Photochemical Addition of Glutathione to Uracil and Thymine

Abstract—Irradiation (Λ > 240 nm) of thymine in aqueous solution in the presence of glutathione produces primarily 5‐S‐glutathione‐5, 6‐dihydropyrimidine and 5‐S, S‐glutathione‐5, 6‐dihydro‐pyrimidine. These adducts are obtained in better yields when the irradiations (Λ > 280 nm) are carried out in the presence of triplet‐state sensitizers. Reduction of 5‐S, S‐glutathione‐5, 6‐dihydropyrimidine with zinc dust in acetic acid yields the corresponding 5, 6‐dihydropyrimidine. When thymine‐glutathione adducts are heated in 6 N HCl for 2h, 5‐S‐cysteine‐5, 6‐dihydrothymine and 5‐S, S‐cysteine‐5, 6‐dihydrothymine are formed. Under these conditions, uracil‐glutathione adducts are less stable and are converted to products other than uracil‐cysteine adducts.