Marinobufagenin (MBG)

Marinobufagenin is a cardiotonic bufadienolide steroid secreted by the toad Bufo rubescens and other related species such as Bufo marinus. It is a vasoconstrictor with effects similar to digitalis. The increase in the emergence of antibiotic-resistant microorganisms and difficult to treat infections caused by these pathogens stimulate research aiming the identification of novel antimicrobials. Skin secretion of amphibian contains a large number of biologically active compounds, including compounds that performance defense mechanisms against microorganisms. In the present work, two antimicrobial bufadienolides, telocinobufagin (402.1609 Da) and marinobufagin (400.1515 Da), were isolated from skin secretions of the Brazilian toad Bufo rubescens. Besides the antimicrobial activity both bufadienolides promoted an increase of the contraction force in isolated frog ventricle strips.