Induction of DNA damage by pyrogallol has been shown at physiological pH, but mutagenesis data also suggest there is inhibition in acidic media. In the present work, the plasmid pBSK was incubated with pyrogallol, under aerobic conditions at 37 degrees C, at pH 7.4, 4.5 or 3.5, for 1, 3 or 5 h, in the absence or presence of Cu(2+). Cleavage of the supercoiled DNA form was analyzed through topology modifications by agarose gel electrophoresis and quantified by densitometry. Independently of the presence of Cu(2+), DNA cleavage at pH 7.4 was significantly (P < 0.001) induced and occurred extensively after 1-h incubation. At pH 4.5, the cleavage was significantly (P < 0.05) induced only after 5 h incubation in the absence of Cu(2+), but was extensive (P < 0.001) after 1-h incubation when the metal ion was present. At pH 3.5, DNA cleavage was inhibited (P > 0.05), after 5-h incubation, even in the presence of Cu(2+). Our results provide evidence that DNA cleavage by pyrogallol is pH-dependent, catalyzed by Cu(2+) , and extensively decreased in acidic pH. Due to the abundant presence of the pyrogallate ion in physiological media, we suggest that this conjugate base form is responsible for DNA cleavage.

中文翻译：

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pH值对邻苯三酚诱导的DNA裂解的抑制作用。

在生理pH下已显示了邻苯三酚对DNA的损伤，但诱变数据也表明在酸性介质中存在抑制作用。在目前的工作中，在有或没有Cu（2+）的情况下，将质粒pBSK与邻苯三酚在37℃，pH 7.4、4.5或3.5的有氧条件下孵育1、3或5 h。通过琼脂糖凝胶电泳通过拓扑修饰分析超螺旋DNA形式的切割，并通过光密度测定法定量。独立于Cu（2+）的存在，在pH 7.4的DNA切割被明显诱导（P <0.001），并在1小时的孵育后广泛发生。在pH 4.5时，仅在不存在Cu（2+）的情况下孵育5小时后，才显着诱导裂解（P <0.05），但是在存在金属离子的情况下，孵育1小时后，裂解作用广泛（P <0.001）。在pH 3.5下，孵育5小时后，即使存在Cu（2 +），DNA切割也被抑制（P> 0.05）。我们的结果提供了证据，即邻苯三酚对DNA的切割是pH依赖性的，由Cu（2+）催化，并且在酸性pH值中广泛降低。由于在生理培养基中焦五酸根离子的大量存在，我们建议这种共轭碱基形式负责DNA裂解。