estradiol sulfate estradiol sulfate estradiol sulfate (e2s), or 17β-estradiol 3-sulfate, is a natural, endogenous steroid and an estrogen ester. e2s itself is biologically inactive, but it can be converted by steroid sulfatase (also called estrogen sulfatase) into estradiol, which is a potent estrogen. simultaneously, estrogen sulfotransferases convert estradiol to e2s, resulting in an equilibrium between the two steroids in various tissues. estrone and e2s are the two immediate metabolic sources of estradiol. e2s can also be metabolized into estrone sulfate (e1s), which in turn can be converted into estrone and estradiol. circulating concentrations of e2s are much lower than those of e1s. high concentrations of e2s are present in breast tissue, and e2s has been implicated in the biology of breast cancer via serving as an active reservoir of estradiol. estradiol sulfate names iupac name 17β-hydroxyestra-1,3,5(10)-trien-3-yl hydrogen sulfate systematic iupac name (1s,3as,3br,9bs,11as)-1-hydroxy-11a-methyl-2,3,3a,3b,4,5,9b,10,11,11a-decahydro-1h-cyclopentaphenanthren-7-yl hydrogen sulfate other names estra-1,3,5(10)-triene-3,17β-diol 3-sulfate identifiers cas number 481-96-94999-79-5 (sodium) 3d model (jsmol) interactive image chebi chebi:4866 chembl chembl1628111 chemspider 59790 pubchem cid 66416 unii 4nkq3751p6 comptox dashboard (epa) dtxsid30964000 inchi inchi=1s/c18h24o5s/c1-18-9-8-14-13-5-3-12(23-24(20,21)22)10-11(13)2-4-15(14)16(18)6-7-17(18)19/h3,5,10,14-17,19h,2,4,6-9h2,1h3,(h,20,21,22)/t14-,15-,16+,17+,18+/m1/s1key: qziglssudxbtlj-zbrfxrbcsa-n smiles cc12ccc3c(c1ccc2o)ccc4=c3c=cc(=c4)os(=o)(=o)o properties chemical formula c18h24o5s molar mass 352.445 g/mol except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references as the sodium salt sodium estradiol sulfate, e2s is present as a minor constituent (0.9%) of conjugated equine estrogens (cees), or premarin. it effectively functions as a prodrug to estradiol in this preparation, similarly to e1s. e2s is also formed as a metabolite of estradiol, as well as of estrone and e1s. aside from its presence in cees, e2s is not available as a commercial pharmaceutical drug. e2s shows about 10,000-fold lower potency in activating the estrogen receptors relative to estradiol in vitro. it is 10-fold less potent than estrone sulfate orally in terms of in vivo uterotrophic effect in rats. estrogen sulfates like estradiol sulfate or estrone sulfate are about twice as potent as the corresponding free estrogens in terms of estrogenic effect when given orally to rodents. this in part led to the introduction of conjugated estrogens (premarin), which are primarily estrone sulfate, in 1941. although inactive at steroid hormone receptors, e2s has been found to act as a potent inhibitor of glutathione s-transferase, an enzyme that contributes to the inactivation of estradiol via conversion of it into an estradiol-glutathione conjugate. as such, e2s can indirectly serve as a positive effector of estrogen signaling. estradiol levels are about 1.5- to 4-fold higher than e2s levels in women. this is in contrast to e1s, the levels of which are about 10 to 15 times higher than those of estrone. e2s at an oral dosage of 5 mg/day in women resulted in inhibition of ovulation in 89% of cycles (47 of 53). affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors estrogen other names rba (%)a rep (%)b er erα erβ estradiol e2 100 100 100 estradiol 3-sulfate e2s; e2-3s ? 0.02 0.04 estradiol 3-glucuronide e2-3g ? 0.02 0.09 estradiol 17β-glucuronide e2-17g ? 0.002 0.0002 estradiol benzoate eb; estradiol 3-benzoate 10 1.1 0.52 estradiol 17β-acetate e2-17a 31–45 24 ? estradiol diacetate eda; estradiol 3,17β-diacetate ? 0.79 ? estradiol propionate ep; estradiol 17β-propionate 19–26 2.6 ? estradiol valerate ev; estradiol 17β-valerate 2–11 0.04–21 ? estradiol cypionate ec; estradiol 17β-cypionate ?c 4.0 ? estradiol palmitate estradiol 17β-palmitate 0 ? ? estradiol stearate estradiol 17β-stearate 0 ? ? estrone e1; 17-ketoestradiol 11 5.3–38 14 estrone sulfate e1s; estrone 3-sulfate 2 0.004 0.002 estrone glucuronide e1g; estrone 3-glucuronide ? <0.001 0.0006 ethinylestradiol ee; 17α-ethynylestradiol 100 17–150 129 mestranol ee 3-methyl ether 1 1.3–8.2 0.16 quinestrol ee 3-cyclopentyl ether ? 0.37 ? footnotes: a = relative binding affinities (rbas) were determined via in-vitro displacement of labeled estradiol from estrogen receptors (ers) generally of rodent uterine cytosol. estrogen esters are variably hydrolyzed into estrogens in these systems (shorter ester chain length -> greater rate of hydrolysis) and the er rbas of the esters decrease strongly when hydrolysis is prevented. b = relative estrogenic potencies (reps) were calculated from half-maximal effective concentrations (ec50) that were determined via in-vitro β‐galactosidase (β-gal) and green fluorescent protein (gfp) production assays in yeast expressing human erα and human erβ. both mammalian cells and yeast have the capacity to hydrolyze estrogen esters. c = the affinities of estradiol cypionate for the ers are similar to those of estradiol valerate and estradiol benzoate (figure). sources: see template page. structural properties of selected estradiol esters estrogenstructureester(s)relativemol. weightrelativee2 contentblog pc position(s)moiet(ies)typelengtha estradiol––––1.001.004.0 estradiol acetatec3ethanoic acidstraight-chain fatty acid21.150.874.2 estradiol benzoatec3benzenecarboxylic acidaromatic fatty acid– (~4–5)1.380.724.7 estradiol dipropionatec3, c17βpropanoic acid (×2)straight-chain fatty acid3 (×2)1.410.714.9 estradiol valeratec17βpentanoic acidstraight-chain fatty acid51.310.765.6–6.3 estradiol benzoate butyratec3, c17βbenzoic acid, butyric acidmixed fatty acid– (~6, 2)1.640.616.3 estradiol cypionatec17βcyclopentylpropanoic acidaromatic fatty acid– (~6)1.460.696.9 estradiol enanthatec17βheptanoic acidstraight-chain fatty acid71.410.716.7–7.3 estradiol dienanthatec3, c17βheptanoic acid (×2)straight-chain fatty acid7 (×2)1.820.558.1–10.4 estradiol undecylatec17βundecanoic acidstraight-chain fatty acid111.620.629.2–9.8 estradiol stearatec17βoctadecanoic acidstraight-chain fatty acid181.980.5112.2–12.4 estradiol distearatec3, c17βoctadecanoic acid (×2)straight-chain fatty acid18 (×2)2.960.3420.2 estradiol sulfatec3sulfuric acidwater-soluble conjugate–1.290.770.3–3.8 estradiol glucuronidec17βglucuronic acidwater-soluble conjugate–1.650.612.1–2.7 estramustine phosphatedc3, c17βnormustine, phosphoric acidwater-soluble conjugate–1.910.522.9–5.0 polyestradiol phosphateec3–c17βphosphoric acidwater-soluble conjugate–1.23f0.81f2.9g footnotes: a = length of ester in carbon atoms for straight-chain fatty acids or approximate length of ester in carbon atoms for aromatic fatty acids. b = relative estradiol content by weight (i.e., relative estrogenic exposure). c = experimental or predicted octanol/water partition coefficient (i.e., lipophilicity/hydrophobicity). retrieved from pubchem, chemspider, and drugbank. d = also known as estradiol normustine phosphate. e = polymer of estradiol phosphate (~13 repeat units). f = relative molecular weight or estradiol content per repeat unit. g = log p of repeat unit (i.e., estradiol phosphate). sources: see individual articles.