Contribution to flower colors of flavonoids including anthocyanins: a review.

Flavonoids are one of the major pigments in higher plants, together with chlorophylls and carotenoids. Though ca. 8,000 kinds of flavonoids have been reported in nature, anthocyanins, chalcones, aurones and some flavonols act as major flower pigments. Flavonoids are present as major components in many flowers. On the other hand, flavones and flavonols, which are colorless or extremely pale yellow, function as copigment substances. Moreover, expression of the flower colors is diversified by inter-molecular and intra-molecular copigmentation, metal chelation, pH change and so on. In this review, I describe the distribution of the flavonoids which act as the pigments, and contribution to flower colors, e.g., yellow, scarlet, red, red-purple, violet, purple, blue and so on, of flavonoids, especially anthocyanins, chalcones, aurones and flavonols.