[In vitro modulation of adriamycin-induced cytotoxicity of fulerol C60(OH)24].

The aim of this paper was to examine the effect of fullerol C60(OH)24 on the growth of tumor cells in culture and its modulating effect on adriamycin (ADR) induced cytotoxicity in three different human breast carcinoma cell lines.Growth inhibition was evaluated by tetrazolium colorimetric WST1 assay. ESR spin "trapping" method was used to assess OH-radical scavenger activity of fullerol during Fenton's reaction.Fullerol C60(OH)24 inhibited human breast cancer cell lines in different manner depending on the cell type, dose and time of exposure to it. However, none of the fullerol concentrations induced 50% growth inhibition. In the model system of ADR-induced cytotoxicity fullerol strongly suppressed ADR cytotoxicity for more than 50% in almost all concentrations, at each time point. ADR cytotoxicity was decreased by 80%, if the fullerol (1.9 micrograms/ml) was added to culture one hour before ADR. The same rate of suppression was achieved with 20 times less concentration in comparison to well defined natural antioxidant proanthocyanidol-BPI. The hydroxyl radical scavenger activity of fullerol during Fenton's reaction, was assassed by the electron spin resonance (ESR) spin "trapping" method. It was shown that fullerol was a potent hydroxyl radical scavenger. RI of ESR signals of PBN-OH adduct in the presence of 0.5 g/ml of fullerol was decreased by 88%.The obtained results suggest that antiproliferative effect of fullerol and its protective effect on ADR cytotoxicity might be mediated through antioxidative and hydroxyl-radical scavenger activity of fullerol, but additional investigations are necessary for better understanding of these mechanisms.