Newly Elucidated Mechanism for Blue Flower Color Development

Tadao Kondo, Minoru Ueda, Kumi Yoshida

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1 Citation (Scopus)


Various flower colors are in great part due to anthocyanins. Recently, we have elucidated two new mechanisms for blue flower color development on blue cornflower and blue morning glory. The composition of protocyanin, a blue pigment from cornflower, Centaurea cyanus, was determined to consist of six molecules of succinylcyanins (Sucy) , six molecules of malonylflavones (Mail) , one ferric ion and one magnesium ion, [Sucy6Mafl6Fe3+Mg2+] . The blue color of protocyanin was due to the LMCT (Ligand to Metal Charge Transfer) interation between Sucy and Fe3+. The structure of protocyanin was examined by using Al, Mg-protocyanin. The gross structure is much similar to that of commelinin. The pigment of blue morning glory, Ipomoea tricolor, is an triacylated anthocyanin, HBA. We measured the vacuoler pH of the petal of morning glory by using a proton selective micro electrode. The pHv of the petal of purplish red bud was 6.6 and that of blue open fiower petal was 7.7. The anhydrobase anion of HBA must be stabilized by intramolecular stacking. We could solve 80 year's problems, one is about cornflower's pigment and the other is the evidence of the pH theory. In both cases hydrophobic interaction followed by formation of supra-molecule is the key of stabilization of anthocyanidin chromophore.

Original languageEnglish
Pages (from-to)56-67
Number of pages12
JournalYuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry
Issue number1
Publication statusPublished - 1996


  • Blue flower color
  • Heavenly blue anthocyanin
  • LMCT
  • Protocyanin
  • Self-assembly supra molecule
  • Vacuolar pH


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