a Department of Pharmacology and Toxicology , College of Pharmacy, University of Oklahoma Health Sciences Center , Oklahoma City , Oklahoma USA.
Redox Rep. 1997 Feb;3(1):17-22. doi: 10.1080/13510002.1997.11747086.
Hydroxylation of salicylate and D-phenylalanine was measured to test the usefulness of these compounds for hydroxyl radical (HO(•)) detection in chemical and biological systems. When HO(•) were produced by the photolytic decomposition of hydrogen peroxide, nearly equal amounts of 2,5- and 2,3-dihydroxybenzoic acid (DHBA) were produced from salicylate, with catechol as a minor product. In the photolytic reaction, nearly equal concentrations of p-,m-, and o-tyrosine were formed from D-phenylalanine. When salicylate or D-phenylalanine was present with Fenton reagents or in iron(II) autoxidation systems, the relative proportions of hydroxylated products were similar to those observed after photolysis, although less total products were usually detected. In contrast, when similar experiments were conducted with isolated hepatic microsomes and perfused livers, 2,5-DHBA was the primary product from salicylate, and p-tyrosine was the major product from D-phenylalanine. Cytochrome P-450 enzymes can hydroxylate salicylate to produce 2,5-DHBA, and it is likely that phenylalanine hydroxylase produces most of the p-tyrosine detected in hepatic tissues. Thus, although both salicylate and D-phenylalanine are useful probes for hydroxyl radical formation in chemical systems, hydroxylated products formed from enzymatic reactions complicate interpretation of data from both compounds in vivo.
测定了水杨酸和 D-苯丙氨酸的羟化作用，以测试这些化合物在化学和生物系统中用于检测羟自由基（HO(•)）的有用性。当 HO(•)通过过氧化氢的光解分解产生时，从水杨酸中几乎等量地生成 2,5-和 2,3-二羟基苯甲酸（DHBA），而儿茶酚则是次要产物。在光解反应中，从 D-苯丙氨酸几乎等量地形成对、间和邻-酪氨酸。当水杨酸或 D-苯丙氨酸与 Fenton 试剂或铁(II)自氧化系统一起存在时，羟化产物的相对比例与光解后观察到的相似，尽管通常检测到的总产物较少。相比之下，当在分离的肝微粒体和灌注肝脏中进行类似的实验时，2,5-DHBA 是水杨酸的主要产物，而 p-酪氨酸是 D-苯丙氨酸的主要产物。细胞色素 P-450 酶可以将水杨酸羟化为 2,5-DHBA，而苯丙氨酸羟化酶可能产生在肝组织中检测到的大部分 p-酪氨酸。因此，尽管水杨酸和 D-苯丙氨酸都是化学系统中羟自由基形成的有用探针，但酶促反应形成的羟化产物使这两种化合物在体内的数据分析变得复杂。
