Estradiol benzoate cyclooctenyl ether

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Estradiol benzoate cyclooctenyl ether.svg
Clinical data
Other namesEBCO; Estradiol 3-benzoate 17β-cyclooctenyl ether
Routes of
By mouth[1]
Drug classEstrogen; Estrogen ester; Estrogen ether
  • [(8R,9S,13S,14S,17S)-17-[(1E)-cycloocten-1-yl]oxy-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-3-yl] benzoate
CAS Number
PubChem CID
Chemical and physical data
Molar mass484.680 g·mol−1
3D model (JSmol)
  • C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@@H]2O/C/4=C/CCCCCC4)CCC5=C3C=CC(=C5)OC(=O)C6=CC=CC=C6
  • InChI=1S/C33H40O3/c1-33-21-20-28-27-17-15-26(36-32(34)23-10-6-5-7-11-23)22-24(27)14-16-29(28)30(33)18-19-31(33)35-25-12-8-3-2-4-9-13-25/h5-7,10-12,15,17,22,28-31H,2-4,8-9,13-14,16,18-21H2,1H3/b25-12+/t28-,29-,30+,31+,33+/m1/s1

Estradiol benzoate cyclooctenyl ether (EBCO), or estradiol 3-benzoate 17β-cyclooctenyl ether, is a synthetic estrogen as well as estrogen ester and ether – specifically, the C3 benzoate ester and C17β cyclooctenyl ether of estradiol – which was described in the early 1970s and was never marketed.[1][2][3][4] It has been found to have a dramatically prolonged duration of action with oral administration in animals, similarly to the related compound quinestrol (the 3-cyclopentyl ether of ethinylestradiol).[1][5][6] A single oral dose of EBCO sustained high uterus weights for 3 weeks in rats.[1] This long-lasting activity may be due to storage of EBCO in fat.[1] It appears that EBCO is absorbed satisfactorily from the gastrointestinal tract, at least partially survives first-pass metabolism in the liver and intestines, and is then sequestered into fat, from which it is slowly released and activated into estradiol.[1] In contrast to quinestrol, the oral activity of EBCO is greatly improved when it is delivered in an oil solution as opposed to an aqueous vehicle.[1]

See also[edit]


  1. ^ a b c d e f g Falconi G, Galletti F, Celasco G, Gardi R (November 1972). "Oral long-lasting estrogenic activity of estradiol 3-benzoate 17-cyclooctenyl ether". Steroids. 20 (5): 627–38. doi:10.1016/0039-128X(72)90020-7. PMID 4654978.
  2. ^ Galletti F, Gardi R (April 1974). "Effect of two orally active estradiol derivatives on sulfobromphthalein retention in rats". Pharmacol Res Commun. 6 (2): 135–45. doi:10.1016/s0031-6989(74)80021-4. PMID 4438394.
  3. ^ Wermuth, Camille G. (2008). "Designing Prodrugs and Bioprecursors". The Practice of Medicinal Chemistry. pp. 721–746. doi:10.1016/B978-0-12-374194-3.00036-6. ISBN 9780123741943.
  4. ^ Stella, V. (1975). "Pro-drugs: An Overview and Definition". Pro-drugs as Novel Drug Delivery Systems. ACS Symposium Series. Vol. 14. pp. 1–115. doi:10.1021/bk-1975-0014.ch001. ISBN 0-8412-0291-5. ISSN 1947-5918.
  5. ^ Epstein JA (1967). "Prolonged menstrual response of patients with gonadal failure following quinestrol administration". Int. J. Fertil. 12 (2): 181–6. PMID 6033895.
  6. ^ Giannina T, Meli A (April 1969). "Prolonged oestrogenic activity in rats after single oral administration of ethinyloestradiol-3-cyclopentyl ether". J. Pharm. Pharmacol. 21 (4): 271–2. doi:10.1111/j.2042-7158.1969.tb08247.x. PMID 4390151. S2CID 19407816.