Yu T W, Anderson D
BIBRA International, Carshalton, Surrey, UK.
Mutat Res. 1997 Oct 6;379(2):201-10. doi: 10.1016/s0027-5107(97)00141-3.
The main purpose of this study was to determine whether well-known reactive oxygen species (ROS)-generating agents can induce DNA damage in a simple chemical system with or without Fenton reaction components (iron and reducing agents), and to explore whether antioxidants which normally exist in the cellular environment can modify such damage, i.e. to determine chemical reactions of relevance to biological systems. A neutral electrophoresis technique was used to investigate DNA double stranded breaks (DSBs) caused by chemical treatments of lambda-DNA in eppendorf tubes by various ROS-generating compounds and the degree of DNA damage was categorised by analysis of enhanced digital images. Double strand breaks were induced by hydroquinone (HQ), benzoquinone (BQ), benzenetriol (BT), hydrogen peroxide (H2O2), bleomycin (BLM) and sodium ascorbate (Vit C). DNA damage was modulated by various agents including catalase (CAT), superoxide dismutase (SOD), desferoxamine mesylate (DFO), ferrous chloride (FeCl2), reduced glutathione (GSH), trolox, silymarin and myricetin. Individual chemicals (except BLM) at the concentration of 1 mM did not induce large numbers of DSBs without iron [Fe(II) or Fe(III) at 25 microM]. GSH enhanced the damaging effect of HQ, BT and Vit C, did not alter the non-damaging effect of H2O2, but had a small protective effect on BLM. When compared with the non-enzyme protein, bovine serum albumin (BSA), SOD had a protective effect against BT, H2O2 and BLM; in the presence of GSH, SOD diminished the effect of HQ, BQ and Vit C but enhanced the effect of BT, H2O2 and BLM. With both GSH and Fe and compared with BSA, SOD enhanced the effect of HQ, BQ and BLM, ameliorated the effect of H2O2, and did not affect the others. CAT showed a protective effect for almost all examined compounds, but had little effect on BLM. With GSH alone, DFO enhanced the effect of HQ, BQ, H2O2 and ameliorated the effect of BT, BLM and Vit C and trolox was largely protective. With GSH and Fe, DFO was protective for all compounds except doxorubicin (Dox), trolox was protective for all compounds except Dox and BLM, silymarin was protective except that it had little effect on BLM and Dox, but myricetin did not show any protective effect. In conclusion, the results from the present study have further highlighted the adverse potential of reducing agents and redox cycling agents, and also the need for a cautious view of antioxidants.
本研究的主要目的是确定知名的活性氧（ROS）生成剂在有或没有芬顿反应成分（铁和还原剂）的简单化学体系中是否能诱导DNA损伤，并探索细胞环境中正常存在的抗氧化剂是否能改变这种损伤，即确定与生物体系相关的化学反应。采用中性电泳技术研究了各种ROS生成化合物在eppendorf管中对λ-DNA进行化学处理所导致的DNA双链断裂（DSB），并通过增强数字图像分析对DNA损伤程度进行分类。对苯二酚（HQ）、苯醌（BQ）、苯三酚（BT）、过氧化氢（H2O2）、博来霉素（BLM）和抗坏血酸钠（维生素C）可诱导双链断裂。DNA损伤受到多种试剂的调节，包括过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、去铁胺甲磺酸盐（DFO）、氯化亚铁（FeCl2）、还原型谷胱甘肽（GSH）、生育三烯酚、水飞蓟素和杨梅素。浓度为1 mM的单一化学物质（除BLM外）在没有铁（25 μM的Fe(II)或Fe(III)）的情况下不会诱导大量DSB。GSH增强了HQ、BT和维生素C的损伤作用，未改变H2O2的无损伤作用，但对BLM有轻微保护作用。与非酶蛋白牛血清白蛋白（BSA）相比，SOD对BT、H2O2和BLM有保护作用；在有GSH存在时，SOD减弱了HQ、BQ和维生素C的作用，但增强了BT、H2O2和BLM的作用。在同时存在GSH和铁的情况下，与BSA相比，SOD增强了HQ、BQ和BLM的作用，改善了H2O2的作用，对其他物质无影响。CAT对几乎所有检测的化合物都有保护作用，但对BLM作用较小。单独使用GSH时，DFO增强了HQ、BQ、H2O2的作用，改善了BT和维生素C的作用，生育三烯酚具有很大的保护作用。在有GSH和铁的情况下，DFO对除阿霉素（Dox）外的所有化合物都有保护作用，生育三烯酚对除Dox和BLM外的所有化合物都有保护作用，水飞蓟素除对BLM和Dox作用较小外具有保护作用，但杨梅素未显示出任何保护作用。总之，本研究结果进一步突出了还原剂和氧化还原循环剂的潜在危害，也强调了对抗氧化剂需谨慎看待。
