Changes in cell viability, apoptosis and content of H2O2, and GSH in U937 tumor cell line treated for 24 h with Qu 100 M. U937 cells treated with 100 M Qu were separately stained with four fluorescent dyes: propidium iodide (PI), 2′,7′-dichlorodihydrofluorescein diacetate (H2-DCFDA), hydroethidine (HE) and monobromobimane (MBB) for the quantification of nuclear DNA, intracellular H2O2, intracellular and intracellular GSH content, respectively. Cells were then analyzed by flow cytometry. In (a) and (b) the physical parameters (identified by forward and side scatter for cell dimension and granularity, resp.) of the cells under investigation are represented. Treating cells with 100 M Qu causes an increase in the number of cells with reduced forward scatter and increased side scatter, typical of apoptosis (indicated in b by an arrow). (c) and (d) Changes in DNA content (PI fluorescence) and side scatter in control and Qu-treated cells. In the ellipse, cells with hypodyploid DNA content and increased side scatter (i.e., those apoptotic) are present, and increase after treatment with Qu. (e) and (f) Show intracellular H2O2 content in both control and treated cells. Qu causes a shift to the left of the fluorescence peak (see, in (e), the histogram shift in relation to the fix position of the red bars) indicating a small reduction in H2O2 content, likely because of the concomitant increase in . Qu also causes a small change in the percentage of cells that do not bind the dye, that is, those undergoing apoptosis (arrow), which are those evidenced in (d). (g) and (h) Represent intracellular content in the absence or in the presence of 100 M Qu. Treating cells with Qu significantly increases the amount of cells with high HE fluorescence (arrow), which represents an increase of intracellular content. (i) and (j) Show GSH content in the absence or after treatment with Qu 100 M. In the presence of Qu, MBB fluorescence decreases in a consistent number of cells (arrow), indicating that Qu is able to deplete intracellular GSH.
