, 2010), it was selected to evaluate the mechanism underlying to their cytotoxic effects after 24 h exposure. The compounds dissolved in DMSO (0.1%) were added to cell cultures of HL-60 cells (3 × 105 cells/mL) to obtain final concentrations of 1 and 2 μM. Doxorubicin (0.6 μM) was used as a positive control (Dox). All flow cytometry analyses were performed in a Guava® EasyCyte Mine using Guava Express Plus CytoSoft 4.1 software (Guava Technologies Inc., Industrial Blvd., Hayward, CA, USA). Five thousand events were evaluated per experiment and cell debris was omitted from the analysis. Cell viability was determined by the trypan blue

Seliciclib dye exclusion test (Kepp et al., 2011). The cell samples were diluted in trypan blue dye

of an acid Vincristine in vivo azo exclusion medium by preparing a 1:1 dilution of the cell suspension using a 0.4% trypan blue solution. Non-viable cells were labeled in blue and are visible with brightfield optics and viable cells were unstained, since viable cells maintain the capacity to extrude this vital dye. The count was performed under the microscope in four 1 × 1 mm squares of a Neubauer chamber. Number of cells (×104 cells/mL) was stated and viable and non-viable cells were expressed as a percentage of total cells. Cells were plated in 24-well tissue culture plates (2 mL/well) and treated with the compounds. After 21 h exposure, 20 μL of 5-bromo-2′-deoxyuridine (BrdU, 10 mM) was added and incubated for 3 h at 37 °C. To determine the amount of BrdU incorporated into DNA (Pera et al., 1977), cells were harvested, transferred to cytospin slides, and allowed to dry for 2 h at room temperature (25 °C). Cells were labeled using direct peroxidase immunocytochemistry by the chromogen

diaminobenzidine (DAB) staining those cells that incorporated Brd. Slides were counterstained with hematoxylin and coverslipped. The determination of BrdU positivity was performed by light microscopy (Olympus, Tokyo, Japan). Two hundred cells were counted per sample to determine below the percentage of BrdU-positive cells (Costa et al., 2008). To determine whether the growth inhibition activity of compounds 2–4 was related to the induction of apoptosis or necrosis, morphological analysis of treated cells was investigated by fluorescent microscopy using acridine orange/ethidium bromide (AO/EB) staining. After 24 h incubation, cells were pelleted and each sample was mixed with 1 L of aqueous AO/EB solution (100 g/mL of AO in PBS; 100 g/mL EB in PBS) just prior to fluorescence microscopy and quantification (Olympus, Tokyo, Japan). Three hundred cells were counted per sample and scored as follows: viable cells, apoptotic cells and necrotic cells (Cury-Boaventura et al., 2004 and Tamatani et al., 2012). The percentage of apoptotic and necrotic cells was then calculated. Cell cycle distribution and DNA fragmentation analysis were evaluated by the incorporation of propidium iodide (50 μg/mL).