2,6-Dichlorophenolindophenol (DCPIP, DCIP or DPIP) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

used as a redox dye. When

oxidized Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

, DCPIP is blue with a maximal absorption at 600 nm; when

reduced Reduction, reduced, or reduce may refer to: Science and technology Chemistry * Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed. ** Organic redox reaction, a redox reacti ...

, DCPIP is colorless. DCPIP can be used to measure the rate of

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. It is part of the Hill reagents family. When exposed to light in a photosynthetic system, the dye is decolorised by chemical reduction. DCPIP has a higher

affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Pa ...

for electrons than

ferredoxin Ferredoxins (from Latin ''ferrum'': iron + redox, often abbreviated "fd") are iron–sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co. and applied t ...

and the photosynthetic electron transport chain can reduce DCPIP as a substitute for NADP⁺, that is normally the final electron carrier in photosynthesis. As DCPIP is reduced and becomes colorless, the resultant increase in light transmittance can be measured using a spectrophotometer. DCPIP can also be used as an indicator for

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...

. If vitamin C, which is a good reducing agent, is present, the blue dye, which turns pink in acid conditions, is reduced to a colorless compound by ascorbic acid. This reaction is a redox reaction: vitamin C (ascorbic acid) is oxidized to

dehydroascorbic acid Dehydroascorbic acid (DHA) is the major oxidized form of ascorbic acid (vitamin C). It is actively imported into the endoplasmic reticulum of cells via glucose transporters. It is trapped therein by reduction back to ascorbic acid by glutathi ...

, and DCPIP is reduced to the colorless compound DCPIPH₂ :DCPIP (blue) + H⁺ → DCPIPH (pink) :DCPIPH (pink) + vitamin C → DCPIPH₂ (colorless) In this

titration Titration (also known as titrimetry and volumetric analysis) is a common laboratory method of Quantitative research, quantitative Analytical chemistry, chemical analysis to determine the concentration of an identified analyte (a substance to be ...

, when all the ascorbic acid in the solution has been used up, there will not be any electrons available to reduce the DCPIPH and the solution remains pink due to the DCPIPH. The end point is a pink color that persists for 10 seconds or more, if there is not enough ascorbic acid to reduce all of the DCPIPH. Pharmacological experiments suggest that DCPIP may serve as a

pro-oxidant Pro-oxidants are chemicals that induce oxidative stress, either by generating reactive oxygen species or by inhibiting antioxidant systems. The oxidative stress produced by these chemicals can damage cells and tissues, for example, an overdose of ...

chemotherapeutic targeting human cancer cells in an animal model of human

melanoma Melanoma is the most dangerous type of skin cancer; it develops from the melanin-producing cells known as melanocytes. It typically occurs in the skin, but may rarely occur in the mouth, intestines, or eye (uveal melanoma). In very rare case ...

; DCPIP-induced cancer cell death occurs by depletion of intracellular

glutathione Glutathione (GSH, ) is an organic compound with the chemical formula . It is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources ...

and upregulation of

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...

References

{{reflist Indophenol dyes Redox indicators Chloroarenes 4-Hydroxyphenyl compounds

See also

References