Yang M H, Schaich K M
Dept. of Food Science, Rutgers University, New Brunswick, NJ 08903-0231, USA.
Free Radic Biol Med. 1996;20(2):225-36. doi: 10.1016/0891-5849(95)02039-x.
Single (SSB) and double strand breaks (DSB) in supercoiled plasmid DNA pBR322 reacted with linoleic acid hydroperoxides (LOOH) were followed by agarose gel electrophoresis to obtain definitive information about factors affecting LOOH interaction with DNA. In water, LOOH induced extensive DSB, which were metal mediated and increased with incubation time. Adventitious metal bound to DNA was sufficient to decompose LOOH to reactive radicals, activity that was not readily inhibited by chelators DTPA and desferrioxamine. Added Fe2+ and Fe3+ increased SSB and DSB, although the effects of Fe2+ were more extensive. Above 100 microM both valences inhibited DNA damage. Strand breakage by LOOH proceeded via lipid alkoxyl and peroxyl radicals. Aldehydic lipid peroxidation products induced strand breaks via oxidation of double bonds, not by reactions of the carbonyl groups. Lipophilic antioxidants BHA, BHT, and alpha-tocopherol were about 20 times more effective than hydrophilic free radical scavengers sodium benzoate, inositol, DMSO, and mannitol in preventing LOOH-induced strand breaks, supporting lipid phase localization of the damage.
通过琼脂糖凝胶电泳跟踪超螺旋质粒DNA pBR322中与亚油酸氢过氧化物（LOOH）反应的单链（SSB）和双链断裂（DSB），以获取有关影响LOOH与DNA相互作用因素的确切信息。在水中，LOOH诱导广泛的DSB，这些DSB由金属介导，并随孵育时间增加。与DNA结合的偶然金属足以将LOOH分解为活性自由基，螯合剂二乙三胺五乙酸（DTPA）和去铁胺不易抑制这种活性。添加的Fe2+和Fe3+增加了SSB和DSB，尽管Fe2+的作用更广泛。两种价态在浓度高于100 microM时均抑制DNA损伤。LOOH引起的链断裂通过脂质烷氧基和过氧自由基进行。醛类脂质过氧化产物通过双键氧化而非羰基反应诱导链断裂。在防止LOOH诱导的链断裂方面，亲脂性抗氧化剂丁基羟基茴香醚（BHA）、二丁基羟基甲苯（BHT）和α-生育酚比亲水性自由基清除剂苯甲酸钠、肌醇、二甲基亚砜（DMSO）和甘露醇有效约20倍，这支持了损伤的脂质相定位。
