Not to be confused with Anthocyanin, their sugar containing counterparts.

Anthocyanidins are sugar-free counterparts of anthocyanins, can be identified based on the structure of a large group of polymethine dye, the benzopyrylium (chromenylium) ion. In particular anthocyanidins are salt derivatives of the 2-phenylchromenylium cation also known as flavylium cation. As shown in the figure below, the phenyl group at the 2-position, can carry different substituents. The counterion of the flavylium cation is mostly chloride. With this positive charge the anthocyanins differ from other flavonoids.

Anthocyanidin R1 R2 R3 R4 R5 R6 R7 Aurantinidin -H -OH -H -OH -OH -OH -OH Cyanidin -OH -OH -H -OH -OH -H -OH Delphinidin -OH -OH -OH -OH -OH -H -OH Europinidin -OCH3 -OH -OH -OH -OCH3 -H -OH Luteolinidin -OH -OH -H -H -OH -H -OH Pelargonidin -H -OH -H -OH -OH -H -OH Malvidin -OCH3 -OH -OCH3 -OH -OH -H -OH Peonidin -OCH3 -OH -H -OH -OH -H -OH Petunidin -OH -OH -OCH3 -OH -OH -H -OH Rosinidin -OCH3 -OH -H -OH -OH -H -OCH3