Structural Aspects of Antioxidant and Genotoxic Activities of Two Flavonoids Obtained from Ethanolic Extract of Combretum leprosum

Combretum leprosum Mart., a member of the Combretaceae family, is a traditionally used Brazilian medicinal plant, although no evidence in the literature substantiates its antioxidant action and the safety of its use. We evaluated the antioxidant properties of the ethanolic extract (EE) from flowers of C. leprosum and its isolated products 5,3′-dihydroxy-3,7,4′-trimethoxyflavone (FCL2) and 5,3′,4′-trihydroxy-3,7-dimethoxyflavone (FCL5) in Saccharomyces cerevisiae strains proficient and deficient in antioxidant defenses. Their mutagenic activity was also assayed in S. cerevisiae, whereas cytotoxic and genotoxic properties were evaluated by MTT and Comet Assays, respectively, in V79 cells. We show that the EE, FCL2, and FCL5 have a significant protective effect against H2O2. FCL2 showed a better antioxidant action, which can be related to the activation of the 3′-OH in the presence of a methoxyl group at 4′ position in the B-ring of the molecule, while flavonoids did not induce mutagenesis in yeast, and the EE was mutagenic at high concentrations. The toxicity of these compounds in V79 cells increases from FCL2 = FCL5 < EE; although not cytotoxic, FCL5 induced an increase in DNA damage. The antioxidant effect, along with the lower toxicity and the absence of genotoxicity, suggests that FCL2 could be suitable for pharmacological use

Efeitos tóxicos e genotóxicos do cloreto de estanho (SnCl2) em bactéria e levedura

A genotoxicidade do SnCl2 foi avaliada nos ensaios Salmonella/Microssoma, WP2 Mutoxiteste e com a utilização de linhagens haplóides e diplóides de S. cerevisiae. O presente estudo pôde demonstrar, claramente, que o SnCl2 apresenta um potencial tóxico e uma significativa atividade mutagênica em diferentes ensaios de reversão. O mutante rad52D, deficiente no mecanismo de reparação recombinacional, incapaz de reparar quebras simples e duplas no DNA, foi o mais sensível. As células tratadas com Sn2+ formaram agregados que levaram a uma superestimativa da toxicidade, quando não corretamente desfeitos. Ensaios de inativação corretos, nas doses de 25 mM e 75 mM de SnCl2, foram obtidos através da desagregação das células com EDTA ou tampão fosfato. O Sn2+ induziu reversão na levedura, nos lócus his1-798 (células diplóides), his1-208 e lys-1-1 (células haplóides), bem como mutação no quadro de leitura em células haplóides no lócus hom3-10. Em células diplóides, o SnCl2 induziu recombinação mitótica intragênica, enquanto que a recombinação intergênica não foi significativamente pronunciada. A mutagenicidade do Sn2+ foi demonstrada pelos ensaios de reversão de auxotrofias, mas não pôde ser evidenciada nos ensaios de mutação para a frente. A morte seletiva dos mutantes espontâneos para a canavanina, quando as células são tratadas com SnCl2, sugeriu uma indução de disfunções da membrana das células As células da levedura em fase de crescimento exponencial apresentaram, com apenas 0,1% da concentração de SnCl2, o mesmo perfil de sobrevivência quando comparado com as células em fase de crescimento respiratório, sugerindo um maior envolvimento de parâmetros fisiológicos na resistência ao estresse oxidativo gerado pelo SnCl2 após as células atingirem a fase pós diáuxica. As superoxido dismutases, mas não a catalase, protegeram contra as espécies reativas de oxigênio que o estanho produziu. O mutante sod1D apresentou uma sensibilidade três vezes maior do que a linhagem selvagem, enquanto que o mutante sod2D demonstrou uma sensibilidade pequena ao SnCl2. O duplo mutante sod1Dsod2D mostrou um aumento acentuado na sensibilidade quando comparado com a linhagem selvagem. No teste de Salmonella/Microssoma, o SnCl2 não induziu mutação no quadro de leitura (TA97 e TA98) e nem substituição de pares de bases (TA100), ao passo que uma resposta positiva foi observada com a linhagem TA102 que detecta mutagênicos oxidativos. O SnCl2 também induziu mutação na linhagem IC203 (uvrA oxyR), e não na linhagem IC188 (uvrA). Esses resultados indicaram que o SnCl2 é um agente mutagênico moderado. Provavelmente, o dano ao DNA é causado por espécies reativas de oxigênio e é reparado por um processo recombinacional e por um processo sujeito a erros

CIRRHOSIS INDUCES APOPTOSIS IN RENAL TISSUE THROUGH INTRACELLULAR OXIDATIVE STRESS

Background Renal failure is a frequent and serious complication in patients with decompensated cirrhosis. Objectives We aimed to evaluate the renal oxidative stress, cell damage and impaired cell function in animal model of cirrhosis. Methods Secondary biliary cirrhosis was induced in rats by ligation of the common bile duct. We measured TBARS, ROS and mitochondrial membrane potential in kidney as markers of oxidative stress, and activities of the antioxidant enzymes. Relative cell viability was determined by trypan blue dye-exclusion assay. Annexin V-PE was used with a vital dye, 7-AAD, to distinguish apoptotic from necrotic cells and comet assay was used for determined DNA integrity in single cells. Results In bile duct ligation animals there was significant increase in the kidney lipoperoxidation and an increase of the level of intracellular ROS. There was too an increase in the activity of all antioxidant enzymes evaluated in the kidney. The percentage viability was above 90% in the control group and in bile duct ligation was 64.66% and the dominant cell death type was apoptosis. DNA damage was observed in the bile duct ligation. There was a decreased in the mitochondrial membrane potential from 71.40% &#177; 6.35% to 34.48% &#177; 11.40% in bile duct ligation. Conclusions These results indicate that intracellular increase of ROS cause damage in the DNA and apoptosis getting worse the renal function in cirrhosis

Methionine and methionine sulfoxide alter parameters of oxidative stress in the liver of young rats : in vitro and in vivo studies

It has been shown that elevation of plasma methionine (Met) and its metabolites may occur in several genetic abnormalities. In this study we investigated the in vitro and in vivo effects of the Met and methionine sulfoxide (MetO) on oxidative stress parameters in the liver of rats. For in vitro studies, liver homogenates were incubated with Met, MetO, and Mix (Met + MetO). For in vivo studies, the animals were divided into groups: saline, Met 0.4 g/kg, MetO 0.1 g/kg, and Met 0.4 g/kg + MetO 0.1 g/kg. The animals were euthanized 1 and 3 h after injection. In vitro results showed that Met 1 and 2 mM and Mix increased catalase (CAT) activity. Superoxide dismutase (SOD) was enhanced by Met 1 and 2 mM, MetO 0.5 mM, and Mix. Dichlorofluorescein oxidation was increased by Met 1 mM and Mix. In vivo results showed that Met, MetO, and Mix decreased TBARS levels at 1 h. Total thiol content decreased 1 h after and increased 3 h after MetO and Met plus MetO administrations. Carbonyl content was enhanced by Met and was reduced by MetO 1 h after administration. Met, MetO and Met plus MetO decreased CAT activity 1 and 3 h after administration. Furthermore, only MetO increased SOD activity. In addition, Met, MetO, and Mix decreased dichlorofluorescein oxidation at 1 and 3 h. Our data indicate that Met/MetO in vivo and in vitro modify liver homeostasis by altering the redox cellular state. However, the hepatic changes caused by these compounds suggest a short-time adaptation of this tissue

Manual acupuncture improves parameters associated with oxidative stress and inflammation in PTZ-induced kindling in mice

The use of acupuncture in the treatment of central nervous system (CNS) disorders is an age-old practice. Although only a few studies have proved its efficacy, evidence has indicated the use of acupuncture to treat different types of seizures. Therefore, the present study aimed to evaluate the effect of manual acupuncture (MAC) using the chemical kindling model. The role of MAC in oxidative stress and inflammation after pentylenetetrazole (PTZ)-induced kindling was investigated by measuring reactive oxygen species (ROS) production, superoxide dismutase (SOD), and catalase (CAT) activities, nitrite content, and deoxyribonucleic acid (DNA) damage in cerebral cortex. Mice received PTZ (60 mg/kg s.c.) once every three days for 16 days, totaling six treatments. MAC was applied at acupoint GV20 daily during the entire experimental protocol. Diazepam (DZP) (2 mg/kg) was used as positive control. Also, we evaluated the MAC effect associated with DZP (MAC/DZP) at a low dose (0.15 mg/kg). The results demonstrated that MAC or MAC/DZP were not able to reduce significantly seizure occurrence or to increase the latency to the first seizure during treatment. MAC/DZP promoted a difference in the first latency to seizure only on the third day. PTZ-induced kindling caused significant neuronal injury, oxidative stress, increased DNA damage, nitric oxide production, and expression of the pro-inflammatory Tumor Necrosis Factor-α (TNF-α). These effects were reversed by treatment with MAC or MAC/DZP. These results indicated that the stimulation of acupoint GV20 by MAC showed no potential antiepileptogenic effect in the model used, although it greatly promoted neuronal protection, which may result from antioxidant and anti-inflammatory effects observed here