tailieunhanh - The MTT viability assay yields strikingly false-positive viabilities although the cells are killed by some plant extracts

The MTT assay is one of the often used cell viability cytotoxicity assays. However, when the methanol extracts of plants are used to test their cytotoxic potential, interference may occur, resulting in false-positive viability results. | Turkish Journal of Biology Turk J Biol (2017) 41: 919-925 © TÜBİTAK doi: Research Article The MTT viability assay yields strikingly false-positive viabilities although the cells are killed by some plant extracts 1, 2, 1, Didem KARAKAŞ *, Ferda ARI *, Engin ULUKAYA ** Department of Medical Biochemistry, Faculty of Medicine, İstinye University, İstanbul, Turkey 2 Department of Biology, Faculty of Arts and Sciences, Uludağ University, Bursa, Turkey 1 Received: Accepted/Published Online: Final Version: Abstract: The MTT assay is one of the often used cell viability/cytotoxicity assays. However, when the methanol extracts of plants are used to test their cytotoxic potential, interference may occur, resulting in false-positive viability results. Therefore, in this study, the reliability of the MTT assay was investigated in the case of plant use. The methanol extracts of three different plants (Hypericum adenotrichum, Salvia kronenburgii, and Pelargonium quercetorum) were tested in breast cancer cell lines (MCF-7 and MDA-MB-231) using the MTT assay and the results were compared to the ATP assay, which is a much more sensitive and reliable assay due to its interference-free feature. Additionally, decreased cell density was confirmed with phase-contrast microscopy and fluorescence staining (Hoechst 33342 dye). Although both of the viability/cytotoxicity assays are considered as metabolic assays, viabilities (in %) in the MTT assay were found to be strikingly higher when compared to the results with the ATP assay. Even in the case of total death, the MTT assay still produced artificial/false increases in viability. The morphology-based evaluation of viability/cytotoxicity by phase-contrast microscopy and Hoechst 33342 staining were greatly compatible with the ATP assay results. Overestimated (false) viabilities in the MTT assay suggests a serious interference between the