Cytotoxicity assay (MTT), flow-cytometric univariate cell cycle analysis, Annexin V-FITC staining and DNA fragmentation for cell death mechanism suggested that compound 3d with chloro-substituted phenyl ring induced enhanced cytotoxicity by an apoptotic pathway with high differential toxicity to breast adenocarcinoma cells (MCF-7) when compared with normal human dermal fibroblast cells.