Tadao Kondo

Bio: Tadao Kondo is an academic researcher from Nagoya University. The author has contributed to research in topics: Pigment & Protocyanin. The author has an hindex of 14, co-authored 30 publications receiving 1602 citations.

Structure and Molecular Stacking of Anthocyanins—Flower Color Variation

Abstract: In 1913 Willstatter made the striking observation that the same pigment can give rise to different colors. Thus, the same pigment, cyanin, is found in the blue cornflower and in the red rose. Willstatter attributed the variety of flower colors to different pH values in solution. Indeed, anthocyanin changes its color with pH; it appears red in acidic, violet in neutral, and blue in basic aqueous solution. Willstatter's pH-theory for explaining flower color variation is still to be found in major text books of organic chemistry. Very recently, however, reinvestigation has disclosed that the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking. The stacking would be mainly brought about by intermolecular or intramolecular hydrophobic interaction between aromatic nuclei such as anthocyanidins, flavones and aromatic acids. In addition, hydrogen bonds and charge transfer interactions may also be involved. The most interesting molecular complexes of anthocyanins are the metalloanthocyanins such as commelinin and protocyanin (blue cornflower pigment). These seemingly pure blue complexes each consist of six anthocyanin and six flavone molecules and two metal ions; their molecular weight is nearly 10000. A structure is proposed for commelinin.

Structure and Molecular Stacking of Anthocyanins - Flower Color Variation

Abstract: In 1913 Willstatter made the striking observation that the same pigment can give rise to different colors. Thus, the same pigment, cyanin, is found in the blue cornflower and in the red rose. Willstatter attributed the variety of flower colors to different pH values in solution. Indeed, anthocyanin changes its color with pH; it appears red in acidic, violet in neutral, and blue in basic aqueous solution. Willstatter's pH-theory for explaining flower color variation is still to be found in major text books of organic chemistry. Very recently, however, reinvestigation has disclosed that the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking. The stacking would be mainly brought about by intermolecular or intramolecular hydrophobic interaction between aromatic nuclei such as anthocyanidins, flavones and aromatic acids. In addition, hydrogen bonds and charge transfer interactions may also be involved. The most interesting molecular complexes of anthocyanins are the metalloanthocyanins such as commelinin and protocyanin (blue cornflower pigment). These seemingly pure blue complexes each consist of six anthocyanin and six flavone molecules and two metal ions; their molecular weight is nearly 10000. A structure is proposed for commelinin.

The involvement of tonoplast proton pumps and Na+(K+)/H+ exchangers in the change of petal color during flower opening of Morning Glory, Ipomoea tricolor cv. Heavenly Blue.

Abstract: ;The petal color of morning glory, Ipomoea tricolor cv. Heavenly Blue, changes from purplish red to blue during flower opening. This color change is caused by an unusual increase in vacuolar pH from 6.6 to 7.7 in the colored adaxial and abaxial cells. To clarify the mechanism underlying the alkalization of epidermal vacuoles in the open petals, we focused on vacuolar H + -ATPase (V-ATPase), H + -pyrophosphatase (V-PPase) and an isoform of Na + /H + exchanger (NHX1). We isolated red and blue protoplasts from the petals in bud and fully open flower, respectively, and purified vacuolar membranes. The membranes contained VATPase, V-PPase and NHX1, which were immunochemically detected, with relatively high transport activity. NHX1 could be detected only in the vacuolar membranes prepared from flower petals and its protein level was the highest in the colored petal epidermis of the open flower. These results suggest that the increase of vacuolar pH in the petals during flower opening is due to active transport of Na + and/ or K + from the cytosol into vacuoles through a sodium- or potassium-driven Na + (K + )/H + exchanger NXH1 and that V

Plant Polyphenols: Chemical Properties, Biological Activities, and Synthesis

Abstract: Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Biosynthesis of plant pigments: anthocyanins, betalains and carotenoids

Abstract: Plant compounds that are perceived by humans to have color are generally referred to as 'pigments'. Their varied structures and colors have long fascinated chemists and biologists, who have examined their chemical and physical properties, their mode of synthesis, and their physiological and ecological roles. Plant pigments also have a long history of use by humans. The major classes of plant pigments, with the exception of the chlorophylls, are reviewed here. Anthocyanins, a class of flavonoids derived ultimately from phenylalanine, are water-soluble, synthesized in the cytosol, and localized in vacuoles. They provide a wide range of colors ranging from orange/red to violet/blue. In addition to various modifications to their structures, their specific color also depends on co-pigments, metal ions and pH. They are widely distributed in the plant kingdom. The lipid-soluble, yellow-to-red carotenoids, a subclass of terpenoids, are also distributed ubiquitously in plants. They are synthesized in chloroplasts and are essential to the integrity of the photosynthetic apparatus. Betalains, also conferring yellow-to-red colors, are nitrogen-containing water-soluble compounds derived from tyrosine that are found only in a limited number of plant lineages. In contrast to anthocyanins and carotenoids, the biosynthetic pathway of betalains is only partially understood. All three classes of pigments act as visible signals to attract insects, birds and animals for pollination and seed dispersal. They also protect plants from damage caused by UV and visible light.