Oury T D, Tatro L, Ghio A J, Piantadosi C A
Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.
Free Radic Res. 1995 Dec;23(6):537-47. doi: 10.3109/10715769509065275.
Peroxynitrite anion is a powerful oxidant which can initiate nitration and hydroxylation of aromatic rings. Peroxynitrite can be formed in several ways, e.g. from the reaction of nitric oxide with superoxide or from hydrogen peroxide and nitrite at acidic pH. We investigated pH dependent nitration and hydroxylation resulting from the reaction of hydrogen peroxide and nitrite to determine if this reaction proceeds at pH values which are known to occur in vivo. Nitration and hydroxylation products of tyrosine and salicyclic acid were separated with an HPLC column and measured using ultraviolet and electrochemical detectors. These studies revealed that this reaction favored hydroxylation between pH 2 and pH 4, while nitration was predominant between pH 5 and pH 6. Peroxynitrite is presumed to be an intermediate in this reaction as the hydroxylation and nitration profiles of authentic peroxynitrite showed similar pH dependence. These findings indicate that hydrogen peroxide and nitrite interact at hydrogen ion concentrations present under some physiologic conditions. This interaction can initiate nitration and hydroxylation of aromatic molecules such as tyrosine residues and may thereby contribute to the biochemical and toxic effects of the molecules.
过氧亚硝酸根阴离子是一种强氧化剂，可引发芳香环的硝化和羟基化反应。过氧亚硝酸根可以通过多种方式形成，例如一氧化氮与超氧阴离子反应，或者在酸性pH条件下由过氧化氢和亚硝酸盐反应生成。我们研究了过氧化氢和亚硝酸盐反应产生的pH依赖性硝化和羟基化反应，以确定该反应是否在已知的体内pH值条件下进行。酪氨酸和水杨酸的硝化和羟基化产物通过高效液相色谱柱分离，并用紫外和电化学检测器进行测定。这些研究表明，该反应在pH 2至pH 4之间有利于羟基化，而在pH 5至pH 6之间硝化作用占主导。由于真实过氧亚硝酸根的羟基化和硝化曲线显示出相似的pH依赖性，因此推测过氧亚硝酸根是该反应的中间体。这些发现表明，过氧化氢和亚硝酸盐在某些生理条件下存在的氢离子浓度下相互作用。这种相互作用可以引发芳香分子（如酪氨酸残基）的硝化和羟基化反应，从而可能导致这些分子的生化和毒性作用。
