4-methoxyestriol 4-methoxyestriol 4-methoxyestriol (4-meo-e3) is an endogenous estrogen metabolite. it is the 4-methyl ether of 4-hydroxyestriol and a metabolite of estriol and 4-hydroxyestriol. 4-methoxyestriol has very low affinities for the estrogen receptors. its relative binding affinities (rbas) for estrogen receptor alpha (erα) and estrogen receptor beta (erβ) are both about 1% of those of estradiol. for comparison, estriol had rbas of 11% and 35%, respectively. 4-methoxyestriol names iupac name 4-methoxyestra-1,3,5(10)-triene-3,16α,17β-triol systematic iupac name (1r,2r,3as,3br,9bs,11as)-6-methoxy-11a-methyl-2,3,3a,3b,4,5,9b,10,11,11a-decahydro-1h-cyclopentaphenanthrene-1,2,7-triol other names 4-meo-e3 identifiers cas number 101534-28-5 3d model (jsmol) interactive image chemspider 8077213 pubchem cid 9901559 inchi inchi=1s/c19h26o4/c1-19-8-7-11-10-5-6-15(20)17(23-2)13(10)4-3-12(11)14(19)9-16(21)18(19)22/h5-6,11-12,14,16,18,20-22h,3-4,7-9h2,1-2h3/t11-,12-,14+,16-,18+,19+/m1/s1key: mtzupvfogaxgjg-juvwiqmmsa-n smiles c12cc3(1c(2o)o)ccc4=c3c=cc(=c4oc)o properties chemical formula c19h26o4 molar mass 318.413 g·mol−1 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references