Yamamoto K, Kawanishi S
Department of Public Health, Faculty of Medicine, Kyoto University, Japan.
Biochem Pharmacol. 1991;41(6-7):905-14. doi: 10.1016/0006-2952(91)90195-b.
Hydralazine caused site-specific DNA damage in the presence of Cu(II), Co(II), Fe(III), or peroxidase/H2O2. The order of inducing effect of metal ions on hydralazine-dependent DNA damage [Cu(II) greater than Co(II) greater than Fe(III)] was related to that of accelerating effect on the O2 consumption rate of hydralazine autoxidation. Catalase completely inhibited DNA damage by hydralazine plus Cu(II), but hydroxyl radical (.OH) scavengers and superoxide dismutase did not. On the other hand, DNA damage by hydralazine plus Fe(III) was inhibited by catalase and .OH scavengers. Hydralazine plus Cu(II) induced piperidine-labile sites predominantly at guanine and some adenine residues, whereas hydralazine plus Fe(III) caused cleavages at every nucleotide. Activation of hydralazine by peroxidase/H2O2 caused guanine-specific modification in DNA. ESR-spin trapping experiment showed that .OH and superoxide are generated during the Fe(III)- or Cu(II)-catalysed autoxidation of hydralazine, respectively, and that nitrogen-centered radical is generated during the Cu(II)- or peroxidase-catalysed oxidation. The generation of nitrogen-centered radical was also supported by HPLC-mass spectrometry. The results suggest that the guanine-specific modification by the enzymatic activation of hydralazine is due to the nitrogen-centered hydralazyl radical or derived active species, whereas .OH participates in DNA damage by hydralazine plus Fe(III). The mechanism of hydralazine plus Cu(II)-induced DNA damage is complex. The possible role of the DNA damage induced by hydralazine in the presence of Cu(II) or peroxidase/H2O2 is discussed in relation to hydralazine-induced lupus, mutation, and cancer.
在铜（II）、钴（II）、铁（III）或过氧化物酶/过氧化氢存在的情况下，肼会导致位点特异性DNA损伤。金属离子对肼依赖性DNA损伤的诱导作用顺序[铜（II）大于钴（II）大于铁（III）]与对肼自氧化耗氧率的加速作用顺序相关。过氧化氢酶完全抑制了肼加铜（II）引起的DNA损伤，但羟基自由基（·OH）清除剂和超氧化物歧化酶则没有。另一方面，过氧化氢酶和·OH清除剂抑制了肼加铁（III）引起的DNA损伤。肼加铜（II）主要在鸟嘌呤和一些腺嘌呤残基处诱导产生哌啶不稳定位点，而肼加铁（III）则导致每个核苷酸处的断裂。过氧化物酶/过氧化氢对肼的激活导致DNA中鸟嘌呤特异性修饰。电子自旋共振-自旋捕获实验表明，在铁（III）或铜（II）催化的肼自氧化过程中分别产生·OH和超氧阴离子，并且在铜（II）或过氧化物酶催化的氧化过程中产生氮中心自由基。高效液相色谱-质谱分析也支持氮中心自由基的产生。结果表明，肼的酶促激活引起的鸟嘌呤特异性修饰是由于氮中心肼基自由基或衍生的活性物种，而·OH参与了肼加铁（III）引起的DNA损伤。肼加铜（II）诱导DNA损伤的机制很复杂。讨论了在铜（II）或过氧化物酶/过氧化氢存在下肼诱导的DNA损伤与肼诱导的狼疮、突变和癌症的可能关系。
