A combined assay of cell viability and in vitro cytotoxicity with a highly water-soluble tetrazolium salt, neutral red and crystal violet

Biol Pharm Bull. 1996 Nov;19(11):1518-20. doi: 10.1248/bpb.19.1518.


Cell viability and in vitro cytotoxicity assay methods were developed using a combination of dyes, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1), neutral red (NR) and crystal violet (CV), with HeLa cells as a bioindicatior. As WST-1 produces a highly water soluble and non-cytotoxic formazan dye, ti allows each assay to be carried out in one culture dish. The combined cell viability assay using WST-1, NR and CV gave an absorbance that correlated linearly with the number of cells over the range 1000 to 50,000 cells/well. The combined assay was applied to the evaluation of IC50 values for sodium dodecyl sulfate as a model toxicant, which yielded similar values to those obtained with each assay independently.

MeSH terms

  • Cell Survival / drug effects*
  • Gentian Violet / pharmacology*
  • HeLa Cells
  • Humans
  • Neutral Red / pharmacology*
  • Tetrazolium Salts / pharmacology*


  • Tetrazolium Salts
  • iodonitrotetrazolium
  • Neutral Red
  • Gentian Violet