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.[1][2] 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%).[1] The compound has been studied clinically.[3]

Composition of conjugated estrogens and properties of constituents

Compound	Synonym	Proportion (%)	Relative potency in the vagina (%)	Relative potency in the uterus (%)	RBA for ERα (%)	RBA for ERβ (%)	ERα / ERβ RBA ratio
Conjugated estrogens	–	100	38	100	–	–	–
Estrone	–	49.1–61.5	30	32	26	52	0.50
Equilin	Δ^7-Estrone	22.4–30.5	42	80	13	49	0.26
17α-Dihydroequilin	Δ^7-17α-Estradiol	13.5–19.5	0.06	2.6	41	32	1.30
17α-Estradiol	–	2.5–9.5	0.11	3.5	19	42	0.45
Δ^8-Estrone	–	3.5–3.9	?	?	19	32	0.60
Equilenin	Δ^6,8-Estrone	2.2–2.8	1.3	11.4	15	20–29	0.50–0.75
17β-Dihydroequilin	Δ^7-17β-Estradiol	0.5–4.0	83	200	113	108	1.05
17α-Dihydroequilenin	Δ^6,8-17α-Estradiol	1.2–1.6	0.018	1.3	20	49	0.40
17β-Estradiol	–	0.56–0.9	100	?	100	100	1.00
17β-Dihydroequilenin	Δ^6,8-17β-Estradiol	0.5–0.7	0.21	9.4	68	90	0.75
Δ^8-17β-Estradiol	–	Small amounts	?	?	68	72	0.94
Notes: All listed compounds are present in conjugated estrogen products specifically in the form of the sodium salts of the sulfate esters (i.e., as sodium estrone sulfate, sodium equilin sulfate, etc.). Sources: See template.

Not to be confused with 17β-Dihydroequilin, 17α-Dihydroequilenin, or 17β-Dihydroequilenin.

17α-Dihydroequilin

Clinical data
Other names	α-Dihydroequilin; 7-Dehydro-17α-estradiol; Estra-1,3,5(10),7-tetraen-3,17α-diol
Routes of administration	By mouth
Drug class	Estrogen
ATC code	G03CA57 (WHO)
Identifiers
IUPAC name (9S,13S,14S,17R)-13-methyl-6,9,11,12,14,15,16,17-octahydrocyclopenta[a]phenanthrene-3,17-diol
CAS Number	651-55-8
PubChem CID	9547222
ChemSpider	7826162
UNII	48P73794OJ
CompTox Dashboard (EPA)	DTXSID70873788
ECHA InfoCard	100.010.440
Chemical and physical data
Formula	C18H22O2
Molar mass	270.372 g·mol^−1
3D 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/s1 Key:NLLMJANWPUQQTA-SPUZQDLCSA-N

See also

• List of estrogens § Equine estrogens

References

1. Fritz MA, Speroff L (28 March 2012). Clinical Gynecologic Endocrinology and Infertility. Lippincott Williams & Wilkins. pp. 751–. ISBN 978-1-4511-4847-3.
2. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans; World Health Organization; International Agency for Research on Cancer (2007). Combined Estrogen-progestogen Contraceptives and Combined Estrogen-progestogen Menopausal Therapy. World Health Organization. pp. 378–. ISBN 978-92-832-1291-1.
3. Wilcox JG, Stanczyk FZ, Morris RS, Gentzschein E, Lobo RA (November 1996). "Biologic effects of 17 alpha-dihydroequilin sulfate". Fertility and Sterility. 66 (5): 748–52. doi:10.1016/S0015-0282(16)58629-4. PMID 8893678.