REQUIMTE, Department of Chemical Sciences, Porto University, 4099-030 Porto, Portugal.
Anal Biochem. 2012 Jan 1;420(1):1-6. doi: 10.1016/j.ab.2011.09.008. Epub 2011 Sep 16.
Melatonin is a hormone, a derivative of tryptophan, that possesses a potent scavenging capacity for the most reactive and dangerous free radicals, being an important protection against oxidative stress. In this work, an automated flow-based procedure for assessment of melatonin, tryptophan, and 5-hydroxytryptophan scavenging capacity was developed. The presented methodology involved a multi-pumping flow system and exploited the ability of selected compounds to inhibit the chemiluminescence reaction of luminol with hydrogen peroxide, hydroxyl radical, and peroxynitrite anion. The system was based on the use of several solenoid actuated micro-pumps as the only active components of the flow manifold. This enabled the reproducible insertion and efficient mixing of very low volumes of sample and reagents as well as the transportation of the sample zone toward detection for monitoring the chemiluminometric response. Furthermore, the high versatility of the proposed multi-pumping flow system allowed the implementation of distinct reactions for the in-line generation of the different reactive species assayed without requiring physical reconfiguration. The results obtained demonstrated that 5-hydroxytryptophan is the most potent scavenger, followed by melatonin and tryptophan. The developed multi-pumping flow system exhibited good measurement precision (relative standard deviations typically <2%, n=10), low operational costs, and low reagent consumption.
褪黑素是一种激素，是色氨酸的衍生物，具有很强的清除最活跃和最危险自由基的能力，是抵御氧化应激的重要保护剂。在这项工作中，开发了一种自动流动分析方法来评估褪黑素、色氨酸和 5-羟色氨酸的清除能力。所提出的方法涉及多泵送流系统，并利用所选化合物抑制发光氨与过氧化氢、羟基自由基和过氧亚硝酸盐阴离子的化学发光反应的能力。该系统基于使用几个螺线管驱动的微泵作为流路的唯一活动部件。这使得可以重复插入和有效混合非常低体积的样品和试剂，以及将样品区输送到检测位置以监测化学发光响应。此外，所提出的多泵送流系统具有高度的多功能性，允许在不要求物理重新配置的情况下，为在线生成不同的反应性物质实施不同的反应。所得到的结果表明，5-羟色氨酸是最强的清除剂，其次是褪黑素和色氨酸。所开发的多泵送流系统具有良好的测量精度（相对标准偏差通常 <2%，n=10）、低运行成本和低试剂消耗。
