<unk> , also known as 15α-hydroxyestriol or as estra-1,3,5(10)-triene-3,15α,16α,17β-tetrol, is an estrane steroid and derivative of estrin (estratriene). It is structurally different from the other estrogens because of the presence of four hydroxyl groups, which explains the abbreviation<unk> . Synthesis<unk>  itself is a naturally-produced estrogen by the human fetal liver. However, for human use,<unk>  is synthesized from estrone, which is obtained from phytosterols extracted from soybeans. The synthesis of<unk>  results in very pure<unk>  (>99.9%) without contaminants.
Estetrol
Gestodene
Hexestrol
Fosfestrol
Benzestrol
Moxestrol
Dimestrol
Dienestrol