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

We have synthesized a flavin‐N(5)‐oxide derivative with a p‐toluenesulfonyl (Ts‐OF) 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. Ts‐OF 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 1H NMR study indicated the reductive elimination of the p‐toluenesulfonyl group from Ts‐OF in the presence of antioxidants and photo‐irradiation. Driving light: Light‐driven fluorescence enhancement is reported in the presence of antioxidant amino acids. A flavin derivative with a p‐toluenesulfonyl group is prepared as a “turn‐on” fluorescent probe for the detection of several antioxidant amino acids and biothiols.