Ximenes, Valdecir Farias [UNESP]Quaggio, Giovana Brino [UNESP]Graciane, Fernanda Silva [UNESP]Menezes, Manoel Lima de [UNESP]2016-01-282016-01-282012Pharmacology and Pharmacy, v. 3, n. 1, p. 29-36, 2012.2157-9423http://hdl.handle.net/11449/133848The long-tem use of chlorpromazine (CPZ) may cause severe side effects. This property of CPZ might be related to pro-oxidant effects of the chlorpromazine cation radical (CPZ•+), which can be easily generated by catalytic action of peroxidases, including the neutrophil myeloperoxidase (MPO) and by methemoglobin. Aiming the comprehension of a putative physiological effect of CPZ•+ upon biomolecules, in this work we studied the reactivity of CPZ•+ with amino acids and the co-catalytic effect of CPZ during the oxidation of amino acids by horseradish peroxidase (HRP)/H2O2 system. We also studied whether natural blood plasma components as ascorbic acid, uric acid and nitrite could inhibit the oxidative effect of CPZ•+. We found that tryptophan, tyrosine and cysteine were easily oxidized by pure CPZ•+. Other amino acids as methionine, glycine, phenylalanine, aspartic acid and lysine were unreactive. The decomposition of CPZ•+ was exacerbated by uric acid, ascorbic acid and nitrite, provoking inhibition in the amino acids oxidation. In experiments with HRP/H2O2, and using CPZ as a co-catalyst, a strong effect upon oxidation of tryptophan, tyrosine and cysteine was obtained. It was also found that tryptophan was more reactive than tyrosine with CPZ•+, a feature that could be related to the recently described favorable interaction between tryptophan and CPZ. The use of CPZ as a co-catalyst is discussed regarding its role in the efficient oxidation of tryptophan.29-36engTryptophanTyrosineNitriteChlorpromazineHorseradish peroxidaseArtigo10.4236/pp.2012.31005Acesso restrito40664139979085724659698040759224