Enhanced DNA damage and anti-proliferative activity of a novel ruthenium complex with a chlorambucil-decorated ligand.

Triphenylphosphine substitution reactions of [RuCl(PPh 3) 2 (tpm)]Cl, 1 , featuring tris(pyrazolyl)methane (tpm) as ligand, with the chlorambucil-decorated pyridine ligand Py CA , 3-aminopyridine (Py NH2 ) and 4-pyridinemethanol (Py OH ) afforded the corresponding pyridine complexes 2–4 in high yields. Py CA was preliminarily obtained via esterification of 4-pyridinemethanol with chlorambucil. The new compounds Py CA and 2–3 were characterized by IR and multinuclear NMR spectroscopy. Additionally, the structure of 3 was ascertained by single crystal X-ray diffraction. The in vitro anti-proliferative activity of 2–4 and Py CA was determined against a panel of cancer cell lines, outlining 2 as the most performing compound. Targeted studies were subsequently undertaken using 2 to elucidate mechanistic aspects, including the assessment of ruthenium cellular uptake, cell cycle arrest, production of reactive oxygen species (ROS), western blotting and DNA damage (comet test). Overall, data highlight that the anticancer activity provided by 2 primarily affects the mitochondria pathway with a potential additional contribution from DNA damage. The anticancer drug chlorambucil was conjugated with a robust ruthenium(II) tris-pyrazolylmethane scaffold through a pyridine ligand. The resulting complex exhibited strong cytotoxicity against cancer cell lines, attributed to disruption of mitochondria functionality and induction of DNA damage. [Display omitted] • Synthesis of new ruthenium-chlorambucil conjugate. • The resulting ruthenium-trispyrazolylmethane complex is highly stable in aqueous media. • Cytotoxicity data reveal favorable effect provided by conjugation. • Relate chlorambucil-lacking complexes have been analyzed for comparison. • Experiments have been carried out to elucidate the mode of action. [ABSTRACT FROM AUTHOR]