Anthocyanins

Abstract

The anthocyanins, which belong to the flavonoid group provide the majority of red to blue colour shades and patterns of flowers, fruits and leaves of angiosperm plants. They are produced, often temporary, during the course of a shoot's growth, but they can also be promoted experimentally, for instance in green leaves by subjecting plants to mineral imbalances. About 650 anthocyanins have been identified. Each anthocyanin consists of an aglycone (anthocyanidin) and one or more glycosyl moieties. Each anthocyanidin may occur on different equilibrium forms, which are influenced by various factors including pH. The anthocyanins are integrated into the plant's strategies for survival by attracting or repelling pollinators and seed dispersers, serving protective roles as shields against abiotic stresses like UV (ultraviolet)–B radiation, visible light, temperature variation, etc., and active defensive roles against pathogens, insects and herbivores. The past two decades have witnessed increased interests in anthocyanins above all because of their potential health‐promoting properties, their use as natural food colorants, as well as their appearance in cultivars and plant mutants with new colours and shapes.

Key Concepts:

  • Anthocyanins provide the majority of red to blue colours of plants.

  • Anthocyanins in plants attract or repel pollinators and seed dispersers, and serve protective and defensive roles.

  • Anthocyanin colours are significantly influenced by structure, copigmentation and external factors like pH.

  • Anthocyanin stability is significantly influenced by structure and external factors like pH.

  • Anthocyanins have been approved for use in foods, in Europe with the label E163.

  • Anthocyanins are regarded as potentially important nutraceuticals.

  • Genetic engineering applied to anthocyanins has been used to modify flower colours and patterns bringing new varieties to the horticultural marked.

Keywords: anthocyanin; flavonoid; structure; colour; stability; copigmentation; genetic; function; nutraceutical; antioxidant

Figure 1.

Structures of some anthocyanins with unusual structures; Sphagnorubin B (a), rosacyanin B (b) and catechin (4α→8) pelargonidin 3‐glucoside (c).

Figure 2.

General scheme for anthocyanidin equilibrium forms. AH+, flavylium cation; A7 and A4′, quinonoidal bases; A4′7 and A74′, ionised quinonoidal bases; B2 and B4, hemiketals (carbinol pseudobases); CE and CZ, chalcones (retrochalcones); X=glycosyl; R=H, OH or OCH3. The individual forms are supplied with their supposed colours as background.

Figure 3.

The supramolecule commelinin isolated from flowers of Asiatic dayflower (Commelina communis) consists of six anthocyanin molecules (M) and six flavones (F) surrounding two magnesium ions (in orange). Adapted from Kondo et al. .

Figure 4.

General biosynthesis of anthocyanins exemplified with pelargonidin 3‐O‐β‐glucoside (major pigment in strawberry), cyanidin 3‐O‐β‐[3″,6″‐di‐(malonyl)glucoside] (occur in red onions) and apigeninidin (occur in ferns and bryophytes). Enzymes catalysing the different transitions are labelled: CHS=chalcone synthase, CHI=chalcone isomerase, F3H=flavanone 3‐hydroxylase, DFR=dihydroflavonol 4‐reductase, ANS=anthocyanidin synthase, FNR=flavanone 4‐reductase, GT=glucosyltransferase, 3MAT=anthocyanin 3‐malonyltransferase.

Figure 5.

Many plants contain a complex mixture of anthocyanins as shown by the high‐performance liquid chromatogram of berries of bog bilberry (Vaccinium uliginosum), which shows the 15 anthocyanidin 3‐monoglycosides typical for blueberries (Table).

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References

Andersen ØM and Fossen T (2005) Characterization of anthocyanins by NMR. In: Wrolstad RE, Acree TE, Decker EA, Penner MH, Reid DS, Schwartz SJ, Shoemaker CF, Smith D and Sporns P (eds) Handbook of Food Analytical Chemistry: Pigments, Colorants, Flavors, Texture, and Bioactive Food Components, pp. 47–69. Hoboken, NJ: Wiley.

Kondo T, Yoshida K, Nakagawa A et al. (1992) Structural basis of blue‐colour development in flower petals from Commelina communis. Nature 358: 515–518.

Tanaka Y, Brugliera F and Chandler S (2009) Recent progress of flower colour modification by biotechnology. International Journal of Molecular Sciences 10: 5350–5369.

Further Reading

Andersen ØM and Jordheim M (2006) The anthocyanins. In: Andersen ØM and Markham KR (eds) Flavonoids: Chemistry, Biochemistry and Applications, pp. 471–553. Boca Raton: CRC Press.

Andersen ØM and Jordheim M (2010) Chemistry of flavonoid‐based colors in plants. In: Mander L and Lui H‐W (eds) Comprehensive Natural Products II, Vol. 3, pp. 547–614. Oxford: Elsevier.

Crozier A, Jaganath IB and Clifford MN (2009) Dietary phenolics: chemistry, bioavailabil. Natural Product Reports 26: 1001–1043.

Gould K, Davies K and Winefield C (2009) Anthocyanins: Biosynthesis, Functions, and Application. New York: Springer.

Quina FH, Moreira PF Jr, Vautier‐Giongo C et al. (2009) Photochemistry of anthocyanins and their biological role in plant tissues. Pure and Applied Chemistry 81: 1687–1694.

Yoshida K, Mori M and Kondo T (2009) Blue flower color development by anthocyanins: from chemical structure to cell physiology. Natural Product Reports 26: 884–915.

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How to Cite close
Andersen, Øyvind M, and Jordheim, Monica(Oct 2010) Anthocyanins. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0001909.pub2]