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Studies on functions of polyphenols through the clarification of the mechanism of flower color development and variation

  • Graduate School of Informatics
  • Department of Complex Systems Science
  • Course of Life-Science Informatics

Kumi Yoshida [Professor]

http://www.info.human.nagoya-u.ac.jp/lab/yoshida/English.html

Outline of Seeds

Flower petals have a wide range of colors. From red, through purple to blue, and it is well established that most of the colors are due to polyphenolic plant pigments, anthocyanins. These beautiful colors cannot be accomplished with anthocyanin molecules alone, but are developed with co-existence of co-pigments, metal ions, and other elements in the colored cell vacuoles to form a supermolecular structures . In the world, some plants have blue flowerslike the Asiatic dayflower (Commelina communis), cornflower (Centaurea cyanus), and morning glory (Ipomoea tricolor), but others do not have them, such as roses, chrysanthemums, and carnations. The latter three are known as the big three in the cutting-flower market, the whole value of sales makesup 50% of all flower shipments. Therefore, many companies and scientists all over the world are in a heated race to breed blue versions of these blooms. Our team does not intense to breed blue roses as our explicit goal, but instead we are highly interested in the chemical and plantphysiological mechanisms of blue flower coloration from the standpoint of basic science. The concentration of anthocyanins in the colored vacuoles (subcellular organelle) of petal tissue is relatively high. We are challenging the quantitative analysis of components in a single cell: measurement of vacuolar pH, composition and content of anthocyanins, co-pigments, and metal ions under the banner of research on the chemistry of natural products in single cells. Organic synthetic studies and functional studies are also in progress so as to reveal the structure and function of polyphenols.

Novelty and originality of this research

Biological functions of polyphenols against life-style related diseases are nowadays attracting a great amount of attention. We are conducting studies on the organic synthesis of polyphenols. Anthocyanins and catechins have been reported to have anti-cancer activities, while proanthocyanidins are said to have anti-allergy activities. However, the supply of the polyphenols is still depends on isolation from plants, causing a bottleneck in functional R&D due to the difficulty to obtaining pure compounds. So far, there has been no report on synthesis of highly stable polyacylated anthocyanins. Our team re-examined the reaction pathways previously reported and established a new synthetic route that could provide efficient and versatile method for large-scale synthesis. We obtained a patent (JP2009137804A), in which we afforded an efficient one-pot transformation of glycosylated flavonols to anthocyanins. We established a stereo-controlled synthesis and a new glycosilation reaction, and synthesized flavones glycosilated with a non-natural L-glucose. We have also succeeded in synthesis of acylquinic acids that show great promise in inhibiting amyloid-beta coagulation, which is known to be a key driver of Alzheimers disease.
In addition to this synthetic work, we are carrying out studies on the vacuolar metal-transporters that play a critical role in the expression of blue flower colors. We obtained vacuolar iron transporter genes in petals of tulip and cornflower. We also identified candidate genes involving in aluminum tolerance of hydrangea.

Application and research area for Industry collaboration

The basic scientific research of blue flower-coloration should enable us to eventually breed new blue flowers. Our functional research on polyphenols, including anthocyanins, and their stabilization mechanisms should be able to apply to the development of functional foods. Supplying various synthetic polyphenol, including unnatural structure, will advance drug discovery and contributing to ADME studies. Finally, new anthocyanins have beautiful colors with high molecular absorptivity, and these pigments are promising for usage for dye-sensitized solar cells. We are performing molecular design and synthesizing new, non-natural anthocyanins and progressing fabrication of dye-sensitized solar cells and their evaluation.

Key Takeaway

Our team conducts world-leading chemical research on anthocyanins and polyphenols. Numerous researchers from universities, laboratories, and companies have already visited and worked with our labs in order to learn and receive assistance with our techniques for compound isolation and analysis as well as those related to structural determinations. We organized Fifth International Anthocyanin Workshop at Nagoya University in 2009, followed by the 27th International Polyphenol Conference in September 2014, putting our university at the center of a global research network.

Keywords

Anthocyanin, polyphenol, mechanism of flower-color development, dye-sensitized solar cells

Technologies

  • No commercially-available anthocyanins and flavonoids can be purchased, which were purified from natural sources and/or synthesized.
  • We can afford micro-HPLC analysis, spectroscopic analysis, general instrumental analysis, structural determination, purification of natural products.
  • Intracellular ion analysis using the microlectrode
  • Single-cell microanalysis (flavonoids, metal ions)

Equipment

  • Intracellular microelectrode system, HPLC (Photodiode array detection), preparative HPLC, rotary-vaccume evaporator, ultracentrifuge

Monographs, Papers and Articles

  • Kimura, Y., Kato, R., Oyama, K-I., Kondo T., Yoshida, K.: Efficient preparation of various O-methylquercetins by selective demethylation. Nat. Prod. Comm., 11, 957-96 1(2016).
  • Oyama, K-I., Yamada, T., Ito, D., Kondo, T., Yoshida, K.: Metal-complex Pigment Involved in the Blue Sepal Color Development of Hydrangea. J. Agric. Food. Chem., 63, 7630-7635 (2015).
  • Oyama, K-I., Watanabe, N., Yamada, T., Suzuki, M., Sekiguchi, Y., Kondo, T., Yoshida, K.: Efficient and versatile synthesis of 5-O-acylquinic acids with a direct esterification using a p-methoxybenzyl quinate as a key intermediate. Tetrahedron,71, 3120-3130 (2015).
  • Yoshida, K., Mori, M., Kondo, T.: Blue Flower Color Development by Anthocyanins: from chemical structure to cell physiology. Nat. Prod. Rep., 26, 884-915 (2009).