17β-Dihydroequilenin

17β-Dihydroequilenin, or β-dihydroequilenin, also known as δ^6,8-17β-estradiol or 6,8-didehydro-17β-estradiol, as well as estra-1,3,5(10),6,8-pentaen-3,17β-diol, is a naturally occurring steroidal estrogen found in horses which is closely related to equilin, equilenin, and estradiol, and, as the 3-sulfate ester sodium salt, is a minor constituent (0.5%) of conjugated estrogens (Premarin).[1] 17β-Dihydroequilenin has unexpectedly shown a selective estrogen receptor modulator (SERM)-like profile of estrogenic activity in studies with monkeys, in which beneficial effects on bone and the cardiovascular system were noted but proliferative responses in breast and endometrium were not observed.[2]

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 17α-Dihydroequilin, 17β-Dihydroequilin, or 17α-Dihydroequilenin.

17β-Dihydroequilenin

Clinical data
Other names	β-Dihydroequilenin; Δ^6,8-17β-Estradiol; 6,8-Didehydro-17β-estradiol; Estra-1,3,5(10),6,8-pentaen-3,17β-diol
Routes of administration	By mouth
Drug class	Estrogen
Identifiers
IUPAC name (13S,14S,17S)-13-methyl-11,12,14,15,16,17-hexahydrocyclopenta[a]phenanthrene-3,17-diol
CAS Number	1423-97-8
PubChem CID	3032407
ChemSpider	2297390
ChEMBL	ChEMBL123405
Chemical and physical data
Formula	C18H20O2
Molar mass	268.356 g·mol^−1
3D model (JSmol)	Interactive image
SMILES C[C@]12CCC3=C([C@@H]1CC[C@@H]2O)C=CC4=C3C=CC(=C4)O
InChI InChI=1S/C18H20O2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h2-5,10,16-17,19-20H,6-9H2,1H3/t16-,17-,18-/m0/s1 Key:RYWZPRVUQHMJFF-BZSNNMDCSA-N

See also

• List of estrogens § Equine estrogens

References

1. Marc A. Fritz; Leon Speroff (28 March 2012). Clinical Gynecologic Endocrinology and Infertility. Lippincott Williams & Wilkins. pp. 751–. ISBN 978-1-4511-4847-3.
2. Cline JM (2007). "Assessing the mammary gland of nonhuman primates: effects of endogenous hormones and exogenous hormonal agents and growth factors". Birth Defects Res. B Dev. Reprod. Toxicol. 80 (2): 126–46. doi:10.1002/bdrb.20112. PMID 17443713.