Flavin-Based Light-Driven Fluorescent Probe for the Detection of Antioxidant Amino Acids.

We have synthesized a flavin-(5)-oxide derivative with a -toluenesulfonyl () group as a "turn-on" fluorescent probe for the detection of several antioxidant amino acids and biothiols. Oxidized flavin was synthesized by using dithiothreitol as the reducing agent. showed a light-driven fluorescence enhancement in the presence of several amino acids and biothiols such as histidine (His), methionine (Met), cysteine (Cys), glutathione (GSH), and homocysteine (Hcy). The H NMR study indicated the reductive elimination of the -toluenesulfonyl group from in the presence of antioxidants and photo-irradiation.