Horita Masako, Wang Da-Hong, Tsutsui Ken, Sano Kuniaki, Masuoka Noriyoshi, Kira Shohei
Okayama University Graduate School of Medicine and Dentistry, Department of Public Health, Okayama, Japan.
Free Radic Res. 2005 Oct;39(10):1035-41. doi: 10.1080/10715760500232008.
Hydroquinone is a benzene-derived metabolite. To clarify whether the reactive oxygen species (ROS) are involved in hydroquinone-induced cytotoxicity, we constructed transformants of Escherichia coli (E. coli) strains that express mammalian catalase gene derived from catalase mutant mice (Cs(b), Cs(c)) and the wild-type (Cs(a)) using a catalase-deficient E. coli UM255 as a recipient. Specific catalase activities of these tester strains were in order of Cs(a) > Cs(c) > Cs(b) > UM255, and their susceptibility to hydrogen peroxide (H2O2) showed UM255 > Cs(b) > Cs(c) > Cs(a). We found that hydroquinone exposure reduced the survival of catalase-deficient E. coli mutants in a dose-dependent manner significantly, especially in the strains with lower catalase activities. Hydroquinone toxicity was also confirmed using zone of inhibition test, in which UM255 was the most susceptible, showing the largest zone of growth inhibition, followed by Cs(b), Cs(c) and Cs(a). Furthermore, we found that hydroquinone-induced cell damage was inhibited by the pretreatment of catalase, ascorbic acid, dimethyl sulfoxide (DMSO), and ethylenediaminetetraacetic acid (EDTA), and augmented by superoxide dismutase (both CuZnSOD and MnSOD). The present results suggest that H2O2 is probably involved in hydroquinone-induced cytotoxicity in catalase-deficient E. coli mutants and catalase plays an important role in protection of the cells against hydroquinone toxicity.
对苯二酚是一种源自苯的代谢产物。为了阐明活性氧（ROS）是否参与对苯二酚诱导的细胞毒性作用，我们以过氧化氢酶缺陷型大肠杆菌UM255作为受体菌，构建了表达源自过氧化氢酶突变小鼠（Cs(b)、Cs(c)）和野生型（Cs(a)）的哺乳动物过氧化氢酶基因的大肠杆菌转化体。这些测试菌株的特异性过氧化氢酶活性顺序为Cs(a) > Cs(c) > Cs(b) > UM255，它们对过氧化氢（H2O2）的敏感性表现为UM255 > Cs(b) > Cs(c) > Cs(a)。我们发现，对苯二酚暴露显著降低了过氧化氢酶缺陷型大肠杆菌突变体的存活率，且呈剂量依赖性，尤其是在过氧化氢酶活性较低的菌株中。使用抑菌圈试验也证实了对苯二酚的毒性，其中UM255最敏感，显示出最大的生长抑制圈，其次是Cs(b)、Cs(c)和Cs(a)。此外，我们发现过氧化氢酶、抗坏血酸、二甲基亚砜（DMSO）和乙二胺四乙酸（EDTA）预处理可抑制对苯二酚诱导的细胞损伤，而超氧化物歧化酶（铜锌超氧化物歧化酶和锰超氧化物歧化酶）则会增强这种损伤。目前的结果表明，H2O2可能参与了过氧化氢酶缺陷型大肠杆菌突变体中对苯二酚诱导的细胞毒性作用，而过氧化氢酶在保护细胞免受对苯二酚毒性方面起着重要作用。
