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 (&lambda; _Ex/&lambda; _Em: 355/420nm) in cells, while the oxidized form ethidium has red fluorescence (&lambda; _Ex/&lambda; _Em: 518/605 nm) upon DNA intercalation.<ul><li>Off-white to light brown solid soluble in DMF or DMSO</li><li>Store at -20&deg;C under nitrogen or argon, and protect from light, especially when in solution</li><li>C₂₁H₂₁N₃</li><li>MW: 315</li><li>[38483-26-0]</li></ul>