Anthocyanins are water soluble plant pigments known as polyphenols, a subgroup of flavonoids.
They have a positive charge, which enables them to absorb light, and thus have colors, typically ranging from red (pink) through purple, to blue, and along with the carotenoids produce most of the bright colors in the plant world.
The pigments are water soluble and are found in the vacuolar sap in the epidermal tissues of the flowers and fruit.
They are also plant sugars, with the sugar linked to the C3 position as 3-monoglycosides, or to the C3 and C5 positions as diglycosides.
Anthocyanin molecule:
Fig. 1 – 2-phenylbenzopyrilium
The basic chemical structure is flavylium cation (2-phenylbenzopyrilium), which links hydroxyl (-OH) and/or methoxyl (-OCH3) groups, and one or more sugars.
The sugar-free molecule is called anthocyanidins.
Depending on the number and position of hydroxyl and methoxyl groups, various anthocyanidins have been described, and of these, six are commonly found in vegetables and fruits: