Kondo T, Krishna C M, Riesz P
Radiation Oncology Branch, National Cancer Institute, Bethesda, Maryland 20892.
Int J Radiat Biol Relat Stud Phys Chem Med. 1988 Jun;53(6):891-9. doi: 10.1080/09553008814551251.
In order to investigate the mechanism of sonolysis of nucleic acid constituents, the yield of thymine radicals generated by 50 kHz ultrasound in Ar-saturated aqueous solution was compared with that formed by gamma-radiolysis in N2O-saturated solutions in the presence of various non-volatile scavengers, which cannot act in the gas phase of the cavitation bubbles. For comparison of thymine radical yields by sonolysis and gamma radiolysis, the method of spin trapping with 3,5-dibromo-4-nitrosobenzenesulphonate (a water-soluble, non-volatile, aromatic nitroso spin trap) combined with ESR was used. The efficiency of OH radical scavenging is expressed by the reciprocal value of C1/2, the scavenger concentration at which the thymine radical yield is decreased by 50 per cent. In gamma radiolysis the scavenging efficiencies of the solutes depend on their rate constants with OH radicals. For sonolysis the C1/2 values were similar to those obtained for gamma radiolysis except for the hydrophobic 5,5-dimethyl-1-pyrroline-N-oxide. These results suggest that thymine radicals induced by ultrasound are produced in the bulk of the solution as well as in the interfacial region.
为了研究核酸成分的声解机制，将50 kHz超声在氩气饱和水溶液中产生胸腺嘧啶自由基的产率，与在各种非挥发性清除剂存在下γ辐射分解在一氧化二氮饱和溶液中形成胸腺嘧啶自由基的产率进行了比较，这些非挥发性清除剂不能在空化气泡的气相中起作用。为了比较声解和γ辐射分解产生的胸腺嘧啶自由基产率，采用了3,5-二溴-4-亚硝基苯磺酸盐（一种水溶性、非挥发性、芳香族亚硝基自旋捕捉剂）与电子自旋共振相结合的自旋捕捉方法。羟基自由基清除效率用C1/2的倒数表示，C1/2是使胸腺嘧啶自由基产率降低50%时的清除剂浓度。在γ辐射分解中，溶质的清除效率取决于它们与羟基自由基的反应速率常数。对于声解，除了疏水性的5,5-二甲基-1-吡咯啉-N-氧化物外，C1/2值与γ辐射分解得到的值相似。这些结果表明，超声诱导产生的胸腺嘧啶自由基是在溶液主体以及界面区域产生的。
