Taurine Chloramine and Hydrogen Peroxide as a Potential Source of Singlet Oxygen for Topical Application

Singlet oxygen (1O2) is the “active principle” in photodynamic therapy. Taurine chloramine (Tau-NHCl) and hydrogen peroxide (H2O2) are well-tolerated and widely used antiseptics. Due to its mild oxidizing features and stability, Tau-NHCl can be directly used to treat skin diseases. We found that a diluted aqueous mixture of Tau-NHCl and H2O2 acts as a slow and long-lasting potential source of 1O2. The reactions were studied by luminol-enhanced chemiluminescence. Evidence of the formation of 1O2 was obtained using deuterium oxide, sodium azide and 9,10-Anthracenediyl-bis(methylene)dimalonic acid, a chemical trap of 1O2. The reaction was optimized, and a mechanism was proposed, including theoretical calculations at B3LYP/6-311++G(3df,2p) level of theory, adding D3Bj empirical dispersion and SMD (Water) solvent effects. Chloramines produced by the reactions between HOCl and L-alanine, 3-amino-1-propanesulfonic acid and gamma-aminobutyric acid were also prepared, and their reactivity and stability were compared with Tau-NHCl. We found that Tau-NHCl is more stable and adequate for the production of 1O2. In conclusion, we propose applying these drugs combination as a potential source of 1O2 with applications for skin diseases treatment.