Anthocyanin biosynthesis

Anthocyanins (also anthocyans; from Greek: ἄνθος (anthos) "flower" and κυάνεος/κυανοῦς kyaneos/kyanous "dark blue") are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, or blue.

Food plants rich in anthocyanins include the blueberry, raspberry, black rice, and black soybean, among many others that are red, blue, purple, or black. Some of the colors of autumn leaves are derived from anthocyanins.

Anthocyanins belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway; they are odorless, but flavorful, contributing to taste as a moderately astringent sensation. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits. Anthoxanthins are clear, white, to yellow counterparts of anthocyanins occurring in plants. Anthocyanins are derived from anthocyanidins by adding sugars.

In flowers, the coloration that is provided by anthocyanin accumulation may attract a wide variety of animal pollinators, while in fruits, the same coloration may aid in seed dispersal by attracting herbivorous animals to the potentially-edible fruits bearing these red, blue, or purple colors.

Anthocyanins have an antioxidant role in plants against reactive oxygen species caused by abiotic stresses, such as overexposure to ultraviolet light and extreme temperatures. Tomato plants protect against cold stress with anthocyanins countering reactive oxygen species, leading to a lower rate of cell death in leaves.

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Wikipedia