Sáez G T, Valls V, Muñiz P, Perez-Broseta C, Iradi A, Oliva M R, Bannister J V, Bannister W H
Department of Biochemistry and Molecular Biology, University of Valencia, Spain.
Free Radic Res Commun. 1993;19(2):81-92. doi: 10.3109/10715769309056502.
Incubation of calf thymus DNA in the presence of rifamycin SV induces a decrease in the absorbance of DNA at 260 nm. The effect, was found to be proportional to the antibiotic concentration and enhanced by copper(II) ions. In the presence of rifamycin SV and copper(II), a significant increase in thiobarbituric acid-reactive (TBA-reactive) material is also observed. This effect is inhibited to different degrees by the following antioxidants: catalase 77%; thiourea 72%; glutathione (GSH) 62%; ethanol 52%; and DMSO 34%, suggesting that both hydrogen peroxide (H2O2) and hydroxyl radicals (OH.) are involved in DNA damage. Rifamycin SV-copper(II) mixtures were also found to induce the production of peroxidation material from deoxyribose and, in this case, glutathione and ethanol were the most effective antioxidant substrates with inhibition rates of 91% and 88% respectively. Electrophoretic studies show that calf thymus DNA becomes damaged after 20 min. incubation in the presence of both agents together and that the damaged fragments run with migration rates similar to those obtained by the metal chelating agent 1,10-phenanthroline. Normal DNA electrophoretic pattern was found to be preserved by catalase, and GSH at physiological concentrations and by thiourea. No protection is observed in the presence of ethanol or DMSO. The results obtained indicate the involvement of different reactive species in the degradation process of DNA due to rifamycin SV-copper(II) complex and emphasize the role of reduced glutathione as an oxygen free radical scavenger.
在利福霉素SV存在的情况下孵育小牛胸腺DNA会导致DNA在260nm处的吸光度降低。发现该效应与抗生素浓度成正比，并被铜（II）离子增强。在利福霉素SV和铜（II）存在的情况下，还观察到硫代巴比妥酸反应性（TBA反应性）物质显著增加。以下抗氧化剂对该效应有不同程度的抑制作用：过氧化氢酶77%；硫脲72%；谷胱甘肽（GSH）62%；乙醇52%；二甲基亚砜34%，这表明过氧化氢（H2O2）和羟基自由基（OH.）都参与了DNA损伤。还发现利福霉素SV - 铜（II）混合物会诱导脱氧核糖产生过氧化物质，在这种情况下，谷胱甘肽和乙醇是最有效的抗氧化底物，抑制率分别为91%和88%。电泳研究表明，小牛胸腺DNA在两种试剂共同存在下孵育20分钟后会受损，受损片段的迁移速率与金属螯合剂1,10 - 菲咯啉获得的迁移速率相似。发现过氧化氢酶、生理浓度的GSH和硫脲能保持正常的DNA电泳图谱。在乙醇或二甲基亚砜存在的情况下未观察到保护作用。所获得的结果表明不同的活性物种参与了由于利福霉素SV - 铜（II）复合物导致的DNA降解过程，并强调了还原型谷胱甘肽作为氧自由基清除剂的作用。
