P-Dimethylaminocinnamaldehyde Explained

p-Dimethylaminocinnamaldehyde (DMACA) is an aromatic hydrocarbon. It is used in an acidic solution to detect indoles.

Use as a testing reagent

The DMACA is any of a number of acidified DMACA solutions:

• 0.117 g of DMACA, 39 mL of ethanol, 5 mL of conc hydrochloric acid and diluted to 50mL with water^[1]
• 1 g DMACA, 1 mL conc. hydrochloric acid and 99 mL water^[2]
• 1 g DMACA in 99 mL conc. hydrochloric acid.^[3]

It is primarily used as a histological dye used to detect indoles, particularly for production in cells. It is used for the rapid identification of bacteria containing tryptophanase enzyme systems. It is also particularly useful for localization of proanthocyanidins compounds in plants, resulting in a blue staining. It has been used for grapevine fruit^[4] or for legumes foliage^[5] histology.

A colorimetric assay based upon the reaction of A-rings with the chromogen. p-Dimethylaminocinnamaldehyde has been developed for flavanoids in beer that can be compared with the vanillin procedure.^[6] The DMACA reagent may be superior to the vanillin procedure for the detection of catechins.^[7]

The DMACA reagent changes color over several days when exposed to air but when refrigerated can be stored for up to two weeks.^[8]

The DMACA reagent may also be referred to as the Renz and Loew reagent.^{[3] [9]}

See also

• Ehrlich's reagent, a simple spot-test to presumptively identify alkaloids

External links

• DMACA on www.bd.com

Notes and References

1. Porubsky . P. . Scott . E. . Williams . T. . 10.1016/j.abb.2008.03.035 . P-Dimethylaminocinnamaldehyde derivatization for colorimetric detection and HPLC–UV/vis–MS/MS identification of indoles . Archives of Biochemistry and Biophysics . 475 . 1 . 14–17 . 2008 . 18423367. 2504418 .
2. Web site: DMACA Reagent for microbiology . 2013-10-29 . Sigma-Aldrich Co. LLC.
3. Chung . K. R. . Shilts . T. . Ertürk . Ã. M. . Timmer . L. W. . Ueng . P. P. . Indole derivatives produced by the fungusColletotrichum acutatumcausing lime anthracnose and postbloom fruit drop of citrus . 10.1016/S0378-1097(03)00605-0 . FEMS Microbiology Letters . 226 . 1 . 23–30 . 2003 . 13129603. free .
4. Bogs . J. . Jaffe . F. W. . Takos . A. M. . Walker . A. R. . Robinson . S. P. . The Grapevine Transcription Factor VvMYBPA1 Regulates Proanthocyanidin Synthesis during Fruit Development . 10.1104/pp.106.093203 . Plant Physiology . 143 . 3 . 1347–1361 . 2007 . 17208963. 1820911 .
5. Li . Y. G. . Tanner . G. . Larkin . P. . TheDMACA-HCl Protocol and the Threshold Proanthocyanidin Content for Bloat Safety in Forage Legumes . 10.1002/(SICI)1097-0010(199601)70:1<89::AID-JSFA470>3.0.CO;2-N . Journal of the Science of Food and Agriculture . 70 . 89–101 . 1996 .
6. A new colourimetric assay for flavonoids in pilsner beers. Jan A. Delcour and Didier Janssens de Varebeke, Journal of the Institute of Brewing, January–February 1985, Volume 91, Issue 1, pages 37–40,
7. 10.1016/j.chroma.2009.03.026. 19339019. Densitometric determination of (+)-catechin and (−)-epicatechin by 4-dimethylaminocinnamaldehyde reagent. Journal of Chromatography A. 1216. 20. 4485–91. 2009. Glavnik . V. . Simonovska . B. . Vovk . I. .
8. 10.1104/pp.42.10.1395. Studies on the Oxidation of Indole-3-Acetic Acid by Peroxidase Enzymes. I. Colorimetric Determination of Indole-3-Acetic Acid Oxidation Products. 1967. Meudt . W. J.. Gaines . T. P.. Plant Physiology. 42. 10. 1395–9 . 16656668 . 1086736.
9. Ehmann . A. . The van URK-Salkowski reagent — a sensitive and specific chromogenic reagent for silica gel thin-layer chromatographic detection and identification of indole derivatives . 10.1016/S0021-9673(00)89300-0 . Journal of Chromatography A . 132 . 2 . 267–276. 1977 . 188858.