Chevion S, Berry E M, Kitrossky N, Kohen R
Department of Pharmacy, Hebrew University of Jerusalem, Israel.
Free Radic Biol Med. 1997;22(3):411-21. doi: 10.1016/s0891-5849(96)00337-1.
The low molecular weight antioxidants (LMWA) of biological samples include many compounds and contribute to the total antioxidant capacity of the system. They act as direct chemical scavengers neutralizing, reactive oxygen-derived species (ROS), and contribute to the ability of the sample to cope with oxidative stress. We propose cyclic voltammetry (CV) as a new method for evaluating the antioxidant capacity of plasma-LMWA and the severity of oxidative stress exerted on the plasma. It is based on the reducing properties of these molecules. CV has been proven to be a simple, sensitive and reliable method. Its tracing does not change during storage of frozen plasma for up to six months. We analyzed the CV tracings by the oxidation potential E1/2, and the current heights Ia of its anodic wave(s). E1/2 indicates the specific component of the LMWA and its ability to donate electron(s); Ia indicates the concentration of this component. Two anodic waves have been identified in human plasma, at E1/2 = 420 +/- 25 and 920 +/- 25 mV. Ascorbate (AA) and urate (UA) were identified as major LMWA components of the first anodic wave, and were confirmed by HPLC-electrochemical detection. Ia was shown to depend linearly on the concentration of either of these LMWA, both in buffer and in plasma. Oxidative stress exerted by exposure to peroxyl radicals, copper ions and ionizing irradiation caused marked changes in the CV tracing. These changes represent corresponding alterations particularly in la, rather than in E1/2. The Ia and E1/2 values reflect the antioxidant capacity of the plasma, while the change of Ia value represents the severity of the oxidative stress induced.
生物样品中的低分子量抗氧化剂（LMWA）包括许多化合物，并对系统的总抗氧化能力有贡献。它们作为直接的化学清除剂，中和活性氧衍生物种（ROS），并有助于样品应对氧化应激的能力。我们提出循环伏安法（CV）作为评估血浆-LMWA抗氧化能力和血浆所受氧化应激严重程度的新方法。它基于这些分子的还原特性。循环伏安法已被证明是一种简单、灵敏且可靠的方法。在冷冻血浆储存长达六个月的过程中，其图谱不会改变。我们通过氧化电位E1/2及其阳极波的电流高度Ia来分析循环伏安图谱。E1/2表明LMWA的特定成分及其提供电子的能力；Ia表明该成分的浓度。在人血浆中已鉴定出两个阳极波，其E1/2分别为420±25和920±25 mV。抗坏血酸盐（AA）和尿酸盐（UA）被鉴定为第一个阳极波的主要LMWA成分，并通过高效液相色谱-电化学检测得到证实。在缓冲液和血浆中，Ia均显示与这些LMWA中任何一种的浓度呈线性相关。暴露于过氧自由基、铜离子和电离辐射所施加的氧化应激导致循环伏安图谱发生显著变化。这些变化尤其在Ia中表现为相应改变，而非E1/2。Ia和E1/2值反映血浆的抗氧化能力，而Ia值的变化代表所诱导的氧化应激的严重程度。
