Rocha, Hugo Alexandre de OliveiraPaiva, Weslley de Souza2022-11-252022-11-252022-07-22PAIVA, Weslley de Souza. Avaliação da atividade antioxidante de quitosana extraída de fungos e de seu derivado conjugado com ácido gálico através de testes in vitro e in vivo utilizando modelo zebrafish (Danio rerio). 2022. Orientador: Hugo Alexandre de Oliveira Rocha. 82f. Tese (Doutorado em Biotecnologia) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2022.https://repositorio.ufrn.br/handle/123456789/49905Oxidative stress is a cause of numerous diseases in humans, this causes a constant search for new molecules that may have antioxidant capacity and prevent the emergence of diseases. The objective of this work was to extract chitosan from fungi (Chit-F) and synthesize a new molecule, conjugating it with gallic acid, which was called Chit-FGal, in order to potentiate its antioxidant action. After collection, isolation and identification of the fungus as being of the species Rhizopus arrhizus, it was possible to extract chitosan and after physical-chemical tests such as high performance liquid chromatography (HPLC), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) ), it was confirmed that the sample was chitosan, with a degree of deacetylation of 86% and low molecular weight, in addition, without the presence of proteins and phenolic compounds. After that, the synthesis of fungal chitosan + AG (Chit-FGal) was successfully performed, confirmed by the 4x increase in the amount of phenolic compounds in relation to Chit-F, as well as the appearance of a peak in the region of the aromatic rings in the NMR analysis. When the 2 samples were extracted/synthesized and characterized, the in vitro antioxidant tests were performed (Copper Chelation, Iron Chelation, Total Antioxidant Capacity (CAT), reducing power and superoxide radical scavenging), where the samples had activities in all the tests, however Chit-FGal obtained results at least 50% (p <0.05) higher, demonstrating the potentiation of activities when modifying the native molecule. When testing Chit-F and Chit-FGal in fibroblast cells (NIH/3T3), there was no decrease in cell viability measured by MTT ((3-(4,5- Dimethylthiazolyl- 2)-2,5-diphenyltetrazolium bromide) in any sample. , in addition, a protection test against damage caused by hydrogen peroxide was performed, where ChitFGal at a concentration of 0.05 mg/mL showed better protection. A protective effect of embryos against damage caused by 0.06 mM hydrogen peroxide (100% live embryos). Subsequently, 3 days after fertilization, regarding the production of reactive oxigen species (ROS), lipid peroxidation and cell death apoptotic rate of larvae treated with Chi-F and Chit-FGal post. In both protection rates against the 3 surveys. These results combine the excellent potential antioxidant of Chit-FGal, as well as this new molecule as a potential to treat various oxidative stress problems.Acesso AbertoEstresse oxidativoQuitosana fúngicaModificação redoxZebrafishdoctoralThesisCNPQ::CIENCIAS BIOLOGICAS