. Author manuscript; available in PMC: 2009 Oct 23.

Published in final edited form as: J Med Chem. 2008 Sep 27;51(20):6334–6347. doi: 10.1021/jm800389v

Table 5.

Binding affinities of bifunctional peptides 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	−8.2 ± 0.06	2.8	−7.1 ± 0.11	36	13	−9.9 ± 0.25	0.084	−9.0 ± 0.10	0.29	3.4
2	−8.8 ± 0.07	0.66	−7.4 ± 0.05	16	24	−10.9 ± 0.10	0.0065	−7.6 ± 0.05	7.3	1100
3	−9.1 ± 0.09	0.44	−8.4 ± 0.03	1.8	4.1	−8.4 ± 0.42	3.20	−5.6 ± 0.06	700	220
Biphalinⁱ		2.6		1.4	0.54
4						−8.8 ± 0.02	0.73	−6.4 ± 0.12	130	180

Competition analyses were carried out using membrane preparations from transfected HN9.10 cells that constitutively expressed the δ and μ opioid receptors, 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 = 0.40 ± 0.17 nM

K_d = 0.16 ± 0.03 nM

The logIC₅₀ ± standard errors are expressed as logarithmic values determined from the non linear regression analysis of data collected from 2 independent experiments performed in duplicate (4 independent experimental values per drug concentration). The K_i values are calculated using the Cheng and Prusoff equation to correct for the concentration of the radioligand used in the assay.

See a reference.³⁸

ⁱ

See a reference.⁸⁵