Electron vs. H-Atom Transfer in Chemical Repair

  • Michael G. Simic
  • Edward P. L. Hunter
  • Slobodan V. Jovanovic


Free radicals are generated by ionizing radiations (e.g., X rays, γ rays, electrons, neutrons, and Rn α-particles),1 and the biological effects they cause are in some ways a consequence of their reactions.2 Free radicals may also be generated by other processes and agents and numerous chemicals generate them under physiological conditions. Cancer promoters3 and antineoplastic drugs4 cause DNA strand breaks via free radical reactions. Metabolic processes are also perceived as possible sources of free radicals.5–7 The repair of free radicals and the elimination (or reduction) of their biological effects by radioprotectors (mainly sulfhydryls) is a well-established defense mechanism in biological systems8. Although the interaction of anticarcinogens (primarily antioxidants) with free radicals is feasible, this is a poorly understood process.8,9


Free Radical Electron Spin Resonance Peroxy Radical Pulse Radiolysis Free Radical Damage 
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  1. 1.
    M. Z. Hoffman, Ed. Radiation Chemistry. J. Chem. Ed. 83 (1981).Google Scholar
  2. 2.
    E. J. Hall, Radiobiology for the Radiobiologist. Rarper & Row, New York, 1978.Google Scholar
  3. 3.
    H. C. Birnboim, Importance of DNA strand-break damage in tumor promotion. In: Radioprotectors and Anticarcinogens (O. F. Nygaard and M. G. Simic, Eds.) pp 539–56. Academic Press, New York, 1983.Google Scholar
  4. 4.
    S. M. Hecht, DNA strand scission by activated bleomycin group antibiotics. This volume.Google Scholar
  5. 5.
    J. M. Mord and I. Fridovich, The reduction of cytochrome-c by milk xanthine oxidase. J. Biol. Chem. 243, 5753 (1968).Google Scholar
  6. 6.
    R. G. Cutler, Antioxidants and Longevity. In: Free Radicals in Molecular Biology, Aging, and Disease (D. Armstrong, R. S. Sohal, R. G. Cutler, and T. F. Slater, Eds.) pp. 371–428 Raven Press, New York, 1984.Google Scholar
  7. 7.
    B. N. Ames, Dietary Carcinogens and Anticarcinogens. Science 221, 1256 (1983).PubMedCrossRefGoogle Scholar
  8. 8.
    O. F. Nygaard and M. G. Simic, Eds., Radioprotectors and Anticarcinogens. Academic Press, New York, 1983.Google Scholar
  9. 9.
    L. W. Wattenberg, Protective effects of 2(3)-tert-butyl-4-hydroxy-anisole on chemical carcinogenesis. Food Chem. Toxicol. 24, 1099 (1986).PubMedCrossRefGoogle Scholar
  10. 10.
    P. Alexander and A. Charlesby, Physico-chemical methods of protection against ionizing radiations. In: Radiobiology Symposium (Z. M. Bacq and P. Alexander, Eds.) pp. 49–59. Academic Press, New York, 1955.Google Scholar
  11. 11.
    T. Alper and P. Howard-Flanders, Role of oxygen in modifying the radiosensitivity of E. coli B, Nature 178, 978 (1956).PubMedCrossRefGoogle Scholar
  12. 12.
    P. M. Cullis and M.C.R. Symmons, Electron spin resonance studies of the mechanisms of radiation damage to DNA. In: Mechanisms of DNA Damage and Repair (M. G. Simic, L. Grossman, and A. C. Upton, Eds.) pp. 29–37. Plenum Press, New York, 1986.Google Scholar
  13. 13.
    M. G. Simic and S. V. Jovanovic, Free radical mechanisms of DNA base damage, ibid, p. 39–49.Google Scholar
  14. 14.
    S. V. Jovanovic and M. G. Simic, Mechanisms of OH radical reactions with thymine and uracil derivatives. J. Am. Chem. Soc. 118, 5968 (1986).CrossRefGoogle Scholar
  15. 15.
    C. von Sonntag, The Chemical Basis of Radiation Biology. Taylor and Francis, London, 1987.Google Scholar
  16. 16.
    S. Fujita and S. Steenken, Pattern of OH radical addition to uracil and methyl- and carboxyl substituted uracils. Electron transfer of OH adducts with N, N,N’,N’-tetramethyl-p-phenylenediamine and tetranitromethane. J. Am. Chem. Soc. 97, 2277 (1981).Google Scholar
  17. 17.
    R. L. Willson, Free radical repair mechanisms, in: “Radioprotectors and Anticarcinogens”, (O. F. Nygaard and M. G. Simic, Eds.) pp. 1–22. Academic Press, New York, 1983.Google Scholar
  18. 18.
    The Merck Index, th ed. Merck & Co., Inc., Rahway, 1983.Google Scholar
  19. 19.
    M. G. Simic and E.P.L. Hunter, Reaction mechanisms of peroxy and C-centered radicals with sulfhydryls. J. Free Radial. Biol. Med. 2, 227 (1986).CrossRefGoogle Scholar
  20. 20.
    E.P.L. Hunter, B. D. Michael, and M. G. Simic, Use of an optical multichannel analyzer for recording absorption spectra of short-lived transients. Rev. Sci. Instrum. 2199 (1985).Google Scholar
  21. 21.
    M. G. Simic and S. V. Jovanovic, Acid-base and redox properties of the guanyl radical. J. Phys. Chem., submitted for publication.Google Scholar
  22. 22.
    M.G. Simic and E.P.L. Hunter, Interaction of free radicals and antioxidants. In: Radioprotectors and Anticarcinogens (O. F. Nygaard and M. G. Simic, Eds.) pp. 449–460. Academic Press, New York, 1983.Google Scholar
  23. 23.
    O. Shulte-Frohlinde, G. Behrens, and A. Onal, Lifetime of peroxy radicals of poly(U), poly(A), and single- and double-stranded DNA and the rate of their reaction with thiols. Int. J. Radiat. Biol. 50, 103 (1986).CrossRefGoogle Scholar
  24. 24.
    L. Karam, M. G. Simic, and M. Dizdaroglu, Free radical-induced cross-linking of polydeoxythymidylic acid in deoxygenated aqueous solution. Int. J. Radiat. Biol. 49, 67 (1986).CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • Michael G. Simic
    • 1
  • Edward P. L. Hunter
    • 1
  • Slobodan V. Jovanovic
    • 1
    • 2
  1. 1.Center for Radiation ResearchNational Bureau of StandardsGaithersburgUSA
  2. 2.Laboratory of Solid State Physics and Radiation ChemistryBoris Kidric Institute of Nuclear SciencesBeogradYugoslavia

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