Figure 9. Effect of the pan-caspase inhibitor (Z-VAD(OMe)-FMK) in the apoptosis induced by piplartine-containing ruthenium complexes on HCT116 cells determined by flow cytometry using annexin V-FITC/PI staining.

(A) Quantification of apoptotic cells (early + late apoptotic cells) determined by flow cytometry using annexin V-FITC/PI staining. (B) Quantification of the cell viability determined by trypan blue staining. The cells were pre-treated for 2 h with 50 μM Z-VAD(OMe)-FMK, then incubated with the complexes in the established concentration (2.5 μM for complex 1 and 5 μM for complex 2) for 48 h. The negative control (CTL) was treated with the vehicle (0.1% of a solution containing 70% sorbitol, 25% tween 80 and 5% water) used for diluting the compounds tested. Oxaliplatin (OXA, 3 μM) and piplartine (PL, 10 μM) were used as the positive controls. Data are presented as the mean ± S.E.M. of three independent experiments performed in duplicate. For flow cytometry analysis, 10,000 events were evaluated per experiment and cellular debris was omitted from the analysis. ^* p < 0.05 compared with the negative control by ANOVA followed by Student Newman-Keuls test. ^# p < 0.05 compared with the respective treatment without inhibitor by ANOVA followed by Student Newman-Keuls test.