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. Author manuscript; available in PMC: 2011 Aug 15.
Published in final edited form as: Bioorg Med Chem. 2010 Jun 25;18(16):6024–6030. doi: 10.1016/j.bmc.2010.06.073

Table 1.

Receptor Binding Affinities and Functional Bioactivities of Compounds 1–14.

receptor affinityb (nM) selectivity functional bioactivity
Structure Kiδ Kiμ Kiμ/Kiδ MVD MVD GPI GPI
pA2d IC50c (nM) pA2d IC50c (nM)
1 H-Dmt-Tic-Asp*-Bide 0.44 53.9 122 0.12 1724
2 H-Dft-Tic-Asp*-Bid 0.162±0.02 (5) 225.1±36 (4) 1390 8.95
3 H-Tyr-Tic-Asp*-Bid 0.177±0.009 (4) 683.9±91 (6) 3864 8.85
4 H-Dmt-Tic-Gly*-Bidf 0.035 0.50 14 0.13 26.92
5 H-Dft-Tic-Gly*-Bid 1.01±0.05 (3) 54.5±4.4 (5) 54 67.3±6.8 >10000
6 H-Tyr-Tic-Gly*-Bid 0.913±0.03 (3) 66.9±8.8 (6) 73 50.1±1.67 4216±544
7 [Dmt1]Deltorphin Bg 0.16±0.03 (4) 1.68±0.14 (3) 10 0.32±0.02 48.2±1.76
8 [Dft1]Deltorphin B 0.241±0.03 (3) 154.3±19 (3) 640 0.40±0.08 3559±566
9 Deltorphin Bg 0.12 638 5317 0.53±0.02 >10000
10 H-Dmt-Tic-Lys-NH-Bzlh 0.50 4.05 8 6.01 7.96
11 H-Dft-Tic-Lys-NH-Bzl 153.4±21 (6) 1029±83 (4) 7
12 H-Tyr-Tic-Lys-NH-Bzl 63.9±7.6 (3) 1649±231 (6) 26
13 N,N(Me)2-Dmt-Tic-OHi 0.118 2435 20636 9.4 5.8
14 N,N(Me)2-Dft-Tic-OH 29.2±3.8 (5) 573.3±69 (4) 20
15 N,N(Me)2-Tyr-Tic-OHi 34.8±1.7 (4) 1234±48.5 (3) 35
16 N,N(Me)2-Dmt-Tic-NH2i 0.309 511.4 1655 9.9 6.3
17 N,N(Me)2-Dft-Tic-NH2 176.4±7.5 (5) 596.4±58 (4) 3
18 N,N(Me)2-Tyr-Tic-NH2 201.3±14 (4) 1451±25 (5) 7
b

The Ki values (nM) were determined according to Cheng and Prusoff.33 The mean ± SEM with n repetitions in parenthesis is based on independent duplicate binding assays conducted with five to eight peptide doses using several different synaptosomal preparations.

c

Agonist activity is expressed as IC50 obtained from dose-response curves. These values represent the mean ± SE for at least four tissue samples. DPDPE and PL017 were the internal standards for MVD (δ-opioid receptor bioactivity) and GPI (μ-opioid receptor bioactivity) tissue preparation, respectively.

d

The pA2 values of opioid antagonists against the δ and μ agonists (deltorphin II and endomorphin-2, respectively) were determined by the method of Kosterlitz and Watt.36

e

Data taken from Balboni et al.12

f

Data taken from Balboni et al.13

g

Affinity data taken from Guerrini et al.17

h

Data taken from Balboni et al.14

i

Data taken from Salvadori et al.15