Structure 

Estrone is a C18 steroid hormone. It is a metabolite of estradiol-17β, and has a phenolic A ring and a ketone on carbon 17. 

Properties 

Molecular formula, C18H22O2; Mr 270.37; soluble in alcohol, acetone, dioxane, and other organic solvents. Almost insoluble in water. 

Synthesis and release 

Gene, mRNA, and precursor 

Converted from androstenedione by aromatase (P450arom encoded by the CYP19 gene) or from estradiol-17β by 17β-hydroxysteroid dehydrogenase (17β-HSD) in the granulosa cells and luteal cells of the ovary, the Leydig cells of the testis, and the placenta (mouse).

Plasma concentration (pg/mL (pmol/L)) 

Human (male) mature 10–68 (37–250) (female) mature follicular phase 30–108 (110–400), luteal phase 84–178 (310–660), postmenopause 6–62 (22–230). 

Regulation of synthesis and release 

Several isozymes of 17β-HSDs have been identified, and 17β-HSD type 2 is associated with the final step of the biosynthesis of estrone.The synthesis of estrone in the rodent placenta is catalyzed by 17β-HSD type 2, thereby inactivating estradiol-17β to estrone.17β-HSD type 2 is found in the breast, uterus, prostate, liver, and kidney in humans.17β-HSD types 1 and 7 catalyze the conversion of estrone to estradiol-17β in the granulosa cells and corpora lutea of the ovary in mice,respectively. The human placenta expresses 17β-HSD type 1 enzyme.Estrone can be converted to estriol via 16-hydroxyestrone.In postmenopausal women, estrone is mainly synthesized in adipose tissue from adrenal dehydroepiandrosterone.

Use for diagnosis and treatment 

As an alternative choice for estrogenic agents, conjugated estrone derivatives from equine origin are available as an oral clinical drug.