Estrin (molecule) explained

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] 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]}

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).

See also

• 1-Keto-1,2,3,4-tetrahydrophenanthrene

Notes and References

1. Biskind. Morton S.. Commercial glandular products. Journal of the American Medical Association. 105. 9. 1935. 667. 0002-9955. 10.1001/jama.1935.92760350007009a.
2. Fluhmann CF . Estrogenic Hormones: Their Clinical Usage . Cal West Med . 49 . 5 . 362–6 . 1938 . 18744783 . 1659459 .
3. Anstead GM, Carlson KE, Katzenellenbogen JA . The estradiol pharmacophore: ligand structure-estrogen receptor binding affinity relationships and a model for the receptor binding site . Steroids . 62 . 3 . 268–303 . 1997 . 9071738 . 10.1016/s0039-128x(96)00242-5. 10080044 .
4. Book: Thomas L. Lemke. David A. Williams. Foye's Principles of Medicinal Chemistry. 24 January 2012. Lippincott Williams & Wilkins. 978-1-60913-345-0. 1395–.
5. Jordan VC, Koch R . Regulation of prolactin synthesis in vitro by estrogenic and antiestrogenic derivatives of estradiol and estrone . Endocrinology . 124 . 4 . 1717–26 . April 1989 . 2924721 . 10.1210/endo-124-4-1717 .
6. Book: Brooks SC, Wappler NL, Corombos JD, Doherty LM, Horwitz JP . Estrogen structure-receptor function relationships . 443–466 . Recent Advances in Steroid Hormone Action . Moudgil VK . 1987 . Walter de Gruyter .
7. Schwartz JA, Skafar DF . Ligand-mediated modulation of estrogen receptor conformation by estradiol analogs . Biochemistry . 32 . 38 . 10109–15 . September 1993 . 8399136 . 10.1021/bi00089a029 .
8. Book: Marc A. Fritz. Leon Speroff. Clinical Gynecologic Endocrinology and Infertility. 28 March 2012. Lippincott Williams & Wilkins. 978-1-4511-4847-3. 750–.