AAT Bioquest

Selecting the right ROS probe

Reactive oxygen species (ROS) are chemically reactive, oxygen-containing chemical species that are generated as byproducts of cellular metabolism. In animal cells, generation of ROS typically occurs in the mitochondria. In plant cells, ROS can also be generated in chloroplasts. More recently, ROS has been shown to be generated in peroxisomes and from plasma membrane oxidases of various cell types.

Reduction of oxygen and its byproducts.

Reduction of oxygen and its byproducts.

When generated in excess, ROS has long been thought to result in damage of cellular macromolecules such as DNA, lipids and proteins. Holistically, this is represented by a cell's oxidative stress state. Such states of stress have been linked to cellular processes such as apoptosis, and more macroscopically, play a role in the pathogenesis of many human diseases.

Because of its damaging effects, cells have several carefully regulated systems for managing excess ROS. The most well studied system is the glutathione-ascorbate cycle, which detoxifies H2O2 into H2O, using NADH and NADPH as electron donors. Other systems include enzymes such as superoxide dismutase, which catalyzes the dismutation of the superoxide anion (O2-) into O2 or H2O2, and catalase, which catalyzes the decomposition of H2O2 into H2O and O2.

While ROS has been extensively studied for their detrimental effect on cells, it is only more recently that studies have looked at the role of ROS in cell signaling. In controlled amounts, ROS has been shown to regulate gene activation. The specific mechanism by which this occurs is, however, still up for debate. It is possible that ROS binds to special receptors which initiate a signaling cascade leading up to gene regulation. It is also possible that ROS directly modifies the proteins in such a signaling cascade, perhaps by regulation of protein phosphorylation.

Due to its importance in biological systems, a plethora of tools have been developed to study ROS both in vitro and in vivo. The table below provides a summary of the most common tools as well as their targets.




Catalog Number


Hydrogen peroxide (H2O2)

a product of many enzymatic ROS scavenging pathways. The most well studied is superoxide dismutase activity, which catalyzes the reduction of superoxide anion to hydrogen peroxide.

live cell



Probe enters cell wherein esterases cleave off diacetate group. Then DCFH is oxidized by hydrogen peroxide to DCF and emits green fluorescence upon excitation.[4]

Dihydrorhodamine 123

15206, 15207

Probe passively permeates cell membrane. Oxidation by hydrogen peroxide yields rhodamine 123, which fluoresces blue upon excitation.

OxiVision™ Blue

11504, 11505

Probe permeates cell and is oxidized by intracellular hydrogen peroxide. Generates fluorescence upon excitation.

OxiVision™ Green

11503, 11506

cell extract; solutions

Amplite® Fluorimetric Hydrogen Peroxide Assay Kit (Red)


Hydrogen peroxide dependent oxidation of ADHP (synonyms: 10-acetyl-3,7-dihydroxyphenoxazine, Amplex® Red) by horseradish peroxidase (HRP) converts ADHP to resorufin. Resorufin can be detected using colorimetric or fluorimetric methods.

Amplite® Colorimetric Hydrogen Peroxide Assay Kit


Amplex™ Red Hydrogen Peroxide/Peroxidase Assay Kit

Not available

Amplite® Fluorimetric Hydrogen Peroxide Assay Kit (Infrared)


Hydrogen peroxide dependent oxidation of Amplite IR by horseradish peroxidase (HRP) generates activated probe. Excitation emits a near-infrared fluorescent signal

Superoxide anion (O2-)

a by-product of aerobic metabolism, such as mitochondrial respiration (particularly Complex I and Complex III).

live cell; cell extract; solutions



Lucigenin is activated by conversion to lucigenin cation radical. Lucigenin cation radical reacts with superoxide anion to produce dioxetane intermediate, which decomposes to N-methylacridone. High energy electrons in N-methylacridone fall to lower energy state, resulting in luminescence.[5]



Oxidation by superoxide anion results in an excited electron state. Upon decay to ground state electron configuration, photons are released as luminescence.[8]



Superoxide-dependent enzyme catalyzed oxidation of luminol results in luminescence.[6]



Probe passively permeates intact cells and localizes in the mitochondria. Probe is activated through oxidation by superoxide. The activated probe intercalates with DNA and, upon excitation, fluoresces. DNA binding is necessary for strong fluorescence signal. For hydroethidine, activated probe is ethidium (ie. same active species as DNA stain ethidium bromide).[3,7,12]

MitoSox™ Red

Not available

MitoROS™ 580

16052, 22970, 22971

MitoROS™ 520


Probe readily passes through intact cell membranes whereupon it localizes in mitochondria. It is then oxidized by superoxide. Upon excitation, it releases a green fluorescence.

Hydroxyl radical (•OH)

can be generated when superoxide anions react with transition metals. Extremely reactive. Can react with hydrogen on DNA backbone, resulting in strand breakage.

live cell; cell extract; solutions

MitoROS™ OH580


Probe is able to freely enter live cells wherein it becomes oxidized specifically by free hydroxyl radicals. Upon excitation, oxidized probe fluoresces red.

Total ROS

includes hydrogen peroxide, superoxide anion, hydroxyl radical, singlet oxygen, nitric oxide, butyl peroxide and hypochlorous acid

live cell; cell extract; solutions

ROS™ Brite 570

16000, 22902

Probe passively permeates intact cell membranes. Once inside the cell, probe is oxidized by intracellular ROS. Probe can also be oxidized by ROS in solution for cell extract assays. Upon excitation, probe emits a fluorescent signal.

ROS™ Brite 670

16002, 22901

ROS™ Brite 700

16004, 22903

Amplite® ROS Green




Catalog Number


SOD dismutase (SOD)
catalyzes conversion (ie. dismutation) of superoxide into oxygen and hydrogen peroxide

Amplite® Colorimetric Superoxide Dismutase (SOD) Assay Kit


First uses xanthine oxidase (XO) to convert xanthine into hydrogen peroxide and uric acid while simultaneously catalyzing the reduction of molecular oxygen (O2) into superoxide anion (O2-). Then uses competitive inhibition of superoxide dismutation by ReadiView™ SOD560 to quantify superoxide dismutase activity. Decrease in absorbance of ReadiView™ SOD560 is directly proportional to SOD activity.

nearly ubiquitous antioxidant enzyme that converts hydrogen peroxide to water and molecular oxygen

Amplite® Fluorimetric Catalase Assay Kit (Red)


Competitive inhibition assay. Amplite® Red probe is activated through oxidation by hydrogen peroxide. Thus, probe competes with catalase for hydrogen peroxidase substrate. Amplite Red absorbance is inversely proportional to catalase activity.

Glutathione (GSH)
very important redox compound. It is a major component of the glutathione-ascorbate cycle which converts hydrogen peroxide into water

Thiolite™ Green

10055, 22810

Probe becomes activated after reaction with glutathione. Upon excitation, probe releases a green fluorescence.

Amplite® Fluorimetric Glutathione GSH/GSSG Ratio Assay Kit

10056, 10060

Uses Thiolite™ Green probe, which becomes activated after reaction with glutathione (GSH), to quantify glutathione. Oxidized glutathione (GSSG) is determined by measuring GSH concentration before and after enzyme-catalyzed reduction of GSSG to GSH. GSSG concentration is calculated by subtracting initial GSH (before enzyme reaction) from total GSH (after enzyme reaction).

Glutathione peroxidase (GPx)
catalyzes the oxidation of GSH to GSSG and the conversion of hydrogen peroxide to water

Amplite® Fluorimetric Glutathione Peroxidase Assay Kit (Blue)


Enzymatic cycling assay. Glutathione peroxidase (GPx) catalyzes the oxidation of glutathione from GSH to GSSG. Glutathione reductase (GR) then catalyzes the reduction of GSSG back into GSH with the coenzyme NADPH, which is oxidized to NADP+. The Quest Fluor™ NADP Probe then quantifies the level of NADP+ which is directly proportional to the original GPx activity.

also called ascorbic acid or vitamin C, it is a major component of the glutathione-ascorbate cycle which converts hydrogen peroxide to water

Amplite® Fluorimetric Ascorbic Acid Assay Kit (Blue)


Relies on the dehydrogenation of ascorbic acid to dehydroascorbic acid (DHA) by an enzyme-catalyzed reaction. Resulting DHA is quantified by Ascorbrite Blue probe.

major component in ATP synthesis that occurs in mitochondria. This coenzyme is thought to be involved in superoxide production, the rate of which is dependent on the NAD+/NADH ratio.

Amplite® NAD/NADH Kits (assorted)

15273, 15258, 15275, 15280, 15263, 15257, 15261, 15262, 15291, 15290, 15259, 15271

Typically, uses a NAD+ specific probe to quantify NAD+ concentration. NAD+/NADH ratio is determined by enzymatic cycling assay.

acts as an electron donor in the glutathione-ascorbate cycle that converts hydrogen peroxide to water

Amplite® NADPH Kits (assorted)

15274, 15272, 15260, 15276, 15264, 15262, 15259, 15291, 15290

Typically, uses a NADPH specific probe to quantify NADPH concentration. NADP/NADPH ratio is determined by enzymatic cycling assay.



  1. Apel, Klaus, and Heribert Hirt. "Reactive oxygen species: metabolism, oxidative stress, and signal transduction." Rev. Plant Biol.55 (2004): 373-399.
  2. Bindokas, Vytautas P., et al. "Superoxide production in rat hippocampal neurons: selective imaging with hydroethidine."Journal of Neuroscience4 (1996): 1324-1336.
  3. Kalyanaraman, Balaraman, et al. "Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations."Free Radical Biology and Medicine1 (2012): 1-6.
  4. LeBel, Carl P., Harry Ischiropoulos, and Stephen C. Bondy. "Evaluation of the probe 2', 7'-dichlorofluorescin as an indicator of reactive oxygen species formation and oxidative stress."Chemical research in toxicology2 (1992): 227-231.
  5. Li, Yunbo, et al. "Validation of lucigenin (bis-N-methylacridinium) as a chemilumigenic probe for detecting superoxide anion radical production by enzymatic and cellular systems."Journal of Biological Chemistry4 (1998): 2015-2023.
  6. Misra, Hara P., and Pamela M. Squatrito. "The role of superoxide anion in peroxidase-catalyzed chemiluminescence of luminol."Archives of biochemistry and biophysics1 (1982): 59-65.
  7. Mukhopadhyay, Partha, et al. "Simple quantitative detection of mitochondrial superoxide production in live cells."Biochemical and biophysical research communications1 (2007): 203-208.
  8. Münzel, Thomas, et al. "Detection of superoxide in vascular tissue."Arteriosclerosis, thrombosis, and vascular biology11 (2002): 1761-1768.
  9. Murphy, Michael P. "How mitochondria produce reactive oxygen species."Biochemical Journal1 (2009): 1-13.
  10. Thannickal, Victor J., and Barry L. Fanburg. "Reactive oxygen species in cell signaling."American Journal of Physiology-Lung Cellular and Molecular Physiology6 (2000): L1005-L1028.
  11. Turrens, Julio F. "Mitochondrial formation of reactive oxygen species."The Journal of physiology2 (2003): 335-344.
  12. Zielonka, Jacek, and B. Kalyanaraman. "Hydroethidine-and MitoSOX-derived red fluorescence is not a reliable indicator of intracellular superoxide formation: another inconvenient truth."Free Radical Biology and Medicine48.8 (2010): 983-1001.