Estradiol palmitate

Estradiol palmitate (brand name Esmopal), or estradiol monopalmitate, also known as estradiol 17β-hexadecanoate, is a naturally occurring^[1] steroidal estrogen and an estrogen ester – specifically, the C17β palmitate ester of estradiol.^[2] It occurs in the body as a very long-lasting metabolite and prohormone of estradiol.^[1] The compound has no affinity for the estrogen receptor, requiring transformation into estradiol for its estrogenic activity.^[3] In addition to its endogenous role, estradiol palmitate was formerly used as a fattening agent in chickens under the brand name Esmopal.^{[4][5][6][7][8]}

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Affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors

Estrogen	Other names	RBATooltip Relative binding affinity (%)a	REP (%)b
		ER	ERα	ERβ
Estradiol	E2	100	100	100
Estradiol 3-sulfate	E2S; E2-3S	?	0.02	0.04
Estradiol 3-glucuronide	E2-3G	?	0.02	0.09
Estradiol 17β-glucuronide	E2-17G	?	0.002	0.0002
Estradiol benzoate	EB; Estradiol 3-benzoate	10	1.1	0.52
Estradiol 17β-acetate	E2-17A	31–45	24	?
Estradiol diacetate	EDA; Estradiol 3,17β-diacetate	?	0.79	?
Estradiol propionate	EP; Estradiol 17β-propionate	19–26	2.6	?
Estradiol valerate	EV; Estradiol 17β-valerate	2–11	0.04–21	?
Estradiol cypionate	EC; Estradiol 17β-cypionate	?c	4.0	?
Estradiol palmitate	Estradiol 17β-palmitate	0	?	?
Estradiol stearate	Estradiol 17β-stearate	0	?	?
Estrone	E1; 17-Ketoestradiol	11	5.3–38	14
Estrone sulfate	E1S; Estrone 3-sulfate	2	0.004	0.002
Estrone glucuronide	E1G; Estrone 3-glucuronide	?	<0.001	0.0006
Ethinylestradiol	EE; 17α-Ethynylestradiol	100	17–150	129
Mestranol	EE 3-methyl ether	1	1.3–8.2	0.16
Quinestrol	EE 3-cyclopentyl ether	?	0.37	?
Footnotes: a = Relative binding affinities (RBAs) were determined via in-vitro displacement of labeled estradiol from estrogen receptors (ERs) generally of rodent uterine cytosol. Estrogen esters are variably hydrolyzed into estrogens in these systems (shorter ester chain length -> greater rate of hydrolysis) and the ER RBAs of the esters decrease strongly when hydrolysis is prevented. b = Relative estrogenic potencies (REPs) were calculated from half-maximal effective concentrations (EC50) that were determined via in-vitro β‐galactosidase (β-gal) and green fluorescent protein (GFP) production assays in yeast expressing human ERα and human ERβ. Both mammalian cells and yeast have the capacity to hydrolyze estrogen esters. c = The affinities of estradiol cypionate for the ERs are similar to those of estradiol valerate and estradiol benzoate (figure). Sources: See template page.

Estradiol palmitate

Clinical data
Trade names	Esmopal
Other names	Estradiol monopalmitate; Estradiol hexadecanoate; Estradiol 17β-hexadecanoate
Drug class	Estrogen; Estrogen ester
Identifiers
IUPAC name [(8R,9S,13S,14S,17S)-3-Hydroxy-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-17-yl] hexadecanoate
CAS Number	5776-45-4
PubChem CID	111095
ChemSpider	99723
UNII	1Q5Y448XT0
CompTox Dashboard (EPA)	DTXSID00973346
ECHA InfoCard	100.024.819
Chemical and physical data
Formula	C34H54O3
Molar mass	510.803 g·mol−1
3D model (JSmol)	Interactive image
SMILES CCCCCCCCCCCCCCCC(=O)O[C@H]1CC[C@H]2[C@@H]3CCc4cc(O)ccc4[C@H]3CC[C@]12C
InChI InChI=1S/C34H54O3/c1-3-4-5-6-7-8-9-10-11-12-13-14-15-16-33(36)37-32-22-21-31-30-19-17-26-25-27(35)18-20-28(26)29(30)23-24-34(31,32)2/h18,20,25,29-32,35H,3-17,19,21-24H2,1-2H3/t29-,30-,31+,32+,34+/m1/s1 Key:XQKLZLWOOGGXMV-KWXXMMNJSA-N

See also

• Estradiol stearate
• Estradiol undecylate
• List of estrogen esters § Estradiol esters