Alpha Zearalanol.svg
Clinical data
Trade namesFrideron, Ralabol, Ralgro, Ralone, Zerano
Other namesZearanol; α-Zearalanol; Zearalanol; MK-188; P-1496
Routes of
By mouth
Drug classNonsteroidal estrogen
  • (3S,7R)-7,14,16-trihydroxy-3-methyl-3,4,5,6,7,8,9,10,11,12-decahydro-1H-2-benzoxacyclotetradecin-1-one
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.043.411 Edit this at Wikidata
Chemical and physical data
Molar mass322.401 g·mol−1
3D model (JSmol)
  • C[C@H]1CCC[C@H](O)CCCCCc2cc(O)cc(O)c2C(=O)O1
  • InChI=1S/C18H26O5/c1-12-6-5-9-14(19)8-4-2-3-7-13-10-15(20)11-16(21)17(13)18(22)23-12/h10-12,14,19-21H,2-9H2,1H3/t12-,14+/m0/s1 ☒N
 ☒NcheckY (what is this?)  (verify)

Zeranol (INN, USAN, BAN) (brand names Frideron, Ralabol, Ralgro, Ralone, Zerano; developmental code names MK-188, P-1496), or zearanol, also known as α-zearalanol or simply zearalanol, is a synthetic nonsteroidal estrogen of the resorcylic acid lactone group related to mycoestrogens found in fungi in the Fusarium genus and is used mainly as an anabolic agent in veterinary medicine.[1][2][3]

Zeranol is approved for use as a growth promoter in livestock, including beef cattle, under the brand name Ralgro (by Merck Animal Health) in the United States.[4] In Canada, it is approved for use in beef cattle only.[5] Its application is not approved for use in the European Union. However, it is marketed under the brand name Ralone in Spain.[2]

Although zeranol may increase cancer cell proliferation in already existing breast cancer,[6] dietary exposure from the use of zeranol-containing implants in cattle is insignificant.[7] Zeranol may be found as a contaminant in fungus-infected crops. It is 3 to 4 times more potent as an estrogen than the related compound zearalenone.[8]

See also


  1. ^ Elks J (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 350–. ISBN 978-1-4757-2085-3.
  2. ^ a b Index Nominum 2000: International Drug Directory. Taylor & Francis. January 2000. pp. 1105–. ISBN 978-3-88763-075-1.
  3. ^ Morton IK, Hall JM (6 December 2012). Concise Dictionary of Pharmacological Agents: Properties and Synonyms. Springer Science & Business Media. pp. 295–. ISBN 978-94-011-4439-1.
  4. ^ Nichols W, Hutcheson J, Streeter M, Corrigan M, Nuttelman B. "Implant Strategies for Finishing Cattle using Revalor® (trenbolone acetate and estradiol), Finaplix® (trenbolone) and/or Ralgro® (zeranol)" (PDF). Merck Animal Health.
  5. ^ Health Canada, Questions and Answers - Hormonal Growth Promoters
  6. ^ Xu P, Ye W, Jen R, Lin SH, Kuo CT, Lin YC (November 2009). "Mitogenic activity of zeranol in human breast cancer cells is enhanced by leptin and suppressed by gossypol". Anticancer Research. 29 (11): 4621–8. PMID 20032412.
  7. ^ Lindsay DG (August 1985). "Zeranol--a 'nature-identical' oestrogen?". Food and Chemical Toxicology. 23 (8): 767–74. doi:10.1016/0278-6915(85)90273-x. PMID 2931335.
  8. ^ Mirocha CJ, Schauerhamer B, Christensen CM, Niku-Paavola ML, Nummi M (October 1979). "Incidence of zearalenol (Fusarium mycotoxin) in animal feed". Applied and Environmental Microbiology. 38 (4): 749–50. doi:10.1128/AEM.38.4.749-750.1979. PMC 243572. PMID 161492.