Nucleobase Derivatives as Building Blocks to Form Ru(II)-Based Complexes with High Cytotoxicity

[Image: see text] Two new Ru(II)-based complexes containing 2-thiouracil derivatives, known as 2-thiouracil (2TU) and 6-methyl-2-thiouracil (6m2TU), were synthesized using cis,trans-[RuCl(2)(PPh(3))(2)(bipy)] as a precursor. The obtained compounds with a general formula trans-[Ru(2TU)(PPh(3))(2)(bipy)]PF(6) (1) and trans-[Ru(6m2TU)(PPh(3))(2)(bipy)]PF(6) (2) were characterized by analytical techniques such as NMR, UV–vis, and IR spectroscopies, elementary analysis, mass spectrometry, and single-crystal X-ray diffraction. Moreover, the investigation of the complexes–DNA interaction were carried out using spectrophotometric titrations and showed that the complexes present a weak interaction with this biomolecule. The compounds were evaluated against HL-60, K-562, HepG2, and B16-F10 cancer cells and against noncancer cells (PBMCs). The results of the biological assay revealed that complex 2 is more promising than complex 1. Finally, the present study suggests that complexes 1 and 2 causes cell death by apoptosis, significantly increasing the percentage of apoptotic HL-60 cells, in which the compounds altered the cell cycle, reducing the cells in G(1)/G(0), G(2)/M, and S phases.