Chemical and functional analyses of Rhinella icterica (Spix, 1824) toad secretion screened on contractions of the heart and oviduct in Locusta migratoria

Rhinella icterica is a Brazilian toad with parotoid secretion that toxic to insects. In this work, we examined the entomotoxicity of in locust (Locusta migratoria) semi-isolated heart and oviduct preparations vitro. The caused negative chronotropism (at highest dose tested: 500 μg) markedly enhanced amplitude spontaneous contractions tonus muscle (0.001–100 μg). addition, neurally-evoked muscle, which was more sensitive low concentrations than heart. (100 neuromuscular blockade. zero calcium-high magnesium saline, still tonus, suggesting release intracellular calcium stimulate contraction. Reverse-phase HPLC yielded eight fractions, only fractions 4 5 affected contractions. No phospholipase A2 activity detected or its chromatographic fractions. analysis by LC-DAD-MS/MS revealed following chemical compounds: suberoyl arginine, hellebrigenin, hellebrigenin 3-suberoyl arginine ester, marinobufagin 3-pimeloyl telocinobufagin bufalin 3-adipoyl marinobufagin, bufotalinin, bufalitoxin. These findings indicate R. active both examined, possibly being mediated bufadienolides.