. Author manuscript; available in PMC: 2012 Apr 14.

Published in final edited form as: J Med Chem. 2011 Mar 2;54(7):2029–2038. doi: 10.1021/jm101023r

Table 1.

Binding affinities of bifunctional peptide derivatives at δ/μ opioid receptors and NK1 receptors

no	hDOR^a, [³H]DPDPE ^b		rMOR^a, [³H]DAMGO ^c		K_i(μ) /K_i(δ)	hNK1^d, [³H]Substance P^e		rNK1^d, [³H]Substance P^f		K_i(hNK1) /K_i(rNK1)

	LogIC₅₀^g	K_i (nM)	LogIC₅₀^g	K_i (nM)		LogIC₅₀^g	K_i (nM)	LogIC₅₀^g	K_i (nM)
1 ^h	−8.84 ± 0.07	0.66	−7.44 ± 0.05	16	24	−10.91 ± 0.10	0.0065	−7.61 ± 0.03	7.3	1100
2 ⁱ	−8.67 ± 0.05	1.0	−7.17 ± 0.07	32	32	−11.57 ± 0.59	0.0028	−7.68 ± 0.03	6.8	2400
3	−7.62 ± 0.10	11	−8.60 ± 0.03	1.2	0.11	−9.78 ± 0.04	0.075	−7.28 ± 0.06	13	170
4	−9.01 ± 0.11	0.46	−8.48 ± 0.1	1.8	3.9	−9.33 ± 0.04	0.21	−7.51 ± 0.08	11	52
5	−8.07 ± 0.06	4.1	−8.82 ± 0.04	0.74	0.18	−8.66 ± 0.04	1.0	−6.41 ± 0.04	140	140
6	−9.50 ± 0.11	0.15	−9.20 ± 0.05	0.34	2.3	−8.70 ± 0.03	0.95	−6.05 ± 0.03	320	340
7	−9.42 ± 0.08	0.18	−8.37 ± 0.15	2.0	11	−10.74 ± 0.04	0.0079	−8.29 ± 0.35	2.3	290
Biphalin ^j		2.6		1.4	0.54
L-732,138						−8.83 ± 0.02	0.73	−6.40 ± 0.03	130	180

Competition analyses were carried out using membrane preparations from transfected HN9.10 cells that constitutively expressed the DOR and MOR, respectively.

K_d = 0.45 ± 0.1 nM.

K_d = 0.50 ± 0.1 nM.

Competition analyses were carried out using membrane preparations from transfected CHO cells that constitutively expressed rat or human NK1 receptors.

K_d = 0.16 ± 0.03 nM.

K_d = 0.40 ± 0.17 nM.

The logIC₅₀ ± standard error are expressed as logarithmic values determined from the non linear regression analysis of data collected from at least two independent experiments performed in duplicate. The K_i values are calculated using the Cheng and Prusoff equation to correct for the concentration of the radioligand used in the assay.

Reference.¹³

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Reference.¹⁴

Reference.³⁸