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

• DOI: 10.1016/j.toxicon.2005.01.017
• Publication Date: 2005-03-17T21:23:48Z
• Authors: Geraldino A. Cunh...; Carlos Alberto Sc...; Inês S. Resck; Maria Márcia Murta; Sebastião S. Lemos; Mariana S. Castro; Cynthia Kyaw; Osmindo R. Pires; José Roberto S. L...; Carlos Bloch; Elisabeth Ferroni...
• Keywords: 0301 basic medicine; Staphylococcus aureus; Cardiotonic Agents; Magnetic Resonance Spectroscopy; Protein Conformation; Microbial Sensitivity Tests; Myocardial Contraction; Bufonidae; Mass Spectrometry; Anti-Bacterial Agents; 3. Good health; Bufanolides; 03 medical and health sciences; Amphibian Venoms; Escherichia coli; Animals; Brazil; Chromatography, High Pressure Liquid; Skin

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. The specimens were collected in Brasilia (Distrito Federal, Brazil), the skin secretions extracted by electric stimulation, and submitted to purification by RP-HPLC. The molecular structure and mass determination were done by (1)H and (13)C NMR and mass spectrometry data, respectively. The antimicrobial activity was performed by liquid growth inhibition against Staphylococcus aureus and Escherichia coli. The minimum inhibitory concentrations of telocinobufagin and marinobufagin were, respectively, 64.0 and 16.0 microg/mL for E. coli and both 128 microg/mL for S. aureus. Besides the antimicrobial activity both bufadienolides promoted an increase of the contraction force in isolated frog ventricle strips.