Anthocyanosides belong to the flavonoid class of compounds. They differ from other compounds in this category such as flavonols, flavanones and flavan-3-ols in the oxidation state. They also appear in the phenolics category because of the polyphenolic groups they contain. Anthocyanosides exist in more than 300 forms that differ structurally from each other because of the differences in the number and arrangement of these phenolic groups.
Anthocyanosides are water soluble pigments. They are responsible for the color of plant parts including flowers. Except for the green color, anthocyanosides impart every other shade of color from blue to red to yellow.
The amino acid phenylalanine reacts with acetic acid present in the cytoplasm of the cell. Through a pathway known as the shikimic acid pathway, acetate reacts with phenylalanine to produce cinnamic acid. This further converts into p-coumaric acid and chalcone by adding on a 3-carbon malonyl Coenzyme A moiety. Chalcone converts into naringenin on which several oxidase enzymes act to produce anthocyanins.
Anthocyanosides are glycosides that contain 2 -- phenylbenzopyrylium salts as polymethoxyl and polyhydroxyl derivatives. Each anthocyanoside has a specific number of hydroxyl groups that are methylated to various degrees. Being glycosidic in nature, they have sugar molecules attached at different positions and in varying quantities. These sugars include arabinose, galactose, rhamnose and glucose. The sugars in the anthocyanoside molecules are further attached to acids that may be aliphatic or aromatic in nature. Aliphatic acids found in anthocyanosides include oxalic, acetic, malic, succinic and malonic acids. Aromatic acids include ferulic, sinapic, caffeic and p-coumaric acid.
The interaction of oxygen with certain molecules within cells leads to the formation of atoms that have an unpaired number of electrons. These atoms, known as free radicals, initiate a chain of reactions with the cell membrane and cellular DNA that can produce a great degree of damage. Anthocyanosides have a chemical structure that is electron deficient. They are therefore highly reactive when in contact with free radicals, and exert an antioxidant action that is protective in nature.