Shikonin

Alkannin

Names
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 Anchusaic acid Anchusin
Identifiers
CAS Number	517-88-4 N
3D model (JSmol)	Interactive image
ChemSpider	65430 Y
ECHA InfoCard	100.007.497
E number	E103 (colours)
KEGG	C10292 Y
PubChem CID	72521
InChI InChI=1S/C16H16O5/c1-8(2)3-4-10(17)9-7-13(20)14-11(18)5-6-12(19)15(14)16(9)21/h3,5-7,10,17-19H,4H2,1-2H3/t10-/m0/s1 Y Key: NEZONWMXZKDMKF-JTQLQIEISA-N Y InChI=1/C16H16O5/c1-8(2)3-4-10(17)9-7-13(20)14-11(18)5-6-12(19)15(14)16(9)21/h3,5-7,10,17-19H,4H2,1-2H3/t10-/m0/s1
SMILES O=C\2c1c(O)ccc(O)c1C(=O)/C(=C/2)[C@@H](O)CC=C(C)C
Properties
Chemical formula	C16H16O5
Molar mass	288.30 g·mol−1
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)
Solubility in water	Sparingly soluble
Hazards
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).
N  (what is YN ?)
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, 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).