anthocyaniner

Anthocyaniner (anthocyanins) are a class of water-soluble pigments in the flavonoid group found in many plants. They are glycosides of anthocyanidins, most commonly cyanidin, delphinidin, pelargonidin, peonidin, petunidin and malvidin, linked to sugars such as glucose or rhamnose. The color they impart ranges from red to blue, and is strongly influenced by pH and by complexation with metal ions or co-pigments.

Distribution and function: They occur in fruits, vegetables, grains and flowers, often accumulating in the vacuoles of plant cells. They contribute to ripe fruit color and may attract pollinators or seed dispersers; they can also protect plant tissues from UV damage and oxidative stress.

Biosynthesis and chemistry: They are produced via the flavonoid pathway from phenylalanine; the core steps involve enzymes such as chalcone synthase, chalcone isomerase, and various hydroxylases, followed by glycosyltransferases that attach sugars to the anthocyanidin aglycones to form anthocyanins. The hue is affected by pH in the vacuole, by acylation of sugars, and by co-pigmentation with other flavonoids or metal ions. They are sensitive to heat, light, and alkaline conditions, which can cause degradation or color loss.

Nutrition and regulation: Anthocyaniner-containing foods include berries, red grapes, red cabbage, purple corn and some flowers. They contribute antioxidant activity in vitro, and dietary intake is associated in some studies with reduced risk of chronic diseases, though bioavailability is limited and results vary. In the body, anthocyanins are metabolized by the gut microbiota and liver to various metabolites, and largely excreted in urine and feces. They are also used commercially as a natural food colorant (E163).