Structures of novel bufadienolides in the eggs of a toad, Bufo marinus

Abstract

In this paper, we report chemical structures of five compounds including four novel polyhydroxylated cardiac steroids in the eggs of a toad, Bufo marinus. These cardiac steroids were purified by high-performance liquid chromatography, and their structures were determined to be lla,19-dihydroxy-telocinobufagin (I), 11 α-hydroxytelocinobufagin (II), 11α,19-dihydroxymarinobufagin (III), 11α-hydroxy-marinobufagin (IV) and 19-hydroxytelocinobufagin (V) on the basis of spectral data of nuclear magnetic resonance and mass spectroscopy. All the five compounds showed biological activity, as tested by inhibition of Na+,K+-ATPase activity and of [3H]ouabain binding to the receptor on Na+,K+-ATPase. This is the first finding of bufadienolides as cardiac steroids in animal eggs. © 1994, The Pharmaceutical Society of Japan. All rights reserved.