| Numerous reactive oxygen species (ROS) are generated in the course of biology metabolism. Hydroxyl radicals (·OH), superoxide anion radical (O2·-) are two typical ones. They have important relations with aging and diseases.·OH is a free radical, which has a high oxidation. It can oxidize numerous organic and inorganic compounds easily with high oxidation efficiency and fast reaction rate. It has relation with tumors, radiation damages and phagocytosis. O2·- has toxic and can generate other reactive oxygen species by a series of reactions. These reactive oxygen species have further damages to organisms and long resident time.About 95% of the total free radicals in the body are reactive oxygen species; therefore the research on the ROS has a special significance to human body. Researches of reactive oxygen species can help us explain the causes of diseases better, strengthen effective preventive measures and reduce the injury extent of the body. In addition, it has great guiding significance and theoretical value in measurement of health food in the antioxidant capacity and the selection of antioxidant substances in Chinese herbal medicine.Because ROS is active, direct determination is difficult. At present, many methods for the indirect determination of superoxide anion radicals and hydroxyl radicals have been developed. After having a comprehensive understanding of these methods, based on fluorescence analysis with the advantages of high sensitivity, selectivity and simple operation, the spectrofluorimetric method was used to detect reactive oxygen species. In the paper, two fluorescent probes were synthesized and their selectivity for O2·- were studied. In addition, the effects of scavenging of reactive oxygen species by some antioxidants were discussed. Three aspects of investigation have been carried out specifically:(1) The fluorescent material, 8-hydroxyguanosine, was a product of the reaction between guanosine and H2O2 by UV light photolysis. The fluorescent characteristics of 8-hydroxyguanosine formed in different conditions were studied, and the relationships between the different forms and the fluorescence intensity of 8-hydroxyguanosine were analyzed. The experimental conditions for the generation of hydroxyl radical and the determination of 8-hydroxyguanosine were optimized. Based on the dose-effect relationship of fluorescence intensity and hydroxyl radical, the reaction mechanism between hydroxyl radical and guanosine was researched. The scavenging effects of tea and garlic on hydroxyl radical were studied to alleviate the harm of hydroxyl radical to guanosine.(2) A novel fluorescent probe, 2-(2-pyridyliminomethyl) phenol was synthesized. The spectrofluorimetric method was developed for the determination of O2·- and SOD activity. The optimum experimental conditions were discussed. Furthermore, SOD activity in garlic, papaya and spinach were successfully determined. The results obtained by the suggested method were also compared with those obtained from the standard method.(3) A novel spectrofluorimetric method using 2-(2-Thienyl)benzothiazo- line as fluorescent probe was developed for the determination of O2·- and SOD activity. The effects of interferences and the selectivity for O2·- of the fluorescent probe were investigated. The sensitivity and precision of the method were studied. It was successfully applied to determine SOD activity in garlic and onion samples.In the paper, the study on molecular mechanism of the interaction between hydroxyl radical generated and guanosine by fluorescent spectroscopy was carried out firstly, and two novel fluorescent probes for the determination of O2·- and SOD activity were synthesized. Moreover, 2-(2-Thienyl)benzothiazoline has a good selectivity for O2·-, these results are satisfied. However, there are still some inadequacies. For example, the spectrofluorimetric method is not sensitive enough in the UV-H2O2 system and the detection method of ROS is not applied in the animal sample, which needs further improvement and discussion.
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