Kukiełka E, Cederbaum A I
Department of Biochemistry, Mount Sinai School of Medicine, New York, NY 10029, USA.
Biochem J. 1995 Apr 15;307 ( Pt 2)(Pt 2):361-7. doi: 10.1042/bj3070361.
Rifamycin SV is an antibiotic anti-bacterial agent used in the treatment of tuberculosis. This drug can autoxidize, especially in the presence of metals, and generate reactive oxygen species. A previous study indicated that rifamycin SV can increase NADH-dependent microsomal production of reactive oxygen species. The current study evaluated the ability of rifamycin SV to interact with iron and increase microsomal production of hydroxyl radical, as detected by conversion of supercoiled plasmid DNA into the relaxed open circular state. The plasmid used was pBluescript II KS(-), and the forms of DNA were separated by agarose-gel electrophoresis. Incubation of rat liver microsomes with plasmid plus NADH plus ferric-ATP caused DNA strand cleavage. The addition of rifamycin SV produced a time- and concentration-dependent increase in DNA-strand cleavage. No stimulation by rifamycin SV occurred in the absence of microsomes, NADH or ferric-ATP. Stimulation occurred with other ferric complexes besides ferric-ATP, e.g. ferric-histidine, ferric-citrate, ferric-EDTA, and ferric-(NH4)2SO4. Rifamycin SV did not significantly increase the high rates of DNA strand cleavage found with NADPH as the microsomal reductant. The stimulation of NADH-dependent microsomal DNA strand cleavage was completely blocked by catalase, superoxide dismutase, GSH and a variety of hydroxyl-radical-scavenging agents, but not by anti-oxidants that prevent microsomal lipid peroxidation. Redox cycling agents, such as menadione and paraquat, in contrast with rifamycin SV, stimulated the NADPH-dependent reaction; menadione and rifamycin SV were superior to paraquat in stimulating the NADH-dependent reaction. These results indicate that rifamycin SV can, in the presence of an iron catalyst, increase microsomal production of reactive oxygen species which can cause DNA-strand cleavage. In contrast with other redox cycling agents, the stimulation by rifamycin SV is more pronounced with NADH than with NADPH as the microsomal reductant. Interactions between rifamycin SV, iron and NADH generating hydroxyl-radical-like species may play a role in some of the hepatotoxic effects associated with the use of this antibacterial antibiotic.
利福霉素SV是一种用于治疗结核病的抗生素抗菌剂。这种药物会自动氧化，尤其是在有金属存在的情况下，并产生活性氧。先前的一项研究表明，利福霉素SV可增加依赖NADH的微粒体活性氧生成。当前的研究评估了利福霉素SV与铁相互作用并增加微粒体羟自由基生成的能力，这是通过将超螺旋质粒DNA转化为松弛的开环状态来检测的。所用的质粒是pBluescript II KS(-)，DNA的形式通过琼脂糖凝胶电泳分离。大鼠肝微粒体与质粒加NADH加铁-ATP孵育会导致DNA链断裂。加入利福霉素SV会使DNA链断裂呈时间和浓度依赖性增加。在没有微粒体、NADH或铁-ATP的情况下，利福霉素SV不会产生刺激作用。除了铁-ATP外，其他铁络合物如铁-组氨酸、铁-柠檬酸盐、铁-EDTA和铁-(NH4)2SO4也会产生刺激作用。利福霉素SV不会显著增加以NADPH作为微粒体还原剂时所发现的高DNA链断裂率。依赖NADH的微粒体DNA链断裂的刺激作用被过氧化氢酶、超氧化物歧化酶、谷胱甘肽和多种羟自由基清除剂完全阻断，但不会被防止微粒体脂质过氧化的抗氧化剂阻断。与利福霉素SV不同，氧化还原循环剂如甲萘醌和百草枯会刺激依赖NADPH的反应；甲萘醌和利福霉素SV在刺激依赖NADH的反应方面优于百草枯。这些结果表明，在铁催化剂存在的情况下，利福霉素SV可增加微粒体活性氧的生成，而活性氧可导致DNA链断裂。与其他氧化还原循环剂不同，以NADH作为微粒体还原剂时，利福霉素SV的刺激作用比以NADPH时更明显。利福霉素SV、铁和NADH之间相互作用产生类似羟自由基的物质可能在与使用这种抗菌抗生素相关的一些肝毒性作用中起作用。
