In Vitro Cytotoxicity Testing of Food Packaging

Colorimetric assays with tetrazolium salts allow rapid evaluation of cytotoxicity endpoints. These assays are based on the ability of viable cells to convert tetrazolium salts into formazan products through the succinate dehydrogenase system in the mitochondrial respiratory chain. In the presence of NADH/NADPH, these salts are reduced to formazan products characterized by an intense and distinct color that depends on the original tetrazolium salt used as the substrate for the reaction. Only viable cells, which contain intact plasma and mitochondrial membranes, will have active dehydrogenase. Agents that break the membranes and interfere with the respiratory chain will deactivate the enzyme and consequently the formation of formazan products. Thus, the amount of formazan product can be correlated with the number of viable cells after exposure to the tested substance. In this chapter, the most common colorimetric cell viability assays with tetrazolium salts are present to assess the cytotoxicity of food packaging.