Estradiol sulfate

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-cyclopenta[a]phenanthren-7-yl hydrogen sulfate
	Other names Estra-1,3,5(10)-triene-3,17β-diol 3-sulfate
Identifiers
CAS Number	481-96-9; 4999-79-5 (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/s1 Key: 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 [77 °F], 100 kPa). Infobox references

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.

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	RBATooltip Relative binding affinity (%)^a	REP (%)^b
Estrogen	Other names	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
Estrogen	Structure	Ester(s)				Relative mol. weight	Relative E2 content^b	log P^c
Estrogen	Structure	Position(s)	Moiet(ies)	Type	Length^a	Relative mol. weight	Relative E2 content^b	log P^c
Estradiol		–	–	–	–	1.00	1.00	4.0
Estradiol acetate		C3	Ethanoic acid	Straight-chain fatty acid	2	1.15	0.87	4.2
Estradiol benzoate		C3	Benzoic acid	Aromatic fatty acid	– (~4–5)	1.38	0.72	4.7
Estradiol dipropionate		C3, C17β	Propanoic acid (×2)	Straight-chain fatty acid	3 (×2)	1.41	0.71	4.9
Estradiol valerate		C17β	Pentanoic acid	Straight-chain fatty acid	5	1.31	0.76	5.6–6.3
Estradiol benzoate butyrate		C3, C17β	Benzoic acid, butyric acid	Mixed fatty acid	– (~6, 2)	1.64	0.61	6.3
Estradiol cypionate		C17β	Cyclopentylpropanoic acid	Cyclic fatty acid	– (~6)	1.46	0.69	6.9
Estradiol enanthate		C17β	Heptanoic acid	Straight-chain fatty acid	7	1.41	0.71	6.7–7.3
Estradiol dienanthate		C3, C17β	Heptanoic acid (×2)	Straight-chain fatty acid	7 (×2)	1.82	0.55	8.1–10.4
Estradiol undecylate		C17β	Undecanoic acid	Straight-chain fatty acid	11	1.62	0.62	9.2–9.8
Estradiol stearate		C17β	Octadecanoic acid	Straight-chain fatty acid	18	1.98	0.51	12.2–12.4
Estradiol distearate		C3, C17β	Octadecanoic acid (×2)	Straight-chain fatty acid	18 (×2)	2.96	0.34	20.2
Estradiol sulfate		C3	Sulfuric acid	Water-soluble conjugate	–	1.29	0.77	0.3–3.8
Estradiol glucuronide		C17β	Glucuronic acid	Water-soluble conjugate	–	1.65	0.61	2.1–2.7
Estramustine phosphate^d		C3, C17β	Normustine, phosphoric acid	Water-soluble conjugate	–	1.91	0.52	2.9–5.0
Polyestradiol phosphate^e		C3–C17β	Phosphoric acid	Water-soluble conjugate	–	1.23^f	0.81^f	2.9^g
Footnotes: ^a = Length of ester in carbon atoms for straight-chain fatty acids or approximate length of ester in carbon atoms for aromatic or cyclic 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.