Synthesis and characterization of new antimicrobial peptides derived from Temporin F

Antimicrobial peptides (AMPs) are a promising source of new compounds against resistant bacteria. Temporins are a class of AMPs found on the amphibian Rana temporaria and show activity against Gram-positive and Gram-negative bacteria. There are few studies on how these antimicrobials have been used, but new Temporin-F derivatives were engineered with Lys-substitutions to assess the impact of the net charge on antimicrobial activity and toxicity. We demonstrated through some assays that it is possible to increase the antibacterial activity while maintaining a reduced peptide hemolytic activity with specific substitutions. Our lead synthetic peptide, G6K-Temporin F, has shown higher antimicrobial activity against Gram-negative and Gram-positive bacteria in vitro (MIC range 2 to 32 μmol L^-1), with low hemolytic activity maintained, resulting in an increase in the therapeutic window (TW), of 12.5. Also, it showed more resistant to enzymatic degradation. On the other hand, more significant increases in net charges, such as in P3K-G11K-Temporin F, result in a severe increase in toxicity with lower gains in antimicrobial activity (TW of 0.65). In conclusion, we demonstrated that a moderate increase in net charge can lead to a more active analog and G6K-Temporin F is revealed to be promising as a candidate for new AMP therapeutics.