Estrogenic and anti-androgenic activities of benzophenones in human estrogen and androgen receptor mediated mammalian reporter gene assays

The estrogenic and anti-androgenic activities of benzophenone and 19 hydroxylated derivatives were measured in reporter gene assays using transfected human estrogen and androgen receptors in Chinese hamster ovary cells. Eighteen benzophenones had estrogenic activity and seventeen also had anti-androgenic activity. In both assays, 2,4,4'-trihydroxybenzophenone and 2,2',4,4'-tetrahydroxybenzophenone showed the strongest activity which were comparable to bisphenol A or 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE). The structure- activity relationships of the estrogenic activity in this mammalian reporter gene assay were mostly similar to the yeast two-hybrid assay as previously reported. Benzophenones hydroxylated at the 3 or 4-position showed the estrogenic activity, while the others showed negative or weakly positive activities. Moreover, a hydroxyl group added at the 2-position of the 4-hydroxylated benzophenone enhanced activity, but reduced activity at the 3-position. In contrast, different results were obtained when a hydroxyl group was added to another benzene ring. The added hydroxyl group enhanced the activity in this reporter gene assay, but reduced it in the yeast two-hybrid assay. Results from the reporter gene assay corresponded with the in vivo, uterotrophic assay. On the other hand, a hydroxyl group at the 2-position generally enhanced the anti-androgenic activity, though the effect of other hydroxyl groups was less clear. Meanwhile, these benzophenones had no or very weak androgen agonistic activities.