Estrone (E1)

Estrone (also oestrone) is an estrogenic hormone secreted by the ovary as well as adipose tissue.Estrone is one of the three estrogens, which also include estriol and estradiol. Estrone is the least abundant of the three hormones, estradiol is present almost always in the reproductive female body, and estriol is abundant primarily during pregnancy.

Estrone is relevant to health and disease states because of its conversion to estrone sulfate, a long-lived derivative. Estrone sulfate acts as a reservoir that can be converted as needed to the more active estradiol.

Estrone is synthesized via aromatase from androstenedione, a derivative of progesterone. The conversion consists of the de-methylation of C-19 and the aromaticity of the 'A' ring. This reaction is similar to the conversion of testosterone to estradiol.