Merck, 199303-5G, Resazurin sodium salt

General description
Resazurin is a small N-oxide derivative of dihydroxyphenoxazone. It is a non-ionic dye containing a small and planar chromophore. It is a redox indicator and changes from bluish violet through pink to colorless upon reduction. It is also used as a pH indicator for Ph 3.5 to 6.5 wherein it changed from orange to bluish violet. It is commercially available as resazurin sodium salt, which is also known as 3H-Phenoxazin-3-one, 7-hydroxy-, 10-oxide, sodium salt. It forms the red, fluorescent hydroxyphenoxazone resorufin on reduction and colorless hydroresorufin on further reduction.
Application
For the measurement of metabolic activity and proliferation of living cells. The bioreduction of the dye reduces the amount of the oxidized form (blue) and concomitantly increases the fluorescent intermediate (red).
Resazurin is mostly used as a biological redox indicator. The bioreduction of the dye reduces the amount of the oxidized form (blue) and concomitantly increases the fluorescent intermediate (red). Its applications include:
the measurement of metabolic activity and the proliferation of living cells
the detection of bacterial reduction in milk
in viability assays as a component of culture media for the detection of viable bacteria
to determine the number of motile sperm in sheep semen
to assay lactate dehydrogenase
as an analytical reagent to quantify L-glutamate