Abstract Background: Cancer is a serious health concern worldwide making the continuous discovery of new cytotoxic agents a challenging issue. In this study, the cytotoxicity of a naturally occurring alkenylmethylresorcinol, ardisinol III was evaluated in a panel of six human carcinoma cell lines and the normal fibroblasts. Methods: The cytotoxicity of samples was evaluated by the neutral red uptake (NR) assay; the activity of caspases in breast adenocarcinoma MCF7 cells was detected by c...