Table 2.

Very low affinity of C-1 for other nuclear receptors.

Nuclear Receptor	hPR	hAR	hGR
Radioligand	[3H] progesterone 0.5 nM	[3H] methyltrienolone 1 nM	[3H] dexamethasone 1.5 nM
Inhibition (%) in the presence of 1 µM C-1	14.7%	−2.3%	4.4%

The binding inhibition rate (%) of compound C-1 for PR, AR, and GR was determined. Each recombinant human nuclear receptor was incubated with the indicated concentration of the radiolabeled ligand and 1 µM C-1 for 6–20 hr at 4 °C. Inhibitory effects of C-1 were determined by scintillation counting. These results show very low affinities of C-1 for other nuclear receptors. Abbreviation: AR, androgen receptor; GR, glucocorticoid receptor; PR, progesterone receptor.