New cerium(III) and neodymium(III) complexes as (III) cytotoxic agents

The cerium(III) and neodymium(III) complexes of 5-aminoorotic acid were synthesized and characterized by means of spectral data (IR, Raman, H-1 NMR and C-13 NMR) and elemental analysis. Significant differences in the IR spectra of the complexes were observed as compared with the spectrum of the ligand. A comparative analysis of the Raman spectra of the complexes with that of the free 5-aminoorotic acid allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. H-1 NMR and C-13 NMR spectra confirmed the formation of the complexes. The ligand and the complexes were tested for the cytotoxic activities on the chronic myeloid leukemia-derived K-562, overexpressing the BCR-ABL fusion protein, and the non-Hodgkin lymphoma-derived DOHH-2, characterized by a rexpression of the antiapoptotic protein bcl-2 cell lines. The results obtained indicate that the tested compounds exerted a considerable cytotoxic activity upon the evaluated cell lines in a concentration-dependent manner, which enabled the construction of dose-response curves and the calculation of the corresponding IC50 values. Cytotoxicity towards tumor cells was determined for a broad concentration range. The inorganic salts exerted a very weak cytotoxic effect on these cells that is in contrast to the lanthanide complexes, which exhibited potent cytotoxic activity towards K-562 and DOHH-2 cell lines. Copyright (c) 2006 John Wiley & Sons, Ltd.