Estrin_(compound)
Estrin (molecule)
Chemical compound
Estrin (American English), or oestrin (British English), also known as estra-1,3,5(10)-triene, is an estrane steroid. It is dehydrogenated estrane with double bonds specifically at the C1, C3, and C5(10) positions. Estrin is a parent structure of the estrogen steroid hormones estradiol, estrone, and estriol, which have also been known as dihydroxyestrin, ketohydroxyestrin, and trihydroxyestrin, respectively.[1][2]
Unlike its estrogen derivatives, estrin itself possesses minimal estrogenic activity, as hydroxyl and/or keto substitutions at the C3 and C17 positions are critical for high binding affinity to the estrogen receptors.[3][4] Estrin has been found to be on the order of 1,000-fold less potent than estradiol in inducing estrogenic responses in vitro.[5][6][3] In addition to estrin, estratrien-17β-ol, which lacks the 3-hydroxyl group of estradiol, and 3-hydroxyestratriene, which lacks the 17β-hydroxyl group of estradiol, both have measurable affinity for the estrogen receptor and are able to activate the receptor and induce progesterone receptor expression.[6][7][3]
The term estrin is also a synonym for estrogen.[8] It was coined by Sir Alan S. Parkes and C. W. Bellerby in 1926 to describe the hormone secreted from the ovaries that induces estrus in animals (i.e., estrogen).[8]
Structures of major endogenous estrogens
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