花の色とナノサイエンス

Abstract

Red, purple and blue flower color is mainly due to anthocyanins. The color development and stability of anthocyanin are effected by co-existence of co-pigment and metal ions, and pH. Our chemical studies elucidated that the color is stabilized and varied by formation of a supramolecule. Especially beautiful blue flower colors, found in blue dayflower and blue salvia, are developed by a metalloanthocyanin, a stoichiometric supramolecular metal complex pigment.The metalloanthocyanins are composed with six molecules of anthocyanins, six molecules of glycosylflavones, and 2 atoms of metal ion and the diameter is ca. 3 nano meter. Under formation of metalloanthocyanin fine chiral molecular recognition occurs. To clarify the mechanism we synthesized chiral glycosylflavones derivatives according to our newly invented method of direct C-and O-glycosylation to the flavonoid nucleus. Reproduction experiment from the components (anthocyanin, flavone and metal ion) including chiral isomer of the flavones bearing L-glucose was carried out. As a result, the 4'-D-glucoside of the flavone is essential for formation of metalloanthocyanin, but the L-sugar is not.As the petal tissue is not homogenous, both the epidermides are colored. For elucidation of true flower color development in a living petal cell, various analytical methodologies including nano-technology must be applied. For this purpose one cell analysis by pH-microelectrode, a nano-HPLC, a pico mole metalanalysis and microscopic photometry were carried out. The mech-anism of flower color change of morning glory, Ipomoea tricolor, from purple to blue during blooming, and color variation of hydrangea was studied.