%0 Journal Article
%T Oxidation of Amino Acids by Chlorpromazine Cation Radical and Co-Catalysis by Chlorpromazine
%A Valdecir F. Ximenes
%A Giovana B. Quaggio
%A Fernanda S. Graciani
%A Manoel L. de Menezes
%J Pharmacology & Pharmacy
%P 29-36
%@ 2157-9431
%D 2012
%I Scientific Research Publishing
%R 10.4236/pp.2012.31005
%X The 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.
%K Tryptophan
%K Tyrosine
%K Nitrite
%K Chlorpromazine
%K Horseradish Peroxidase
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=16956