Cytotoxic profile of natural and some modified bufadienolides from toad Rhinella schneideri parotoid gland secretion.

Cutaneous secretions of toad species are an important source of bufadienolides, compounds that exhibit interesting structural features and biopharmacological properties. Here we describe the isolation of bufadienolides from the Brazilian toad Rhinella schneideri parotoid glands secretion, including: marinobufagin (1), bufalin (2), telocinobufagin (3), hellebrigenin (4), and the atypical 20S,21R-epoxymarinobufagin (5) besides the widespread beta-sitosterol (6). Starting from natural bufadienolides four derivatives were prepared: 3beta-acetoxy-marinobufagin (7), 3beta-acetoxy-bufalin (8), 3beta-acetoxy-telocinobufagin (9), and 3beta-acetoxy-20S,21R-epoxymarinobufagin (10).

Antimicrobial activity of the bufadienolides marinobufagin and telocinobufagin isolated as major components from skin secretion of the toad Bufo rubescens.

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.