Antibacterial Activity and Toxicity of Analogs of Scorpion Venom IsCT Peptides

Seven analogs of the natural, α-helix peptides IsCT1 and IsCT2-found in the venom of scorpion Opithancatus Madagascariensis-have been synthesized and tested to compare their antibacterial and hemolytic activity against natural peptides. In general, results show that increasing hydrophobicity by substituting positions 5 and 9 of the sequences with alanine, valine, and leucine, enhances antibacterial activity. However, this also increases hemolytic activity. The analog with an increased net positive charge from +1 to +3 produces moderate bacterial growth inhibition but also has high hemolytic activity. On the other hand, the analog with a negative net charge (-1) has low antibacterial properties but also no cytotoxicity under the tested conditions, a similar result was found for five of the seven studied analogs.