• Quenching of nucleotide-derived radicals bybisbenzimidazole derivative Hoechst-33258 in aqueous solution

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    • Keywords

       

      Nucleotide-derived radicals; Hoechst-33258; pulse radiolysis

    • Abstract

       

      The pulse radiolysis technique has been employed to investigate the reaction of DNA-minor-groove ligand bisbenzimidazole Hoechst 33258 with pyrimidine and purine nucleotide-derived radicals. Formation of an N-centred Hoechst-33258 radical is observed. Bimolecular rate constants and the yields of Hoechst-33258 radical have been evaluated. While the rate constant for the reaction of pyrimidine-derived radicals with Hoechst-33258 remained the same (1–2) × 109 dm3 mol−1 s−1, the yields of the Hoechst-33258 radical varied from 25% (5′-cytidine monophosphate) to 75% (5′-guanosine monophosphate) under anoxic conditions. The rate constant values for the reaction of purine-derived radicals with Hoechst-33258, under oxic and anoxic conditions, remained the same whereas with pyrimidine-derived radicals, the rate constant value under oxic conditions was about two orders of magnitude lower than under anoxic conditions. The difference in the yields of Hoechst-33258 radical with various nucleotide-derived radicals suggest the formation of different types of radicals and that the reaction mainly occurs by electron transfer from Hoechst-33258 to the nucleotide radicals.

    • Author Affiliations

       

      H Mohan1 A Adhikary2 V Jain2 J P Mittal1 3

      1. Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085, India
      2. Department of Biocybernetics, Institute of Nuclear Medicine and Allied Sciences, Lucknow Marg, Delhi - 110 054, India
      3. Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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  • Journal of Chemical Sciences | News

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