View source for 17β-Dihydroequilin

{{Short description|Chemical compound}}
{{Distinguish|17α-Dihydroequilin|17α-Dihydroequilenin|17β-Dihydroequilenin}}
{{Drugbox
| Verifiedfields = 
| Watchedfields = 
| verifiedrevid = 
| IUPAC_name = (9''S'',13''S'',14''S'',17''S'')-13-Methyl-6,9,11,12,14,15,16,17-octahydrocyclopenta[''a'']phenanthrene-3,17-diol
| image = 17β-Dihydroequilin.svg
| width = 225px

<!--Clinical data-->
| tradename = 
| pregnancy_AU = <!-- A / B1 / B2 / B3 / C / D / X -->
| pregnancy_US = <!-- A / B / C / D / X -->
| pregnancy_category = 
| legal_AU = <!-- Unscheduled / S2 / S3 / S4 / S5 / S6 / S7 / S8 / S9 -->
| legal_CA = 
| legal_UK = 
| legal_US = 
| legal_status = 
| routes_of_administration = [[Oral administration|By mouth]]
| class = [[Estrogen (medication)|Estrogen]]

<!--Pharmacokinetic data-->
| bioavailability = 
| protein_bound = 
| metabolism = 
| elimination_half-life = 
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<!-- Identifiers -->
| CAS_number_Ref = 
| CAS_number = 3563-27-7
| CAS_supplemental = 
| ATC_prefix = 
| ATC_suffix = 
| ATC_supplemental = 
| PubChem = 11954027
| IUPHAR_ligand = 
| DrugBank_Ref = 
| DrugBank = 
| ChemSpiderID_Ref = 
| ChemSpiderID = 10128322
| UNII = WXG88DST4R
| KEGG = 
| ChEBI = 62851
| ChEMBL = 121458
| synonyms = β-Dihydroequilin; Δ<sup>7</sup>-17β-Estradiol; 7-Dehydro-17β-estradiol; Estra-1,3,5(10),7-tetraen-3,17β-diol; NSC-12170

<!--Chemical data-->
| C=18 | H=22 | O=2
| SMILES = C[C@]12CC[C@H]3C(=CCC4=C3C=CC(=C4)O)[C@@H]1CC[C@@H]2O
| StdInChI_Ref = 
| StdInChI = 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/s1
| StdInChIKey_Ref = 
| StdInChIKey = NLLMJANWPUQQTA-UBDQQSCGSA-N
}}

'''17β-Dihydroequilin''' is a [[natural product|naturally occurring]] [[estrogen (medication)|estrogen]] [[sex hormone]] found in [[horse]]s as well as a [[medication]].<ref name="pmid16112947">{{cite journal | vauthors = Kuhl H | title = Pharmacology of estrogens and progestogens: influence of different routes of administration | journal = Climacteric | volume = 8 | pages = 3–63 | year = 2005 | issue = Suppl 1 | pmid = 16112947 | doi = 10.1080/13697130500148875 | s2cid = 24616324 | url = http://hormonebalance.org/images/documents/Kuhl%2005%20%20Pharm%20Estro%20Progest%20Climacteric_1313155660.pdf}}</ref><ref name="FritzSperoff2012">{{cite book| vauthors = Fritz MA, Speroff L | chapter = Postmenopausal Hormone Therapy |title=Clinical Gynecologic Endocrinology and Infertility| chapter-url = https://books.google.com/books?id=KZLubBxJEwEC&pg=PA751 |date=28 March 2012|publisher=Lippincott Williams & Wilkins|isbn=978-1-4511-4847-3|pages=751–}}</ref> As the C3 [[sulfate]] [[ester]] [[sodium]] [[salt (chemistry)|salt]], it is a minor constituent (1.7%) of [[conjugated estrogens]] (CEEs; brand name '''Premarin''').<ref name="pmid16112947" /> However, as [[equilin]], with [[equilin sulfate]] being a major component of CEEs, is transformed into 17β-dihydroequilin in the body, analogously to the conversion of [[estrone (medication)|estrone]] into estradiol, 17β-dihydroequilin is, along with estradiol, the most important estrogen responsible for the effects of CEEs.<ref name="pmid16112947" />

==Pharmacology==

===Pharmacodynamics===
17β-Dihydroequilin is an estrogen, or an [[agonist]] of the [[estrogen receptor]]s (ERs), the [[ERα]] and [[ERβ]].<ref name="pmid16112947" /> In terms of [[relative binding affinity]] for the ERs, 17β-dihydroequilin has about 113% and 108% of that of estradiol for the ERα and ERβ, respectively.<ref name="pmid16112947" /> 17β-Dihydroequilin has about 83% of the relative potency of CEEs in the [[vagina]] and 200% of the relative potency of CEEs in the [[uterus]].<ref name="pmid16112947" /> Of the [[equine estrogen]]s, it shows the highest [[estrogen (medication)|estrogen]]ic [[biological activity|activity]] and greatest estrogenic [[potency (pharmacology)|potency]].<ref name="pmid16112947" />

Like CEEs as a whole, 17β-dihydroequilin has disproportionate effects in certain [[tissue (biology)|tissue]]s such as the [[liver]] and [[uterus]].<ref name="pmid16112947" /> [[Equilin]], the second major component of conjugated estrogens after [[estrone (medication)|estrone]], is reversibly [[biotransformation|transformed]] into 17β-dihydroequilin analogously to the transformation of estrone into estradiol.<ref name="pmid16112947" /> However, whereas the balance of mutual interconversion of estrone and estradiol is largely shifted in the direction of estrone, it is nearly equal in the case of equilin and 17β-dihydroequilin.<ref name="pmid16112947" /> As such, although 17β-dihydroequilin is only a minor constituent of CEEs, it is, along with estradiol, the most important estrogen relevant to the estrogenic activity of the medication.<ref name="pmid16112947" />

{{Relative oral potencies of estrogens}}

===Pharmacokinetics===
17β-Dihydroequilin has about 30% of the [[relative binding affinity]] of [[testosterone]] for [[sex hormone-binding globulin]] (SHBG), relative to 50% for [[estradiol (medication)|estradiol]].<ref name="pmid16112947" /> The [[metabolic clearance rate]] of 17β-dihydroequilin is 1,250&nbsp;L/day/m<sup>2</sup>, relative to 580&nbsp;L/day/m<sup>2</sup> for estradiol.<ref name="pmid16112947" />

==Chemistry==
{{See also|List of estrogens#Equine estrogens}}

17β-Dihydroequilin, or simply β-dihydroequilin, also known as δ<sup>7</sup>-17β-estradiol or as 7-dehydro-17β-estradiol, as well as estra-1,3,5(10),7-tetraen-3,17β-diol, is a [[natural product|naturally occurring]] [[estrane]] [[steroid]] and an [[structural analog|analogue]] of [[estradiol (medication)|estradiol]].<ref name="pmid16112947" /> In terms of [[chemical structure]] and [[pharmacology]], equilin (δ<sup>7</sup>-estrone) is to 17β-dihydroequilin as [[estrone (medication)|estrone]] is to estradiol.<ref name="pmid16112947" />

==References==
{{Reflist}}


{{Estrogens and antiestrogens}}
{{Estrogen receptor modulators}}

{{DEFAULTSORT:Dihydroequilin, 17β-}}

[[Category:Secondary alcohols]]
[[Category:Estranes]]
[[Category:Estrogens]]
[[Category:Human drug metabolites]]