Dressing up an Old Drug: An Aminoacyl Lipid for the Functionalization of Ru(III)-Based Anticancer Agents

In the search for more efficient anticancer treatments, Ru(III) complexes have attracted much interest among metal-based candidate drugs, showing marked antitumor and antimetastatic activity associated with lower systemic toxicity. Remarkable examples are the Ru(III) complexes NAMI-A and KP1019, which have reached advanced clinical evaluation. In order to improve the in vivo stability of Ru(III)-based drugs, as well as their cellular uptake and effectiveness, a new approach has been proposed by our research group, based on the incorporation of the active, NAMI-A-like Ru(III) complex into highly functionalized nucleolipidic structures, i.e., hybrid molecules containing a nucleoside or nucleotide central core derivatized with a lipid chain, ensuring both efficient protection against extracellular degradation and high cellular internalization of the metal. Aiming at expanding the chemical diversity of available amphiphilic Ru(III) complexes, we here selected a trifunctional alpha-amino acid to replace the nucleosidic core of previously prepared nucleolipid-based Ru(III) complexes. The amino acidic scaffold, linked to the Ru(III) complex, is decorated with both hydrophilic and lipophilic moieties, conferring high propensity to form stable aggregates in water, which is required to obtain a suitable nanocarrier for the drug delivery. Following this approach, a novel compound, indicated here as compound I, was successfully prepared and characterized, then studied in coformulation with the biocompatible cationic lipid 1,2-dioleyl-3-trimethylammoniumpropane chloride (DOTAP) by dynamic light scattering (DLS), small angle neutron scattering (SANS), and UV-vis analysis. Evaluated in vitro on a panel of human and nonhuman cell lines, it showed good antiproliferative activity on cancer cells, with IC50 values in the mu M range, and no relevant cytotoxicity on the healthy cells used as control.