Benznidazole (BZN) is a nitroimidazole derivative which has a notable trypanocide activity, and it is the only drug used in Brazil and Argentina for the treatment of Chagas' disease. The drug in current use is thought to act, at least in part, by inducing oxidative stress within the parasite. Imidazolic compounds are involved in the production of reactive oxygen species (ROS). In order to evaluate the effect of BZN on ROS production and on the antioxidant status of the host, male rats were treated for different periods of time (2, 4, 6, 10 and 30 days) with 40 mg BZN/kg body weight. After treatment, biomarkers of oxidative stress such as the activities of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST) and glutathione reductase (GR), and also thiobarbituric acid reactive species (TBARS), reduced glutathione (GSH), total glutathione (TG) and oxidized glutathione (GSSG) concentrations, were measured in crude hepatic homogenates. Our results revealed that BZN is able to cause tissue damage as shown by increased TBARS content, inhibition of some antioxidants and induction of other antioxidants in a concentration- and time-dependent manner. The tissue damage measured as TBARS increased up to the 10th day of treatment. GST activity was inhibited during the BZN treatment. On the other hand, CAT and GR showed similar increased activities at the beginning, followed by decreased activities at the end of the treatment. After 30 days of treatment, GR activity remained low while CAT activity was high, compared to controls. The SOD activities remained unchanged throughout the experimental period. GSH showed lower values at the beginning of BZN treatment but the hepatic concentrations were enhanced at the end of the experimental period. Total glutathione showed a similar profile, and oxidized glutathione showed higher values in rats treated with BZN. In conclusion, these results indicate that, at therapeutic doses, BZN treatment elicits an oxidative stress in rat hepatocytes.

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Recebido em 28/9/04; aceito em 23/5/05; publicado na web em 01/12/05 CHITOSAN MICROSPHERES CROSSLINKED WITH TRIPOLYPHOSPHATE USED FOR THE REMOVAL OF THE ACIDITY, IRON (III) AND MANGANESE (II) IN WATER CONTAMINATED IN COAL MINING.Considerable attention has been paid to chitosan and derivatives as efficient adsorbents of pollutants such as metal ions and dyes in aqueous medium. Nevertheless, no report can be found on the remedial actions of chitosan microspheres crosslinked with tripolyphosphate to control acidity, iron (III) and manganese (II) contents in wastewaters from coal mining. In this work, chitosan microspheres crosslinked with tripolyphosphate were used for the neutralization of acidity and removal of Fe (III) and Mn (II) from coal mining wastewaters. The study involved static and dinamic methods. The neutralization capacity of the surface of the static system was 395 mmol of H 3 O + per kilogram of microspheres, higher than that of the dynamic one (223 mmol kg -1). The removal of Fe(III) in wastewater was of 100% and that of Mn(II) was 90%.Keywords: chitosan-tripolyphosphate; microspheres; remediation. INTRODUÇÃOO carvão mineral é um combustível fóssil sólido, formado a partir da matéria orgânica de vegetais depositados em bacias sedimentares. Por ação de pressão e temperatura em ambiente sem contato com o ar, em decorrência de soterramento e atividade orogênica, os restos vegetais ao longo do tempo geológico solidificam-se, perdem oxigênio e hidrogênio e enriquecem-se em carbono, em um processo denominado carbonificação. Quanto mais intensas a pressão e a temperatura a que a camada de matéria vegetal for submetida e quanto mais tempo durar o processo, mais alto será o grau de carbonificação e, conseqüentemente, maior a qualidade do carvão 1 . Intensificada nos últimos anos pela expansão da economia nacional, a atividade mineradora e seus processos (método de lavra, beneficiamento, transportes, uso e transformação) proporcionaram um complexo dinamismo econômico, produziram marcas profundas nos ecossistemas regionais e, também, baixos índices de qualidade de vida e de qualidade ambiental na região sul de Santa Catarina 2 . Dentre os impactos ambientais relacionados com a mineração do carvão, o mais agravante deles é, certamente, a poluição dos mananciais hídricos das regiões próximas às jazidas, onde o mineral é explorado 3 . A poluição hídrica, observada nas áreas de mineração, é decorrente da geração de efluentes ácidos, provenientes das minas e dos rejeitos de carvão. Essa característica ácida dos efluentes da mineração se dá, principalmente, pela presença da pirita (FeS 2 ), um mineral sulfetado muito comum nos carvões brasileiros. A pirita é rapidamente oxidada e dissociada quando exposta ao ar e à água, A mineração de carvão, além de promover a exposição de grandes áreas por meio dos processos de lavra, gera uma quantidade de rejeitos depositados em pilhas ou barragens próximas às áreas mineradas. Estes depósitos, ricos em sulfetos, podem tornar-se fontes geradoras de drenagem ácida com elevados n...

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