Fuciarelli A F, Sisk E C, Thomas R M, Miller D L
Biology and Chemistry Department, Battelle, Pacific Northwest Laboratory, Richland, WA 99352, USA.
Free Radic Biol Med. 1995 Feb;18(2):231-8. doi: 10.1016/0891-5849(94)00119-5.
Ultrasound can damage macromolecules by the mechanical (shearing) and sonochemical (free radical generating) action of ultrasonic cavitation. Attributing macromolecular damage to either direct mechanical stress or to indirect mechanisms involving free radicals or other sonochemicals is a challenging problem. DNA damage induced by ultrasound was evaluated by measuring the formation of purine and pyrimidine products using combined gas chromatography-mass spectrometry with selected ion monitoring. Samples of DNA were prepared in 10 mmol dm-3 phosphate buffered saline (pH 7.4) and saturated with a mixture of argon:oxygen (3:1). Continuous 2.17 MHz ultrasound exposures at 0.82 mPa spatial peak negative pressure amplitude were performed in a 60 rpm rotating tube exposure system. Hydrogen peroxide yields were measured after each exposure to quantify the cavitation activity and ranged up to 350 mumol dm-3 for 1-h exposures. Purine and pyrimidine products identified were those typically observed following exposure of DNA to hydroxyl radical-generating systems, such as ionizing radiation, hypoxanthine/xanthine oxidase, or hydrogen peroxide in the presence of transition metal ions. The yields of these products were directly correlated with cavitation activity as measured by residual hydrogen peroxide concentrations. The yields of DNA products increased in the following order: thymine glycol approximately cytosine glycol > 8-oxoAde > FAPyAde approximately 5-HMU approximately 5,6-diOHCyt > FAPyGua. Unexpectedly, 8-oxoguanine did not exhibit a dose-dependent increase above background levels, and this observation is inconsistent with processes involving metal ion-dependent formation of hydroxyl radicals from hydrogen peroxide. In addition, the product yields were far too large to result from the residual hydrogen peroxide. Thus, ultrasonic cavitation appears to have a mode of action distinct from either ionizing radiation or formation of hydroxyl radicals via Fenton-like reaction with transition metals.
超声可通过超声空化的机械（剪切）和声化学（产生自由基）作用破坏大分子。将大分子损伤归因于直接机械应力或涉及自由基或其他声化学物质的间接机制是一个具有挑战性的问题。通过使用结合气相色谱 - 质谱联用和选择离子监测来测量嘌呤和嘧啶产物的形成，评估超声诱导的DNA损伤。DNA样品在10 mmol dm-3磷酸盐缓冲盐水（pH 7.4）中制备，并用氩气：氧气（3:1）的混合物饱和。在60 rpm旋转管暴露系统中，以0.82 mPa空间峰值负压振幅进行连续2.17 MHz超声暴露。每次暴露后测量过氧化氢产量以量化空化活性，1小时暴露的产量高达350 μmol dm-3。鉴定出的嘌呤和嘧啶产物是DNA暴露于产生羟基自由基的系统（如电离辐射、次黄嘌呤/黄嘌呤氧化酶或在过渡金属离子存在下的过氧化氢）后通常观察到的产物。这些产物的产量与通过残留过氧化氢浓度测量的空化活性直接相关。DNA产物的产量按以下顺序增加：胸腺嘧啶二醇≈胞嘧啶二醇＞8-氧代腺嘌呤＞FAPy腺嘌呤≈5-HMU≈5,6-二羟基胞嘧啶＞FAPy鸟嘌呤。出乎意料的是，8-氧代鸟嘌呤在背景水平以上未表现出剂量依赖性增加，并且该观察结果与涉及过氧化氢依赖金属离子形成羟基自由基的过程不一致。此外，产物产量远大于残留过氧化氢所导致的产量。因此，超声空化似乎具有与电离辐射或通过与过渡金属的类芬顿反应形成羟基自由基不同的作用模式。
