Banca de DEFESA: Joyce Silva dos Santos

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Joyce Silva dos Santos
DATE: 10/04/2023
TIME: 14:30
LOCAL: Meio virtual
TITLE:

Characterization of the biological properties of a dermaseptin isolated from the cutaneous secretion of Pithecopus rohdei (Anura: Phyllomedusidae)

KEY WORDS:

anurans; Pithecopus rohdei; skin secretion; antimicrobial peptides; Dermaseptins; neutrophils; quimiotaxis; Polimixin B; KPC; synergism.

PAGES: 49
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

The indiscriminate use of antibiotics has caused high levels of bacterial resistance around the world. This scenario intensified significantly after the SARS-COV 2 pandemic period, where antimicrobial agents were wildly and erroneously used, even if indicated only in the case of confection with bacteria or fungi. As a result, there was a significant increase in resistant superbugs, leading to the need for the use of high-spectrum antibiotics and serious side effects, such as Polymyxin B, one of the last treatment alternatives for hospital superbugs associated with intense nephrotoxicity. In view of this, research involving molecules with antimicrobial potential is of great importance to society and has gained space in the scientific community. An interesting option for this scenario is the study of natural antimicrobial molecules, such as antimicrobial peptides (AMPs) also called host defense peptides (PDH's). These peptides are short molecules, cationic, amphipathic and abundant in nature, being often found in the cutaneous secretion of amphibians. In this work, a potent antimicrobial peptide present in the cutaneous secretion of Pithecopus rohdei, a species of the Phylomedusidae family, was isolated. The active fraction was identified by High Performance Liquid Chromatography and had a mass of 3080.66 Da. The molecule was sequenced by Edman degradation and presented a peptide sequence of 30 amino acid residues (GLWKMLAKGAGKVLGHVASKFLGSQGQPES-COOH). of Dermaseptin Pr-1 (Pr in reference to the species Pithecopus rohdei). Through the cellular dichroism (DC) test, the secondary structure of the peptide in the presence of SDS and TFE was evaluated, making it possible to infer that dermaseptin Pr-1 forms an alpha helix structure when in contact with membranes, a pattern associated with antimicrobial responses in other defense peptides. With regard to biological tests, the peptide showed inhibitory results on the growth of Gram-positive bacteria Staphylococcus aureus (MIC = 4 M), Staphylococcus epidermidis (MIC = 4 M) e Enterococcus faecalis (MIC = 16 M) and Gram-negative Escherichia coli (MIC = 1 M), Klebsiella pneumoniae (MIC = 2 M) e Pseudomonas aeruginosa (MIC = 4 M), and antibacterial activity was also observed in a multiresistant clinical isolate of Klebsiella pneumoniae Carbapenemase, a result that was corroborated by scanning electron microscopy (SEM) test where it was possible to observe the formation of pores and deep roughness in the membrane of this bacterium, which leads to disruption of the wall and lysis of the microorganism. Furthermore, as a preliminary test to evaluate the immunomodulatory capacity of this dermaseptin, the peptide was tested for its ability to induce neutrophil chemotaxis, where a moderate chemotactic activity was observed. These results suggest that the peptide can act in a dual way, eradicating bacteria directly and indirectly. Finally, the hemolytic activity of the peptide was evaluated and resulted in a low percentage of hemolysis in the concentrations related to the MICs of sensitive bacteria (2% to 9%) also observing a moderate hemolytic activity in the inhibitory concentration of the superbug Klebsiella pneumoniae carbapenemase (23%).

BANKING MEMBERS:
Presidente - 1189826 - MARIANA DE SOUZA CASTRO
Interno - 1354514 - OSMINDO RODRIGUES PIRES JUNIOR
Externo ao Programa - 404930 - CARLOS ANDRE ORNELAS RICART
Externo à Instituição - MARLON HENRIQUE E SILVA CARDOSO - UFMS