Anthocyanins

Anthocyanins (from Greek anthos = flower, kyaneos = dark blue) are water-soluble dyes found in plants, which are formed by almost all higher plants, but not by animals, microorganisms or water plants. They are responsible for the intensive red, violet or blue colouring of flowers, leaves and fruits. Anthocyanins are counted among the secondary plant substances.
Anthocyanins are glycosidic compounds (flavonoids) which are close to the yellow dyes of the flavone and flavonol groups and to catechins.
Anthocyanins are highly soluble in water; they owe their solubility in water to the glycosidically bound sugar content. Only the sugar-free part, the aglycone of the anthocyanin, is decisive for the colour. The aglycone is called anthocyanidin.

Pharmacologically anthocyanins inhibit the absorption of glucose, modulate postprandial glycaemia. A meta-analysis has shown that anthocyanins reduce total cholesterol and triglycerides in serum.

The glycosides of pelargonidin, cyanidin, delphinidin and their methyl ethers malvidin, peonidin and petunidin occur most frequently in nature. Examples of versch. Anthycans and their occurrence in various plants:

• Chokeberry, blackberry, poppy, rose, cranberry, elderberry, cornflower, cherries, red cabbage, sour cherries, (cyanidin).
• Eggplant (Delphinidin)
• Strawberry (pelargonidin)
• Primula species and blue grape, red wine (malvidin)
• Blackcurrant (delphinidin and peonidin)
• Petunia (petunidin)
• Red currant, golden balm, nasturtium (pelargonidin)
• Blueberry
  

In the higher plants anthocyanins occur alongside flavones, carotenoids, anthoxanthins and betalaines. They are responsible for the colouring of the leaves in autumn. Their colour comes into its own when photosynthesis is stopped and chlorophyll is no longer formed.

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