Danos oxidativos promovidos por espécies de Mn(III) sobre biomoléculas e células em situação de estresse / Oxidative damage induced by Mn(III) species over biomolecules and stressed cells

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

08/03/2012

RESUMO

Manganese is an essential trace element, however there is considerable concern regarding its neurological effects when in excess, giving rise to a condition termed manganism which is characterized by Parkinson disease-like symptoms. Most evaluations of manganese toxicity use poorly defined Mn(II) species, although Mn(III) is known to accumulate preferentially in the brain. Therefore, in this work we proposed a study of oxidative damage and citotoxicity of Mn(III) derivatives of citrate, pyrophosphate and salycilenediamine (respectively, MnCit, MnPPi and EUK8). The species were synthesized and characterized by spectroscopic methods. Their pro-oxidant abilities were assessed over markers of oxidant activity dihydrorhodamine (DHR), tyrosine (Tyr), albumin (BSA) and dopamine (DA). In addition, their effect over granular cerebral cells (CGC) and HeLa cells stressed by ultraviolet irradiation was studied, and treated with ascorbate. Tests with DHR were repeated treating the samples with H2O2 and ascorbate. Pro-oxidant ability tested by both DHR and Tyr fluorescence suggest that ascorbate is antioxidant towards Mn(III)-induced oxidative damage. MnCit and MnPPi (but not EUK8), when in presence of peroxide, are less oxidants. An analogous trend was observed for BSA, although without statistical significance. Evaluation of DA formation by luminescence was inconclusive, but competition studies of DA+DHR mixtures indicated that DA is preferentially oxidized by all the complexes. To CGC, little difference was observed for the toxicities of the complexes. An inverse relationship of toxicity and lipophilicity has been observed. However this was not observed for HeLa cells, to which EUK8 was more toxic. In addition, and in opposition to the DHR solution study, ascorbate was found to be pro-oxidant. A negative synergic effect was observed between complex doses and irradiation. Treatment of the cells with paraaminosalicylate was beneficial only for non-irradiated cells.

ASSUNTO(S)

biomoléculas biomolecules manganês manganese neurônio redox toxicidade neurons redox toxicity

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