Synthesis, characterization, and DNA modification induced by a novel Pt-berenil compound with cytotoxic activity

In the present paper, we show that the reaction of the antitrypanosomatid berenil drug with K2PtCl4 resulted in the synthesis of a covalent Pt(II)-berenil compound of formula [Pt2Cl4(berenil)(2)]Cl-4 . 4H(2)O as shown by IR, H-1, C-13, and Pt-195-NMR. The Pt-berenil compound was tested for in vitro antitumor activity against HL-60 and U-937 human leukemic cells. The results show that the LC(70) values of the Pt-berenil are about two-fold lower than those of cis-DDP in both HL-60 and U-937 cell lines. Melting data of Pt-berenil:DNA and berenil:DNA complexes indicate that the platinated compound produces on a DNA secondary structure higher compaction than the berenil ligand. The mobility in agarose gels and the circular dichroism spectra of the compounds:DNA complexes revealed, moreover, that both induce drastic changes on a DNA secondary and tertiary structure. The total reflection X-ray fluorescence data showed, in addition, that DNA platination in Pt-berenil:DNA complexes occurs within minutes after addition of the drug, in contrast to what that observed in cis-DDP:DNA complexes. On the basis of these results, we propose that in Pt-berenil, the berenil ligand acts as a carrier of the active cis-P(II) centers towards DNA.