17β-Methyl-17α-dihydroequilenin

Chemical compound (13S,14S,17R)-13,17-dimethyl-12,14,15,16-tetrahydro-11H-cyclopenta[a]phenanthrene-3,17-diol 17β-Methyl-17α-dihydroequilenin.svg skin-invert-image Estrogen correct CAS 1011733-40-6 correct FDA ZP488KVU9Q 9549180 7828102 NCI-122; 17β-Methyl-6,8-didehydro-17α-estradiol; 17β-Methylestra-1,3,5(10),6,8-pentaene-3,17α-diol 19 22 2 C[C@]12CCC3=C([C@@H]1CC[C@@]2(C)O)C=CC4=C3C=CC(=C4)O 1S/C19H22O2/c1-18-9-7-15-14-6-4-13(20)11-12(14)3-5-16(15)17(18)8-10-19(18,2)21/h3-6,11,17,20-21H,7-10H2,1-2H3/t17-,18-,19+/m0/s1 FQMQOMRDADWGJJ-GBESFXJTSA-N 17β-Methyl-17α-dihydroequilenin (developmental code name NCI-122), also known as 17β-methyl-6,8-didehydro-17α-estradiol, is a synthetic steroidal estrogen which was never marketed. Hsieh RW, Rajan SS, Sharma SK, Greene GL Molecular characterization of a B-ring unsaturated estrogen: implications for conjugated equine estrogen components of premarin Steroids 73 1 59–68 January 2008 17949766 2225582 10.1016/j.steroids.2007.08.014 Flores VA, Taylor HS The Effect of Menopausal Hormone Therapies on Breast Cancer: Avoiding the Risk Endocrinol. Metab. Clin. North Am. 44 3 587–602 September 2015 26316245 4555991 10.1016/j.ecl.2015.05.007 It is the C17β methylated derivative of 17α-dihydroequilenin, an equine estrogen and constituent of conjugated estrogens (Premarin). 17α-Dihydroequilenin itself is an analogue of 17α-estradiol, the C17 epimer of estradiol (or 17β-estradiol). NCI-122 has respective relative binding affinities of about 8.1% and 16% for the ERα and ERβ when compared to estradiol. It is far less potent as an estrogen in comparison to estradiol, with relative estrogenic potencies at the ERα and ERβ of 1.4% and 0.81%, respectively. Nonetheless, NCI-122 acts as a full agonist of the ERα (ERβ was not assessed) and has estrogenic activity similar to that of estradiol at sufficiently high concentrations. The mechanisms of the lower potency of NCI-122 and related estrogens (e.g., 17α-estradiol and equilenin) relative to estradiol have been studied. References Category:Estranes Category:Synthetic estrogens Category:Hydroxyarenes Category:Tertiary alcohols