Cell cytotoxicity refers to the ability of certain chemicals or mediator cells to destroy living cells. By using a cytotoxic compound, healthy living cells can either be induced to undergo necrosis (accidental cell death) or apoptosis (programmed cell death).
While it can be measured in a number of different ways, assessing cell viability through the use of vital dyes (formazan dyes), protease biomarkers or by measuring ATP content are some of the most commonly used methods in determining cytotoxicity. The formazan dyes are chromogenic products formed by the reduction of tetrazolium salts by dehydrogenases, such as lactate dehydrogenase (LDH) and reductases that are released at cell death. Common tetrazolium salts include INT, MTT, MTS and XTT. Cell cytotoxicity can likewise be monitored by using the SRB and WST-1 assays which are both considered ideal for high throughput screening.