Background Exposure to high altitude in hypobaric hypoxia (HH) is considered to be a physiological oxidative/nitrosative stress. Quercetin (Que) is an effective antioxidant and free radical scavenger against oxidative/nitrosative stress. Aims The aim of this study was to investigate the cardioprotective effects of Que in animals exposed to intermittent HH (IHH) and therefore exposed to oxidative/nitrosative stress. Materials and methods Wistar albino male rats were exposed to short-term (2 days) or long-term (4 weeks; 5 days/week) IHH in a hypobaric chamber (5,500 m, 8 h/day, 380 mmHg, 12% O2, and 88% N2). Half of the animals received natural antioxidant Que (body weight: 30 mg/kg) daily before each IHH exposure and the remaining rats received vehicle (carboxymethylcellulose solution). Control rats were kept under normobaric normoxia (Nx) and treated in a corresponding manner. One day after the last exposure to IHH, we measured the cardiac hypoxia-induced oxidative/nitrosative stress biomarkers: the malondialdehyde (MDA) level and protein carbonyl (PC) content, the activity of some antioxidant enzymes [superoxide dismutase (SOD) and catalase (CAT)], the nitrite plus nitrate (NOx) production, and the inducible nitric oxide synthase (iNOS) protein expression. Results Heart tissue MDA and PC levels, NOx level, and iNOS expression of IHH-exposed rats had increased, and SOD and CAT activities had decreased compared with those of the Nx-exposed rats (control groups). MDA, CP, NOx, and iNOS levels had decreased in Que-treated IHH-exposed rats compared with IHH-exposed rats (control groups). However, Que administration increased SOD and CAT activities of the heart tissue in the IHH-exposed rats. Conclusion HH exposure increases oxidative/nitrosative stress in heart tissue and Que is an effective cardioprotective agent, which further supports the oxidative cardiac dysfunction induced by hypoxia.

http://rvq.sbq.org.br Quercetina na Melhora do Estresse Oxidativo/Nitrosativo no Cérebro de Ratos Expostos a Hipóxia Hipobárica Intermitente Resumo: Exposição à alta altitude é um extremo fisiológico do estresse oxidativo/nitrosativo, onde o cérebro é o tecido mais sensível do corpo. A quercetina (Que) é um flavonóide natural abundante em frutas e legumes. O presente estudo investigou mudanças específicas na região do cérebro do estriado, hipocampo e córtex, sobre marcadores de estresse oxidativo/nitrosativo, e os efeitos da administração de Que em ratos expostos à hipóxia hipobárica intermitente (IHH). Ratos Wistar machos foram expostos a curto prazo (dois dias) ou de longo prazo (4 semanas, 5 dias/semana) à IHH em uma câmara hipobárica. Metade dos ratos receberam Que (30 mg / kg de peso corporal) diariamente, antes de cada exposição à IHH. Os ratos de controle foram mantidos sob condições de normóxia normobárica (Nx), tratando de uma maneira correspondente. Após a última exposição à IHH, o cérebro foi removido e os marcadores de estresse oxidativo/nitrosativo foram determinados nas três partes de tecido homogeneizado do cérebro (estriado, hipocampo e córtex): os radicais livres (malondialdeído, MDA e proteínas carboniladas, CP), nitrito mais nitrato (NOx) produção e atividade de enzimas antioxidantes (superóxido dismutase, SOD, e catalase, CAT). Os resultados indicam um aumento na produção de radicais livres e de NOx, com uma redução do sistema de defesa antioxidante em todas as três regiões do cérebro, após a exposição à IHH. O tratamento com Que reduziu significativamente os radicais livres e produção de NOx e significativamente aumentou os níveis de SOD e CAT em todos as três regiões do cérebro após a exposição à IHH. A observação sugere que a hipóxia afeta diferencialmente as regiões do cérebro, e Que fornece neuroproteção substancial contra danos oxidativo/nitrosativo induzido por IHH.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that reduces life quality and requires long-life therapy. Quercetin (Que) is a natural flavonoid with antioxidant and anti-inflammatory effects. (3-(2-(4-Chlorophenyl)-2-oxoethyl)-5-((6-methyl-4-oxo-4H-chromen-3-yl)methylene) thiazolidine-2,4-dione (TZD) is a thiazolidinedione derivative synthesized in our laboratory. This study was designed to investigate the antioxidant effects of the Que and TZD derivative administration in adjuvant-induced arthritic (AIA) rats. AIA was induced in Wistar rats by the intraplantar injection of Freund�s complete adjuvant (FCA), unilaterally in the right hind paw. The control non-arthritic rats and the arthritic rats were treated with Que (30 mg/kg/day) or TZD derivative (12 mg/kg/day) for 21 days. The antioxidant effects of 5-chromen-yl- thiazolidinedione were compared to Que. The serum levels of malondialdehyde (MDA) and protein carbonyl (PC) groups, the superoxide dismutase (SOD) and catalase (CAT) activity were assessed. AIA rats showed significatly increased oxidative stress parameter levels in the blood. The results indicated that the TZD derivative decreased the blood oxidative stress parameters in the treated arthritic rats, compared to Que. The antioxidant effects of 5-chromen-yl-thiazolidinedione in AIA suggest its therapeutic properties for the clinical treatment of RA.

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