Two New Triterpene Saponins from Acanthophyllum laxiusculum

Two new triterpene glycosides, 1 and 2 , together with three known ones, were isolated from roots of Acanthophyllum laxiusculum Schiman ‐Czeika . The structures of the new compounds were established by extensive 1D‐ and 2D‐NMR spectroscopic experiments and MS analyses as 23‐O‐β‐D ‐galactopyranosylgypsogenic acid 28‐O‐{β‐D ‐glucopyranosyl‐(1→2)‐6‐O‐[4‐carboxy‐3‐hydroxy‐3‐methyl‐1‐oxobutyl]‐β‐D ‐glucopyranosyl‐(1→6)}‐[β‐D ‐glucopyranosyl‐(1→3)]‐β‐D ‐galactopyranosyl ester ( 1 ) and gypsogenic acid 28‐O‐{β‐D ‐glucopyranosyl‐(1→2)‐6‐O‐[4‐carboxy‐3‐hydroxy‐3‐methyl‐1‐oxobutyl]‐β‐D ‐glucopyranosyl‐(1→6)}‐[β‐D ‐glucopyranosyl‐(1→3)]‐β‐D ‐galactopyranosyl ester ( 2 ).     

Secondary metabolites from the roots of Paronychia chionaea

Two novel secondary metabolites, compounds (1-2) were isolated from the roots of Paronychia chionaea. On the basis of spectroscopic data including 1D and 2D NMR experiments (COSY, TOCSY, HSQC, and HMBC), and mass spectroscopy, their structures were established as 6-C-[alpha-L-arabinopyranosyl-( 1 --> 2)-beta-D-glucopyranosyl]-7-O-[beta-D-glucopyranosyl]-luteolin 3'-methyl ether (1), and 2-(methoxy)-2-(3,5-dimethoxy 4-hydroxyphenyl)-ethane-1,2-diol 1-O-beta-D-glucopyranoside (2).     

New Acylated Presenegenin Saponins from Two Species of Muraltia

Six new acylated bisdesmosidic triterpene glycosides 1 – 6 were isolated from the roots of Muraltia heisteria (L.) DC., as three inseparable mixtures 1 / 2, 3 / 4 , and 5 / 6 of the (E)‐ and (Z)‐3,4,5‐trimethoxycinnamoyl derivatives. The compound pair 1 / 2 along with four known saponins were also isolated from the roots of Muraltia satureioides DC. Their structures were elucidated mainly by spectroscopic experiments including 2D‐NMR techniques as 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐β‐D ‐apiofuranosyl‐(1→3)‐O‐[β‐D ‐xylopyranosyl‐(1→4)]‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[6‐O‐acetyl‐β‐D ‐galactopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4,5‐trimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 1 ) and its (Z)‐isomer 2 , 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐6‐O‐acetyl‐β‐D ‐galactopyranosyl‐(1→3)‐O‐[3‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)]‐4‐O‐[(E)‐3,4,5‐trimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 3 ) and its (Z)‐isomer 4 , and 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐3‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[β‐D ‐xylopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4,5‐trimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 5 ) and its (Z)‐isomer 6 , respectively.     

Consecutive elongation of alanine oligopeptides at the second time range under hydrothermal conditions using a microflow reactor system

During the course of the study of the hydrothermal stability of alanine oligopeptides, a small amount of oligopeptides longer than the starting oligopeptides was found in the reaction products. On the basis of this unexpected finding and the investigation of the reaction mechanism, the elongation of oligopeptides using (Ala)3, (Ala)4, and (Ala)5 was attempted in aqueous solution at 275-310 degrees C within the second time range using a microflow reactor system. The elongation of (Ala)4 and (Ala)5 succeeded in the presence of an excess amount of Ala monomer. This is probably due to the fact that the elongation rate is competitive or somewhat faster than the degradation of peptide bonding. On the contrary, the elongation of (Ala)3 was not possible since it was immediately converted to diketopiperazine.     

Fluorescence enhancement by hydroperoxides based on a change in the intramolecular charge transfer character of benzofurazan

Strong fluorescence signals were observed after the reaction of novel reagents with hydroperoxides.     

Synthesis and properties of a new fluorescent bicyclic 4-N-carbamoyldeoxycytidine derivative

[reaction: see text] A bicyclic 4-N-carbamoyldeoxycytidine derivative (1, dC(hpp)) geometrically locked was synthesized as a new fluorescent nucleobase. The hybridization properties of oligodeoxynucleotides containing dC(hpp) were investigated by use of T(m) analysis. It was found that dC(hpp) forms stable base pairs not only with the complementary guanine base, but also with the adenine base. Interestingly, the fluorescence of dC(hpp) was suppressed only when a dC(hpp)-dG base pair was formed.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

Strangeness Nuclear Physics at J-PARC

After the big earthquake in the east part of Japan on March 11, 2011, the beams in the hadron experimental hall at J-PARC have been successfully recovered in February, 2012. The experimental program using pion beams is now on-going with the primary proton beam power of ~5 kW. Before a long summer shutdown scheduled in 2013, several experiments in strangeness nuclear physics are going to take data. In this period, we anticipate the beam power would exceed 10 kW and the experiments to use K ^? beams will start. The experimental program is explained briefly.     

Fluorescence determination of N-acetylaspartic acid in the rat cerebrum homogenate using high-performance liquid chromatography with pre-column fluorescence derivatization

N-acetyl-L-aspartic acid (NAA) is an endogenous compound, and its brain concentration is suggested to be altered in neurological disorders. In the present study, a fluorescence determination method for NAA was developed by employing reversed-phase high-performance liquid chromatography (HPLC) with pre-column fluorescence derivatization using 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Using methylsuccinic acid as the internal standard, a linear calibration curve for NAA was constructed in the range 125-1000 microM (n=3). The detection limit on the column was approximately 5.0 fmol (signal-to-noise ratio 3). The proposed HPLC method was applied to determine NAA in the rat cerebrum homogenate. Cerebrum NAA was successfully determined using 10 microL of the homogenate, and the validation data for the proposed HPLC method demonstrated satisfactory results. Intra- and inter-day precision and accuracy were within 1.1-7.0 and -8.1-6.3%, respectively. The concentration of NAA in the male rat cerebrum (13 weeks old) was 84+/-4.6 micromol/mg protein (n=3).     

Orbital views of the electron transport in molecular devices

Extended pi-conjugated molecules are interesting materials that have been studied theoretically and experimentally with applications to conducting nanowire, memory, and diode in mind. Chemical understanding of electron transport properties in molecular junctions, in which two electrodes have weak contact with a pi-conjugated molecule, is presented in terms of the orbital concept. The phase and amplitude of the HOMO and LUMO of pi-conjugated molecules determine essential properties of the electron transport in them. The derived rule allows us to predict single molecules' essential transport properties, which significantly depend on the type of connection between a molecule and electrodes. Qualitative predictions based on frontier orbital analysis about the site-dependent electron transport in naphthalene, phenanthrene, and anthracene are compared with density functional theory calculations for the molecular junctions of their dithiolate derivatives, in which two gold electrodes have strong contact with a molecule through two Au-S bonds.