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. Author manuscript; available in PMC: 2009 Apr 8.
Published in final edited form as: J Med Chem. 2008 Mar 1;51(6):1817–1823. doi: 10.1021/jm7014765

Table 1.

Receptor binding affinities and functinal bioactivities of compounds 1–2.

Comp. Structure Receptor affinitya (nM) Selectivity Functional bioactivity
Kiδ Kiμ Kiμ/ Kiδ MVD pA2c MVD IC50b (nM) GPI IC50b (nM)
Ref. 1 H-Dmt-Tic-ε-Lys(R)-R’ d 0.21–2.64 0.60–3.43 1.7–16.3 7.81–8.27 434–1990
1 graphic file with name nihms87863t1.jpg 0.172±0.003 (3) 41.2±1.76 (3) 240 8.25 1916±554
Ref. 2 H-Dmt-Tic-Phe-Lys(Z)-OHe 0.019 2.75 145 11.43 >10000
2 graphic file with name nihms87863t2.jpg 0.248±0.019 (3) 13.2±1.13 (3) 53 9.45 5176±1400 50.6±6.9
*

μ selectivity Kiδ/ Kiμ.

a

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

b

Agonist activity was expressed as IC50 obtained from dose-response curves representing the mean ± SE for at least five to six fresh GPI tissue samples. Deltorphin II and endomorphin-2 were the internal standards for MVD (δ-opioid receptor bioactivity) and GPI (μ-opioid receptor bioactivity) in the tissue preparations, respectively.

c

The pA2 values of opioid antagonists were determined against the agonists deltorphin II and endomorphin-2 according to the method of Kosterlitz and Watt.36

d

Data taken from Balboni et al.22

e

Data taken from Balboni et al.23