Singlet Oxygen In Samples Of Biological Drugs And Its Analytical Determination

Various reactive oxygen species (ROS) are generated in the course of biological metabolism, such as superoxide (O2-.), hydrogen peroxide (H2O2), hydroxyl radical (HO.) and singlet oxygen (1O2); these ROS play a vital role in physiology. 1O2 is an excitation state of oxygen molecule existing in ground state, much more active and instable in chemical properties. There are multiplicate dual effects on organism. On the one hand it has a stronger toxicity leading to damage to biological molecules and causing aging and various diseases, such as cancer, inflammation, and peroxidation and signal transduction; on the other hand it is also a primary bactericide on biologic immunity system. Moreover, it has played a unique role in photodynamic therapy of cancer.We emphasize on the research and analytical applications of generation systems of singlet oxygen. Using molecule spectroscopy (fluorescence and UV-Vis spectroscopy) as research instrument, we have discussed the production mechanism of singlet oxygen generating from copper ion-curcumin, indoleacetic acid-horseradish peroxidase and methylene blue photosensitized systems. Simultaneously, we have made correlative determination on the mentioned above systems respectively.There are four chapters in this paper.The first part of this paper reviews applications and progresses in determination of singlet oxygen. The detection methods, progresses and analytical applications of singlet oxygen were reviewed. ESR, phosphorescence, spectrophotometry, chromatography, chemiluminescence and fluorescence methods were involved. We summarized their traits and emphased on the last two methods.In the second part, production mechanism study of singlet oxygen in copper ion-catalyzed curcumin using 1,3-diphenylisobenzofuran as fluorescence probe and its determination in the presence of superoxide anion radical. The fluorescence intensity of 1,3-diphenylisobenzofuran was quenched by copper ion-catalyzed curcumin system resulting from the generation of 1O2. We discussed its production mechanism and detected it. It is important to evaluate the use of security of curcumin.In the third part, reactive oxygen species produced from horseradish peroxidase (HRP)-catalyzed oxidation of indole-3-acetic acid (IAA) in an acidic solution was investigated using rhodamine 6G (Rh6G)-I- as fluorescence probe. Rh6G reacted with I3-, which was from I- oxidized by ROS, leading to the fluorescence quenching of Rh6G.. According to the principle, we studied the generation mechanism, output and dynamics behavior of ROS from IAA-HRP catalysis system. The proposed method was simple and accurate. There is an important referenced value to study the mechanism of cell apoptosis induced by IAA cooperated with HRP.In the fourth part, we evaluated the antioxidant effect of tea and determined two natural antioxidants using spectrofluorimetric method. Firstly, we estimated scavenging effect of tea on singlet oxygen using 1,3-diphenylisobenzofuran as fluorescence probe. 1O2 generated by irradiation of methylene blue (MB) could oxidize DPBF resulting in its fluorescence quenching at 447 nm, however, the relative fluorescence intensity of DPBF in the system would recover in the presence of antioxidant which could scavenge 1O2. So, we could evaluate the scavenging capacity of tea to 1O2 according to the recovery extent of the relative fluorescence intensity of DPBF, which was a simple, precise and selective method. Secondly, we detected quercetin and rutin in tablets in view of their various physiological activities with Rh6G as fluorescence probe. The fluorescence intensity of Rh6G was quenched by quercetin and rutin, respectively. Their quenching mechanisms were studied simultaneously.