Estradiol 3-glucuronide

Estradiol 3-glucuronide (E2-3G), also known as 17β-estradiol 3-(β-D-glucuronide), is a naturally occurring and endogenous estrogen conjugate.[1] It is specifically the C3 glucuronide conjugate of estradiol, the major estrogen in the body.[1] It is formed from estradiol in the liver by UDP-glucuronosyltransferase via attachment of glucuronic acid and is eventually excreted in urine and bile.[2][3] Similarly to estrogen sulfates like estrone sulfate, estrogen glucuronides have much higher water solubility than do unconjugated estrogens like estradiol.[3]

Estradiol 3-glucuronide
Names
IUPAC name
17β-Hydroxyestra-1,3,5(10)-trien-3-yl β-D-glucopyranosiduronic acid
Systematic IUPAC name
(2S,3S,4S,5R,6S)-3,4,5-Trihydroxy-6-{[(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]oxy}oxane-2-carboxylic acid
Other names
E2-3G; 17β-Estradiol 3-(β-D-glucuronide)
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
KEGG
  • InChI=1S/C24H32O8/c1-24-9-8-14-13-5-3-12(10-11(13)2-4-15(14)16(24)6-7-17(24)25)31-23-20(28)18(26)19(27)21(32-23)22(29)30/h3,5,10,14-21,23,25-28H,2,4,6-9H2,1H3,(H,29,30)/t14-,15-,16+,17+,18+,19+,20-,21+,23-,24+/m1/s1
    Key: MUOHJTRCBBDUOW-QXYWQCSFSA-N
  • C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@@H]2O)CCC4=C3C=CC(=C4)O[C@H]5[C@@H]([C@H]([C@@H]([C@H](O5)C(=O)O)O)O)O
Properties
C24H32O8
Molar mass 448.512 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Estrogen glucuronides can be deconjugated into the corresponding free estrogens by β-glucuronidase in tissues that express this enzyme, such as the mammary gland.[2] As a result, estrogen glucuronides have estrogenic activity via conversion into estrogens.[2]

Estradiol 3-glucuronide is a positional isomer of estradiol 17β-glucuronide.

Affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors
Estrogen Other names RBATooltip Relative binding affinity (%)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.

See also

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References

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  1. ^ a b "Human Metabolome Database: Showing metabocard for 17-beta-Estradiol-3-glucuronide (HMDB0006224)".
  2. ^ a b c Zhu BT, Conney AH (January 1998). "Functional role of estrogen metabolism in target cells: review and perspectives". Carcinogenesis. 19 (1): 1–27. doi:10.1093/carcin/19.1.1. PMID 9472688.
  3. ^ a b Kuhl H (2005). "Pharmacology of estrogens and progestogens: influence of different routes of administration" (PDF). Climacteric. 8 (Suppl 1): 3–63. doi:10.1080/13697130500148875. PMID 16112947. S2CID 24616324.
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