Epitestosterone

Epitestosterone
Names
	IUPAC name 17α-Hydroxyandrost-4-en-3-one
	Systematic IUPAC name (1R,3aS,3bR,9aR,9bS,11aS)-1-Hydroxy-9a,11a-dimethyl-1,2,3,3a,3b,4,5,8,9,9a,9b,10,11,11a-tetradecahydro-7H-cyclopenta[a]phenanthren-7-one
	Other names Isotestosterone; 17α-Testosterone; Androst-4-en-17α-ol-3-one
Identifiers
CAS Number	481-30-1 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:42534 ;
ChEMBL	ChEMBL196228 ;
ChemSpider	9789 ;
DrugBank	DB07768 ;
ECHA InfoCard	100.169.813
PubChem CID	10204;
UNII	48L726977Z;
CompTox Dashboard (EPA)	DTXSID8022329 ;
	InChI InChI=1S/C19H28O2/c1-18-9-7-13(20)11-12(18)3-4-14-15-5-6-17(21)19(15,2)10-8-16(14)18/h11,14-17,21H,3-10H2,1-2H3/t14-,15-,16-,17+,18-,19-/m0/s1 Key: MUMGGOZAMZWBJJ-KZYORJDKSA-N;
	SMILES C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@H]2O)CCC4=CC(=O)CC[C@]34C;
Properties
Chemical formula	C19H28O2
Molar mass	288.431 g/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Epitestosterone, or isotestosterone, also known as 17α-testosterone or as androst-4-en-17α-ol-3-one, is an endogenous steroid and an epimer of the androgen sex hormone testosterone. It is a weak competitive antagonist of the androgen receptor (AR) and a potent 5α-reductase inhibitor.^[1]^[2]

Structurally, epitestosterone differs from testosterone only in the configuration at the hydroxy-bearing carbon, C17. Epitestosterone is believed to form in a similar way to testosterone; a 1993 study found that around 50% of epitestosterone production in human males can be ascribed to the testis,^[3] although the exact pathway of its formation is still the subject of research. It has been shown to accumulate in mammary cyst fluid and in the prostate.^[3] Epitestosterone levels are typically highest in young males; however, by adulthood, most healthy males exhibit a testosterone to epitestosterone ratio (T/E ratio) of about 1:1.^[4]

^ P. Michael Conn (29 May 2013). Animal Models for the Study of Human Disease. Academic Press. pp. 376–. ISBN 978-0-12-415912-9.
^ Stárka L, Bicíková M, Hampl R (1989). "Epitestosterone--an endogenous antiandrogen?". J. Steroid Biochem. 33 (5): 1019–21. doi:10.1016/0022-4731(89)90255-0. PMID 2532272.
^ ^a ^b Dehennin L (February 1993). "Secretion by the human testis of epitestosterone, with its sulfoconjugate and precursor androgen 5-androstene-3 beta,17 α-diol". J. Steroid Biochem. Mol. Biol. 44 (2): 171–7. doi:10.1016/0960-0760(93)90025-R. PMID 8439521. S2CID 54290658.
^ Bellemare V, Faucher F, Breton R, Luu-The V (2005). "Characterization of 17α-hydroxysteroid dehydrogenase activity (17α-HSD) and its involvement in the biosynthesis of epitestosterone". BMC Biochem. 6: 12. doi:10.1186/1471-2091-6-12. PMC 1185520. PMID 16018803.

[Conn2013-1] P. Michael Conn (29 May 2013). Animal Models for the Study of Human Disease. Academic Press. pp. 376–. ISBN 978-0-12-415912-9.

[pmid2532272-2] Stárka L, Bicíková M, Hampl R (1989). "Epitestosterone--an endogenous antiandrogen?". J. Steroid Biochem. 33 (5): 1019–21. doi:10.1016/0022-4731(89)90255-0. PMID 2532272.

[Dehennin93-3] Dehennin L (February 1993). "Secretion by the human testis of epitestosterone, with its sulfoconjugate and precursor androgen 5-androstene-3 beta,17 α-diol". J. Steroid Biochem. Mol. Biol. 44 (2): 171–7. doi:10.1016/0960-0760(93)90025-R. PMID 8439521. S2CID 54290658.

[4] Bellemare V, Faucher F, Breton R, Luu-The V (2005). "Characterization of 17α-hydroxysteroid dehydrogenase activity (17α-HSD) and its involvement in the biosynthesis of epitestosterone". BMC Biochem. 6: 12. doi:10.1186/1471-2091-6-12. PMC 1185520. PMID 16018803.

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