Oxidative Damage in Lymphocytes of Copper Smelter Workers Correlated to Higher Levels of Excreted Arsenic

Arsenic has been associated with multiple harmful effects at the cellular level. Indirectly these defects could be related to impairment of the integrity of the immune system, in particular in lymphoid population. To characterize the effect of Arsenic on redox status on this population, copper smelter workers and arsenic unexposed donors were recruited for this study. We analyzed urine samples and lymphocyte enriched fractions from donors to determinate arsenic levels and lymphocyte proliferation. Moreover, we studied the presence of oxidative markers MDA, vitamin E and SOD activity in donor plasma. Here we demonstrated that in human beings exposed to high arsenic concentrations, lymphocyte MDA and arsenic urinary levels showed a positive correlation with SOD activity, and a negative correlation with vitamin E serum levels. Strikingly, lymphocytes from the arsenic exposed population respond to a polyclonal stimulator, phytohemaglutinin, with higher rates of thymidine incorporation than lymphocytes of a control population. As well, similar in vitro responses to arsenic were observed using a T cell line. Our results suggest that chronic human exposure to arsenic induces oxidative damage in lymphocytes and could be considered more relevant than evaluation of T cell surveillance

A comparison of methods employed to evaluate antioxidant capabilities

Thrce ditferent methodologies frequently employed to evaluate the indexes that report the antioxidant capabilities of pure compounds and/or complex mixtures of antioxidants are applied to a series of mono- and polyphenols, as well as to two wine (red and white) samples. These methodologies are based on the bleaching of a stable radical, the effect of the additive upon luminol chemiluminescence induced by peroxyl radicals, and the effect of the additive upon the bleaching of the fluorescence from a dye molecule. Widely ditferent responses are obtained from the different methodologies. These differences are interpreted in terms of the different factors (stoichiametric factors and/or reactivities) that determines the indexes evaluated by these different methodologie

Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals

The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROO.), follows a complex mechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towards ROO. should be strongly affected by its inclusion in peptides and proteins. To examine the latter, we investigated (by fluorescence) the kinetic of the consumption of free, peptide-and protein-Trp residues towards AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride)-derived free radicals. Interestingly, the initial consumption rates (R-i) were only slightly influenced by the inclusion of Trp in small peptides and proteins (human serum albumin and human superoxide dismutase). Depending on the Trp concentration, the R-i versus Trp concentration ([Trp]) plots showed three regions. At low Trp concentrations (1-10 mu M), a linear dependence was observed between R-i and [Trp]; at intermediate Trp concentrations (10-50 mu M), the values of R-i were nearly constant; and at high Trp concentrations (50 mu M to 1 mM), a slower increase of R-i than expected for chain reactions. Similar behavior was detected for all three systems (free Trp, and Trp in peptides and proteins). For the first time we are showing that alkoxyl radicals, formed from self-reaction of ROO., are responsible of the Trp oxidation at low concentrations, while at high Trp concentrations, a mixture of peroxyl and alkoxyl radicals are involved in the oxidation of Trp residuesFondecyt 1141142 3140307 Novo Nordisk Foundation NNF13OC000429

Atypical antioxidant activity of non-phenolic amino-coumarins

Coumarin compounds have been described as anti-inflammatories, and chemotherapeutic agents as well as antioxidants. However, the origin of the antioxidant activity of non phenolic coumarins remains obscure. In the present report, we demonstrate that non-phenolic 7-dialkyl-aminocoumarins may also have significant antioxidant properties against free radicals derived from 2,2′-azobis(2-amidinopropane) dihydrochloride under aerobic conditions. This atypical behaviour is due to the presence of traces of very reactive hydroxycinnamic acid-type compounds. Changing functional groups at the C-3 and C-4 positions shifts the reactivity of the compounds from peroxyl to alkoxyl free radicals. Kinetic and theoretical studies based on Density Functional Theory support the formation of reactive hydroxycinnamic acid and directly link the antioxidant behaviour of the compounds to hydrogen atom transfer.Fil: Zúñiga Núñez, Daniel. Universidad de Santiago de Chile; ChileFil: Barrias, Pablo. Universidad de Santiago de Chile; ChileFil: Cárdenas Jirón, Gloria. Universidad de Santiago de Chile; ChileFil: Ureta Zañartu, M. Soledad. Universidad de Santiago de Chile; ChileFil: Lopez Alarcón, Camilo. Pontificia Universidad Católica de Chile; ChileFil: Moran Vieyra, Faustino Eduardo. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; ArgentinaFil: Borsarelli, Claudio Darío. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; ArgentinaFil: Alarcón, Emilio. University of Ottawa; CanadáFil: Aspee, Alexis. University of Ottawa; Canad