Estrin (molecule)

Estrin
Names
	IUPAC name Estra-1,3,5(10)-triene
	Systematic IUPAC name (3aS,3bS,9bS,11aS)-11a-Methyl-2,3,3a,3b,4,5,9b,10,11,11a-decahydro-1H-cyclopenta[a]phenanthrene
	Other names Estratriene
Identifiers
CAS Number	1217-09-0;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1627934;
ChemSpider	133001;
PubChem CID	150899;
UNII	F274X7VR4M ;
CompTox Dashboard (EPA)	DTXSID10923933 ;
	InChI 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 Key: HLCRYAZDZCJZFG-BDXSIMOUSA-N;
	SMILES C[C@@]12CCC[C@H]1[C@@H]3CCC4=CC=CC=C4[C@H]3CC2;
Properties
Chemical formula	C18H24
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). Infobox references

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]

Quick Facts Names, Identifiers ...

The estrin hydrocarbon itself possesses minimal estrogenic activity, as alcohol 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]