2,6-Dibromohydroquinone (2,6-DBrHQ) has been identified as an reactive metabolite of many brominated phenolic environmental pollutants such as tetrabromobisphenol-A (TBBPA), bromoxynil and 2,4,6-tribromophenol, and was also found as one of disinfection byproducts in drinking water. In this study, we found that the combination of 2,6-DBrHQ and Cu(II) together could induce synergistic DNA damage as measured by double strand breakage in plasmid DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, while either of them alone has no effect. 2,6-DBrHQ/Cu(II)-induced DNA damage could be inhibited by the Cu(I)-specific chelating agent bathocuproine disulfonate and catalase, but not by superoxide dismutase, nor by the typical hydroxyl radical (•OH) scavengers such as DMSO and mannitol. Interestingly, we found that Cu(II)/Cu(I) could be combined with DNA to form DNA-Cu(II)/Cu(I) complex by complementary application of low temperature direct ESR, circular dichroism, cyclic voltammetry and oxygen consumption methods; and the highly reactive •OH were produced synergistically by DNA-bound-Cu(I) with H₂O₂ produced by the redox reactions between 2,6-DBrHQ and Cu(II), which then immediately attack DNA in a site-specific manner as demonstrated by both fluorescent method and by ESR spin-trapping studies. Further DNA sequencing investigations provided more direct evidence that 2,6-DBrHQ/Cu(II) caused preferential cleavage at guanine, thymine and cytosine residues. Based on these data, we proposed that the synergistic DNA damage induced by 2,6-DBrHQ/Cu(II) might be due to the synergistic and site-specific production of •OH near the binding site of copper and DNA. Our findings may have broad biological and environmental implications for future research on the carcinogenic polyhalogenated phenolic compounds.

2,6-二溴对苯二酚（2,6-DBrHQ）已被确定为许多溴化酚类环境污染物的反应性代谢产物，例如四溴双酚A（TBBPA），溴苯腈和2,4,6-三溴苯酚，也被发现是饮用水中的消毒副产物。在这项研究中，我们发现，通过质粒DNA和8-oxo-7,8-dihydro-2'-deoxyguanosine的双链断裂检测，2,6-DBrHQ和Cu（II）的组合可以诱导协同DNA损伤。 （8-oxodG）的形成，而单独使用它们中的任何一个都不起作用。2,6-DBrHQ / Cu（II）诱导的DNA损伤可通过Cu（I）特异性螯合剂浴铜宁二磺酸盐和过氧化氢酶来抑制，但不能被超氧化物歧化酶或典型的羟基自由基（•OH）清除剂抑制作为DMSO和甘露醇。有趣的是 我们发现，通过低温直接ESR，圆二色性，循环伏安法和耗氧法的互补应用，Cu（II）/ Cu（I）可以与DNA结合形成DNA-Cu（II）/ Cu（I）配合物。DNA结合的Cu（I）与H协同产生高活性的•OH2，6-DBrHQ与Cu（II）之间的氧化还原反应产生₂ O ₂，然后立即以位点特异性方式攻击DNA，如荧光方法和ESR自旋捕获研究所证明。进一步的DNA测序研究提供了更直接的证据，表明2,6-DBrHQ / Cu（II）导致鸟嘌呤，胸腺嘧啶和胞嘧啶残基的优先切割。基于这些数据，我们提出由2,6-DBrHQ / Cu（II）诱导的协同DNA损伤可能是由于铜和DNA结合位点附近•OH的协同和位点特异性产生。我们的发现可能对致癌多卤代酚类化合物的未来研究具有广泛的生物学和环境意义。