Synthesis and structure-activity relationships of 17beta-substituted 14beta-hydroxysteroid 3-(alpha-L-rhamnopyranoside)s: steroids that bind to the digitalis receptor

J Med Chem. 1997 May 9;40(10):1439-46. doi: 10.1021/jm960880l.

Abstract

The preparation of 17beta-substituted 14beta-hydroxysteroid C-3 alpha-L-rhamnopyranosides is described. These derivatives have a 14beta,20-ether, 14beta,20-lactone, or 17beta-CH2CH2OH, -CH2CH2NH2, -CH=CHNO2(E), -CH=CHCOOH(E), -CH(OH)CH2NO2(R), -CH(OMe)CH2NO2(R), -CH2-CH2COOH, or -CH(OH)CH2NH2(R) group. Derivatives were assayed in a radioligand binding assay for [3H]ouabain in membranes from canine heart muscle. The digitalis "receptor" comprises isoenzymes of the ion-pumping enzyme, Na+,K+-ATPase. The 17beta-CH=CHNO2(E), 17beta-CH=CHCOOH(E), and 17beta-CH(OMe)CH2NO2(R) derivatives were the most potent and equivalent to ouabain with low-nanomolar IC50 values. The very potent binding affinity of the disubstituted compound 17beta-CH(OMe)CH2NO2(R) further demonstrates that 17beta-unsaturated substitution is not required for potent binding affinity. This observation may be of value in the separation of cardiotonic and cardiotoxic effects. Tosylation of the 17beta-CH2OH, prepared from the 17beta-CHO by lithium aluminum hydride reduction, yielded the 14beta,17beta-ether. Synthesis of the 17beta-CH2COOH gave the epimeric 14alpha,17alpha- and 14beta,17beta-lactones. Structures have been established by NMR analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dogs
  • Magnetic Resonance Spectroscopy
  • Microsomes / metabolism
  • Myocardium / metabolism
  • Ouabain / metabolism
  • Protein Binding
  • Radioligand Assay
  • Rhamnose / chemical synthesis*
  • Rhamnose / chemistry
  • Rhamnose / metabolism
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Structure-Activity Relationship

Substances

  • digitalis receptor
  • Ouabain
  • Sodium-Potassium-Exchanging ATPase
  • Rhamnose