Present Knowledge of the Chemistry of Proanthocyanidins

The chemical nature and origin of the bright red and blue colouring matters of flowers, fruits and leaves have been attracting the attention of scientists from very early times. But it was only during the years 1913-1917 which included the first World War that Wills-tatter succeeded in the isolation of the main anthocyanins in a pure condition and established their chemical constitution. Be showed that anthocyanidins are responsible for the colour of the molecules and they are in combination with sugars fanning the antho­cyanins. A typical example is cyanin in of the red rose, a diglucoside of cyanidin(I). The exact positions of the sugar units wore finally established by Robinson by adopting the methods of synthesis. He not only synthesised the anthocyanidine but also accomplished the synthesis of the glycosidic anthocyanins. Cyanin was coiiectly represented by structure II. Much work has been done subsequently on the possible biosynthesis of these colouring matters and also on their utilization for the study of genetics.