Caracterização redox-ativa do ácido úsnico e seu efeito citotóxico em células SH-SY5Y

• Ano de defesa: 2013
• Autor(a) principal: Rabelo, Thallita Kelly
• Orientador(a): Gelain, Daniel Pens
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Sergipe
• Programa de Pós-Graduação: Pós-Graduação em Ciências da Saúde
• País: BR
• Palavras-chave em Português: Ácido úsnico; Radicais livres; Estresse oxidativo; Viabilidade celular; Células SH-SY5Y
• Palavras-chave em Inglês: Usnic acid; Free radicals; Cellular viability; Oxidative stress; SH-SY5Y cells
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE
• Link de acesso: https://ri.ufs.br/handle/riufs/3890

Usnic acid (UA) is the most common and abundant lichenic secondary metabolite with potential therapeutic application. Anti-inflammatory and antitumour properties have already been reported and UA-enriched extracts are widely used to treat several diseases in the folk medicine. On the other hand, a growing body of evidence has suggested that UA present pro-oxidant properties, which might induce cellular damage mediated by reactive species. Based on this data, first we performed in silico evaluation of UA interactions with genes/proteins and important compounds for cellular redox balance. Then, we assessed UA redox properties against different reactive species (RS) generated in vitro, and evaluated its action on SH-SY5Y neuronal-like cells subjected to hydrogen peroxide (H2O2) treatment, since no in vitro neurotoxicological data has been reported so far. Total reactive antioxidant potential index (TRAP) showed a significant antioxidant capacity of UA at 20 μg/mL; UA was also effective against hydroxyl radicals and reduced nitric oxid formation. However, in vitro lipoperoxidation was enhanced by UA, and cell viability was decreased along 24 hours of treatment, according to MTT assay (3-[4,5-dimethythiazol-2-yl]-2,5-diphenyl tetrazolium bromide) and morphological analysis. Moreover, UA did not display protective effects against H2O2-induced cell death in any case. The DCFH- DA (2,7-dichlorfluorescein-diacetate) based assay indicated that UA enhanced basal reactive species production at 20 μg/mL for 1 hour and from 2 ng/mL to 20 μg/mL for 4 and 24 hours. In addition, UA appears to potentiate H2O2-induced reactive species production. Our results suggest that UA displays variable redox-active properties, acting either as antioxidant or pro-oxidant agent according to different system conditions and/or cellular environment. These pro-oxidant properties in SH-SY5Y might be responsible by potential neurotoxic effects of UA