In this study we compared the potential of five commonly employed cytotoxicity assays (WST-1, XTT, MTT, Brilliant blue and Neutral red assay) to detect anti-proliferative effects of three selenium compounds, sodium selenite, seleno-L-methionine (SeMet) and Se-(Methyl)selenocysteine (SeMCys) on three colorectal cancer cell lines in vitro. Cells were exposed to the selected selenium compounds in the concentration range of 0-256 uM during 48 hours.
WST-1 and XTT failed to detect cytotoxic effect. Conversely, the metabolic activity of selenium treated cells measured by WST-1 and XTT significantly increased in comparison to untreated controls.
MTT, Neutral red and Brilliant blue assays were more sensitive and yielded mutually comparable results, with significant decrease of measured parameters in a concentration-dependent manner. To a smaller extent, the results were affected by the different chemical nature of the selenium compounds tested as well as by the biological properties of individual cell lines.