17α-dihydroequilin 17α-dihydroequilin 17α-dihydroequilin, or α-dihydroequilin, also known as 7-dehydro-17α-estradiol, as well as estra-1,3,5(10),7-tetraene-3,17α-diol, is a naturally occurring steroidal estrogen found in horses which is closely related to equilin, equilenin, and 17α-estradiol. the compound, as the 3-sulfate ester sodium salt, is present in conjugated estrogens (premarin), a pharmaceutical extract of the urine of pregnant mares, and is the third highest quantity constituent in the formulation (13.8%). the compound has been studied clinically. not to be confused with 17β-dihydroequilin, 17α-dihydroequilenin, or 17β-dihydroequilenin. 17α-dihydroequilinclinical dataother namesα-dihydroequilin; 7-dehydro-17α-estradiol; estra-1,3,5(10),7-tetraen-3,17α-diolroutes ofadministrationby mouthdrug classestrogenatc codeg03ca57 (who) identifiers iupac name (9s,13s,14s,17r)-13-methyl-6,9,11,12,14,15,16,17-octahydrocyclopentaphenanthrene-3,17-diol cas number651-55-8pubchem cid9547222chemspider7826162unii48p73794ojcomptox dashboard (epa)dtxsid70873788 echa infocard100.010.440 chemical and physical dataformulac18h22o2molar mass270.372 g·mol−13d model (jsmol)interactive image smiles cc12ccc3c(=ccc4=c3c=cc(=c4)o)c1ccc2o inchi inchi=1s/c18h22o2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h3-5,10,14,16-17,19-20h,2,6-9h2,1h3/t14-,16+,17-,18+/m1/s1key:nllmjanwpuqqta-spuzqdlcsa-n