Structural Parallels Between the Cardiotonic Steroids and the Erythrophleum Alkaloids - II. Synthesis and Na(1+),K(1+)-ATPase Inhibitory Activity of Novel Erythrophleum Alkaloid Analogues

Article abstract of DOI:10.1016/S0040-4020(01)81950-5

Erythrophleum alkaloid analogues, which differ in the ester side-chain configuration, in the nature of the 14-axial substituent (H, Me, Et) and in their absolute configuration, have been prepared.A pronounced trend towards increased Na(1+),K(1+)-ATPase inhibitory activity occurs through the H, Me and Et series, with the E side-chain configuration more active than the Z.This trend is largely confined to the analogues with an absolute configuration matching that of the natural alkaloids.A structural parallel between the 14-axial alkyl substituent of the alkaloids and the D-ring of the cardiotonic steroids is proposed.