Chemistry of the Anthocyanins

Abstract

THE classical paper of Willstatter and Everest (1913),, on the isolation of the pigment of blue cornflowers, heralded a dramatic transformation of the state of our knowledge of the blue and red colouring matters of flowers and blossoms, and the present position is that we not only know the molecular structure of the more important and widespread anthocyanins, but also that many of them have been made artificially in the laboratory. With the simultaneous growth of precise information about chlorophyll, the carotenoids, the poly-saccharides and the terpenes, one may say that all the more obvious challenges of vegetative Nature to the organic chemist have been taken up, and taken up successfully. Deep mysteries there are still, it is true, but one must probe beneath the surface in order to find them. Willstatter owed his triumph largely to recognition of the fkct that the anthocyanins, although non-nitrogenous, form salts with strong acids, and these salts can be purified by means of the technique appropriate to many ammonium salts, that is, solution in a hydroxylic solvent and precipitation with a non-hydroxylic solvent.