Allenolic acid

Allenolic acid, or allenoic acid, is a synthetic, non-steroidal estrogen discovered in 1947 or 1948 that, although studied clinically, was never marketed. It is an open-ring or seco analogue of steroidal estrogens like estrone and equilenin. The compound was named after Edgar Allen, one of the pioneers in estrogen research. Although described as an estrogen, allenolic acid has also been reported to be inactive as an estrogen, whereas a derivative, allenestrol (α,α-dimethyl-β-ethylallenolic acid), is reported to be a potent estrogen. Another derivative of allenolic acid (specifically, a methyl ether of allenestrol), methallenestril (brand name Vallestril), is also a potent estrogen and, in contrast to allenolic acid and allenestrol, has been marketed.