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 naturally occurring mycoestrogen found in fungi in the Fusarium genus and a non-steroidal estrogen used mainly as an anabolic agent in veterinary medicine.