A Study of Sulfur and Selenium Containing Antioxidants Using ITC and Absorption Spectroscopy

Metal ions are capable of binding to DNA along the phosphate backbone as well as to the nucleotide bases. These ions are then susceptible to reaction with hydrogen peroxide. When metal ions react with hydrogen peroxide, reactive oxygen species (ROS) are formed, with hydroxyl radicals being a prime example. These radicals, being so close to DNA, are able to react with the chemical bonds of the ribose-phosphate backbone, thus breaking apart the strand, or altering a nucleotide base chemically. When these reactions occur, it can cause major reactions within a cell. However, some antioxidants have been shown to to be able to bind to metal ions to protect DNA from this series of reactions. Certain sulfur and selenium containing compounds are known antioxidants and show promise in use for preventing oxidative DNA damage; unfortunately, the method and reaction of this activity can be theorized, but is unknown. One possible method is that these compounds bind to the metal ions before the ions even reach the DNA; another possibility is that, once the metal ions are bound to DNA, the antioxidants excuses the ion from the DNA entirely. The third possibility is that these antioxidants form a complex with the metal ion while it is still attached to the DNA. With this research, we hope to show in what way these compounds function as antioxidants and how they are preventing DNA damage through isothermal titration calorimetry and UV/vis absorption spectroscopy experiments. With an understanding of how this mechanism works, scientists may be able to use this knowledge in applications that are capable of bettering society and the overall health of people