Developmental Potential for Endomorphin Opioidmimetic Drugs

Table 2

Opioid receptor affinities of opioid ligands 51–70.

Nos.	Compounds	Kiμ(nM)	Kiδ(nM)	Kiδ/Kiμ	Reference
51	Dmt-NH-(CH2)2-NH-Dmt	1.43	115.7	81	[18]
52	Dmt-NH-(CH2)4-NH-Dmt	0.041	53.4	1302	[18]
53	Dmt-NH-(CH2)6-NH-Dmt	0.053	46.1	870	[18]
54	Dmt-NH-(CH2)8-NH-Dmt	0.19	14.8	78	[18]
55	3,6-bis[Dmt-NH-CH2]-5-methyl-2(1H)-pyrazinone	1.16	15.7	13.5	[19]
56	3,6-bis[Dmt-NH(CH2)2]-5-methyl-2(1H)-pyrazinone	0.115	7.26	63	[19]
57	3,6-bis[Dmt-NH(CH2)3]-5-methyl-2(1H)-pyrazinone	0.042	13.2	307	[19]
58	3,6-bis[Dmt-NH(CH2)4]-5-methyl-2(1H)-pyrazinone	0.114	23.2	204	[19]
59	3,6-bis[Dmt-Tic-NH-CH2]-5-methyl-2(1H)-pyrazinone	3.76	0.163	0.043	[20]
60	3,6-bis[Dmt-Tic-NH(CH2)2]-5-methyl-2(1H)-pyrazinone	2.83	0.095	0.034	[20]
61	3,6-bis[Dmt-Tic-NH(CH2)3]-5-methyl-2(1H)-pyrazinone	3.08	0.155	0.05	[20]
62	3,6-bis[Dmt-Tic-NH(CH2)4]-5-methyl-2(1H)-pyrazinone	1.74	0.323	0.185	[20]
63	3-[Dmt-Tic-NH(CH2)3]-6-[Dmt-Tic-NH(CH2)4]-5-methyl-2(1H)-pyrazinone	1.56	0.16	0.1	[20]
64	3-[Dmt-Tic-NH(CH2)4]-6-[Dmt-Tic-NH(CH2)3]-5-methyl-2(1H)-pyrazinone	2.28	0.092	0.04	[20]
65	3-[Dmt-Tic-NH(CH2)2]-6-[Dmt-Tic-NH(CH2)4]-5-methyl-2(1H)-pyrazinone	1.37	0.107	0.078	[20]
66	bis[Dmt-Tic-NH]butane	5.72	0.124	0.021	[20]
67	bis[Dmt-Tic-NH]hexane	1.79	0.129	0.072	[20]
68	bis[Dmt-Tic-NH]decane	4.86	1.53	0.315	[20]
69	bis[N,N-dimethyl-Dmt-Tic-NH]	2.21	0.06	0.027	[20]
	hexane
70	3,6-bis[N,N-dimethyl-Dmt-Tic-NH-	1.68	0.287	0.17	[20]
	propyl]-5-methyl-2(1H)-pyrazinone

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.