Resazurin / Alamar Blue®

Resazurin (7-Hydroxy-3H-phenoxazin-3-one 10-oxide) is a dye and oxidation-reduction indicator. First introduced under the Alamar Blue trademark, the dye has been incorporated in commercial assay kits under different names, such as Vision Blue. Visualization of resazurin relies on the activity of cellular dehydrogenases in the presence of NADH/NADPH. In metabolically active cells undergoing aerobic respiration, resazurin is irreversibly reduced to resorufin, which turns from blue to pink and emits strong red fluorescence in the 590 nm range. Resazurin is used in staining eukaryotic and microbial cells in flow cytometery, fluorescence microscopy and high-throughput screening applications to study cell metabolism and viability.