Proc Jpn Acad Ser B Phys Biol Sci. 2006 May;82(4):142-54. doi: 10.2183/pjab.82.142.
Proceedings of the Japan Academy. Series B, Physical and biological sciences
Kosaku Takeda
PMID: 25792777 PMCID: PMC4323046 DOI: 10.2183/pjab.82.142
The blue pigment of cornflower, protocyanin, has been investigated for a long time, but its precise structure was not entirely explained until recently. The molecular structure of the pigment was recently shown to be a metal complex of six molecules each of anthocyanin and flavone glycoside, with one ferric iron, one magnesium and two calcium ions by X-ray crystallographic analysis. The studies provided the answer to the question posed in the early part of the last century, "why is the cornflower blue and rose red when both flowers contain the same anthocyanin?" This work was achieved on the basis of the results of long years of the studies made by many researchers. In this review, the author focuses on the investigations of the blue metal complex pigments involved in the bluing of flowers, commelinin from Commelina commusis, protocyanin from Centaurea cyanus, protodelphin from Salvia patens and hydrangea blue pigment.
Keywords: Flower color; anthocyanin; blue pigment; commelinin; metal complex; protocyanin
