Receptor affinity assessed with either [3H]Org 43553 or 125I-hCG, and receptor activity of compounds 1-6 and recombinant LH at the human luteinizing hormone receptor.
 |  | ||||||
|---|---|---|---|---|---|---|---|
| 1-5 | 6 | ||||||
| Compound | R1 | R2 | R3 | [3H]Org 43553 Bindinga | [125I]hCG Bindingb | EC50c | |
| nM | |||||||
| 1 (Org 41841) | SMe | OMe | tBu | 17 ± 5 | 1 (0-1) | 13 ± 1 | |
| 2 (Org 41247) | Ph | OMe | iPr | 100 ± 6 | 4 (0-8) | 119 ± 18 | |
| 3 (Org 42619) | SMe |
| tBu | 4.7 ± 0.7 | 0 (0-0) | 3.0 ± 0.5 | |
| 4 (Org 43311) | SMe |
| tBu | 4.1 ± 0.7 | 4 (0-7) | 1.3 ± 0.4 | |
| 5 (Org 43553) | SMe |
| tBu | 3.3 ± 0.3 | 7 (6-8) | 1.7 ± 0.2 | |
| 6 (Org 43983) | 82 ± 17 | 0 (0-0) | 111 ± 3 | ||||
| recLH |
|
|
| 32 (31-33)d | 0.61 ± 0.1e | 0.078 ± 0.002 | |
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* Position of the tritium substitution in Org 43553.
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↵ a Displacement of specific [3H]Org 43553 binding from human luteinizing hormone receptors stably expressed on CHO-K1 cell membranes [Ki ± S.E.M. (nM), n ≥ 3, duplicate].
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↵ b Percentage displacement of specific 125I-hCG binding from human luteinizing hormone receptors stably expressed on CHO-K1 cell membranes at 10 μM concentrations (n = 2, duplicate).
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↵ c cAMP-mediated luciferase activity in CHO-K1 cells that stably express the human luteinizing hormone receptor and CRE-luciferase reporter gene (mean ± S.E.M., n ≥ 3, duplicate).
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↵ d Percentage displacement of specific [3H]Org 43553 binding at 70 nM recLH (n = 4, duplicate).
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↵ e Displacement of specific 125I-hCG binding [Ki ± S.E.M. (nM), n = 3, duplicate].