Estrin (compound)

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IUPAC name
Systematic IUPAC name
Other names
3D model (JSmol)
  • InChI=1S/C18H24/c1-18-11-4-7-17(18)16-9-8-13-5-2-3-6-14(13)15(16)10-12-18/h2-3,5-6,15-17H,4,7-12H2,1H3/t15-,16-,17+,18+/m1/s1
  • C[C@@]12CCC[C@H]1[C@@H]3CCC4=CC=CC=C4[C@H]3CC2
Molar mass 240.39 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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
Chemical structures of major endogenous estrogens
Estrone (E1)
Estriol (E3)
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Note the hydroxyl (–OH) groups: estrone (E1) has one, estradiol (E2) has two, estriol (E3) has three, and estetrol (E4) has four.

See also[edit]


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