Dyes and Fluorophores 

Resazurin, which is the N-oxide of the fluorescent dye resorufin, is useful for detecting reductive activities in cells and has been widely used for measuring cell proliferation (1,2) and mitochondrial metabolic activity. Resazurin itself is non-fluorescent until it is reduced to the highly red fluorescent resorufin (λEx/λEm: 563/587 nm). Usually, NADPH or NADH is the reductant that converts resazurin to resorufin in the presence of diaphorase as the enzyme. Thus, resazurin can be used to detect NADH, NADPH, or diaphorase levels. Furthermore, the resazurin/diaphorase/NADPH system can be used to detect any biochemical or enzyme activity that is involved in a biochemical reaction generating NADH or NADPH (3-9).

Although resazurin is available from most of the chemical suppliers, a trace amount of resorufin contaminant often makes the material unsuitable for bioassay applications. We supply a high grade resazurin that has a minimal background fluorescence. Please also see the ready-to-use Resazurin Cell Viability Assay Kit (30025).