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 11 alpha,19-dihydroxy-telocinobufagin (I), 11 alpha-hydroxytelocinobufagin (II), 11 alpha,19-dihydroxymarinobufagin (III), 11 alpha-hydroxymarinobufagin (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.
We have previously described the structures of four novel unconjugated bufadienolides in the ovary of the toad, Bufo marinus. In this study, we report the separation and characterization of three novel bufadienolide conjugates. These compounds were purified by HPLC, and their structures were determined to be 11alpha, 19-dihydroxytelocinobufagin-3-(12-hydroxydodecanoic acid) ester, 11alpha,19-dihydroxytelocinobufagin-3-(14-hydroxy-7-tetra decenoic acid) ester, and 11alpha, 19-dihydroxytelocinobufagin-3-(14-hydroxytetradecanoic acid) ester on the basis of NMR and MS data. Numerous dicarboxylic acid esters of bufadienolides have previously been described, but the three bufadienolide conjugates described in this report differ from previously described esters in that they contain hydroxylated monocarboxylic acids. The function of these three conjugates is not known but they are, like bufotoxins, potent inhibitors of Na+, K+-ATPase and may play a developmental role in the differentiation of toad oocytes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.