Green Tea Suppresses Brain Aging

Epidemiological studies have demonstrated that the intake of green tea is effective in reducing the risk of dementia. The most important component of green tea is epigallocatechin gallate (EGCG). Both EGCG and epigallocatechin (EGC) have been suggested to cross the blood–brain barrier to reach the brain parenchyma, but EGCG has been found to be more effective than EGC in promoting neuronal differentiation. It has also been suggested that the products of EGCG decomposition by the intestinal microbiota promote the differentiation of nerve cells and that both EGCG and its degradation products act on nerve cells with a time lag. On the other hand, the free amino acids theanine and arginine contained in green tea have stress-reducing effects. While long-term stress accelerates the aging of the brain, theanine and arginine suppress the aging of the brain due to their anti-stress effect. Since this effect is counteracted by EGCG and caffeine, the ratios between these green tea components are important for the anti-stress action. In this review, we describe how green tea suppresses brain aging, through the activation of nerve cells by both EGCG and its degradation products, and the reductions in stress achieved by theanine and arginine.     

Fourier analysis based phase shift interferometric tomography for three-dimensional reconstruction of concentration field around a growing crystal

The present work is concerned with the three-dimensional reconstruction of concentration field around a crystal growing from its aqueous solution using Fourier analysis based phase shift interferometric tomography. Projection data of convective field around a growing NaClO₃ crystal have been recorded using a Mach–Zehnder interferometer. A new numerical method based on the concept of real time phase shift interferometry has been employed for the analysis of the interferograms. By interpreting the interferograms as projection data, the 3-D distribution of salt concentration has been determined using principles of tomography. Study shows that the Fourier analysis-based phase shift method is a novel approach for crystal growth studies as it requires only one interferometric image for the determination of full phase information as opposed to the conventional real time phase shift interferometry wherein at least three or more phase-shifted interferograms are needed. Results have been presented in the form of interferograms, path-integrated concentration contours and three-dimensional concentration profiles over select horizontal planes above the growing crystal. Based on the reconstruction results, distribution of salt concentration in the crystal vicinity is determined and an appropriate mechanism of buoyancy-induced fluid movement in the growth chamber is discussed.     

Study on the biodistribution of deuterated biomolecules in mice aiming at new diagnostic radio-imaging agents

Deuterated compounds (2H-compounds) labeled with 14C prepared from deuterated algae, Chlorella ellipsoidea, were examined for their time-coursed distribution in mice after intravenous administration. The 14C-2H-compounds were fractionated and isolated from algae grown in practically 100 mol% 2H2O in the presence of 14C-bicarbonate. The fractions obtained were the "basic" and "acid" fractions, composed mainly of amino acids and sugar phosphates, respectively, and glucose, galactose, and lipid fractions. All fractions were examined for their biodistribution in mice bearing Ehrlich solid tumor in comparison with the fractions isolated from ordinary Chlorella (1H-Chlorella). 2H-Compounds thus examined showed some behaviors different from 1H-compounds. The 2H- "basic" fraction distributed more slowly in heart, lung and liver than the 1H-fraction. The 2H-specific large distribution in tumor was also observed on this fraction. The 2H-dependent characteristics in the distribution of glucose and galactose differed. The 2H-glucose level was lower in blood and higher in brain, resulting in a brain/blood ratio approximately twice that of 1H-glucose, while 2H-galactose did not show such a characteristic. These findings may be useful for the application of 2H-biomolecules to functional radio-imaging agents for nuclear medicine.     

Phosphorescence from pyrimidine vapor

The phosphorescence from pyrimidine vapor has been observed by a method of time-resolved laser spectroscopy. The phosphorescence spectrum commences at 350.5 nm and consists mainly of three totally symmetric vibrations in the ground state, v_6a, v₁₂ and v_9a as in the case of the zero-point vibrational level fluorescence of pyrimidine vapor. The phosphorescence quantum yield and lifetime are found to be about 1 × 10^?4 and 50 μs.     

Asymmetric synthesis of activated cyclopropanes catalyzed by cinchonidine as a chiral Brønsted base

Cinchonidine catalyzed the cyclopropanation reaction between chloromethyl ketones and β-substituted methylidenemalononitriles to give trans-cyclopropanes with enantioselectivity up to 82% ee. Experimental evidence suggests that cinchonidine functions as a chiral Brønsted base catalyst in the reaction and hydrogen bonding is essential for inducing high enantioselectivity.     

Stereoselectivity control by oxaspiro rings during Diels-Alder cycloadditions to cross-conjugated cyclohexadienones: the syn oxygen phenomenon

The diastereofacial selectivity operating in Diels-Alder additions involving spirocyclic cross-conjugated cyclohexadienones with dienes of varying reactivity has been investigated. The study has included the ether series 1a-c as well as the lactone/ketone pair 2a/2b. In all cases, the preferred [4+2] cycloaddition pathway consisted of bonding from that pi-surface syn to the oxygen atom. 4-Substituted-4-methyl-2,5-cyclohexadienones (monocyclic systems) were also examined and found to undergo bond formation preferentially from the face bearing the more electron-withdrawing of the two groups at the 4 position. Kinetic parameters were determined for the cycloaddition of 1a and 2a to cyclopentadiene. The rate acceleration profile of solvents was in the order CF(3)CH(2)OH > CH(3)CN approximately CH(2)Cl(2) for the production of 9a from 1a and CF(3)CH(2)OH > CH(2)Cl(2) > CH(3)CN for the production of 21a from 2a, respectively. This spread in polarity had no major impact on product distribution, a phenomenon also reflected in the behavior of 4-substituted-4-methyl-2,5-cyclohexadienones under comparable conditions. Theoretical assessment of these experimental facts was undertaken at the HF/6-31G level. The facial selectivity is understandable in terms of the secondary interaction between the HOMO of the diene and LUMO of the dienophile as well as the effective hyperconjugation between the newly forming bond and the 4-anti-C-C sigma-orbital due to the more electron-donating bond, as defined by the Cieplak model.     

Pentacyclic laddersiloxane

A novel method which effects ring extension of the ladder oligosilsesquioxanes was developed. By applying this method, we synthesized the first functionalized tricyclic laddersiloxanes and pentacyclic laddersiloxane. The reaction of (i-PrSi(OH)O)4 with (i-PrPhClSiO)2 in pyridine gave the tetraphenyl tricyclic laddersiloxane. Following dephenylchlorination with AlCl3/HCl, and hydrolysis enabled us to isolate the tetrahydroxyl tricyclic laddersiloxane in good yield. We repeated the similar reaction from this tetrahydroxyl laddersiloxane, and the first pentacyclic laddersiloxane was obtained. The structures of the tetraphenyl and tetrahydroxyl tricyclic laddersiloxanes, and pentacyclic laddersiloxane were determined by X-ray crystallography.     

Ligand design for the improvement of stability of metal complex.protein hybrids

We have succeeded in improving the stability of Fe(Schiff-base).heme oxygenase (HO) hybrids by ligand design based on the crystal structure of Fe(N,N'-bis(salicylidene)-3.4-diaminobenzene propionic acid).HO.