Phenol red 1429597 226144278 2008-07-17T00:45:59Z Thijs!bot 1392310 robot Adding: [[tr:Fenol kırmızısı]] {{Chembox new | Name = Phenol red | ImageFile = Phenol-red-zwitterionic-form-2D-skeletal.png <!-- | ImageSize = 180px --> | ImageName = Phenol red | ImageFile1 = Phenol-red-zwitterionic-form-3D-balls.png <!-- | ImageSize1 = 180px --> | ImageName1 = Phenol red | Section1 = {{Chembox Identifiers | CASNo = 143-74-8 | SMILES = Oc1ccc(cc1)C(=C2C=CC(=[OH+])C=C2)c3ccccc3S(=O)([O-])=O }} | Section2 = {{Chembox Properties | Formula = C<sub>19</sub>H<sub>14</sub>O<sub>5</sub>S | MolarMass = 354.377 g/mol | Density = | MeltingPt = | BoilingPt = }} }} '''Phenol red''' (also known as '''phenolsulfonphthalein''' or '''PSP''') is a [[pH indicator]] that is frequently used in [[cell biology]] laboratories. ==Chemical structure and properties== Phenol red exists as a red crystal that is stable in air. Its solubility is 0.77 grams per liter (g/L) in water and 2.9 g/L in [[ethanol]].<ref name=merck>''[[Merck Index]]'', 11th ed., 7213 Phenolsulfonphtalein</ref> It is a [[weak acid]] with [[pKa|pK<sub>a</sub>]] = 8.00 at 20°C. A solution of phenol red is used as a [[pH indicator]]: its color exhibits a gradual transition from yellow to red over the pH range 6.6 to 8.0. Above pH 8.1, phenol red turns a bright pink ([[fuchsia (color)|fuchsia]]) color. {{pH_indicator_template|indicator_name=Phenol red|low_pH=6.6|high_pH=8.0|low_pH_color=yellow|high_pH_color=red}} This observed color change is because phenol red loses protons (and changes color) as the pH increases. In crystalline form, and in solution under very acidic conditions (low pH), the compound exists as a [[zwitterion]] as in the structure shown above, with the [[sulfate]] group negatively charged, and the [[ketone]] group carrying an additional proton. This form is sometimes symbolically written as H<sub>2</sub><sup>+</sup>PS<sup>&minus;</sup> and is orange-red. If the pH is increased (pKa = 1.2), the proton from the ketone group is lost, resulting in the yellow negatively charged ion HPS<sup>&minus;</sup>. At still higher pH (pKa = 7.7), the [[phenol]]'s [[hydroxide group]] loses its proton, resulting in the red ion PS<sup>2&minus;</sup>.<ref>Tamura Z, Maeda M. Differences between phthaleins and sulfonphthaleins. ''Yakugaku Zasshi''. 1997 Nov;117(10-11):764-70. (Japanese) PMID 9414589</ref> In several sources, the structure of phenol red is shown with the sulfur atom being part of a cyclic group, similar to the structure of [[phenolphthalein]].<ref name=merck/><ref>[http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=4766 Phenolsulfonphthalein], from the [[PubChem]] Compound database</ref> However, this cyclic structure could not be confirmed by [[X-ray crystallography]].<ref>Yamaguchi K., Tamura Z., Maeda M. [http://www.journalarchive.jst.go.jp/jnlpdf.php?cdjournal=analsci1985&cdvol=13&noissue=3&startpage=521 Molecular structure of the zwitterionic form of phenolsulfonphthalein.] ''Analytical Sciences'' 1997, vol. 13, no3, pp. 521-522</ref> Several indicators share a similar structure to phenol red, including [[bromothymol blue]], [[thymol blue]], [[bromocresol purple]], [[thymolphthalein]], and [[phenolphthalein]]. (A table of other common chemical indicators is available in the article on [[pH indicator]]s.) ==Phenolsulfonphthalein test== Phenol red was used in the '''phenolsulfonphthalein test''', also known as the PSP test. This test was used to estimate the overall blood flow through the [[kidney]] and is now obsolete. The test is based on the fact that phenol red is excreted almost entirely in the urine. By measuring the amount of phenol red excreted [[colorimetry|colorimetrically]], kidney function can be determined.<ref>[[Encyclopedia Britannica]], [http://www.britannica.com/eb/article-9059617/phenolsulfonphthalein-test Phenolsulfonphthalein Test], accessed 1 October 2006.</ref> Phenol red solution is administered [[intravenous]]ly, all of the [[urine]] produced is collected and the phenol red present determined.<ref>[[MedlinePlus]], [http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202456.html Phenolsulfonphthalein (Diagnostic)], accessed 1 October 2006.</ref> ==Indicator for cell cultures== Most [[biological tissue|living tissues]] prosper at a near-neutral [[pH]]; that is, a pH close to 7. The pH of [[blood]] ranges from 7.35 to 7.45, for instance. When [[Cell (biology)|cells]] are grown in [[tissue culture]], the medium in which they grow is held close to this physiological pH. A small amount of phenol red added to this growth medium will have a pink-red color under normal conditions. Typically 15 mg / 1 L is used for cell culture. In the event of problems, waste products produced by dying cells or overgrowth of contaminants will cause a change in pH, leading to a change in indicator color. For example, a culture of relatively slowly-dividing [[mammal]]ian cells can be quickly overgrown by [[bacteria]]l contamination. This usually results in an [[acid]]ification of the medium, turning it yellow. Many [[biologist]]s find this a convenient way to rapidly check on the health of tissue cultures. In addition, the waste products produced by the mammalian cells themselves will slowly decrease the pH, gradually turning the solution orange and then yellow. This color change is an indication that even in the absence of contamination, the medium needs to be replaced (generally, this should be done before the medium has turned completely orange). Since the color of phenol red can interfere with some [[spectrophotometry|spectrophotometric]] and [[fluorimetry|fluorescent]] assays, many types of tissue culture media are also available without phenol red. ==Estrogen mimic== Phenol red is a weak [[estrogen]] mimic, and in cell cultures can enhance the growth of cells that express the estrogen receptor.<ref>Berthois Y. ''et al.'' (1986) [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=3458212 Phenol red in tissue culture media is a weak estrogen: implications concerning the study of estrogen-responsive cells in culture]. '' Proc. Nat. Acad. Sci.'' '''83'''(8):2496-500.</ref> An important breakthrough in biotechnology was reported in the scientific literature on May 5th, 2005. Using phenol red as a [[differentiation]] factor, scientists at the University of Tennessee produced human [[oocyte]]s (eggs) from cells scraped from the surface of adult [[ovaries]]. These cells on the outer ovarian surface are known as ovarian surface [[epithelial]] cells. Such cells had been taken from five women aged 39 to 52 and were cultured in the presence of phenol red, inducing [[oogenesis]].<ref>Bukovsky, A., [http://www.rbej.com/content/3/1/17 Oogenesis in Cultures Derived from Adult Human Ovaries], ''Reproductive Biology and Endocrinology'', '''2005''', 3:17. {{DOI|10.1186/1477-7827-3-17}}</ref> Previously, human eggs had only been produced [[in vitro]] from [[totipotent]], blastomeric [[embryonic stem cells]]. One of the significant aspects of this experiment is that it demonstrated viable human egg cells can easily be produced from an adult cell that already has some degree of specialization. Furthermore, it lessens the implications associated with the fact that women are born with all of the egg cells they will ever have throughout their lives. While this breakthrough was not without controversy, it provides hope for infertile women wishing to undergo [[in vitro fertilization]], and hints at the possibility of new options for post-menopausal women as well. It also suggests that the future of stem cell research may not have to rely as heavily on human embryos as a source of unspecialized, totipotent cells for research. ==Use in swimming pool test kits== Phenol red, sometimes labelled with a different name, such as "Guardex Solution #2", is used as a pH indicator in home swimming pool test kits.<ref>[http://web.archive.org/web/20040326143901/http://www.mnsu.edu/bldgserv/msds/guardex_solution_2.pdf Guardex Solution 2 - Phenol Red Material Safety Data Sheet]</ref> ==References== {{reflist}} ==External links== *[http://video.google.com/videoplay?docid=9209311783284955887 Video of phenol red activity demonstration and medium preparation] [[Category:pH indicators]] [[Category:Triarylmethane dyes]] [[de:Phenolrot]] [[fr:Rouge de phénol]] [[it:Rosso fenolo]] [[ja:フェノールスルホンフタレイン]] [[pl:Czerwień fenolowa]] [[pt:Vermelho de fenol]] [[tr:Fenol kırmızısı]]