Alkannin

Alkannin
IUPAC name

5,8-Dihydroxy-2-[(1S)-1-hydroxy-4-methylpent-3-en-1-yl]naphthalene-1,4-dione
Other names

C.I. Natural Red 20; Alkanet extract
Identifiers
CAS number 517-88-4 Y
PubChem 72521
ChemSpider 65430 Y
KEGG C10292 Y
ChEMBL CHEMBL28457 Y
Jmol-3D images Image 1
Properties[1]
Molecular formula C16H16O5
Molar mass 288.29 g/mol
Appearance Red-brown crystalline prisms
Melting point

149 °C, 422 K, 300 °F
Solubility in water Sparingly soluble
Hazards
LD50 3.0 g/kg (mice)
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Alkannin is a natural dye that is obtained from the extracts of plants from the borage family Alkanna tinctoria that are found in the south of France. The dye is used as a food coloring and in cosmetics. It is used as a red-brown food additive in regions such as Australia,[2] and is designated in Europe as the E number E103, but is no longer approved for use..[3]

The chemical structure as a naphthoquinone derivative was first determined by Brockmann in 1936.[4] Alkannin has a deep red color in a greasy or oily environment and a violet color in an alkaline environment. Biosynthetically, alkannin is produced in plants from the intermediates 4-hydroxybenzoic acid and geranyl pyrophosphate.[5]

Alkannin is an antioxidant[6] and has an antimicrobial effect against Staphylococcus aureus and Staphylococcus epidermidis. It is also known to have wound healing, antitumor, and antithrombotic properties.[5]

References

  1. ^ The Merck Index, 11th Edition, 243
  2. ^ Additives, Food Standards Australia New Zealand
  3. ^ "Current EU approved additives and their E Numbers", Food Standards Agency website, retrieved 15 Dec 2011
  4. ^ H. Brockmann (1936). "Die Konstitution des Alkannins, Shikonins und Alkannans". Justus Liebigs Ann. Chem. 521: 1–47. doi:10.1002/jlac.19365210102. 
  5. ^ a b Vassilios P. Papageorgiou, Andreana N. Assimopoulou, Elias A. Couladouros, David Hepworth, and K. C. Nicolaou (1999). "The Chemistry and Biology of Alkannin, Shikonin, and Related Naphthazarin Natural Products". Angew. Chem. Int. Ed. 38 (3): 270–300. doi:10.1002/(SICI)1521-3773(19990201)38:3<270::AID-ANIE270>3.0.CO;2-0. 
  6. ^ A.N. Assimopoulou, D. Boskou, V.P. Papageorgiou (2004). "Antioxidant activities of alkannin, shikonin and Alkanna tinctoria root extracts in oil substrates". Food Chemistry 87 (3): 433–438. doi:10.1016/j.foodchem.2003.12.017.