Glutathione (GSH), ascorbate (VitC), and NADH are biological reductants found in all human cells at high concentration. Taurine (Tau) and hypotaurine (Hyp) also are highly concentrated biological molecules known to react with reactive oxygen species. Tau and Hyp are commonly called antioxidants, but their ability to protect biological molecules from oxidation has not been well demonstrated. We are performing qualitative and kinetic experiments to determine if Tau and Hyp limit the oxidation of GSH, VitC, and NADH in the presence of hydrogen peroxide and superoxide. The study employs Raman spectroscopy, mass spectrometry, and fluorescence spectroscopy to identify products of the reactions and the rates at which the products are produced. We expect that Tau and Hyp will protect the biological reductants from oxidation by superoxide, which would indicate that Tau and Hyp are biologically-relevant antioxidants in humans.