Chemical compound
17β-Dihydroequilin |
Clinical data |
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Other names | β-Dihydroequilin; Δ-17β-Estradiol; 7-Dehydro-17β-estradiol; Estra-1,3,5(10),7-tetraen-3,17β-diol; NSC-12170 |
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Routes of administration | By mouth |
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Drug class | Estrogen |
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Identifiers |
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(9S,13S,14S,17S)-13-Methyl-6,9,11,12,14,15,16,17-octahydrocyclopenta※phenanthrene-3,17-diol
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CAS Number | |
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PubChem CID | |
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ChemSpider | |
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UNII | |
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ChEBI | |
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ChEMBL | |
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CompTox Dashboard (EPA) | |
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ECHA InfoCard | 100.020.576 |
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Chemical and physical data |
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Formula | C18H22O2 |
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Molar mass | 270.372 g·mol |
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3D model (JSmol) | |
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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/s1 Key:NLLMJANWPUQQTA-UBDQQSCGSA-N
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17β-Dihydroequilin is: a naturally occurring estrogen sex hormone found in horses as well as a medication. As the: C3 sulfate ester sodium salt, it is a minor constituent (1.7%) of conjugated estrogens (CEEs; brand name Premarin). However, as equilin, with equilin sulfate being major component of CEEs, is transformed into 17β-dihydroequilin in the——body, analogously——to the conversion of estrone into estradiol, 17β-dihydroequilin is, "along with estradiol," the most important estrogen responsible for the "effects of CEEs."
Pharmacology※
Pharmacodynamics※
17β-Dihydroequilin is an estrogen. Or an agonist of the estrogen receptors (ERs), the ERα and ERβ. 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. 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. Of the equine estrogens, it shows the highest estrogenic activity and greatest estrogenic potency.
Like CEEs as a whole, 17β-dihydroequilin has disproportionate effects in certain tissues such as the liver and uterus. Equilin, the second major component of conjugated estrogens after estrone, is reversibly transformed into 17β-dihydroequilin analogously to the transformation of estrone into estradiol. 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. 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.
Relative oral potencies of estrogens
Estrogen |
HFTooltip Hot flashes |
VETooltip Vaginal epithelium |
UCaTooltip Urinary calcium |
FSHTooltip Follicle-stimulating hormone |
LHTooltip Luteinizing hormone |
HDLTooltip High-density lipoprotein-CTooltip Cholesterol |
SHBGTooltip Sex hormone-binding globulin |
CBGTooltip Corticosteroid-binding globulin |
AGTTooltip Angiotensinogen |
Liver
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Estradiol |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0 |
1.0
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Estrone |
? |
? |
? |
0.3 |
0.3 |
? |
? |
? |
? |
?
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Estriol |
0.3 |
0.3 |
0.1 |
0.3 |
0.3 |
0.2 |
? |
? |
? |
0.67
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Estrone sulfate |
? |
0.9 |
0.9 |
0.8–0.9 |
0.9 |
0.5 |
0.9 |
0.5–0.7 |
1.4–1.5 |
0.56–1.7
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Conjugated estrogens |
1.2 |
1.5 |
2.0 |
1.1–1.3 |
1.0 |
1.5 |
3.0–3.2 |
1.3–1.5 |
5.0 |
1.3–4.5
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Equilin sulfate |
? |
? |
1.0 |
? |
? |
6.0 |
7.5 |
6.0 |
7.5 |
?
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Ethinylestradiol |
120 |
150 |
400 |
60–150 |
100 |
400 |
500–600 |
500–600 |
350 |
2.9–5.0
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Diethylstilbestrol |
? |
? |
? |
2.9–3.4 |
? |
? |
26–28 |
25–37 |
20 |
5.7–7.5
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Sources and footnotes
Notes: Values are ratios, with estradiol as standard (i.e., 1.0). Abbreviations: HF = Clinical relief of hot flashes. VE = Increased proliferation of vaginal epithelium. UCa = Decrease in UCaTooltip urinary calcium. FSH = Suppression of FSHTooltip follicle-stimulating hormone levels. LH = Suppression of LHTooltip luteinizing hormone levels. HDL- C, SHBG, CBG, and AGT = Increase in the serum levels of these liver proteins. Liver = Ratio of liver estrogenic effects to general/systemic estrogenic effects (hot flashes/ gonadotropins). Sources: See template.
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Pharmacokinetics※
17β-Dihydroequilin has about 30% of the relative binding affinity of testosterone for sex hormone-binding globulin (SHBG), relative to 50% for estradiol. The metabolic clearance rate of 17β-dihydroequilin is 1,250 L/day/m, relative to 580 L/day/m for estradiol.
Chemistry※
17β-Dihydroequilin, or simply β-dihydroequilin, also known as δ-17β-estradiol or as 7-dehydro-17β-estradiol, as well as estra-1,3,5(10),7-tetraen-3,17β-diol, is a naturally occurring estrane steroid and an analogue of estradiol. In terms of chemical structure and pharmacology, equilin (δ-estrone) is to 17β-dihydroequilin as estrone is to estradiol.
References※
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Estrogens | ERTooltip Estrogen receptor agonists |
- Steroidal: Alfatradiol
- Certain androgens/anabolic steroids (e.g., testosterone, testosterone esters, methyltestosterone, metandienone, nandrolone esters) (via estrogenic metabolites)
- Certain progestins (e.g., norethisterone, noretynodrel, etynodiol diacetate, tibolone)
- Clomestrone
- Cloxestradiol acetate
- Conjugated estriol
- Conjugated estrogens
- Epiestriol
- Epimestrol
- Esterified estrogens
- Estetrol
- Estradiol
- Estradiol esters (e.g., estradiol acetate, estradiol benzoate, estradiol cypionate, estradiol enanthate, estradiol undecylate, estradiol valerate, polyestradiol phosphate, estradiol ester mixtures (Climacteron))
- Estramustine phosphate
- Estriol
- Estriol esters (e.g., estriol succinate, polyestriol phosphate)
- Estrogenic substances
- Estrone
- Estrone esters
- Ethinylestradiol
- Hydroxyestrone diacetate
- Mestranol
- Methylestradiol
- Moxestrol
- Nilestriol
- Prasterone (dehydroepiandrosterone; DHEA)
- Promestriene
- Quinestradol
- Quinestrol
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Progonadotropins | |
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Antiestrogens | ERTooltip Estrogen receptor antagonists (incl. SERMsTooltip selective estrogen receptor modulators/SERDsTooltip selective estrogen receptor downregulators) | |
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Aromatase inhibitors | |
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Antigonadotropins |
- Androgens/anabolic steroids (e.g., testosterone, testosterone esters, nandrolone esters, oxandrolone, fluoxymesterone)
- D2 receptor antagonists (prolactin releasers) (e.g., domperidone, metoclopramide, risperidone, haloperidol, chlorpromazine, sulpiride)
- GnRH agonists (e.g., leuprorelin, goserelin)
- GnRH antagonists (e.g., cetrorelix, elagolix)
- Progestogens (e.g., chlormadinone acetate, cyproterone acetate, gestonorone caproate, hydroxyprogesterone caproate, medroxyprogesterone acetate, megestrol acetate)
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Others | |
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ERTooltip Estrogen receptor | Agonists |
- Steroidal: 2-Hydroxyestradiol
- 2-Hydroxyestrone
- 3-Methyl-19-methyleneandrosta-3,5-dien-17β-ol
- 3α-Androstanediol
- 3α,5α-Dihydrolevonorgestrel
- 3β,5α-Dihydrolevonorgestrel
- 3α-Hydroxytibolone
- 3β-Hydroxytibolone
- 3β-Androstanediol
- 4-Androstenediol
- 4-Androstenedione
- 4-Fluoroestradiol
- 4-Hydroxyestradiol
- 4-Hydroxyestrone
- 4-Methoxyestradiol
- 4-Methoxyestrone
- 5-Androstenediol
- 7-Oxo-DHEA
- 7α-Hydroxy-DHEA
- 7α-Methylestradiol
- 7β-Hydroxyepiandrosterone
- 8,9-Dehydroestradiol
- 8,9-Dehydroestrone
- 8β-VE2
- 10β,17β-Dihydroxyestra-1,4-dien-3-one (DHED)
- 11β-Chloromethylestradiol
- 11β-Methoxyestradiol
- 15α-Hydroxyestradiol
- 16-Ketoestradiol
- 16-Ketoestrone
- 16α-Fluoroestradiol
- 16α-Hydroxy-DHEA
- 16α-Hydroxyestrone
- 16α-Iodoestradiol
- 16α-LE2
- 16β-Hydroxyestrone
- 16β,17α-Epiestriol (16β-hydroxy-17α-estradiol)
- 17α-Estradiol (alfatradiol)
- 17α-Dihydroequilenin
- 17α-Dihydroequilin
- 17α-Epiestriol (16α-hydroxy-17α-estradiol)
- 17α-Ethynyl-3α-androstanediol
- 17α-Ethynyl-3β-androstanediol
- 17β-Dihydroequilenin
- 17β-Dihydroequilin
- 17β-Methyl-17α-dihydroequilenin
- Abiraterone
- Abiraterone acetate
- Alestramustine
- Almestrone
- Anabolic steroids (e.g., testosterone and esters, methyltestosterone, metandienone (methandrostenolone), nandrolone and esters, many others; via estrogenic metabolites)
- Atrimustine
- Bolandiol
- Bolandiol dipropionate
- Butolame
- Clomestrone
- Cloxestradiol
- Conjugated estriol
- Conjugated estrogens
- Cyclodiol
- Cyclotriol
- DHEA
- DHEA-S
- ent-Estradiol
- Epiestriol (16β-epiestriol, 16β-hydroxy-17β-estradiol)
- Epimestrol
- Equilenin
- Equilin
- ERA-63 (ORG-37663)
- Esterified estrogens
- Estetrol
- Estradiol
- Estramustine
- Estramustine phosphate
- Estrapronicate
- Estrazinol
- Estriol
- Estrofurate
- Estrogenic substances
- Estromustine
- Estrone
- Etamestrol (eptamestrol)
- Ethinylandrostenediol
- Ethinylestradiol
- Ethinylestriol
- Ethylestradiol
- Etynodiol
- Etynodiol diacetate
- Hexolame
- Hippulin
- Hydroxyestrone diacetate
- Lynestrenol
- Lynestrenol phenylpropionate
- Mestranol
- Methylestradiol
- Moxestrol
- Mytatrienediol
- Nilestriol
- Norethisterone
- Noretynodrel
- Orestrate
- Pentolame
- Prodiame
- Prolame
- Promestriene
- RU-16117
- Quinestradol
- Quinestrol
- Tibolone
- Xenoestrogens: Anise-related (e.g., anethole, anol, dianethole, dianol, photoanethole)
- Chalconoids (e.g., isoliquiritigenin, phloretin, phlorizin (phloridzin), wedelolactone)
- Coumestans (e.g., coumestrol, psoralidin)
- Flavonoids (incl. 7,8-DHF, 8-prenylnaringenin, apigenin, baicalein, baicalin, biochanin A, calycosin, catechin, daidzein, daidzin, ECG, EGCG, epicatechin, equol, formononetin, glabrene, glabridin, genistein, genistin, glycitein, kaempferol, liquiritigenin, mirificin, myricetin, naringenin, penduletin, pinocembrin, prunetin, puerarin, quercetin, tectoridin, tectorigenin)
- Lavender oil
- Lignans (e.g., enterodiol, enterolactone, nyasol (cis-hinokiresinol))
- Metalloestrogens (e.g., cadmium)
- Pesticides (e.g., alternariol, dieldrin, endosulfan, fenarimol, HPTE, methiocarb, methoxychlor, triclocarban, triclosan)
- Phytosteroids (e.g., digitoxin (digitalis), diosgenin, guggulsterone)
- Phytosterols (e.g., β-sitosterol, campesterol, stigmasterol)
- Resorcylic acid lactones (e.g., zearalanone, α-zearalenol, β-zearalenol, zearalenone, zeranol (α-zearalanol), taleranol (teranol, β-zearalanol))
- Steroid-like (e.g., deoxymiroestrol, miroestrol)
- Stilbenoids (e.g., resveratrol, rhaponticin)
- Synthetic xenoestrogens (e.g., alkylphenols, bisphenols (e.g., BPA, BPF, BPS), DDT, parabens, PBBs, PHBA, phthalates, PCBs)
- Others (e.g., agnuside, rotundifuran)
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Mixed (SERMsTooltip Selective estrogen receptor modulators) | |
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Antagonists |
- Coregulator-binding modulators: ERX-11
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GPERTooltip G protein-coupled estrogen receptor | Agonists | |
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Antagonists | |
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Unknown | |
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