| Resazurin | |
|---|---|
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7-hydroxy-10-oxidophenoxazin-10-ium-3-one |
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| Identifiers | |
| CAS number | 550-82-3 , [62758-13-8] (sodium salt) |
| PubChem | 11077 |
| ChEMBL | CHEMBL1616414 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C12H7NO4 |
| Molar mass | 229.19 g mol−1 |
| Solubility in water | soluble |
| Hazards | |
| R-phrases | R22 R36/37/38 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Resazurin (7-Hydroxy-3H-phenoxazin-3-one 10-oxide) is a blue dye, itself nonfluorescent until it is reduced to the pink colored and highly red fluorescent resorufin. It is used mainly as an oxidation-reduction indicator in cell viability assays for bacteria and mammalian cells. Usually it is available commercially as the sodium salt.
Resazurin solution has one of the highest values known of Kreft's dichromaticity index.[1] This means that it has a large change in perceived color hue when the thickness or concentration of observed sample increases or decreases.
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Resazurin was first used to quantify bacterial content in milk by Pesch and Simmert in 1929.[2] It is also used as an indicator for cell viability in mammalian cell cultures.[3] It was introduced commercially initially under Alamar Blue trademark (Trek Diagnostic Systems, Inc), and now also available under other names such as AB assay, Vybrant (Molecular Probes) and UptiBlue (Interchim).
Resazurin based assays show excellent correlation to reference viability assays such as formazan-based assays (MTT/XTT) and tritiated thymidine based techniques, while being much easier and safer to use for the user.[4] It also allows for longer studies (minimally toxic to living cells), works for adherents cells and bacteria/fungi.[4] Besides standard applications as cell culture assays (cell counting, cell proliferation assays) and cytotoxicity testing, it also can be multiplexed with several chemiluminescent assays, such as cytokine assays, caspase assays to measure apoptosis, or reporter assays to measure a gene or a protein expression.[4]
Resazurin is effectively reduced in mitochondria, making it useful also to assess mitochondrial metabolic activity.
Usually, in the presence of diaphorase as the enzyme, NADPH or NADH is the reductant that converts resazurin to resorufin. Hence the resazurin/diaphorase/NADPH system can be used to detect NADH, NADPH, or diaphorase level, and any biochemical or enzyme activity that is involved in a biochemical reaction generating NADH or NADPH.[5]
Resazurin can be used to assay L-Glutamate, achieving a sensitivity of 2.0 pmol per well.[6]
10-acetyl-3,7-dihydroxyphenoxazine (also known as Amplex Red), structurally related to resazurin, reacts with H2O2 in a 1:1 stoichiometry to produce the same by-product resorufin (used in many assays combining for example horseradish peroxidase (HRP), or NADH, NADPH using enzymes).
7-ethoxyresorufin, is a compound used as the substrate in the measurement of cytochrome P450 (CYP1A1) induction using the ethoxyresorufin-O-deethylase (EROD) assay system in cell culture and environmental samples, produced in response to exposure to aryl hydrocarbons. The compound is catalysed by the enzyme to produce the same fluorescent product, resorufin.