Table 1.
Calculated EC50 value and RCP for several natural and synthetic steroids as determined in the yeast glucocorticoid and U2-OS GR-CALUX bioassays
| Compound | Yeast glucocorticoid assay | GR-CALUX | ||
|---|---|---|---|---|
| EC50 (μM) | RCP | EC50 (nM) | RCP | |
| Dexamethasone | 120 | 1.0 | 2.2 | 1.0 |
| Budesonide | 6 | 20 | 2.2 | 1.0 |
| Betamethasone | 149 | 0.8 | 11 | 0.2 |
| Cortisol | 123 | 1.0 | 37 | 0.06 |
| Corticosterone | 71 | 1.7 | 80 | 0.03 |
| Cortisone | Not active | 0.0 | Not active | 0 |
| Aldosterone | 705 | 0.2 | 495 | 0.004 |
| Fludrocortisone-21-acetate | Not active | 0.0 | 11 | 0.2 |
| Prednisolone | 643 | 0.2 | 12 | 0.2 |
| Prednisone | Not active | 0.0 | Not active | 0 |
| Triamcinolone | Activea | Active | 19 | 0.1 |
| Mifepristone | 578 | 0.2 | Not activeb | 0 |
| 17β-Estradiol (E2) | Not active | 0.0 | Not active | 0 |
| 5α-Dihydrotestosterone | Not active | 0.0 | Not active | 0 |
| Progesterone (P4) | Activea | Active | Activea | Active |
aTriamcinolone and progesterone are slightly active in the yeast bioassay, but their maximal responses are only about 10% and 6%, respectively, of the maximal response as obtained with dexamethasone; thus, it is not appropriate to give an EC50 value or RCP. Progesterone is also active in the GR-CALUX, but its response is only about 4% of the maximal response as obtained with dexamethasone
bMifepristone is not active as an agonist in the GR-CALUX and acts as a pure antagonist in this assay