Estradiol 3-glucuronide

Estradiol 3-glucuronide (E2-3G), also known as 17β-estradiol 3-(β--glucuronide), is a naturally occurring and endogenous estrogen conjugate. It is specifically the C3 glucuronide conjugate of estradiol, the major estrogen in the body. It is formed from estradiol in the liver by UDP-glucuronosyltransferase via attachment of glucuronic acid and is eventually excreted in urine and bile. Similarly to estrogen sulfates like estrone sulfate, estrogen glucuronides have much higher water solubility than do unconjugated estrogens like estradiol.
Estrogen glucuronides can be deconjugated into the corresponding free estrogens by β-glucuronidase in tissues that express this enzyme, such as the mammary gland. As a result, estrogen glucuronides have estrogenic activity via conversion into estrogens.
Estradiol 3-glucuronide is a positional isomer of estradiol 17β-glucuronide.