MTT assay to evaluate the cytotoxic potential of a drug

Quantification of cell viability and proliferation form the fundamental for numerous in vitro assays in response to external factors. An MTT assay is a colorimetric assay based on assessing the cell metabolic activity. A549 Lung adenocarcinoma cell line was used to see the cytotoxic potential of a new drug for initial screening of apoptosis or necrosis. The biochemical mechanism behind the MTT assay involves NAD(P)H-dependent cellular oxidoreductase enzyme that converts the yellow tetrazolium MTT [3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide] into insoluble (E,Z)-5-(4,5-dimethylthiazol-2-yl)-1,3-diphenylformazan (formazan). The formed formazan can be dissolved with dimethyl sulfoxide (DMSO) to give a purple color with characteristic absorption at 540 nm. Intensity of purple color is directly proportional to the cell number and thus indicating the cell viability.