Components of protocyanin, a blue pigment from the blue flowers of Centaurea cyanus

The components of protocyanin were shown to be cyanidin 3-O-(6-O-succinylglucoside)- 5-O-glucoside] 1, apigenin 7-O-glucuronide-4′-O-(6-O-malonylglucoside)] 2 and metals, Fe, Mg and Ca, by reconstruction experiments. Substitution of the metal components in protocyanin with other metals was also examined.