Tetrazolium red is used in a biochemical viability test for seeds. The test relies on dehydrogenase enzymes to release hydrogen ions, which subsequently reduce the colorless tetrazolium salt solution to a red compound called formazan. Living cells turn red while dead cells remain colorless.

Tetrazolium salt compounds are commonly used to detect viability. There are two basic categories of tetrazolium salts: (1) Cationic salts that can permeate viable eukaryotic cells through electrostatic interactions with the anionic plasma membrane.

Triphenyl tetrazolium chloride in vitro reduction by cells produces a red formazan pellet which can be extracted and measured. We have shown that such reduction is associated with animal cell growth, and particularly with the specific growth rate, so the measurement of Triphenyl tetrazolium chloride reduction is proposed as a physiological marker of the exponential growth of cultured cells.

TETRAZOLIUM SALT AR TTC 235 triphenyl tetrazolium chloride