Rubiadin
Chemical compound
From Wikipedia, the free encyclopedia
Rubiadin is a bioactive anthraquinone dye that occurs naturally in several plant species, including Morinda citrifolia.[1]
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| Names | |
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| Preferred IUPAC name
1,3-Dihydroxy-2-methylanthracene-9,10-dione | |
| Other names
Rubiadine; 1,3-Dihydroxy-2-methyl-9,10-anthraquinone; 1,3-Dihydroxy-2-methylanthraquinone | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.208.613 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C15H10O4 | |
| Molar mass | 254.241 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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History
Although rubiadin was first isolated in 1853 by Edward Schunck from the Rubia tinctorum, it was not until 1893 that Schunck and Leon Marchlewski succeeded in isolating rubiadin glucoside from Dutch madder root. The first synthesis of the compound was achieved in 1927.[2]
Occurrence
Rubiadin occurs in plants of the genus Rubia and others.[3][4][5] It is one of the pigments of dyer's madders, where it is present as a glucoside. Its monomethyl ether has been isolated from Morinda longiflora and Morinda citrifolia.[6]
Extraction and presentation
Several methods for synthesizing rubiadin have been described. One approach is the synthesis of rubiadin from phthalic anhydride and 2,6-dihydroxytoluene in two reaction steps. However, the yields of both steps were low (33% and 54%, respectively), and the reproducibility of this method was very poor. Another synthesis route proceeds via 2-methylpurpurin (1,3,4-trihydroxy-2-methylanthraquinone), but this method requires five steps and each reaction step affords a low yield. A further described synthesis of rubiadin derivatives involves Diels-Alder reactions with halogenated naphthoquinones and dienes. In addition, rubiadin can be obtained by the condensation of 3-bromo-2,6-dimethoxytoluene with a phthalide.[7][8]
Properties
Use
Rubiadin is a constituent of natural colorants.[11]
