Alkannin

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 477247480

| ImageFile = Alkannin v2.svg

| ImageAlt = Skeletal formula of alkannin

| ImageFile1 = Alkannin 3D spacefill.png

| ImageAlt1 = Space-filling model of the alkannin molecule

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

| OtherNames = {{Unbulleted list|C.I. Natural red 20|Alkanet extract|Anchusaic acid|Anchusin}}

|Section1={{Chembox Identifiers

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = C10292

| 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

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 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

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = NEZONWMXZKDMKF-JTQLQIEISA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 517-88-4

| UNII_Ref = {{cascite|correct|CAS}}

| UNII = 075CRZ9995

| PubChem = 72521

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 65430

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 28457

| SMILES = O=C\2c1c(O)ccc(O)c1C(=O)/C(=C/2)[C@@H](O)CC=C(C)C

}}

|Section2={{Chembox Properties

| Properties_ref = The Merck Index, 11th Edition, 243

| C=16|H=16|O=5

| Appearance = Red-brown crystalline prisms

| Density = 1.15 g/mL

| MeltingPtC = 149

| BoilingPtC = 567

| Solubility = Sparingly soluble

}}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

| LD50 = 3.0 g/kg (mice)

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Alkannin is a natural dye that is obtained from the extracts of the plant dyer's alkanet (Alkanna tinctoria) which is found in the Mediterranean region. The dye is used as a food coloring and in cosmetics; within the European E number schedule, it is numbered E103. It is used as a red-brown food additive in regions such as Australia.[http://www.foodstandards.gov.au/_srcfiles/Additives%20alpha.pdf Additives] {{Webarchive|url=https://web.archive.org/web/20110406040011/http://www.foodstandards.gov.au/_srcfiles/Additives%20alpha.pdf |date=2011-04-06 }}, Food Standards Australia New Zealand Alkannin is deep red in an acid and blue in an alkaline environment.{{cite book | chapter = Alkanet | url = http://www.henriettesherbal.com/eclectic/usdisp/alkanna.html | title = Dispensatory of the United States of America | date = 1918 | editor = Joseph P. Remington and Horatio C. Wood }} The chemical structure as a naphthoquinone derivative was first determined by Hans Brockmann in 1936.{{cite journal | doi = 10.1002/jlac.19365210102 | author = H. Brockmann | title = Die Konstitution des Alkannins, Shikonins und Alkannans | journal = Justus Liebigs Ann. Chem. | year = 1936 | volume = 521 | issue = 1 | pages = 1–47}} The (R)-enantiomer of alkannin is known as shikonin, and the racemic mixture of the two is known as shikalkin.{{cite book | title = Dictionary of Food Compounds | page = 478 | author = Shmuel Yannai | publisher = CRC Press | date = 2012}}{{cite journal | doi = 10.1002/(SICI)1521-3773(19990201)38:3<270::AID-ANIE270>3.0.CO;2-0 | title = The Chemistry and Biology of Alkannin, Shikonin, and Related Naphthazarin Natural Products | author = Vassilios P. Papageorgiou |author2=Andreana N. Assimopoulou |author3=Elias A. Couladouros |author4=David Hepworth | author5-link = K. C. Nicolaou |author5=K. C. Nicolaou |display-authors=3| journal = Angew. Chem. Int. Ed. | year = 1999 | volume = 38 | pages = 270–300 | issue = 3| pmid = 29711637 }}