Neutral Red versus MTT assay of cell viability in the presence of copper compounds

Anal Biochem. 2017 Oct 15:535:43-46. doi: 10.1016/j.ab.2017.07.027. Epub 2017 Aug 2.

Abstract

Copper is essential for numerous physiological functions, and copper compounds may display therapeutic as well as cytotoxic effects. The MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay is a standard test largely used in cytotoxicity studies. This report shows that low micromolar levels of copper compounds such as Cu(II)Urea2, Cu(II)Ser2 and CuCl2 can interfere with the MTT assay making improper the detection of formazan product of MTT reduction. Comparatively, the Neutral Red assay appears to be sensitive and showing no interference with these compounds. The lactate dehydrogenase alternative assay cannot be used because of inhibitory effect of these copper compounds on the enzyme activity.

Keywords: Amino acid copper complexes; Copper salts; MTT assay; Neuron viability; Neutral Red assay; Urea copper complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Assay*
  • Cell Survival / drug effects
  • Cells, Cultured
  • Copper / chemistry
  • Copper / pharmacology*
  • Mice
  • Neutral Red / chemistry*
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry
  • Organometallic Compounds / pharmacology*
  • Structure-Activity Relationship
  • Tetrazolium Salts / chemistry*
  • Urea / analogs & derivatives
  • Urea / chemistry
  • Urea / pharmacology

Substances

  • 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide
  • Organometallic Compounds
  • Tetrazolium Salts
  • Neutral Red
  • Copper
  • Urea
  • cupric chloride