Estrone

Estrone (also oestrone) is an estrogenic hormone secreted by the ovary.

Estrone is one of the three estrogens, which also include estriol and estradiol. Estrone is the least prevalent of the three hormones, estradiol being prevalent almost always in a female body, estriol being prevalent primarily during pregnancy. Estrone is relevant to health and disease due to its conversion to estrone sulfate, a long-lived derivative of estrone. Estrone sulfate acts as a pool of estrone which can be converted as needed to the more active estradiol.

Synthesis
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.

Additional images
Estrone エストロン Estrona Эстрон