Diseño, síntesis y actividad biológica de péptidos antimicrobianos catiónicos

Abstract

Antibacterial resistance to conventional antibiotics is an emerging problem worldwide. This urge to develop alternative antibiotics has motivated researchers to look for new molecules to overcome this resistance problem, such as antimicrobial peptides (PAMs). PAMs are important effector molecules of the innate immune system, which is the main defense mechanism for most living organisms. Alyteserin 1c, is an antimicrobial peptide secreted in the skin of the toad Alytes obstetricans characterized by having a net charge +2 (WT). Based on the WT peptide, an analogue (ΔM) was developed, which presents a +5 net charge as a result of different amino acid substitutions in the polar face of the Alyteserin 1c helix. Both peptides were synthesized using the solid phase peptide synthesis method. The yield of the unpurified synthesis was 29.7% for each peptide. After the process of purification by reverse phase high efficiency liquid chromatography, the yield was 4.95% for the WT and 13.2% for the ΔM. Subsequently, the purity of the peptides was verified using the Bruker Daltonics MALDI-TOF mass spectrophotometer, which was 95% in both peptides. Regarding the antibacterial activity, the WT peptide exhibited a minimum inhibitory concentration (MIC) of 62.5 μM and 250 μM, against the bacteria Staphylococcus aureus and Salmonella typhimuriom, respectively, on the other hand, with the ΔM MICs were obtained from 125 μM and 62.5 μM, for both strains respectively. Regarding the hemolytic activity of the peptide WT and ΔM, it was observed that the minimum hemolytic concentration is 62.5 μM in each one.