###### Abstract
Therefore, various Ru complexes have been obtained and intensively studied due to their proper physicochemical and biochemical properties, such as selective bioactivity as well as the ability to overcome the resistance encountered with platinum-based drugs, which is associated with low toxicity profiles [21; 22]. Ruthenium (III) complexes have shown remarkable antitumor activity with various advantages over traditional platinum drugs, including potent efficacy, low toxicity, and less drug resistance. Research in this area has shown over the last decade that subtle changes in the structure often have a significant effect on the pharmacological properties of metal complexes [20; 23]. In the last years, many research studies were focused on obtaining complexes with remarkable activity using quinolones molecules as ligands [24]. Quinolones represent a class of synthetic antibacterial agents that is widely prescribed for the treatment of infections in humans or for veterinary use. The bactericidal activity of these agents arises from their capacity to inhibit two bacterial key enzymes: DNA gyrase (a type II topoisomerase) and DNA topoisomerase IV [25; 26]. While quinolone-based drugs were developed to inhibit the prokaryotic DNA gyrase [27], the antineoplastic drugs have eukaryotic type II topoisomerase as their primary target [28]. Moving the activity of quinolone from antibacterial to anticancer activity [29] represents a current challenge considering the increasing resistance to chemotherapy and the severe side effects of anti-neoplastic agents. To accomplish this goal, different synthetic strategies were approached. The first of these directions involves chemical modifications on the quinolone nucleus, either by disruption of the zwitterionic properties of the compounds (which can be achieved by modifying the C7 basic substituent, or the C3 carboxyl group, or both) or by increasing the number of aromatic/condensed rings [30]. The most successful example is represented by vasaroxin (formely voreloxin), which is a first-in-class anticancer quinolone derivative that inhibits topoisomerase II and induces selective double-strand breaks, G2 arrest, and apoptosis [31; 32]. Vosaroxin passed Phase 2 clinical trials in acute myeloid leukemia (AML) and platinum-resistant ovarian cancer, while in a Phase III trial, the addition of vasaroxin to cytarabine offered clinical benefit to some patients with relapsed or refractory AML [33]. Vosaroxin displays some valuable pharmacokinetic properties such as the minimal metabolization and a lack of free radical production; in addition, it is not a substrate for the glycoprotein efflux pump, and its antineoplastic activity is independent of P53 function [34]. A second direction aiming to extend the scale of biological activities for a molecular entity with coordinating properties is to obtain metal complexes with selected metal ions. In this regard, a starting point could be the complexes of quinolone antibiotics with Ru(III) ion based on the success of the already recognized NAMI-A [35] and KP1019 [36]. So far, only few Ru(III) complexes with quinolone antibiotics were reported. In these complexes, the quinolone molecules bind to the metal ions in two ways: as monoanionic bidentate generating metal chelates or as neutral unidentate ligand through the nitrogen atom of piperazin-1-yl moiety. The chelate complex of Ru(III) with nonfloxacin of general formula [Ru(nor)\({}_{3}\)] (nor = nonfloxacin, C\({}_{16}\)H\({}_{17}\)FN\({}_{3}\)O\({}_{3}\)\({}^{-}\)) remarkably enhances the water solubility of nonfloxacin and interacts with human serum albumin [37], while the chelate of ciprofloxacin [Ru(C\({}_{17}\)H\({}_{17}\)FN\({}_{3}\)O\({}_{3}\))\({}_{3}\)]\(\cdot\)4H\({}_{2}\)O is fully water soluble and stable under physiological pH for at least 48 h, and it interacts with ct-DNA [38].