Table 3. Experimental kinetic/thermodynamic data and steroidogenic parameters for TSPO ligands.
| TSPO ligand | EC50(μM) | Emax (at 100 μM)(vehicle set to 100%) | Equilibrium Ki or Kd(nM) | RT (min) |
|---|---|---|---|---|
| PK11195 | 19.5 ± 1.8 | 153 ± 4 | 3.30 ± 0.34 | 34 ± 3 |
| Ro5-4864 | 36.2 ± 2.5 | 150 ± 4 | 20.04 ± 2.36 | 32 ± 3 |
| PIGA719 | 12.9 ± 1.5 | 146 ± 2 | 12.24 ± 1.1 | 11 ± 2 |
| PIGA720 | 29.7 ± 3.1 | 144 ± 4 | 1.40 ± 0.28 | 26 ± 2 |
| PIGA745 | 34.6 ± 3.6 | 140 ± 5 | 13.14 ± 1.16 | 17 ± 1 |
| PIGA823 | 12.2 ± 1.3 | 272 ± 11 | 3.30 ± 0.31 | 127 ± 4 |
| PIGA835 | 25.6 ± 2.3 | 149 ± 4 | 0.91 ± 0.11 | 17 ± 1 |
| PIGA839 (M-PIGA) | 16.3 ± 1.4 | 254 ± 5 | 5.50 ± 0.47 | 109 ± 4 |
| PIGA925 | 9.71 ± 1.0 | 166 ± 5 | 12.23 ± 3.14 | 15 ± 2 |
| PIGA1128 | 26.1 ± 1.5 | 179 ± 7 | 0.31 ± 0.02 | 55 ± 2 |
| PIGA1138 | 13.1 ± 1.4 | 275 ± 5 | 0.34 ± 0.03 | 141 ± 4 |
| PIGA1214 | 92.0 ± 5.6 | 141 ± 4 | 343.01 ± 15.94 | 39 ± 2 |
Values are means ± SEM of three experiments performed in duplicate. Potency (EC50 value) of TSPO ligands was derived by sigmoidal concentration-dependent curves. Efficacy (Emax) corresponds to amount of pregnenolone production by 100 μM TSPO ligand concentration.