## 3 Results and Discussion
### Cell Cycle Progression Changes in LoVoC Cells Treated with Ru(III) Complexes  
The cell cycle is the ordered sequence of events that occur to enable DNA replication and cell division, and it can be divided in two phases (interphase and mitosis) and four stages. During these stages, the cell increases in size (gap 1/G1 stage), copies its DNA (synthesis, or S stage), prepares to divide (gap 2, or G2 stage), and then divides (mitosis or M stage). The stages G1, S, and G2 belong to the interphase, which accounts for the span between cell divisions. Some cells exit the G1 stage and enter in a resting state called G0. Based on stimulatory and inhibitory messages received by a cell, it \"decides\" whether it should enter into the cell cycle and divide. Regulation of the cell cycle machinery, resulting in an arrest of cells in different phases of the cell cycle, might be altered by anticancer agents, and thereby, the growth and proliferation of cancerous cells could be reduced [16; 19; 71]. To reveal the anti-carcinogenic effects of Ru(III) complexes with quinolones that may have an inhibitory potential, cells were cultured and treated as in the experiment described above, and the end-point assay of LoVoC cell progression through cell cycle phases was studied by flow cytometry. Perturbations in cell cycle progression may account for the anti-carcinogenic effects. Flow cytometry assays are useful techniques that became standard tools to analyze the DNA content of cells and show the cell cycle distribution. Therefore, non-treated control LoVoC cells or cells treated either with Ru(III) complexes or CisPt were further subjected to RNase treatment, PI labeling, followed by data acquisition and analysis by flow cytometry. DNA progression through cell cycle phases is shown in Figure 5 for all drug-treated samples vs. control, which is represented by non-treated cells. The nuclear DNA content and progression through cell cycle phases were evaluated in acquired 3 \(\times\) 10\({}^{4}\) nuclei. Figure 5: Modulation of LoVo cell cycle progression by Ru(III) complexes vs. CisPt. Effects of treatments with Ru(III) complexes on the modulation of cell cycle phases was studied in the LoVo human colon adenocarcinoma cell line and compared to CisPt-treated or non-treated cells. DNA progression through cell cycle phases was evaluated by PI labeling, which was followed by flow cytometry acquisition and analysis using a FACS CantoII flow-cytometer (BD Biosciences) and ModFit software. Cell treatments with 10 uM of Ru-cipro and Ru-nf induced similar decreases in the S phase as CisPt (34.1%, and 34.94%), while Ru-oflo, Ru-levo, Ru-enoxa, and Ru-enrox induced a decrease in cell distribution in the S phase between 31.7% and 22.47%. At the same time, percentages of nuclei blocked in the G0/G1 phase were between 49.7% for Ru-enoxa and 54.40% for Ru-enrox (Table 3, Figure 6). When cells were treated with 50 uM of Ru(III) complexes, a higher decrease in the S phase distribution was observed for all treated samples. So, the highest effect was observed for Ru-pip (18.82%), Ru-nf (16.77%), Ru-oflo (13.43%), Ru-enrox (9.97%), and Ru-enoxa (8.81%) treated cells. Treatments with 50 uM of Ru-cipro, Ru-nf, Ru-oflo, and Ru-pip increased also the cell distribution of over 60% in the G0/G1 phase, while Ru-enoxa and Ru-enrox induced also an increase in the G2M phase, to 43.09% and 41.75%, respectively (Table 3, Figure 6). When the proliferation indexes were calculated as the sum of the percentages of cells distributed in the S and G2M cell phases, the highest decreases were found for 50 uM treatments with Ru-cipro (33.98%), Ru-nf (36.31%), Ru-oflo (34.24%), and Ru-pip (38.49%) as compared to the non-treated cells (55.45%) or CisPt (43.34%). In addition, 10 uM treatments induced significant decreases of the proliferation index, which was mainly for Ru-cipro (47.59%), Ru-nf (48.82%), Ru-levo (45.62%), Ru-oflo (47.76%), or Ru-enro (45.61%). Both 10 uM and 50 uM of Ru-levo treatments showed similar proliferation indexes (Table 3, Figure 6).