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Skeletal formula of alkannin
Space-filling model of the alkannin molecule
IUPAC name
Other names
C.I. Natural red 20; Alkanet extract
517-88-4 N
ChemSpider 65430 YesY
Jmol-3D images Image
KEGG C10292 YesY
PubChem 72521
Molar mass 288.29 g/mol
Appearance Red-brown crystalline prisms
Density 1.15 g/mL
Melting point 149 °C (300 °F; 422 K)
Boiling point 567 °C (1,053 °F; 840 K)
Sparingly soluble
Lethal dose or concentration (LD, LC):
3.0 g/kg (mice)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N verify (what isYesY/N?)
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.

The enzyme 4-hydroxybenzoate geranyltransferase utilizes geranyl diphosphate and 4-hydroxybenzoate to produce 3-geranyl-4-hydroxybenzoate and diphosphate. These compounds are then used to form alkannin.[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]

Effect of shikonin on the microtubule cytoskeleton.[7]

Shikonin is also found in the Chinese herbal medicine plant Lithospermum erythrorhizon, the red-root gromwell, (紫草 zicao, Pinyin: zǐcǎo). The dried root is a Chinese herbal medicine with various antiviral and biological activities, including inhibition of human immunodeficiency virus type 1 (HIV-1).[8][9][10]


  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. 
  7. ^ Wiench, B; Eichhorn, T; Paulsen, M; Efferth, T (2012). "Shikonin Directly Targets Mitochondria and Causes Mitochondrial Dysfunction in Cancer Cells". Evidence-based Complementary and Alternative Medicine : eCAM 55: 555. doi:10.1155/2012/726025. PMC 3478753. PMID 23118796. 
  8. ^ Chen, X (Sep 2003). "Shikonin, a component of chinese herbal medicine, inhibits chemokine receptor function and suppresses human immunodeficiency virus type 1.". Antimicrob Agents Chemother 47 (9): 2810–6. doi:10.1128/aac.47.9.2810-2816.2003. PMID 12936978. 
  9. ^ Gao, H. et al. (2011). "Anti-adenovirus activities of shikonin, a component of Chinese herbal medicine in vitro". Biol Pharm Bull 34 (2): 197–202. doi:10.1248/bpb.34.197. 
  10. ^ Chen, J; Xie, J; Jiang, Z; Wang, B; Wang, Y; Hu, X (2011). "Shikonin and its analogs inhibit cancer cell glycolysis by targeting tumor pyruvate kinase-M2.". Oncogene 30: 4297–4306. doi:10.1038/onc.2011.137. 

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