Figure 1.

Effect of Plumbagin on cell proliferation. (A) Morphological changes observed on HCT116 cells after treatment for 24 h with the indicated doses of Plumbagin. The compound was added either when cells were already attached or at the time of seeding, when cells were still unattached for several hours; cells were observed by phase-contrast microscopy (x10). (B) Dose-dependent cytotoxicity effects of Plumbagin on HCT116 cells treated as indicated; results are expressed as the mean percentage of surviving cells relative to the untreated control cells; experiments were done in triplicate. Cell cycle analyses were performed with attached (C) and unattached (D) cells exposed for 24 h to the indicated doses of Plumbagin; cells were harvested, washed with PBS, fixed with ice cold 70% ethanol, stained with propidium iodide, and analyzed by flow cytometry; numbers in parentheses indicate relative percentages of cells in the indicated phases out of the total populations of cycling cells. In all cases, DMSO treated HCT116 cells served as control.