Banca de QUALIFICAÇÃO: GEOVANNA MARIA DE MEDEIROS MOURA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GEOVANNA MARIA DE MEDEIROS MOURA
DATE: 22/11/2024
TIME: 09:00
LOCAL: Videoconferência - Link para acesso: https://meet.google.com/djo-porj-nre
TITLE:

Unveiling the Antibiotic Modulating and Antioxidant Properties of the Wild Mushroom Langermannia bicolor

KEY WORDS:

Wild mushroom, toxicity, multiresistant bacteria, in vivo antioxidant, ROS, zebrafish.

PAGES: 117
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

The emergence of multidrug-resistant bacteria has driven the search for new therapeutic agents and adjuvants. In this study, we investigated the properties of an extract from the mushroom Langermannia bicolor as a modulator of antibiotics (gentamicin, norfloxacin, and ampicillin) against multidrug-resistant strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, as well as its antioxidant action and toxicity. The crude aqueous extract of L. bicolor was fractionated with increasing volumes of acetone, resulting in three fractions (F0.5, F1, and F2), which exhibited different biochemical profiles. Tests with human erythrocytes revealed that the extract and fractions did not have hemolytic activity, while MTT reduction assays in fibroblast cells (NHI/3T3) showed that the crude extract reduced viability by 50%. In vivo tests with zebrafish embryos (Danio rerio) confirmed the absence of toxicity from the fractions. Although no fraction demonstrated direct antibacterial activity, all exhibited significant modulatory effects when combined with conventional antibiotics against the tested multidrug-resistant bacteria. Notably, fraction F2, rich in proteins, reduced the Minimum Inhibitory Concentration (MIC) of gentamicin across all tested strains. The fractions also proved to be potent antioxidants in vitro and in vivo. Fraction F0.5, rich in phenolic compounds and flavonoids, displayed the broadest spectrum of antioxidant activities, including metal chelation (Fe²⁺ and Cu²⁺), free radical scavenging (OH• and O₂•⁻), and cellular protection against hydrogen peroxide (H₂O₂)-induced oxidative stress in 3T3 cells. Fraction F1, which was carbohydrate-rich, was able to correct oxidative damage following H₂O₂ stress. In vivo, all fractions protected zebrafish embryos exposed to H₂O₂. When quantifying reactive oxygen species (ROS) using a fluorescent probe (DFCH), zebrafish larvae treated with F0.5 followed by H₂O₂ significantly reduced ROS production in their cells, showing even lower values than those of larvae not exposed to the oxidizing agent. To a lesser extent, F1 and F2 also protected zebrafish cells by reducing ROS production. By pioneering the therapeutic potential of L. bicolor, our study paves the way for future investigations into the bioactive composition of this mushroom and its respective molecular mechanisms involved in its observed properties: antibiotic potentiation and protection against oxidative stress.

COMMITTEE MEMBERS:
Externa à Instituição - ELIZABETH CRISTINA GOMES DOS SANTOS - UFRN
Externa à Instituição - MARÍLIA MEDEIROS FERNANDES DE NEGREIROS - IFRR
Presidente - 2832746 - MONIQUE GABRIELA DAS CHAGAS FAUSTINO ALVES