Synthesis and Structure−Activity Relationships of 17β-Substituted 14β-Hydroxysteroid 3-(α-<scp>l</scp>-Rhamnopyranoside)s: Steroids That Bind to the Digitalis Receptor
作者:John F. Templeton、Yangzhi Ling、Kirk Marat、Frank S. LaBella
DOI:10.1021/jm960880l
日期:1997.5.1
The preparation of 17 beta-substituted 14 beta-hydroxysteroid C-3 alpha-L-rhamnopyranosides is described. These derivatives have a 14 beta,20-ether, 14 beta,20-lactone, or 17 beta-CH2CH2OH, -CH2CH2NH2, -CH=CHNO2(E), -CH=CHCOOH(E), -CH(OH)CH2NO2(R), -CH(OMe)CH2NO2(R), -CH2CH2COOH, or -CH(OH)CH2NH2(R) group. Derivatives were assayed in a radioligand binding assay for [H-3]ouabain in membranes from canine heart muscle. The digitalis ''receptor'' comprises isoenzymes of the ion-pumping enzyme, Na+,K+-ATPase. The 17 beta-CH=CHNO2(E), 17 beta-CH=CHCOOH(E), and 17 beta-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 17 beta-CH(OMe)CH2NO2(R) further demonstrates that 17 beta-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 17 beta-CH2OH, prepared from the 17 beta-CHO by lithium aluminum hydride reduction, yielded the 14 beta,17 beta-ether. Synthesis of the 17 beta-CH2COOH gave the epimeric 14 alpha,17 alpha- and 14 beta, 17 beta-lactones. Structures have been established by NMR analysis.