Investigation of the Alamar Blue (resazurin) fluorescent dye for the assessment of mammalian cell cytotoxicity

• DOI: 10.1046/j.1432-1327.2000.01606.x
• Publication Date: 2003-03-11T17:52:29Z
• Authors: John O'Brien; Ian Wilson; Terry Orton; François Pognan
• Keywords: Resazurin; Oxazines

We show here the identity of Alamar Blue as resazurin. The 'resazurin reduction test' has been used for about 50 years to monitor bacterial and yeast contamination milk, also assessing semen quality. Resazurin (blue nonfluorescent) is reduced resorufin (pink highly fluorescent) which further hydroresorufin (uncoloured nonfluorescent). It still not known how this occurs, intracellularly via enzyme activity or in medium a chemical reaction, although fluorescent form was found cytoplasm living cells nucleus dead cells. Recently, dye gained popularity very simple versatile way measuring cell proliferation cytotoxicity. This presents numerous advantages over other cytotoxicity tests but we observed several drawbacks routine use Blue. Tests with toxicants different lines rat primary hepatocytes have shown accumulation product could lead an overestimation population. Also, extensive by metabolically active led final nonfluorescent product, hence underestimation cellular activity.