C.I. Natural red 20
3D model (JSmol)
|E number||E103 (colours)|
|Molar mass||288.30 g·mol−1|
|Appearance||Red-brown crystalline prisms|
|Melting point||149 °C (300 °F; 422 K)|
|Boiling point||567 °C (1,053 °F; 840 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|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).
|what is ?)(|
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, and is designated in Europe as the E number E103, but is no longer approved for use. Alkannin has a deep red color in a greasy or oily environment and a violet color in an alkaline environment.
The chemical structure as a naphthoquinone derivative was first determined by Brockmann in 1936. The enantiomer of alkannin is known as shikonin, and the racemic mixture of the two is known as shikalkin.
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.
Alkannin is an antioxidant and has an antimicrobial effect against Staphylococcus aureus and Staphylococcus epidermidis. It is also known to have wound healing, antitumor, and antithrombotic properties.
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).
- The Merck Index, 11th Edition, 243
- Additives, Food Standards Australia New Zealand
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- H. Brockmann (1936). "Die Konstitution des Alkannins, Shikonins und Alkannans". Justus Liebigs Ann. Chem. 521: 1–47. doi:10.1002/jlac.19365210102.
- Shmuel Yannai (2012). Dictionary of Food Compounds. CRC Press. p. 478.
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- 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.
- 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. PMID 21516121. doi:10.1038/onc.2011.137.