Antitumor activity of C1, C2, and C5 against (A) HL60 and (B) M14 cell lines. A total of 1 × 106 cells/mL were exposed to increasing concentrations (25 to 100 μg/mL) of each compound for 18 hours and cell death was determined by the MTT assay (HL60) or crystal violet assay (M14) as described in Materials and Methods. Data shown are the mean ± SD of three independent experiments performed in triplicate. (C) To assess apoptotic phenotype, HL60 cells (1 × 106) were exposed to 100 μg/mL of C1, C2, or C5 for 12 hours and externalization of inner membrane PS was detected by annexin V-FITC (1 μg/mL) staining and analysis by flow cytometry. At least 10,000 events were analyzed by WINMDI software. Arrows indicate log increase in fluorescence over untreated control cells.
