Avaliação da atividade antioxidante de compostos de coordenação com os metais de transição ferro, cobre e manganês

Abstract

Reactive oxygen species (ROS) play a key role in cell metabolism. However, when in excess, surpassing the capacity of the antioxidant system, or due to its deficiency, it can generate oxidative stress. The yeast Saccharomyces cerevisiae is one of the best models of the unicellular eukaryotic system for studies on oxidative stress. The active components of metabolic activation and detoxification, which are not present in bacteria, allow tests to assess the antioxidant activity of compounds in a fast, economical and reproducible way. In addition to the S. cerevisiae yeasts, additional Galleria mellonella larvae expand as an excellent study model to replace animal experimentation models due to their ease of handling, similarity between their innate immune system to that of mammals, reproduction of those found in animals. experimentation and lack of ethical religion. Coordination compounds combine one or more central atoms or ions, to which neutral or charged molecules are attached, in addition the central atom is generally a transition metal, capable of forming coordinated bonds with its ligands. The medicinal properties of the compounds have motivated the synthesis and characterization of new antitumor and/or antioxidant compounds. This work aimed to study the antioxidant potential of three coordination complexes with metals iron, copper and manganese. Antioxidant activity was analyzed in vitro by DPPH reduction and in vivo through the use of Saccharomyces cerevisiae and Galleria mellonella In S. cerevisiae the antioxidant activity was performed in fermentative metabolism cells, and treated for 1h with each compound by direct addition to the culture cell phone. After treatments, cells were collected by centrifugation, washed with sterile H2O, resuspended in 2% YPD medium and then stressed with 1.0mM H2O2 or 30mM menadione for 1h. For lipid peroxidation, the TBARS method is used, which consists of detecting malondialdehyde formed during the lipid peroxidation process in cells. For induction and activation of Hsp104-GFP, the cells were treated with the compounds for 1h and then visualized under a fluorescence microscope. The analysis of catalase and SOD activation was performed by monitoring the decomposition of H2O2 and the inhibition of the reduction of nitrotetrazolium blue (NBT) to formazan, respectively, in the presence or absence of treatment with coordination compounds. For the chronological aging experiments how cells were grown to the stationary phase, and subjected to treatment (or not) with the compounds, and kept at 28°C at 160rpm for 28 days. Compound absorption was performed by ICP-MS. To analyze the antioxidant activity in Galleria mellonella, G. mellonella larvae were treated with the compounds through injection directly into the hemocoel and then stressed with 5M H2O2. The larvae were followed for 7 days. The DPPH assay indicates moderate antioxidant activity with an EC50 (μM) value of 64.3, 67.1 and 30.81 for coordination compounds containing the metals Fe, Cu and Mn, respectively. In in vivo tests they provide greater protection in the 12.5, 25 and 50μM standards. The compounds reduced between 25% and 68% the values of lipid peroxidation when compared to the damage emitted by H2O2. It was observed that the compounds induced the expression of the heat shock protein Hsp104, but not its activation. Treatment with compounds not active to catalase, however, was able to activate Sod. Furthermore, treatment with the compounds was also able to prolong the chronological lifespan of cells. An increase in the absorption of Fe, Mn and Cu metals was observed with the increase in the concentration to which the cells were exposed, in addition to changes in the concentration of other metals. G. mellonella larvae treated with the main compounds after stress caused by 5M H2O2, in addition, the treatment did not affect the differentiation between the stages of the larvae's life cycle.