and semiquinones, and this has been hypothesized to contribute to estrogen-induced carcinogenesis.

Similarly to estradiol and estrone, catechol estrogens possess estrogenic activity. 2-Hydroxylated catechol estrogens are weak and possibly antiestrogenic estrogens, whereas their 4-hydroxylated counterparts are more potent in their estrogenic activity. For instance, 2-hydroxyestrone reportedly shows negligible uterotrophic