中文摘要：

本文利用激光光解法研究了二氟沙星激发态氧化损伤氨基酸和脱氧鸟苷酸等生物小分子。实验结果显示二氟沙星激发态水溶液氧化损伤色氨酸，酪氨酸，半胱氨酸和脱氧鸟苷酸的速率常数分别为1．97×10^8，1．48×10^8，1．72×10^8，6．92×10^8dm^3·mol^-1·s^-1。通过光谱分析和实验数据分析可以得出激发态二氟沙星氧化损伤色氨酸，酪氨酸，半胱氨酸和脱氧鸟苷酸是通过电子转移的方式进行的。

英文摘要：

The reactions of triplet-state difloxacin （DFX） with various amino acids and deoxyguanylic acid in aqueous media were studied using laser flash photolysis. Tryptophan, tyrosine, cysteine, and 2＇-deoxyguanosine- 5＇-monophosphate （dGMP） were found to completely quench the triplet state of DFX in aqueous solution, the corresponding second-order rate constants being 1.97×10^8,1.48×10^8,1.72×10^8,and 6.92×10^8dm^3·mol^-1·s^-1. The quenching mechanism involves electron transfer to the photoexcited triplet state of DFX from the tryptophan, tyrosine, cysteine, and dGMP moieties, followed by fast protonation of the resulting DFX anion radical.