Novas alternativas para o tratamento contra infecções bacterianas: avaliação do potencial do inibidor de tripsina isolado de sementes de tamarindo (ITT) como agente anti-infeccioso

Abstract

Infections have become a worrying threat to public health, especially when caused by bacteria resistant to currently available antimicrobials. This thesis aimed to study new alternatives for treatments against bacterial infections. 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 of new biomedical alternatives in antibacterial treatments. As a result, it was found that some areas of research aiming to control bacterial infections have been highlighted, 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 developing antimicrobial agents, and their mechanisms of action and strategies to minimize the consequences of bacterial resistance. The review will present current alternatives 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 isolated 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 analysescarried out, they were previously exposed to different concentrations of TTI, from stage L1 to L4, in addition to a group control without treatment. Besides, the toxicity test was performed by evaluatingoviposition, 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. Nematodes were exposed to the stressor tert-butyl hydroperoxide (TBOOH) in an oxidative stress test. Then, bacterial growth curve and 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 than the 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 than 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 about 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. In this way, the study contributed to consolidating theoretical and scientific understanding through narrative review and ITT tests, respectively, on new alternatives for controlling bacterial infection.