NH-propyl]-5-methyl-2(1H)-pyrazinone		6.94	77.8	11	[10]

Opioid receptor affinities are determined using rat brain P₂  synaptosomal preparations with [³H]DAMGO for μ-opioid receptors and [³H]DPDPE for  δ-opioid receptors.