Hypervalent chromium mimics reactive oxygen species as measured by the oxidant-sensitive dyes 2,′7′-dichlorofluorescin and dihydrorhodamine
Hypervalent chromium mimics reactive oxygen species as measured by the oxidant-sensitive dyes 2,′7′-dichlorofluorescin and dihydrorhodamine
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DOI：
10.1021/tx9801559
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发表时间：
1998-12-01
影响因子：
4.1
通讯作者：
Sugden, KD
中科院分区：
文献类型：
--
作者：
Martin, BD;Schoenhard, JA;Sugden, KD
致癌物铬酸盐 [Cr(VI)] 的细胞内代谢会产生与其遗传毒性相关的氧化应激和氧化 DNA 损伤。这种氧化应激此前已通过使用氧化剂敏感染料的荧光进行测量，并归因于活性氧（ROS）的形成。然而，Cr(VI)的代谢也会产生Cr-(IV)和Cr(V)，它们可以直接损伤生物大分子，而不产生ROS。我们使用高价铬物种双(2-乙基-2-羟基丁酸)氧铬酸(V) [Cr(V)-EHBA]来测试高价铬是否也会与氧化剂敏感染料2',7'-二氯荧光素(DCFH)和二氢罗丹明(DHR)发生反应。 Cr(V)-EHBA 使两种染料在宽动态范围内发出荧光，并且在表明 Cr(V) 已直接与两种染料反应而没有首先形成可扩散自由基物质的条件下发出荧光。二甲基硫脲（DMTU和乙醇）不会影响Cr（V）诱导的体外荧光或Cr（VI）诱导的A549细胞中的荧光。在相同条件下，乙醇和DMTU增加了过氧化氢诱导的荧光程度。由于铬诱导的荧光不受自由基清除剂的影响，并且与过氧化氢诱导的荧光有质的不同，我们得出结论，铬酸盐处理的A549细胞中的DCP和R123荧光是定性和累积测量细胞内 Cr(V) 形成而不是 ROS。
Intracellular metabolism of the carcinogen chromate [Cr(VI)] produces the oxidative stress and oxidative DNA damage associated with its genotoxicity. Such oxidative stress has previously been measured by fluorescence using oxidant-sensitive dyes and attributed tn the formation of reactive oxygen species (ROS). However, metabolism of Cr(VI) also produces Cr-(IV) and Cr(V) which can directly damage biological macromolecules without for ming ROS. We used the high-valence chromium species, bis(2-ethyl-2-hydroxybutyrato)oxochromate(V) [Cr(V)-EHBA], to test whether high-valence chromium would also react with the oxidant-sensitive dyes 2',7'-dichlorofluorescin (DCFH) and dihydrorhodamine (DHR). Cr(V)-EHBA caused both dyes to fluoresce over a wide dynamic range and under conditions which indicated that Cr(V) had reacted directly with both dyes without first forming a diffusible radical species. Dimethylthiourea (DMTU, and ethanol did not affect Cr(V)-induced fluorescence in vitro or Cr(VI)-induced fluorescence in A549 cells. Under the same conditions, ethanol and DMTU increased the extent of hydrogen peroxide-induced fluorescence. As chromium-induced fluorescence was unaffected by radical scavengers and was qualitatively different from hydrogen peroxide-induced fluorescence, we conclude that DCP and R123 fluorescence in chromate-treated A549 cells is a qualitative and cumulative measure of intracellular Cr(V) formation and not ROS.