Avaliação da atividade protetora de antioxidantes sintéticos contra danos no dna em Saccharomyces cerevisiae

Abstract

DNA damage caused by chemical and physical agents compromises cellular integrity, potentially leading to mutagenesis, mitochondrial dysfunction, and cell death. Antioxidant complexes have been studied for their ability to protect cells against oxidative stress and genotoxic damage. This thesis evaluated the protective activity of complexes containing iron, manganese, and copper, coordinated to the H2BPClNOL ligand, against damage induced by methyl methanesulfonate (MMS) and UVA and UVB radiation in Saccharomyces cerevisiae. For MMS analysis, three strains of S. cerevisiae were used: a wild-type strain (BY4741) and two DNA repair-deficient strains, rad9Δ and rad54Δ. For UVA and UVB radiation analysis, two strains were used: a wildtype strain (FF18733) and a strain deleted for a yeast NADPH oxidase, yno1Δ. To evaluate cellular protection, survival, mutagenesis, and mitochondrial dysfunction assays were performed using spot test or plating methodologies, in addition to intracellular oxidation assays to measure the antioxidant capacity of the complexes. Furthermore, proteomic analysis was conducted to identify proteins differentially expressed in cells treated with the complexes for 1 hour. The results demonstrated that all complexes significantly increased the survival of the strains exposed to MMS, UVA, and UVB, indicating a protective action independent of the specific DNA repair pathway. Mitochondrial dysfunction assays revealed a significant reduction in mitochondrial damage caused by the stress agents, while induced mutagenesis was attenuated. Intracellular oxidation analysis showed that exposure to stress agents increased reactive oxygen species levels, whereas the complexes reduced this oxidative stress, suggesting a direct antioxidant mechanism. Proteomic analysis identified proteins differentially expressed in response to treatments, including proteins involved in DNA repair, oxidative stress response, and maintenance of cellular integrity. Proteins related to antioxidant defense and molecular chaperones were consistently regulated by the complexes, corroborating the functional results observed in survival and mutagenesis assays. Overall, the results indicate that complexes containing the H2BPClNOL ligand exert a multifactorial protective action in S. cerevisiae, mitigating oxidative stress and preserving DNA integrity and mitochondrial function. Proteomic analysis supports the hypothesis that these complexes modulate cellular pathways related to DNA repair and antioxidant defense, providing insights into cellular protection mechanisms that may be explored in future studies. Therefore, this work contributes to understanding the protective effects of metallic antioxidant complexes and highlights their potential as tools to study the interaction between oxidative stress, DNA damage, and adaptive cellular responses in eukaryotic models. These findings also reinforce the relevance of using S. cerevisiae as an experimental model to evaluate antioxidant complexes and investigate cellular repair and protection mechanisms.