Английская Википедия:Alkannin

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Шаблон:Chembox 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 colouring and in cosmetics. It is used as a red-brown food additive in regions such as Australia.[1] Alkannin is deep red in an acid and blue in an alkaline environment.[2] The chemical structure as a naphthoquinone derivative was first determined by Brockmann in 1936.[3] The R-enantiomer of alkannin is known as shikonin, and the racemic mixture of the two is known as shikalkin.[4][5]

Biosynthesis

The enzyme 4-hydroxybenzoate geranyltransferase utilises geranyl diphosphate and 4-hydroxybenzoate to produce 3-geranyl-4-hydroxybenzoate and diphosphate. These compounds are then used to form alkannin.[5]

Research

Because the root bark (cork layers) of this plant contains large amounts of red naphthoquinone pigments, the roots of these plants are red-purple. If shikonin is extracted from fresh tissues, it gradually darkens over several days, finally forming black precipitates, which are thought to be polymers.[6]

References

Шаблон:Reflist

External links

  1. Additives Шаблон:Webarchive, Food Standards Australia New Zealand
  2. "Alkanet" in Dispensatory of the United States of America, year 1918, edited by Joseph P. Remington and Horatio C. Wood.
  3. Шаблон:Cite journal
  4. Шаблон:Cite book
  5. 5,0 5,1 Шаблон:Cite journal
  6. Kazufumi Y. (2017). Lithospermum erythrorhizon cell cultures: Present and future aspects. Plant Biotechnology 34: 131–142.