Dihydrorhodamine 123 is the reduced form of rhodamine 123, which is a commonly used fluorescent mitochondrial dye. It is non-fluorescent, but it readily enters most of the cells and is oxidized by oxidative species or by cellular redox systems to the fluorescent rhodamine 123 that accumulates in mitochondrial membranes. It is useful for detecting reactive oxygen species including superoxide (in the presence of peroxidase or cytochrome c) and peroxynitrite. Dihydrorhodamine 123 dihydrochloride is functionally equivalent to dihydrorhodamine 123 but with increased stability toward air oxidation and light during storage. Dihydroethidium (also called hydroethidium) is the chemically reduced form of the commonly used DNA dye ethidium bromide. The probe is useful to detect oxidative activities in viable cells, including respiratory burst in phagocytes. Dihydroethidium itself has blue fluorescence (355/420 nm) in cells, while the oxidized form ethidium has red fluorescence (518/605 nm) upon DNA intercalation. H2DCFDA (2′,7′-Dichlorodihydrofluorescein diacetate) is a useful fluorogenic reagent to detect reactive oxygen intermediates in cells. On oxidation, H2DCFDA becomes the highly green fluorescent 2′,7′-dichlorofluorescein, 504/529 nm (end product).

• Detect reactive oxygen species including superoxide
• Detect oxidative activities in viable cells, including respiratory burst in phagocyte

Commonly used fluorescent dyes for detection of oxidative activities in cells.