PEPTÍDEO ANTIMICROBIANO SINTÉTICO DERIVADO DE INIBIDOR DE PEPTIDASE: SÍNTESE, ANÁLISE ESTRUTURAL E ENSAIOS BIOLÓGICOS

Abstract

ABSTRACT

Since a long time, the disease-causing microorganisms and humanity relationship is well-known established. Bacteria is one of the main agents for causing diseases in humans, which can be controlled through the use of antibiotics. On the other hand, over time, the emergence and increasing of bacterial resistance to such drugs has become a growing concern. Reports of infections and deaths from antimicrobial-resistant bacteria are growing daily in the world and WHO has warned about the importance of developing new effective drugs against these superbacteriae. The discovery of new agents from plants led to the isolation of many substances that are still used clinically today or as prototypes for the synthesis of bioactive molecules. Thus, the development of new strategies for combating this growing resistance has received greater attention, and antimicrobial peptides (AMP) emerge as a work perspective, in addition to being involved in innate immunity. They are promising tools for the development of new antibiotics. As dynamic as pharmaceutical companies are, the search for new antimicrobial has not accompanied the development of multidrug resistance. In this study, we described the design of IKR18, a PAM that, through in silico simulations, was bioinspired in the amino acid sequence of the trypsin inhibitor Inga laurina (ILTI). The peptide obtained was tested in different computational models aiming at predicting possible antibacterial effects, considering synthesis for future tests, with the perspective that these agents act as new weapons against the constant evolution of bacterial resistance. IKR18 showed antimicrobial activity against Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). In addition, our results showed that MIC for S. aureus (MSSA) was 1 µM and MBC 1 µM. In contrast, MRSA underwent bactericidal effect at the same MIC (2 µM). Peptide activity against Acinetobacter baumannii infectious isolates was also analyzed, showing bactericidal action at a concentration of 1 μM. The peptide was also able to inhibit all tested strains biofilm growth. CD studies revealed that IKR18 assumes an alpha-helical structure in the presence of a membrane mimetic environment. IKR18 mechanism of action involves damage to the bacterial membrane, as demonstrated by Sytox green and violet crystal uptake. Furthermore, IKR18 showed synergistic and additive effects in combination with vancomycin and ciprofloxacin. The peptide showed antibiofilm activity, in concentration and efficiency compared to commercial antibiotics, involving the direct killing of bacteria, confirmed by scanning electron microscopy. The IKR18 anti-infective was demonstrated with the Galleria mellonella model infected with MSSA, MRSA and A. baumannii. To sum up, the new bioinspired peptide, IKR18, proved to be effective in controlling bacterial infection, opening opportunities for the development of new assays, including preclinical models.

Keywords: antimicrobial peptides, computational design, bacteria, antibiofilm, infection model, anti-infective, MRSA.