Chemotherapy is one of the main strategies for reducing the rate of cancer progression or, in some cases, curing the tumour. Since a great number of chemotherapeutic agents are cytotoxic compounds, i.e.similarly affect normal and neoplastic cells, application of antitumour drugs is preferred in cancer management and therapy. In this study, the cytotoxicity of diversin was evaluated in 5637 cells, a tran- sitional cell carcinoma (TCC) subline (bladder carcinoma), and normal human fibroblast cells using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay. Chromatin con-densation and DNA damage induced by diversin were also determined by means of 40,6-diamidino-2-phenylindole (DAPI) staining and the comet assay, respectively. In addition, the mechanism of action of diversin was studied in more detail by the caspase 3 colourimetric assay and flow cytometry-based cell-cycle analyses (PI staining). Our results revealed that diversin has considerable cytotoxic effects in 5637 cells, but not on HFF3 (human foreskin fibroblast) and HDF1 (human dermal fibroblast) cells. Further studies showed that diversin exerts its cytotoxicity via induction of chromatin condensation, DNA damage, and activation of caspase 3 in 5637 cells. In addition, flow cytometric analyses revealed that 5637 cells are mostly arrested at the G2 phase of the cell cycle in the presence of diversin

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