Lipoidal estradiol

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Estradiol stearate, one of the estradiol esters that represents lipoidal estradiol.

Lipoidal estradiol (LE2) is the variety of endogenous C17β long-chain fatty acid esters of estradiol which are formed as metabolites of estradiol.[1][2] Important examples of these esters include estradiol arachidonate, estradiol lineolate, estradiol oleate, estradiol palmitate, and estradiol stearate.[1][2] LE2 are estrogens but do not bind to the estrogen receptor, instead acting as prohormones of estradiol.[1][2] Relative to estradiol, they have far longer-lasting durations of effect due to their much slower rates of metabolism and clearance.[1][2] It has been hypothesized that LE2 may serve as a store of estrogen for when estradiol levels become low.[1][2] LE2 are highly lipophilic and hydrophobic and are found in highest concentrations in adipose tissue and other estrogen-sensitive tissues and in low but detectable concentrations in circulation, with none excreted in urine.[1][2] They have been referred to as the "endogenous counterparts of the synthetic esters of estrogens" like estradiol valerate and estradiol cypionate.[1][2]

Two of the estradiol esters that compose LE2, estradiol palmitate and estradiol stearate, have been developed and marketed for medical use as long-acting estrogens for use via depot intramuscular injection.[3][4]

Estradiol is esterified into LE2 by lecithin–cholesterol acyltransferase (LCAT).[5]

See also[edit]


  1. ^ a b c d e f g Michael Oettel; Ekkehard Schillinger (6 December 2012). Estrogens and Antiestrogens I: Physiology and Mechanisms of Action of Estrogens and Antiestrogens. Springer Science & Business Media. pp. 235–237. ISBN 978-3-642-58616-3.
  2. ^ a b c d e f g Hochberg RB, Pahuja SL, Larner JM, Zielinski JE (1990). "Estradiol-fatty acid esters. Endogenous long-lived estrogens". Ann. N. Y. Acad. Sci. 595: 74–92. doi:10.1111/j.1749-6632.1990.tb34284.x. PMID 2197972. S2CID 19866729.
  3. ^ J. Elks (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. p. 898. ISBN 978-1-4757-2085-3.
  4. ^ Index Nominum 2000: International Drug Directory. Taylor & Francis. January 2000. pp. 405–. ISBN 978-3-88763-075-1.
  5. ^ Clarkson TB, Appt SE, Wood CE, Cline JM (September 2004). "Lessons to be learned from animal studies on hormones and the breast". Maturitas. 49 (1): 79–89. doi:10.1016/j.maturitas.2004.06.012. PMID 15351099.