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EPR studies of free radicals in A-2058 human melanoma cells treated by valproic acid and 5,7-dimethoxycoumarin

Magdalena Zdybel 1Ewa Chodurek 2Barbara Pilawa 1

1. Department of Biophysics, Medical University of Silesia, Jedności 8, Sosnowiec 41-200, Poland
2. Department of Biopharmacy, Medical University of Silesia, Jedności 8, Sosnowiec 41-200, Poland


Electron paramagnetic resonance (EPR) examination pointed out the strong effect of valproic acid (VPA) and 5,7-dimethoxycoumarin (DMC) on free radicals in A-375 and G-361 human melanoma malignum cells [1].

In this work changes in free radical concentrations in tumor A-2058 cells after treatment by VPA and DMC cells were tested, and compared to those for A-375 and G-361 cells. Human melanoma malignum A-2058 cells were exposed to interactions with VPA, DMC, and both VPA and DMC. The malignant melanoma A-2058 cell line were purchased from LGC Prochem (Lomianki, Poland), and they were grown in the standard conditions: at temperature 37 oC and in an atmosphere containing 95% air and 5% CO2, in the Minimum Essential Medium Eagle (MEM, Sigma-Aldrich). The cells were incubated with VPA (1 mM) and DMC (10 μM) for 7 days. Free radicals in A-2058 cells were studied by an X-band (9.3 GHz) EPR spectroscopy. The first derivative EPR spectra were measured for the original A-2058 cells, and the cells cultured with VPA, DMC or VPA and DMC together. The following parameters of the EPR spectra: amplitude, integral intensity, linewidths, and g-factor, were analysed. The effect of microwave power in the range of 2.2-70 mW on the EPR spectra of the cells was evaluated. Free radical concentrations were determined via double integration of the spectra, as the values proportional to the area under the absorption lines. o-Semiquinone free radicals of melanin biopolymer are mainly responsible for the EPR lines of melanoma malignum

A-2058 cells. The changes in free radical system in A-2058 cells caused by the tested substances (VPA, DMC) and their application as the antitumor agents were discussed. The usefulness of electron paramagnetic resonance spectroscopy in the study of free radicals in tumor cells treated with drugs was confirmed.


1. Chodurek E., Zdybel M., Pilawa B. (2013). Application of EPR spectroscopy to examination of free radicals in melanins from A-375 and G-361 human melanoma malignum cells. Journal of Applied Biomedicine, Vol. 11, pp. 173-185.


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Submitted: 2014-03-14 10:59
Revised:   2014-05-02 19:48