The production of anthocyanins and anthocyanidins

The idea that the anthocyan pigments are closely related to the flavone and flavonol glucosides is by no means new. Attempts to solve the problem of their relationship have come chiefly from botanists, and, as a result of their researches, a number of hypotheses have sprung up around which quite considerable controversy has been centred. Miss Wheldale puts forward the suggestion that anthocyan pigments are the oxidation products of colourless or faintly coloured chromogens; and that these chromogens are products of hydrolysis of glucosides present in the tissues of the plant (probably glucosides of flavone or flavonol derivatives). The hydrolysis of the glucoside she considers as essential to the production of the anthocyan pigment. She represents the changes taking place by means of the following equations :— Glucoside + water ⇆ chromogen + sugar. Then— Oxidation of chromogen → anthocyan pigment.