PubMed Health⌕ Search

Biomedical subjects

Kumi Yoshida

Publications and source records attributed to Kumi Yoshida.

14 recordsLinked to original sources
PubMed2006

Perianth bottom-specific blue color development in Tulip cv. Murasakizuisho requires ferric ions.

The entire flower of Tulipa gesneriana cv. Murasakizuisho is purple, except the bottom, which is blue. To elucidate the mechanism of the different color development in the same petal, we prepared protoplasts from the purple and blue epidermal regions and measured the flavonoid composition by HPLC, the vacuolar pH by a proton-selective microelectrode, and element contents by the inductively coupled plasma (ICP) method. Chemical analyses revealed that the anthocyanin and flavonol compositions in both purple and blue colored protoplasts were the same; delphinidin 3-O-rutinoside (1) and major three flavonol glycosides, manghaslin (2), rutin (3) and mauritianin (4). The vacuolar pH values of the purple and blue protoplasts were 5.5 and 5.6, respectively, without any significant difference. However, the Fe(3+) content in the blue protoplast was approximately 9.5 mM, which was 25 times higher than that in the purple protoplasts. We could reproduce the purple solution by mixing 1 with two equimolar concentrations of flavonol with lambda(vismax) = 539 nm, which was identical to that of the purple protoplasts. Furthermore, addition of Fe(3+) to the mixture of 1-4 gave the blue solution with lambda(vismax) = 615 nm identical to that of the blue protoplasts. We have established that Fe(3+) is essential for blue color development in the tulip.

Chromatography, High Pressure Liquid↗
PubMed2006

Novel and efficient synthesis of cyanidin 3-O-beta-D-glucoside from (+)-catechin via a flav-3-en-3-ol as a key intermediate.

[reaction: see text] A novel and efficient synthesis of cyanidin 3-O-beta-D-glucoside (1) was accomplished the first time by a biomimetic oxidation route. From (+)-catechin, 3-OH was glucosylated, and the 4-position of the nucleus was then oxidized and dehydrated to give the 5,7,3',4'-tetra-O-(tert-butyldimethylsilyl)flav-3-en-3-ol 3-O-glucoside (8) as a key intermediate. 8 was deprotected and oxidized under air in hydrogen chloride-MeOH to give 1.

Anthocyanins↗
PubMed2006

Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis.

The Himalayan blue poppy, Meconopsis grandis, has sky blue-colored petals, although the anthocyanidin nucleus of the petal pigment is cyanidin. The blue color development in this blue poppy involving ferric ions was therefore studied. We analyzed the vacuolar pH, and the organic and inorganic components of the colored cells. A direct measurement by a proton-selective microelectrode revealed that the vacuolar pH value was 4.8. The concentrations of the total anthocyanins in the colored cells were around 5mM, and ca. three times more concentrated flavonols were detected. Fe was detected by atomic analysis of the colored cells, and the ratio of Fe to anthocyanins was ca. 0.8 eq. By mixing the anthocyanin, flavonol and metal ion components in a buffered aq. solution at pH 5.0, we were able to reproduce the same blue color; the visible absorption spectrum and CD were identical to those in the petals, with Fe(3+), Mg(2+) and flavonol being essential for the blue color. The blue pigment in Meconopsis should be a new type of metal complex pigment that is different from a stoichiometric supramolecular pigment such as commelinin or protocyanin.

Anthocyanins↗
PubMed2006

Structure of anthocyanin from the blue petals of Phacelia campanularia and its blue flower color development.

The dicaffeoyl anthocyanin, phacelianin, was isolated from blue petals of Phacelia campanularia. Its structure was determined to be 3-O-(6-O-(4'-O-(6-O-(4'-O-beta-d-glucopyranosyl-(E)-caffeoyl)-beta-d-glucopyranosyl)-(E)-caffeoyl)-beta-d-glucopyranosyl)-5-O-(6-O-malonyl-beta-d-glucopyranosyl)delphinidin. The CD of the blue petals of the phacelia showed a strong negative Cotton effect and that of the suspension of the colored protoplasts was the same, indicating that the chromophores of phacelianin may stack intermolecularly in an anti-clockwise stacking manner in the blue-colored vacuoles. In a weakly acidic aqueous solution, phacelianin displayed the same blue color and negative Cotton effect in CD as those of the petals. However, blue-black colored precipitates gradually formed without metal ions. A very small amount of Al(3+) or Fe(3+) may be required to stabilize the blue solution. Phacelianin may take both an inter- and intramolecular stacking form and shows the blue petal color by molecular association and the co-existence of a small amount of metal ions. We also isolated a major anthocyanin from the blue petals of Evolvulus pilosus and revised the structure identical to phacelianin.

Anthocyanins↗
PubMed2005

UV-B protective effect of a polyacylated anthocyanin, HBA, in flower petals of the blue morning glory, Ipomoea tricolor cv. Heavenly Blue.

The protective effects of polyacylated anthocyanin, heavenly blue anthocyanin (HBA), in blue flower petals of morning glory (Ipomoea tricolor cv. Heavenly Blue) against UV-B induced DNA damage were examined. We first clarified the concentration of HBA in epidermal vacuoles to be 12mM, and then constructed a UV-B irradiating apparatus resembling flower petal tissue to assess the screening effect of HBA. Monochromatic (280 and 310nm) or broad UV-B induced DNA lesions were reduced completely by the HBA filter to the same molecular numbers as those in living petal epidermis. However, diluted HBA solution and trisdeacyl HBA did not have the same reduction effect. HBA was more tolerant to solar radiation than trisdeacyl HBA. These data strongly suggest that polyacylated anthocyanins in flower petals can screen harmful UV-B efficiently. This action might be largely due to aromatic acyl residues.

Acylation↗
PubMed2005

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.

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 V-ATPase, 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-PPase and V-ATPase may prevent the over-alkalization. This systematic ion transport maintains the weakly alkaline vacuolar pH, producing the sky-blue petals.

Arabidopsis Proteins↗
PubMed2004

Swertisin dihydrate.

The title compound, 6-C-glucopyranosyl-7-O-methylapigenin dihydrate, C(22)H(22)O(10).2H(2)O, is a natural C-glucosylflavone. The flavone skeleton is almost planar, the dihedral angle between the pyran moiety and the 4-hydroxyphenyl ring being 9.8 (3) degrees. The basal plane of the pyranosyl ring of the glucose moiety is almost perpendicular to the benzopyran ring system. The flavone skeletons are stacked along the a axis, forming layers parallel to (001). Between these hydrophobic layers, the glucose groups and water molecules of crystallization are connected via O-H...O hydrogen bonds, forming hydrophilic layers.

Flavones↗
PubMed2004

Fecal-oral transmission of the cyst form of Blastocystis hominis in rats.

The infectivity of two Blastocystis hominis strains, RN94-9 and NIH:1295:1, was examined in 3-week-old SPF Wistar rats. The NIH:1295:1 strain, originally isolated from a guinea pig, was only able to infect rats via intracecal inoculation of the cultured organisms, while the RN94-9 strain, originally isolated from a laboratory rat, was able to infect rats by oral inoculation of the cultures due to the presence of a cystic form in the in vitro culture. Since many cysts were discharged in the feces of the infected rats, the infectivity of the concentrated cysts was compared between the two strains. Successful oral infection was observed in rats inoculated with 1 x 10(2)-1 x 10(6) cysts of the RN94-9 and NIH:1295:1 strains. The infectivity of the ten cysts varied in the three experiments of ten rats, being 20-100% and 30-100% in the RN94-9 and NIH:1295:1 strains, respectively. When an uninfected normal rat was housed with five experimentally inoculated rats, the normal rat became infected, demonstrating the fecal-oral transmission of the cyst form of this parasite. These results show that the Wistar rat is an ideal host for the propagation of strains RN94-9 and NIH:1295:1 of B. hominis, and demonstrate that the cyst form is the only transmissible form of this parasite.

Animals↗
PubMed2004

MexAB-OprM specific efflux pump inhibitors in Pseudomonas aeruginosa. Part 3: Optimization of potency in the pyridopyrimidine series through the application of a pharmacophore model.

The addition of substituents to the pyridopyrimidine scaffold of MexAB-OprM specific efflux pump inhibitors was explored. As predicted by a pharmacophore model, the incorporation substituents at the 2-position improved potency. Piperidines were found to be optimal, and further introduction of polar groups without compromising the activity was shown to be feasible. Careful positioning of the essential acidic moiety of the pharmacophore relative to the scaffold led to the discovery of vinyl tetrazoles with still greater potency.

Bacterial Outer Membrane Proteins↗
PubMed2003

MexAB-OprM-specific efflux pump inhibitors in Pseudomonas aeruginosa. Part 1: discovery and early strategies for lead optimization.

The identification of a series of compounds that specifically inhibit efflux by the MexAB-OprM pump system in Pseudomonas aeruginosa is described. Synthesis and in vitro structure-activity relationships (SARs) are outlined. Early leads lacked activity in animal models, and efforts to improve solubility and reduce serum protein binding by the introduction of polar groups are discussed.

Animals↗
PubMed2003

MexAB-OprM specific efflux pump inhibitors in Pseudomonas aeruginosa. Part 2: achieving activity in vivo through the use of alternative scaffolds.

Problems of low solubility, high serum protein binding, and lack of efficacy in vivo in first generation MexAB-OprM specific efflux pump inhibitors were addressed. Through the use of pharmacophore modelling, the key structural elements for pump inhibition were defined. Use of alternative scaffolds upon which the key elements were arrayed gave second generation leads with greatly improved physical properties and activity in the potentiation of antibacterial quinolones (levofloxacin and sitafloxacin) versus Pseudomonas aeruginosa in vivo.

Animals↗
PubMed2003

Mechanism of dusky reddish-brown "kaki" color development of Japanese morning glory, Ipomoea nil cv. Danjuro.

The mechanism of dusky reddish-brown "kaki" color development of morning glory, Ipomoea nil cv. Danjuro, was studied. Three major known anthocyanins were isolated as glucosylated pelargonidin derivatives. Measurement of the vacuolar pH with proton-selective microelectrodes revealed the vacuolar pH of the colored cell of open flowers to be 6.8, while that of buds was 5.8. Mixing of the three anthocyanins according to the composition ratio in petals at pH 6.8 allowed the identical color to that of petals to be reproduced. The typical "kaki" color development was mostly caused by 5-OH free acylated anthocyanins, which have two lambdamax around 435 and 535 nm in the visible region.

Anthocyanins↗
PubMed2003

Sepal color variation of Hydrangea macrophylla and vacuolar pH measured with a proton-selective microelectrode.

Sepal color of hydrangea varies with the environmental conditions. Although chemical and biological studies on this color variation have a long history, little correct knowledge has been generated about color development. All colored sepals contain the same anthocyanin, delphinidin 3-glucoside. Thus, there must be some other system for developing the wide variety of colors. In hydrangea sepals the cells of the epidermis are colorless and only the second layer of cells contain pigment. We prepared protoplasts without any color change during enzyme treatment of sepals and measured the vacuolar pH of each of the colored cells. We could correlate the color of a single hydrangea cell with its vacuolar pH using a combination of micro-spectrophotometry and a proton-selective microelectrode. Values for the vacuolar pH of blue (lambda vismax: 589 nm) and red cells (lambda vismax: 537 nm) were 4.1 and 3.3, respectively, the vacuolar pH of blue cells being significantly higher.

Anthocyanins↗