estradiol palmitate estradiol palmitate estradiol palmitate (brand name esmopal), or estradiol monopalmitate, also known as estradiol 17β-hexadecanoate, is a naturally occurring steroidal estrogen and an estrogen ester – specifically, the c17β palmitate ester of estradiol. it occurs in the body as a very long-lasting metabolite and prohormone of estradiol. the compound has no affinity for the estrogen receptor, requiring transformation into estradiol for its estrogenic activity. in addition to its endogenous role, estradiol palmitate was formerly used as a fattening agent in chickens under the brand name esmopal. affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors estrogen other names rba (%)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 palmitateclinical datatrade namesesmopalother namesestradiol monopalmitate; estradiol hexadecanoate; estradiol 17β-hexadecanoatedrug classestrogen; estrogen esteridentifiers iupac name phenanthren-17-yl] hexadecanoate cas number5776-45-4pubchem cid111095chemspider99723unii1q5y448xt0comptox dashboard (epa)dtxsid00973346 echa infocard100.024.819 chemical and physical dataformulac34h54o3molar mass510.803 g·mol−13d model (jsmol)interactive image smiles cccccccccccccccc(=o)o1cc23ccc4cc(o)ccc43cc12c 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/s1key:xqklzlwooggxmv-kwxxmmnjsa-n