2-Hydroxyestradiol

2-Hydroxyestradiol (2-OHE2) is a metabolite of estradiol, which is the primary female sex hormone. It is formed in the body through the action of enzymes known as cytochrome P450s, specifically the subtypes CYP1A1, CYP1A2, and CYP1B1.

Chemistry

2-Hydroxyestradiol is a steroid and a phenol, with two hydroxyl groups. It is structurally similar to estradiol, but with an additional hydroxyl group at the 2-position on the steroid ring. This modification increases its water solubility and alters its biological activity.

Biological activity

2-Hydroxyestradiol has been found to have both estrogenic and anti-estrogenic properties. It can bind to estrogen receptors and exert estrogenic effects, but its affinity for these receptors is much lower than that of estradiol. In contrast to estradiol, 2-hydroxyestradiol does not stimulate cell proliferation, and may even inhibit the growth of certain types of cancer cells.

Health implications

The balance between 2-hydroxyestradiol and other estradiol metabolites, such as 16α-hydroxyestrone, may have implications for breast cancer risk. Some studies have suggested that a higher ratio of 2-hydroxyestradiol to 16α-hydroxyestrone is associated with a lower risk of breast cancer.

See also

• Estradiol
• Estrogen
• Cytochrome P450
• Breast cancer