Banca de QUALIFICAÇÃO: LÍDIA LEONIZE RODRIGUES MATIAS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LÍDIA LEONIZE RODRIGUES MATIAS
DATE: 18/12/2023
TIME: 09:00
LOCAL: Videoconferencia - Link para acesso: https://meet.google.com/ghv-bsgp-ppz
TITLE:

Study of new alternatives and anti-infectious agents for the treatment against bacterial infections

KEY WORDS:

Antimicrobial agents; Infections; Trypsin inhibitor; Caenorhabditis elegans.

 

PAGES: 97
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Infections have become a worrying threat to public health, especially when caused by bacteria resistant to currently available antimicrobials. In this context, this thesis aimed to study new alternatives in antibacterial treatments. For this purpose, a narrative review and an in vitro and in vivo study were performed. Thus, the first chapter of this thesis presents a narrative review that aims to present new biomedical alternatives in antibacterial treatments developed to control bacterial infections, aiming at new antibacterial therapies. As a result, it was found that some areas of research aimed at antibacterial treatments have been emerging, namely bioinformatics, nanotechnology, and genomics, in addition to studies developed with natural molecules such as antimicrobial peptides. Furthermore, the articles in this narrative review presented promising research in the development of antimicrobial agents, and their mechanisms of action and strategies to minimize the consequences of bacterial resistance. The review will present current alternatives and may contribute to future studies in the area. In the second chapter, the effect of trypsin inhibitor isolated from tamarind seeds (TTI) on the survival of Caenorhabditis elegans (C. elegans) (wild strain) under conditions of bacterial infection was investigated. The TTI was obtained by isolation in Trypsin-Sepharose CNBr-4B affinity chromatography. Its protein quantification was performed using the Bradford method, and an antitryptic assay monitored its specific activity. The animals were maintained in Nematode Growth Medium (NGM) and Escherichia coli bacteria (OP50) as a food source at 20 ⸰C and, for the analyses executed, they were previously exposed to different concentrations of TTI, from stage L1 to L4, in addition to a group control without treatment. In addition, a toxicity test was performed, which evaluated parameters related to oviposition, progeny, locomotion, and body size. Subsequently, the bacterial infection test was carried out with Staphylococcus aureus in C. elegans previously subjected to concentrations of 0.1 and 1.0 mg/mL of TTI. The oxidative stress test was performed, in which nematodes were exposed to the stressor tert-butyl hydroperoxide (TBOOH). Then, bacterial growth curve, antioxidant and antibacterial activity tests were carried out in vitro. In the toxicity test, no statistical difference was found between the control group and the other concentrations tested (p> 0.05). Regarding body size, the tested TTI concentrations showed a statistical difference (p<0.05) and presented higher length compared to tha untreated group. Regarding bacterial infection analyses, animals subjected to 0.1 mg/mL and 1.0 mg/mL of TTI showed survival of 16.10% and 30.32%, respectively, higher compared to the group infected without treatment (8.08%). To understand the role of TTI on animal survival, in the oxidative stress test, at all tested TTI concentrations, greater survival was observed about the control at 12h and 18h (p< 0.05). In in vitro studies regarding the bacterial growth curve, no inhibitory activity of TTI was observed about Escherichia coli (OP50) (p>0.05) at the concentrations tested, nor was antibacterial and antioxidant activity observed. Given the results, a greater survival of C. elegans was found when previously exposed to TTI; however, in a different antioxidant and antibacterial pathway. Considering studies already published with TTI regarding its action as an insulin-like peptide, it is assumed that TTI may be acting as an antagonist of the DAF-2 pathway, providing the nuclear translocation of DAF-16 that induced greater survival of the animals in this study. Therefore, TTI acted as a protective and anti-infective agent in C. elegans, and further studies are needed to understand the role of TTI in other experimental models. Thus, the study contributed to consolidating theoretical and scientific understanding through narrative review and TTI tests on new alternatives for controlling bacterial infection.

COMMITTEE MEMBERS:
Presidente - 2085604 - SUSANA MARGARIDA GOMES MOREIRA
Externa ao Programa - 2275877 - THAIS SOUZA PASSOS - UFRNExterna à Instituição - MAYARA SANTA ROSA LIMA - UFRB