###### Abstract
The complexes of Ru(III) with unidentate ligands levofloxacin (LEV), gatifloxacin (GAT), and pipemidic acid (Pip-H: L) with formulas [Ru(LEVO)\({}_{3}\)(C)\({}_{3}\)]\(\cdot\)8H\({}_{2}\)O [39], [Ru(GAT-NH\({}_{4}\))(C)\({}_{3}\)(H\({}_{2}\)O)\({}_{2}\)] [40], and [M(L)\({}_{3}\)(Cl)\({}_{3}\)]\(\cdot\)6H\({}_{2}\)O, respectively, were prepared and physicochemically characterized [41]. The biological evaluation of the Ru(III) complex with pipemidic acid revealed antibacterial efficiency against four kinds of bacteria--G(+) (_Staphylococcus epidermidis_ and _Staphylococcus aureus_) and G(-) (_Klebsiella_ and _Escherichia coli_)--and inhibitory activity against the human breast cancer (MCF-7) tumor cell line [41]. During previous research studies, our group also synthesized and characterized a series of some novel ruthenium (III) complexes with mixed ligands of the type RuCl\({}_{3}\)L\({}_{2}\)(DMSO)\({}_{m}\)\(\cdot\)\(\cdot\)\(\cdot\)H\({}_{2}\)O [42; 43], as described in Table 1.  
All these complexes display an octahedral stereochemistry with the quinolone ligand acting as monodentate, coordinated through the N4 atom of the piperazinyl ring (Figure 1). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Complex** & **X1** & **X2** & **R1** & **R2** & **R3** \\ \hline [RuCl\({}_{3}\)(pip)\({}_{2}\)(DMSO)]\(\cdot\)2H\({}_{2}\)O & N & N & C\({}_{2}\)H\({}_{5}\) & - & H \\ (pip = pipemidic acid); Ru-pip & & & & & \\ \hline [RuCl\({}_{3}\)(env)\({}_{2}\)(DMSO)] & N & C & C\({}_{2}\)H\({}_{5}\) & F & H \\ (errx = enoxacin); Ru-enoxa & & & & & \\ \hline [RuCl\({}_{3}\)(nf)\({}_{2}\)(DMSO)]\(\cdot\)H\({}_{2}\)O & CH & C & C\({}_{2}\)H\({}_{5}\) & F & H \\ (nf = nonffloxacin); Ru-nf & & & & & \\ \hline [RuCl\({}_{3}\)(cp)\({}_{2}\)(DMSO)]\(\cdot\)DMSO\(\cdot\)2H\({}_{2}\)O & CH & C & \({}_{\triangle}\) & F & H \\ (cp = ciprofloxacin); Ru-cipro & & & & & \\ \hline [RuCl\({}_{3}\)(enro)\({}_{2}\)(DMSO)]\(\cdot\)H\({}_{2}\)O & CH & C & \({}_{\triangle}\) & F & C\({}_{2}\)H\({}_{5}\) \\ (enro = enrofloxacin); Ru-enro & & & & & \\ \hline [RuCl\({}_{3}\)(of)\({}_{2}\)(DMSO)]\(\cdot\)H\({}_{2}\)O & CH & C & \({}_{\triangle}\)\(\cdot\)\Our previous studies showed that these Ru(III) complexes interacted in vitro with biomolecules such as calf thymus DNA [44] and human serum transferrin [45], and they presented antimicrobial activity in vitro [46] and antitumor activity in vivo [47]. In one previous study, the fluorescence intensity of the DNA-EtBr system was registered in the absence and in the presence of increasing amounts of complexes. The competitive study revealed the quenching of the fluorescence intensity of the DNA-EtBr system for all complexes, suggesting an intercalative mode for interaction with DNA [44]. The phenomenon is not singular, since other studies performed by our research group showed that organo-metal compounds induced cell lysis and apoptosis in several human cancer cell lines [48; 49; 50]. Apoptosis or \"programmed cell death\", along with the cell cycle, represented important research directions addressed by our group, due to the implications that these biological processes could have in the evolution of neoplastic diseases and the therapeutic approaches in cancer. The evaluation of the apoptosis process and cell cycle phases, added by the characterization of related molecules, key regulators, in human cancer cells, was addressed by other previous in vitro studies performed by our group, which were carried out mainly in colon [7; 11], renal [51], mammary [52], ovarian [53], or head and neck cells [54; 55]. Moreover, due to the fact that often, the effect of cancer therapy could be amplified by combined treatments, in vitro approaches were made in testing the biological activity of several biocomputonds as additional treatments to classical chemotherapy [7; 11; 52; 55].