Origin of the Conformational Stability of Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate] and Its Halogenated Derivatives.

In order to elucidate the origins of the stable structures of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] and the four derivatives with halogenated aromatic rings, the conformational stability and intramolecular interactions were investigated by DFT calculations. In all of these complexes, the conformation in which all ligands face in the same direction is the most stable. When adjacent ligands are in the same orientation, destabilization due to exchange repulsion is larger than that when they are in opposite orientations. However, this destabilizing effect is reversed by the sum of the stabilizing effects of the electronic and charge transfer interactions. The imide carbonyl group plays an important role in these stabilizing interactions. The negatively charged site and bond orbitals in the imide carbonyl group interact with the positively charged sites and bond orbitals in the aromatic ring, the carboxylate group, and the α-position of the carboxylate group in the adjacent ligands. In addition, the lone-pair orbitals of the halogen atoms contribute to conformational stabilization by interacting with the vacant orbitals in the adjacent ligands. However, the combinations of these charged sites or bond orbitals, which effectively contribute to the stabilization, are different for each complex.

Standardization of strawberry sourness and sweetness intensities using a taste sensor system and an invariant taste standard solution.

Taste is an essential factor for evaluating the quality of agricultural products. However, it is usually difficult to compare data acquired at different times or by different people because there is no invariant reference and because the evaluation methods are largely subjective. Here, we addressed these problems by developing a method for standardizing strawberry sourness and sweetness intensities using a taste sensor approach with a taste standard solution composed of sour and sweet compounds. This standard solution allows highly efficient sensor measurements because it contains the standard compounds citric acid and sucrose. In addition, we found that polyphenol destabilized the sensor response for strawberry sweetness, and its removal from the sample by appropriate treatment with polyvinylpolypyrrolidone allowed stable evaluation of the sweetness intensity. The taste sensor data obtained using this method were in good agreement with the chemical analysis values related to human sensory evaluation.

Detection of catechins using a fluorescent molecule and its application toward the evaluation of astringent intensity.

To evaluate sensory intensities of tastes, astringency, or pungency with ease and high reproducibility, the present study proposes a method using a fluorescent substance as a sensor. Unlike conventional taste sensors that each require a specialized system, this approach has the advantage in that it can be conducted using common analytical equipment such as a fluorescence spectrometer. In this report, a method to detect catechins and its application toward astringent evaluation is described. The binding of a sensor molecule with eight catechins revealed that the sensor molecule has higher affinity for catechins with stronger astringency. The complexation with the more astringent catechins showed larger fluorescence quenching. The change in the fluorescence intensity of a sample solution with the sensor molecule based on a reference solution was defined as the astringent intensity. Evaluation tests of green tea astringency demonstrated that the outputs of the sensor molecule correlate highly with the results by the human sense.

Standardization of tomato juice tastes using a taste sensor approach.

To enable the taste evaluation of many food samples at a time as well as the comparison of taste evaluation data acquired at different times, a standardization method for taste intensities was developed by a combination of a taste sensor system and a standard solution prepared with taste substances. In the case of tomato juices, citric acid, sucrose, and monosodium glutamate were used as standard taste substances for sourness, sweetness, and umami taste, respectively. Each standard point of the taste intensities was determined using only one standard solution including these standard substances. The taste intensity was described as a value on a scale based on discrimination thresholds of human gustation, where intensities of sourness, sweetness, and umami taste of the tomato juices were classified into multiple levels. Organoleptic evaluation supported these results. Validation for the present standardization method revealed that this approach has enough precision for practical tomato taste evaluation.

Hydrothermal processing of ß-glucan from Aureobasidium pullulans produces a low molecular weight reagent that regulates inflammatory responses induced by TLR ligands.

The Kururu no ß-glu® (KBG) is a commercial hydrothermal-treated Aureobasidium pullulans ß-glucan produced by a unique hydrothermal process that results in high solubility of the ß-glucan. In this study, we examined the biological activities of this reagent. RAW264.7 cells do not express Dictin-1 on the cell surface, but cells still respond to various pathogen molecular patterns. Lipopolysaccharide (LPS) induced nitrogen oxide (NO) synthesis and TNF-α production in RAW264.7 cells, and those were suppressed by KBG in a dose-dependent manner. The major signaling cell surface receptor respond to LPS is the TLR4/MD-2 complex. The UT12 antibody against to the TLR4/MD-2 complex mimics LPS function and induces cell responses. NO generation and TNF-α production were similarly induced in cells by stimulation with the antibody, but those were not suppressed by KBG. Cell responses induced by other TLR ligands, such as CPG (TLR9 ligand) and Pam3CSK4 (TLR1/TLR2 ligand), were also suppressed by KBG. Therefore, the target molecule for KBG is different from TLR receptors and Dictin-1. Although we also examined the suppressive activities of several other ß-glucan products, comparable activities were not detected with other reagents. A unique hydrothermal process may produce the active reagent. Reprocessing KBG increased low molecular weight fractions, and suppressive activities were markedly enhanced. Therefore, low molecular weight fractions obtained by hydrothermal processing of KBG may result in potential reagents that control inflammation induced by various pathogens.

Complex Structures of Monoglucosylrutin with ent-Gallocatechin-3- O-gallate and Epigallocatechin-3- O-gallate in Aqueous Solutions and the Mechanism of Color Change Induced by Complexation.

The addition of ent-gallocatechin-3- O-gallate ( ent-GCg) or epigallocatechin-3- O-gallate (EGCg) to an aqueous solution of 4G-α-glucopyranosylrutin (monoglucosylrutin, MGR) causes the color of the solution to weaken due to complexation between MGR and these flavan-3-ols. Copigmentation is a well-known color change phenomenon resulting from the complexation of flavonoids that deepens and strengthens the color of the solution, whereas MGR/catechin complexation results in the opposite change in color (i.e., weakening). In order to gain insight into the mechanism underlying the rare changes in the color of solutions of complexes between flavonoids, the structures of the MGR monomer and the complexes in aqueous solutions and their photochemical properties were investigated by computational methods. Molecular dynamics simulations and subsequent density functional theory (DFT) calculations revealed that the complex structures are stabilized through aromatic/aromatic, CH/π, and OH/O interactions as direct intermolecular forces and that many solvent water networks would contribute to the complexations. Time-dependent DFT calculations showed that the change in the color of an MGR/ ent-GCg solution is due only to a decrease in absorbance, whereas that of an MGR/EGCg solution is due to both a decrease in absorbance and a hypsochromic shift.

Present clinical practices of stereotactic irradiation for metastatic brain tumors in Japan: results of questionnaire survey of the Japanese Radiation Oncology Study Group (JROSG) working subgroup for neurological tumors.

BACKGROUND: To determine the current practice of stereotactic irradiation (STI) for brain metastases in Japan by a questionnaire survey. METHODS: A questionnaire was distributed to 313 institutions performing STI with one of the following machines: Gamma Knife (GK), CyberKnife (CK), Novalis (Nov), or other linear accelerator (LINAC)-based systems (OLS). The participation was voluntary. RESULTS: There were 163 responding institutions. The total number of STI treatments between April 2013 and March 2014 was 10,684. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) were performed in 8624 (80.7%) and 2060 (19.3%) cases, respectively. Whole-brain radiation therapy (WBRT) was performed for a total of 3515 cases. For a case model of a 1.5-cm solitary brain metastasis in a non-eloquent area, the most common GTV-PTV margin was 2 mm (22 of 114 institutions), and an institutional standard fraction was 1 (75 of 114 institutions). The doses for the model case also varied from 13.0 to 26.0 Gy (Median 20 Gy) when converted to SRS (α/ß = 10). A prescription point was at the PTV margin the most. The median dose constraints which were converted to SRS (α/ß = 3) to organs at risk were 12.2, 12.7, and 13.7 Gy for optic nerves, cavernous sinus, and brainstem, respectively. CONCLUSIONS: STI for brain metastases in current practice varied significantly among institutions. These different strategies relied mostly on the type of treatment machine used. It is thus necessary to establish a common guideline to express dose prescriptions and plan qualities for different STI machines.

Identification and detoxification of glycolaldehyde, an unattended bioethanol fermentation inhibitor.

Although there have been approximately 60 chemical compounds identified as potent fermentation inhibitors in lignocellulose hydrolysate, our research group recently discovered glycolaldehyde as a key fermentation inhibitor during second generation biofuel production. Accordingly, we have developed a yeast S. cerevisiae strain exhibiting tolerance to glycolaldehyde. During this glycolaldehyde study, we established novel approaches for rational engineering of inhibitor-tolerant S. cerevisiae strains, including engineering redox cofactors and engineering the SUMOylation pathway. These new technical dimensions provide a novel platform for engineering S. cerevisiae strains to overcome one of the key barriers for industrialization of lignocellulosic ethanol production. As such, this review discusses novel biochemical insight of glycolaldehyde in the context of the biofuel industry.

Effect of Orbital Interactions between Vicinal Bonds and between Hydroxy Groups on the Conformational Stabilities of 1,2-Ethanediol and 2,3-Butanediols.

The geometries of the two hydroxy groups in 1,2-ethanediol or 2,3-butanediols are more stable in a gauche orientation than those in an anti orientation. This has been generally explained in terms of the gauche effect, which is stabilization due to antiperiplanar electron delocalization between an antibonding orbital of the C-O bond (σCO*) and a bonding orbital of the C-H or C-C bond (σCH or σCC). However, a C-C single bond rotation simultaneously determines the geometries of the six vicinal bonds. Therefore, it is important to understand the effects on conformational stability of other interactions of the bond orbitals adjacent to the rotating C1-C2 bond. Bond model analysis revealed that antiperiplanar bond orbital interactions as a whole contribute to the higher stabilities of hydroxy/hydroxy gauche conformers, where the C-O/C-H or C-O/C-C combination including the σCO*/σCH or σCO*/σCC delocalization is not the dominant interaction stabilizing hydroxy/hydroxy gauche conformers. Rather, our results show that a large destabilization due to the antiperiplanar C-O/C-O combination in hydroxy/hydroxy anti conformers relatively increases the stabilities of hydroxy/hydroxy gauche conformers. This destabilization results mainly from the repulsion between the antiperiplanar bonding orbitals (σCO/σCO), which have a larger overlap compared to the synclinal σCO/σCO combination. The sum of the interbond energies between the vicinal bond orbitals of these 1,2-alkanediols is more advantageous for stability in gauche conformers. In addition, interactions between the gauche-oriented hydroxy groups provide large stabilization energies and the corresponding interactions in anti conformers are negligible. The relative conformational stabilities of 1,2-ethanediol and erythro-2,3-butanediol can be explained by the interactions between the antiperiplanar bond orbitals, between the vicinal bond orbitals, or between the hydroxy groups in addition to the combination of interactions between the vicinal bond orbitals and between the hydroxy groups. In contrast, in threo-2,3-butanediol, differences in the relative stabilities of the three conformers can be understood by the combination of the interactions between the vicinal bond orbitals and between the hydroxy groups.

Conformations of Flavan-3-ols in Water: Analysis Using Density Functional Theory.

To elucidate the conformations and their relative stabilities of flavan-3-ols in water, the optimized structures and energies were calculated by density functional theory, in which M06-2X, ωB97X-D, B3LYP, and CAM-B3LYP were examined as exchange-correlation functionals. The results were evaluated by comparing calculated spin-spin coupling constants of vicinal protons with the corresponding values observed in experimental 1H NMR spectra in D2O. The M06-2X and ωB97X-D results showed good agreement with the experimental NMR data and revealed that the B-ring (pseudoequatorial)/3-O (pseudoaxial) conformers were more stable [5.4-8.7 kJ/mol (1.3-2.1 kcal/mol)] than the B-ring (pseudoaxial)/3-O (pseudoequatorial) conformers in the 2,3-cis-flavan-3-ols, while the B-ring (pseudoequatorial)/3-O (pseudoequatorial) conformers and the B-ring (pseudoaxial)/3-O (pseudoaxial) conformers had similar stabilities in the 2,3-trans-flavan-3-ols.

Association of Catechin Molecules in Water: Quantitative Binding Study and Complex Structure Analysis.

Associations between catechin molecules were investigated by (1)H NMR titration experiments. Eight green tea catechins formed self-assembled dimers in water, and gallate-type catechins had a greater tendency to self-associate than non-gallate-type catechins. All eight catechins also associated as 1:1 heterodimer complexes. Investigation of complex formation of epigallocatechin-3-O-gallate (EGCg) and epigallocatechin (EGC) with the other catechins showed that the affinity between EGCg and 2,3-trans-gallate-type catechins was remarkably high, and the binding affinity of EGCg for ECg was also rather strong. In contrast, the non-gallate-type catechin EGC exhibited generally low binding affinity for other catechins. Structural analyses of the complexes by ROESY experiments and density functional theory calculations demonstrated that the higher binding abilities of gallate-type catechins are due to providing multiple intermolecular interactions that remain effective in an aqueous environment, such as aromatic/aromatic or CH/π interactions.

SUMO expression shortens the lag phase of Saccharomyces cerevisiae yeast growth caused by complex interactive effects of major mixed fermentation inhibitors found in hot-compressed water-treated lignocellulosic hydrolysate.

The complex inhibitory effects of inhibitors present in lignocellulose hydrolysate suppress the ethanol fermentation of Saccharomyces cerevisiae. Although the interactive inhibitory effects play important roles in the actual hydrolysate, few studies have investigated glycolaldehyde, the key inhibitor of hot-compressed water-treated lignocellulose hydrolysate. Given this challenge, we investigated the interactive effects of mixed fermentation inhibitors, including glycolaldehyde. First, we confirmed that glycolaldehyde was the most potent inhibitor in the hydrolysate and exerted interactive inhibitory effects in combination with major inhibitors. Next, through genome-wide analysis and megavariate data modeling, we identified SUMOylation as a novel potential mechanism to overcome the combinational inhibitory effects of fermentation inhibitors. Indeed, overall SUMOylation was increased and Pgk1, which produces an ATP molecule in glycolysis by substrate-level phosphorylation, was SUMOylated and degraded in response to glycolaldehyde. Augmenting the SUMO-dependent ubiquitin system in the ADH1-expressing strain significantly shortened the lag phase of growth, released cells from G2/M arrest, and improved energy status and glucose uptake in the inhibitor-containing medium. In summary, our study was the first to establish SUMOylation as a novel platform for regulating the lag phase caused by complex fermentation inhibitors.

Engineering redox cofactor utilization for detoxification of glycolaldehyde, a key inhibitor of bioethanol production, in yeast Saccharomyces cerevisiae.

Hot-compressed water treatment of lignocellulose liberates numerous inhibitors that prevent ethanol fermentation of yeast Saccharomyces cerevisiae. Glycolaldehyde is one of the strongest fermentation inhibitors and we developed a tolerant strain by overexpressing ADH1 encoding an NADH-dependent reductase; however, its recovery was partial. In this study, to overcome this technical barrier, redox cofactor preference of glycolaldehyde detoxification was investigated. Glycolaldehyde-reducing activity of the ADH1-overexpressing strain was NADH-dependent but not NADPH-dependent. Moreover, genes encoding components of the pentose phosphate pathway, which generates intracellular NADPH, was upregulated in response to high concentrations of glycolaldehyde. Mutants defective in pentose phosphate pathways were sensitive to glycolaldehyde. Genome-wide survey identified GRE2 encoding a NADPH-dependent reductase as the gene that confers tolerance to glycolaldehyde. Overexpression of GRE2 in addition to ADH1 further improved the tolerance to glycolaldehyde. NADPH-dependent glycolaldehyde conversion to ethylene glycol and NADP+ content of the strain overexpressing both ADH1 and GRE2 were increased at 5 mM glycolaldehyde. Expression of GRE2 was increased in response to glycolaldehyde. Carbon metabolism of the strain was rerouted from glycerol to ethanol. Thus, it was concluded that the overexpression of GRE2 together with ADH1 restores glycolaldehyde tolerance by augmenting the NADPH-dependent reduction pathway in addition to NADH-dependent reduction pathway. The redox cofactor control for detoxification of glycolaldehyde proposed in this study could influence strategies for improving the tolerance of other fermentation inhibitors.

Removal of acidic or basic α-amino acids in water by poorly water soluble scandium complexes.

To recognize α-amino acids with highly polar side chains in water, poorly water soluble scandium complexes with both Lewis acidic and basic portions were synthesized as artificial receptors. A suspension of some of these receptor molecules in an α-amino acid solution could remove acidic and basic α-amino acids from the solution. The compound most efficient at preferentially removing basic α-amino acids (arginine, histidine, and lysine) was the receptor with 7,7'-[1,3-phenylenebis(carbonylimino)]bis(2-naphthalenesulfonate) as the ligand. The neutral α-amino acids were barely removed by these receptors. Removal experiments using a mixed amino acid solution generally gave results similar to those obtained using solutions containing a single amino acid. The results demonstrated that the scandium complex receptors were useful for binding acidic and basic α-amino acids.

Improvement of tolerance of Saccharomyces cerevisiae to hot-compressed water-treated cellulose by expression of ADH1.

Hot-compressed water treatment of cellulose and hemicellulose for subsequent bioethanol production is a novel, economically feasible, and nonhazardous method for recovering sugars. However, the hot-compressed water-treated cellulose and hemicellulose inhibit subsequent ethanol fermentation by the yeast Saccharomyces cerevisiae. To overcome this problem, we engineered a yeast strain with improved tolerance to hot-compressed water-treated cellulose. We first determined that glycolaldehyde has a greater inhibitory effect than 5-HMF and furfural and a combinational effect with them. On the basis of the hypothesis that the reduction of glycolaldehyde to ethylene glycol should detoxify glycolaldehyde, we developed a strain overexpressing the alcohol dehydrogenase gene ADH1. The ADH1-overexpressing strain exhibits an improved fermentation profile in a glycolaldehyde-containing medium. The conversion ratio of glycolaldehyde to ethylene glycol is 30 ± 1.9% when the control strain is used; this ratio increases to 77 ± 3.6% in the case of the ADH1-overexpressing strain. A glycolaldehyde treatment and the overexpression of ADH1 cause changes in the fermentation products so as to balance the metabolic carbon flux and the redox status. Finally, the ADH1-overexpressing strain shows a statistically significantly improved fermentation profile in a hot-compressed water-treated cellulose-containing medium. The conversion ratio of glycolaldehyde to ethylene glycol is 33 ± 0.85% when the control strain is used but increases to 72 ± 1.7% in the case of the ADH1-overexpressing strain. These results show that the reduction of glycolaldehyde to ethylene glycol is a promising strategy to decrease the toxicity of hot-compressed water-treated cellulose. This is the first report on the improvement of yeast tolerance to hot-compressed water-treated cellulose and glycolaldehyde.

Identification of glycolaldehyde as the key inhibitor of bioethanol fermentation by yeast and genome-wide analysis of its toxicity.

Degradation of lignocellulose with pressurised hot water is an efficient method of bioethanol production. However, the resultant solution inhibits ethanol fermentation by Saccharomyces cerevisiae. Here, we first report that glycolaldehyde, which is formed when lignocellulose is treated with pressurised hot water, inhibits ethanol fermentation. The final concentration of glycolaldehyde formed by the treatment of lignocellulose with pressurised hot water ranges from 1 to 24 M, and 1-10 mM glycolaldehyde was sufficient to inhibit fermentation. This result indicates that glycolaldehyde is one of the main substances responsible for inhibiting fermentation after pressurised hot water degradation of lignocellulose. Genome-wide screening of S. cerevisiae revealed that genes encoding alcohol dehydrogenase, methylglyoxal reductase, polysomes, and the ubiquitin ligase complex are required for glycolaldehyde tolerance. These novel findings will provide new perspectives on breeding yeast for bioethanol production from biomass treated with pressurised hot water.

Synthesis of NH006--a photostable fungicide effective against Botrytis cinerea--according to the asymmetric total synthesis of MK8383.

MK8383, isolated from Phoma sp. T2526 in 1993, exhibits potent antibiotic activities against a variety of phytopathogens and has been considered a promising fungicide against Botrytis cinerea. Unfortunately, MK8383 is a photosensitive compound and it undergoes irreversible decomposition. Although much effort has been devoted to improving the photostability of MK8383 by chemical modification of its structure by a research group organized by Meiji Seika Kaishya, Ltd. and Mitsubishi Chemical Corporation, a photostable MK8383 derivative has never been prepared. We have found that a C13-14 double bond of MK8383 and (+)-phomopsidin is responsible for the photosensitivity, and herein, we report the synthesis of NH006, an MK8383 derivative with a saturated C13-14 double bond and (S) configuration at C14, based on the asymmetric total synthesis of MK8383. NH006 exhibits good photostability and potent antifungal activity against B. cinerea.

Mechanism of Copigmentation of Monoglucosylrutin with Caffeine.

4G-α-Glucopyranosylrutin (monoglucosylrutin, MGR) is a flavonol glycoside with quercetin as an aglycone, is pale yellow in color, and engages in both copigmentation and anticopigmentation. In this study, we elucidated the mechanism underlying the copigmentation of MGR upon complexation with caffeine. Three approaches were used: binding analyses based on changes in the absorbance spectrum, NOESY experiments, and DFT and TDDFT calculations using an explicit solvation model. Our findings show that copigmentation mainly results from a bathochromic shift in the absorbance spectrum and not a from hyperchromic effect. MGR and caffeine form a complex in both 1:1 and 1:2 stoichiometric ratios. The calculated optimized 1:1 and 1:2 complex structures were supported by the NOESY spectrum and form a cluster with 13 and 11 water molecules, respectively, through hydrogen bonds. Although HOMO and LUMO contribute most to the excitation of both the MGR monomer and the complexes, these frontier molecular orbitals in the complexes are distributed more widely than those in the MGR monomer. In particular, LUMO in the complexes spreads into the copigment caffeine and the solvent water molecules. This increase in electron delocalization reduces the energy gap between the frontier molecular orbitals, resulting in copigmentation with a bathochromic shift.

Hypochromic effect of an aqueous monoglucosyl rutin solution caused by green tea catechins.

Eight catechins reduced the color of a monoglucosyl rutin solution, the gallate-type catechins having a greater effect than the non-gallate-type catechins. Each catechin formed a 1:1 complex with monoglucosyl rutin. The binding constants of the gallate-type catechins were larger than those of the non-gallate type. These results indicate that the degree of color change in the monoglucosyl rutin solution depended on the ability of each catechin to form a complex with monoglucosyl rutin.

Identification of Japanese and chinese green tea cultivars by using simple sequence repeat markers to encourage proper labeling.

To identify commercial Japanese monovarietal green tea and imported green tea samples, leading Japanese cultivars were fingerprinted by using six simple sequence repeat markers analyzed by a capillary sequencer. Two well-authenticated imported Chinese monovarietal green tea samples were also fingerprinted by the same markers, one of which, was Fuyun, was a clonally propagated cultivar, and the other, Jiukengzhong, was seed-propagated. At least three markers used in this study identified 16 leading Japanese cultivars and Fuyun. Although Jiukengzhong was a mixed population with diverse genotypes, some individuals had a unique allele in one simple sequence repeat marker that was not detected in the 16 leading Japanese cultivars, an additional 39 cultivars, and Fuyun. This allele was effective as a detection marker for Jiukengzhong. These results support the use of simple sequence repeat markers for the identification of Japanese monovarietal green tea and also of imported green tea made from foreign cultivars.