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

| OtherNames = C.I. Natural red 20<br>Alkanet extract<br>Anchusaic acid<br>Anchusin

| CASNo_Ref = {{cascite|changed|??}}

'''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,<ref>[http://www.foodstandards.gov.au/_srcfiles/Additives%20alpha.pdf Additives], [[Food Standards Australia New Zealand]]</ref> and is designated in Europe as the [[E number]] E103, but is no longer approved for use.<ref>"[http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist Current EU approved additives and their E Numbers]", Food Standards Agency website, retrieved 15 Dec 2011</ref> Alkannin has a deep red color in a greasy or oily environment and a violet color in an alkaline environment.{{cn|date=May 2017}}

The chemical structure as a [[naphthoquinone]] derivative was first determined by Brockmann in 1936.<ref>{{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 | pages = 1–47}}</ref> The [[enantiomer]] of alkannin is known as shikonin, and the [[racemic mixture]] of the two is known as shikalkin.<ref>{{Cite book | title = Dictionary of Food Compounds | page = 478 | author = Shmuel Yannai | publisher = CRC Press | date = 2012}}</ref><ref name=Nicolaou>{{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=[[K. C. Nicolaou]] | journal = Angew. Chem. Int. Ed. | year = 1999 | volume = 38 | pages = 270–300 | issue = 3}}</ref>

The enzyme [[4-hydroxybenzoate geranyltransferase]] utilizes [[Geranyl pyrophosphate|geranyl diphosphate]] and [[4-Hydroxybenzoic acid|4-hydroxybenzoate]] to produce [[3-geranyl-4-hydroxybenzoate]] and diphosphate. These compounds are then used to form alkannin.<ref name=Nicolaou/>

Alkannin is an antioxidant<ref>{{cite journal | doi = 10.1016/j.foodchem.2003.12.017 | title = Antioxidant activities of alkannin, shikonin and Alkanna tinctoria root extracts in oil substrates |author1=A.N. Assimopoulou |author2=D. Boskou |author3=V.P. Papageorgiou | journal = Food Chemistry | volume = 87 | year = 2004 | pages = 433–438 | issue = 3}}</ref> and has an antimicrobial effect against ''[[Staphylococcus aureus]]'' and ''[[Staphylococcus epidermidis]]''. It is also known to have wound healing, antitumor, and antithrombotic properties.<ref name=Nicolaou/>

[[File:Shikonin-Directly-Targets-Mitochondria-and-Causes-Mitochondrial-Dysfunction-in-Cancer-Cells-726025.f2.ogv|thumb|right|Effect of shikonin on the microtubule cytoskeleton.<ref>{{cite journal | last1 = Wiench | first1 = B | last2 = Eichhorn | first2 = T | last3 = Paulsen | first3 = M | last4 = Efferth | first4 = T | year = 2012 | title = Shikonin Directly Targets Mitochondria and Causes Mitochondrial Dysfunction in Cancer Cells | url = | journal = Evidence-Based Complementary and Alternative Medicine | volume = 2012 | issue = | page = 726025 | doi = 10.1155/2012/726025 | pmid = 23118796 |pmc=3478753 }}</ref>]]

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).<ref>{{cite journal | last1=Chen | first1=X| pmid = 12936978 | volume=47 | issue=9 | title=Shikonin, a component of chinese herbal medicine, inhibits chemokine receptor function and suppresses human immunodeficiency virus type 1. | date=Sep 2003 | journal=Antimicrob Agents Chemother | pages=2810–6 | doi=10.1128/aac.47.9.2810-2816.2003 | pmc=182643}}</ref><ref>{{cite journal | last1 = Gao | first1 = H. | year = 2011 | title = Anti-adenovirus activities of shikonin, a component of Chinese herbal medicine in vitro | url = | journal = Biol Pharm Bull | volume = 34 | issue = 2| pages = 197–202 | doi=10.1248/bpb.34.197|display-authors=etal}}</ref><ref>{{cite journal | last1 = Chen | first1 = J | last2 = Xie | first2 = J | last3 = Jiang | first3 = Z | last4 = Wang | first4 = B | last5 = Wang | first5 = Y | last6 = Hu | first6 = X | year = 2011 | title = Shikonin and its analogs inhibit cancer cell glycolysis by targeting tumor pyruvate kinase-M2 | url = | journal = Oncogene | volume = 30 | issue = | pages = 4297–4306 | doi = 10.1038/onc.2011.137 | pmid=21516121}}</ref>

== External links ==

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* [http://www.sigmaaldrich.com/catalog/product/sigma/s7576?lang=fr&region=FR Shikonin at Sigma-Aldrich]

[[Category:Hydroquinones]]

[[Category:Hydroxyquinones]]