Marian Valko - research interests
 








Research Interests



  • Bioinorganic chemistry
    • Our research in bioinorganic chemistry involves synthetic inorganic chemistry of transition-metal compounds with biologically active ligands. We employ various techniques to characterize our model complexes including X-ray crystallography and spectroscopic techniques, in particular Electron Paramagnetic Resonance (EPR) spectroscopy. (investigated in collaboration with Joshua Telser, Chicago). Finally, we examine the biological activity of the model complexes.

    Selected papers:
    A. Huber, L. Mueller, H. Elias, R. Klement, M. Valko:
    Cobalt(II) Complexes with Substituted Salen-Type Ligands and Their Dioxygen Affinity in N,N-Dimethylformamide at Various Temperatures.
    Eur. J. Inorg. Chem. 8 1459-1467 (2005).

    J. Moncol, B. Kalinakova, J. Svorec, M. Kleinova, M. Koman, D. Hudecova, M. Melnik, M. Mazur, M. Valko:
    Spectral properties and bio-activity of copper(II) clofibriates, part III: crystal structure of Cu(clofibriate)2(2-pyridylmethanol)2, Cu(clofibriate)2(4-pyridylmethanol)2(H2O) dihydrate, and Cu2(clofibriate)4(N,N-diethylnicotinamide)2.
    Inorg. Chim. Acta 357 3211-3222 (2004).

    C. J. Williams, H. Morris, J. Svorec, M. Valkova, M. Valko, J. Moncol, M. Mazur, F. Valach, M. Melnik:
    A study of Copper(II)-carboxylato complexes with the biological ligands Nicotinamide and Papaverine.
    J. Mol. Struct. 659 53-60 (2003).

    M. Valko, H. Morris, M. Mazur, J. Telser, E. McInnes, F. Mabbs:
    High affinity binding site for copper(II) in human and dog serum albumins. (An EPR study).
    J. Phys. Chem. B 103 5591-5597 (1999).

  • Free radicals and antioxidants in biological systems
    • Oxygen free radicals or more generally reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role as both deleterious and beneficial species. In the case of disturbed balance between formation of free radicals and antioxidant defense, in the cell we have oxidative stress which plays an important role in the development of various diseases. Overproductions of free radicals have been implicated in the etiology of host degenerative diseases including cardiovascular diseases, diabetes, cancer, Alzheimers disease, and other neurodegenerative disorders and aging (investigated in collaboration with Klaudia Jomova, UKF Nitra). In our laboratory we study the the role of oxygen free radical generating mechanisms in the colon, in particular the role of semiquinone radicals of vitamin K in the aetiology of colon cancer. Our current experiments involve (i) study of the oxidative stress in a rat model of chronic brain hypoperfusion (in collaboration with Svatava Kasparova, Bratislava) and (ii) the experimental conditions affecting antioxidant and prooxidant properties of carotenoids (in collaboration with Mark T.D. Cronin, Andy Young and Judy C. Madden, Liverpool,UK). In the field of free-radical mediated drug action our attention has been focued on the role of free radicals and singlet oxygen in photoactivated DNA cleavage by the anticancer drug camptothecin. In our laboratory free radicals are investigated using an appropriately varied range of techniques centred around Electron Paramagnetic Resonance (EPR) spectroscopy.

    Selected papers:
    K. Jomova, O. Kysel, J.C. Madden, H. Morris, S.J. Enoch, S. Budzak, A.J. Young, M.T.D. Cronin, M. Mazur, M. Valko:
    Electron transfer from all-trans beta-carotene to the t-butyl peroxyl radical at low oxygen pressure
    (an EPR spectroscopy and computational study).
    Chem. Phys. Letters 478, 266-270 (2009). PDF PDF Full Text (479 K)

    M. Valko, H. Morris, M.T.D. Cronin:
    Metals, toxicity and oxidative stress.
    Curr. Med. Chem. 12 1161-1209 (2005).

    S. Kasparova, V. Brezova, M. Valko, J. Horecky, V. Mlynarik, T. Liptaj, O. Vancova, O. Ulicna, D. Dobrota:
    Study of the oxidative stress in a rat model of chronic brain hypoperfusion.
    Neurochem. Internat. 46 601-611 (2005).

    M. Valko, M. Izakovic, M. Mazur, C. J. Rhodes, J. Telser:
    Role of oxygen radicals in DNA damage and cancer incidence.
    Mol. Cell. Biochem. 266 37-56 (2004).

    V. Brezova, M. Valko, M. Breza, H. Morris, J. Telser, D. Dvoranova, K. Kaiserova, L. Varecka, M. Mazur, D. Leibfritz:
    Role of Radicals and Singlet Oxygen in Photoactivated DNA Cleavage by the Anticancer Drug Camptothecin: An Electron Paramagnetic Resonance Study.
    J. Phys. Chem. B 107 2415-2425 (2003).

    M. Valko, H. Morris, P. Rapta, M. Mazur, R. F. Bilton:
    Oxygen free radical generating mechanisms in the colon: do the semiquinones of vitamin K play a role in the aetiology of colon cancer?
    Biochim. Biophys. Acta 1527 161-166 (2001).

    S. Stolc, L. Valko, M. Valko, V. Lombardi:
    A Technique for the fast sampling of biological tissues for Electron Paramagnetic Resonance Spectroscopy.
    Free Rad. Biol. Med. 20 89-91 (1996).



    EPR laboratory at the Department of Physical Chemistry, STU

    The EPR group has the following measurement equipments in use:
    (i) Bruker EMX EPR spectrometer; X-band frequency, variable temperature unit.
    (ii) Portable EPR spectrometer ADANI PS100.X EPR Spectrometer; for routine work at X-Band frequencies at temperatures from 77 K to 300 K.