Cells treatment with the cytotoxic compound may undergo necrosis, in which they lose membrane integrity. Hence cytotoxicity can be detected by the quantification of plasma membrane damage. Lactate dehydrogenase (LDH) is a stable enzyme exists in nearly all living cells. When damage of the plasma membrane, LDH is rapidly released into the cell culture supernatant.

 The LDH-Cytotoxicity Colorimetric Assay Kit provides a simple and fast way for the quantification of cytotoxicity based on the measurement of activity of LDH released from damaged cells, which can be detected by a coupled enzymatic reaction: LDH oxidizes lactate to pyruvate which reacts with tetrazolium salt INT to form formazan. The formazan dye is water-soluble and can be detected by spectrophotometer at 500 nm. The assay is convenient, precise and sensitive, and is suitable for a variety of cytotoxicity studies and only takes 0.5-1 h.