Abstract
One-electron oxidation plays a major role in oxidative DNA damage in biological cells. Guanine, the most oxidizable DNA base, has been the major focus of studies on oxidative damage to DNA initiated by one-electron oxidation (OEO). Recently, the Roginskaya group has discovered a novel type of products of dGuo· dimerization, D1 and D2, formed as a result of oxidation reaction of 2´-deoxyguanosine (dGuo), initiated by OEO. A proposed reaction mechanism assumes recombination of the two dGuo· radicals and further hydrolysis of the resultant intermediates to form diastereomers of D1A and D1B along with their oxidized product D2. The oxidation of isolated D1A and D1B yields D2 in basic medium. The current study aims at understanding the mechanisms of photooxidation of guanine derivatives with OEO in acidic buffers. D1A* and D1B*, which are the products of dGuo in acidic medium, were obtained from dGuo upon photolysis at 485 nm of the reaction mixture in the presence of S2O82- as the oxidant and Ru(II)(bpy)32+ as a photosensitizer. D1A* and D1B* were purified by semipreparative HPLC, and their structures were confirmed by 1H-NMR. The OEO of isolated D1A* and D1B* does not yield D2* in acidic medium, which indicates that the structures of D1A* and D1B* and D2* are different from the structures of D1A and D1B, and D2, respectively. This has been confirmed by 1H-NMR. Stability studies were performed on D1A* and D1B* at 40 ˚C and pH of 10.
Start Time
16-4-2025 9:00 AM
End Time
16-4-2025 11:30 AM
Presentation Type
Poster
Presentation Category
Science, Technology and Engineering
Student Type
Graduate Student - Masters
Faculty Mentor
Marina Roginskaya
Faculty Department
Chemistry
Effects of pH on products yield of one-electron oxidation to guanine derivatives
One-electron oxidation plays a major role in oxidative DNA damage in biological cells. Guanine, the most oxidizable DNA base, has been the major focus of studies on oxidative damage to DNA initiated by one-electron oxidation (OEO). Recently, the Roginskaya group has discovered a novel type of products of dGuo· dimerization, D1 and D2, formed as a result of oxidation reaction of 2´-deoxyguanosine (dGuo), initiated by OEO. A proposed reaction mechanism assumes recombination of the two dGuo· radicals and further hydrolysis of the resultant intermediates to form diastereomers of D1A and D1B along with their oxidized product D2. The oxidation of isolated D1A and D1B yields D2 in basic medium. The current study aims at understanding the mechanisms of photooxidation of guanine derivatives with OEO in acidic buffers. D1A* and D1B*, which are the products of dGuo in acidic medium, were obtained from dGuo upon photolysis at 485 nm of the reaction mixture in the presence of S2O82- as the oxidant and Ru(II)(bpy)32+ as a photosensitizer. D1A* and D1B* were purified by semipreparative HPLC, and their structures were confirmed by 1H-NMR. The OEO of isolated D1A* and D1B* does not yield D2* in acidic medium, which indicates that the structures of D1A* and D1B* and D2* are different from the structures of D1A and D1B, and D2, respectively. This has been confirmed by 1H-NMR. Stability studies were performed on D1A* and D1B* at 40 ˚C and pH of 10.