Research on Chemical Intermediates

, Volume 26, Issue 9, pp 885–896

EPR study of Fremy’s salt nitroxide roduction by ascorbic acid; influence of the bulk pH values

  • S. Colacicchi
  • V. Carnicelli
  • G. Gualtieri
  • A. Di Giulio


EPR and UV spectroscopy were used to investigate the efficiency of ascorbic acid in reducing Fremy’s salt. Our data indicates that the first proton electron transfer from ascorbate occurs within the mixing time. Even after the disappearance of the UV signal of the ascorbate, EPR measurements showed that the reaction goes forward, indicating a biphasic redox process. The slower time-course of this second phase was related to the initial concentrations of the reductant. Experiments performed at four different pH values demonstrated that the reduction was a function of the bulk solution pH. At the lower pH, after a fast initial reduction, the Fremy’s salt EPR signal remained constant, while at physiological or higher pH a further reduction was found.

The reaction rates demonstrate that the reducing power of ascorbic acid towards Fremy’s salt strongly depends on its dissociation state.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    B.J. Gaffney. In: L.J. Berliner (Ed.) Spin Labeling. Theory and Applications, Academic Press, New York, 183 (1976).Google Scholar
  2. 2.
    H.M. Swartz, Free Rad. Res. Commun. 9, 399 (1990).CrossRefGoogle Scholar
  3. 3.
    Z.L. Liu, Z.X. Han, P. Chen and Y.C. Liu, Chem. Phys. Lipid, 56, 73 (1990).CrossRefGoogle Scholar
  4. 4.
    L.R.C. Barclay and K.U. Ingold, J. Am. Chem. Soc. 103, 6478 (1981).CrossRefGoogle Scholar
  5. 5.
    A. Sotgiu, G. Placidi, G. Gualtieri, C. Tatone and C. Campanella, Magn. Reson. Chem. 33, S160 (1995).CrossRefGoogle Scholar
  6. 6.
    T.P. Holler and P.B. Hopkins, Biochemistry 29, 1953 (1990).CrossRefGoogle Scholar
  7. 7.
    A. Di Giulio, V. Carnicelli, S. Colacicchi and G. Gualtieri, Appl. Magn. Reson. 13, 553 (1997).CrossRefGoogle Scholar
  8. 8.
    J.D. Morrisett and H.D. Drott, J. Biol. Chem. 244, 5083 (1969).Google Scholar
  9. 9.
    R.J. Mehlhorn, J. Biol. Chem. 266, 2724 (1991).Google Scholar
  10. 10.
    W.R. Couet, R.C. Brasch, G. Sosnovsky and T.N. Tozer, Magn. Reson. Imaging 3, 83 (1985).CrossRefGoogle Scholar
  11. 11.
    F. Vianello, F. Momo, M. Scarpa and A. Rigo, Magn. Reson. Imaging 13, 219 (1995).CrossRefGoogle Scholar
  12. 12.
    M. Sentjurc, S. Pecar, K. Chen, M. Wu and H. Swartz, Biochim. Biophys. Acta 1073, 329 (1991).Google Scholar
  13. 13.
    C. Mathieu, A. Mercier, D. Witt, L. Debmkowski and P. Tordo, Free Radic. Biol. Med. 22, 803 (1997).CrossRefGoogle Scholar
  14. 14.
    M. Kveder, G. Pifat, S. Pecar, M. Schara, P. Ramos and H. Esterbauer, Chem. Phys. Lipids 17, 1 (1997).CrossRefGoogle Scholar
  15. 15.
    G.P. Laroff, R.W. Fessenden and R.H. Schuler, J. Am. Chem. Soc. 94, 9062 (1972).CrossRefGoogle Scholar
  16. 16.
    A.I. Al-Alayash and M.T. Wilson, Biochem. J. 177, 641 (1979).Google Scholar
  17. 17.
    V. Jakular, P.M. Kelley and D. Nijus, J. Biol. Chem. 266, 6878 (1991).Google Scholar
  18. 18.
    N.H. Williams and J.K. Yandell, Austr. J. Chem. 35, 1133 (1982).CrossRefGoogle Scholar
  19. 19.
    D. Njius, V. Jakular, J. Zu and P.M. Kelley, Am. J. Clin. Nutr. 54, 1179s (1991).Google Scholar
  20. 20.
    T. Iyanagi, I. Yamazaki and K.F. Anan, Biochim. Biophys. Acta, 806, 255 (1985).CrossRefGoogle Scholar
  21. 21.
    M. Okazaki and K. Toriyama, J. Magnet. Reson. 79, 158 (1988).Google Scholar
  22. 22.
    J.A. Weil, J.R. Bolton and J.E. Wertz, Electron Paramagnetic Resonance, Elementary Theory and Practical Application, Appendix E, John Wiley & Sons Inc., New York, 1994.Google Scholar
  23. 23.
    H.F. Bennett, R.D. Brown, J.F.W. Keana, S.H. Koenig and H.M. Swartz, Magn. Reson. Med. 14, 40 (1990).CrossRefGoogle Scholar
  24. 24.
    M. Ferrari, S. Colacicchi, G. Gualtieri, M.T. Santini and A. Sotgiu, Biochem. Biophys. Res. Commun. 166, 168 (1990).CrossRefGoogle Scholar
  25. 25.
    M. Santjurc, S. Pecar, K. Chen, M. Wu and H.M. Swartz, Biochim. Biophys. Acta 1073, 329 (1991).Google Scholar
  26. 26.
    Y. Miura, H. Utsumi and A. Hamada, Biochem. Biophys. Res. Commun. 182, 1108 (1992).CrossRefGoogle Scholar
  27. 27.
    M. Mazur, M. Valko, R. Klement and H. Morris, Anal. Chim. Acta 333, 249 (1996).CrossRefGoogle Scholar

Copyright information

© VSP 2000

Authors and Affiliations

  • S. Colacicchi
    • 1
  • V. Carnicelli
    • 1
  • G. Gualtieri
    • 1
  • A. Di Giulio
    • 1
  1. 1.Dipartimento di Scienze e Tecnologie BiomedicheUniversità degli Studi L’AquilaL’AquilaItaly

Personalised recommendations