Estrogen receptor binding tolerance of 16α-substituted estradiol derivatives

Thomas L. Fevig, Michael K. Mao, John A. Katzenellenbogen

Research output: Contribution to journalArticlepeer-review


In order to examine the tolerance of the estrogen receptor for 16α-substituents in estradiol, we have synthesized various 16α-substituted estrogens and determined their binding affinity for receptor by a competitive radiometric binding assay. The substituents ranged from small, single-atom substituents (halogens), two-atom substituents (halomethyl groups), to larger alkyl groups and ultimately alkyl groups bearing various functionality, including fluorescent (nitrobenzoxadiazole, NBD) and photoreactive (nitroazidophenyl, NAP) groups. The estrogen receptor seems to have a moderate tolerance for bulky substituents: All of the halogen and halomethyl substituents bind with an affinity at least 50% that of estradiol; in the three atom alkyl series, the affinity declined markedly from propargyl (44%) and allyl (38%) to propyl (5%), suggestive of detailed steric constraints or a preference for unsaturation. The larger, more highly functionalized derivatives ranged in affinity from 0.1 - 7%,with the highest affinity binders being benzyl (5%) and 4-phenoxy-2(E)-butenyl (7%); most of the lowest affinity ones were the bulky fluorescent and photoreactive derivatives. Thus, the estrogen receptor has good tolerance for estradiol derivatives substituted at the 16α-position with nonpolar groups of moderate bulk; however, with groups of larger bulk, affinity is much lower and becomes highly dependent upon the polarity and detailed structure of the substituents.

Original languageEnglish (US)
Pages (from-to)471-497
Number of pages27
Issue number5-6
StatePublished - 1988

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry


Dive into the research topics of 'Estrogen receptor binding tolerance of 16α-substituted estradiol derivatives'. Together they form a unique fingerprint.

Cite this