Jpn. J. Infect. Dis., 57, S34-S35, 2004

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Reactions of 1-Methyl-2-Mercaptoimidazole with Hypochlorous Acid and Superoxide

Masao Nakamura*, Naomi Shishido and Hiroaki Akutsu

Department of Chemistry, Asahikawa Medical College, Hokkaido, Japan

*Corresponding author: nmasao@asahikawa-med.ac.jp

SUMMARY: Reactions of thioureylene antithyroid drugs (1-methyl-2-mercaptoimidazole and carbimazole) with hypochlorous acid (HOCl) and superoxide were followed optically and products were analyzed by mass spectrometry. 1-Methyl-2-mercaptoimidazole (MMI) and carbimazole reacted rapidly with HOCl with a rate constant of 1 ×10⁷ and 7×10⁶ M^-1s^-1, respectively. The characteristic spectrum assigned to MMI disulfide appeared immediately after addition of HOCl, followed by a slow conversion to a final spectrum. The conversion was dependent upon the ratio of HOCl to MMI and both antithyroid drugs uptake 3 moles HOCl for complete conversion. A similar sequence of spectral changes was also observed when the HOCl was replaced by myeloperoxidase (MPO)/H2O2/Cl^- system. The final oxidation product of MMI and carbimazole with HOCl and superoxide was 1-methylimidazole.