Novel chiral porphyrins with C2 symmetry

Described is the preparation of chiral octaethylporphyrin derivatives having two 2-substituted naphthyl groups in a trans orientation at the 5- and 15-meso positions and formyl or hydroxymethyl or alkoxymethyl group derived therefrom at the 10-meso position. One of the derivatives has been successfully resolved into enantiomers by means of HPLC.     

NMR and quantum chemical study on the OH...pi and CH...O interactions between trehalose and unsaturated fatty acids: implication for the mechanism of antioxidant function of trehalose

Trehalose is a disaccharide that attracts much attention as a stress protectant. In this study, we investigated the mechanism of the antioxidant function of trehalose. The spin-lattice relaxation times (T(1)) of (1)H and (13)C NMR spectra were measured to investigate the interaction between trehalose and unsaturated fatty acid (UFA). We selected several kinds of UFA that differ in the number of double bonds and in their configurations (cis or trans). Several other disaccharides (sucrose, maltose, neotrehalose, maltitol, and sorbitol) were also analyzed by NMR. The T(1) values for the (1)H and (13)C signals assigned to the olefin double bonds in UFA decrease with increasing concentration of trehalose and the changes reaches plateaus at integer ratios of trehalose to UFA. The characteristic T(1) change is observed only for the combination of trehalose and UFA with cis double bond(s). On the other hand, from the (13)C-T(1) measurements for trehalose, the T(1) values of the C-3 (C-3') and C-6' (C-6) are found to change remarkably by addition of UFA. (1)H[bond](1)H NOESY measurements provide direct evidence for complexation of trehalose with linoleic acid. These results indicate that one trehalose molecule stoichiometrically interacts with one cis-olefin double bond of UFA. Computer modeling study indicates that trehalose forms a stable complex with an olefin double bond through OH...pi and CH...O types of hydrogen bonding. Furthermore, a significant increase in the activation energy is found for hydrogen abstraction reaction from the methylene group located between the double bonds that are both interacting with the trehalose molecules. Therefore, trehalose has a significant depression effect on the oxidation of UFA through the weak interaction with the double bond(s). This is the first study to elucidate the antioxidant function of trehalose.     

Theoretical study on spin alignments in ferromagnetic heterospin chains with competing exchange interactions: a generalized ferrimagnetic system containing organic biradicals in the singlet ground state

Spin alignments in heterospin chains are examined from numerical calculations of model spin Hamiltonians. The Hamiltonians of the heterospin chains mimic an open-shell molecular assemblage composed of an organic biradical in a singlet (S = 0) ground state and a doublet (S = 1/2) monoradical, which are coupled by intermolecular ferromagnetic exchange interactions. It is found from numerical calculations of the spin Hamiltonians that the spin value S2 of the ground-state singlet biradical embedded in the exchange-coupled assemblage deviates from zero and contributes to the bulk magnetization. The alternating chain is found to have two kinds of ground spin states, a high- and a low-spin state. All the spins are parallel to each other in the high-spin state, which is characterized by the spin correlation function of (S(i).S(j)) = 0.25. On the other hand, the spin alignment in the low-spin state is found to be dependent on the topology of the intermolecular exchange interactions. The energy preference of the two states depends on the relative amplitude of the exchange interactions in the chain. The intermolecular ferromagnetic couplings are competing in the ground-state singlet biradical with the intramolecular antiferromagnetic interaction. The appearance of the two kinds of ground states is attributed to a quantum spin frustration effect inherent in the triangular motif of the competing interactions. Magnetic properties of a zigzag chain complex composed of a nitronyl nitroxide biradical with a singlet ground state and Cu(hfac)2 are examined on the basis of the theoretical calculations. The vanishing magnetic moments, or the product of susceptibility and temperature chiT, at low temperatures observed for the complex are consistent with those of the low-spin state predicted in the theoretical calculations.     

Function of the Reaction Center of Green Sulfur Bacteria

The reaction center (RC) of green sulfur bacteria belongs to the Fe-S type RC, as do the photosystem I of oxygenic photosynthetic organisms and the RC of heliobacteria. The core parts of the green sulfur bacterial and the heliobacterial RC are assumed to be homodimeric, in contrast to those of purple bacteria, photosystem I and photosystem II. This paper describes recent advances in the study of the function of the green sulfur bacterial RC.     

Site-specific cleavage of glycated human serum albumin in the presence of iron.

Nonenzymatically glycated human serum albumin was incubated with ferric ion at 37 degrees C in 0.2 M phosphate buffer, pH 7.4, up to 30 days. In the incubation mixture, amino acids, tyrosine and phenylalanine, were detected, suggesting site specific cleavage of glycated human serum albumin.     

Swelling of poly(N-isopropylacrylamide) gels in water-aprotic solvent mixtures

The swelling volume of poly(N-isopropylacrylamide) (PIPAAm) gel in aprotic solvents (acetonitrile (AcN)-, tetrahydrofuran (THF)-, 1,4-dioxane (DO)- and dimethylsulfoxide (DMSO))-water mixtures was measured at 25°C. The gel swollen in water shrank first and then reswelled with addition of the aprotic solvents. At an intermediate mole fraction (XDMSO) range of DMSO-water mixtures, the gel demonstrated a reentrant swelling phenomenon the hydrated gel shrank first on addition of a small amount of solvent, showed a typical wide reentrant transition, and gradually reswelled in the range near pure solvent. On the other hand, the gels in AcN-, THF-, and DO-water mixtures demonstrated a reentrant-convex swelling phenomenon: the gels reswelled after a reentrant phase transition in low Xorg (XAcN, XTHF and XDO), showed a maximum swelling in the intermediate Xorg region, and shrank again gradually in the high Xorg region. Such a swelling behavior of the gel was interpreted by correlating with solution properties of the aqueous aprotic solvent mixtures.The strength of hydrogen bonding around amide groups of the homopolymer was examined in pure solvents (water, THF, and DMSO) and in all proportion of aqueous THF to observe the relation with swelling behavior of gel by spectrum analysis of the amide I and II bands of Fourier Transform Infrared Spectroscopy (FT-IR). The swelling properties of gels in solvents and the aqueous mixtures were well correlated with the peak shifts of amide groups of the homopolymer.     

Structural difference between a superconducting sodium cobalt oxide and its related phase

Monolayer hydrate (MLH) Na_xCoO₂·y′H₂O was obtained from superconducting bilayer hydrate (BLH) Na_xCoO₂·yH₂O by partial extraction of H₂O molecules between the CoO₂ layers. Magnetization measurements indicated that electron densities in the CoO₂ layer of the MLH phase remained unchanged after the water extraction. Nevertheless, superconductivity was completely suppressed in the MLH phase. This strongly suggests that the highly 2D nature in the BLH phase due to its thick insulating layers consisting of H₂O molecules and Na⁺ ions plays an important role for inducing superconductivity.     

CO2 laser Stark spectroscopy of the Coriolis-coupled ν2 and ν5 bands of CD3Br

The ν₂ (CD₃ symmetrical deformation) and ν₅ (CD₃ degenerate deformation) fundamental bands of CD₃Br were studied by 9.4- and 10.4-μm CO₂ laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν₂ and ν₅ bands, respectively, were assigned for each of the isotopic species, CD₃⁷⁹Br and CD₃⁸¹Br. These two bands were simultaneously analyzed with explicit inclusion of the ν₂-ν₅ Coriolis interaction, yielding precise molecular constants in the ν₂ and ν₅ excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are

     

59.

Isolation of heptadepsin, a novel bacterial cyclic depsipeptide that inhibits lipopolysaccharide activity     

Ohno O  Ikeda Y  Sawa R  Igarashi M  Kinoshita N  Suzuki Y  Miyake K  Umezawa K 《Chemistry & biology》2004,11(8):1059-1070

Lipopolysaccharide (LPS) is considered to cause various inflammatory reactions. We searched among microbial secondary metabolites for compounds that could inhibit LPS-stimulated adhesion between human umbilical vein endothelial cells (HUVEC) and human myelocytic cell line HL-60 cells. In the course of our screening, we isolated a novel cyclic depsipeptide, which we named heptadepsin, from the whole culture broth of Paenibacillus sp. The addition of heptadepsin prior to LPS stimulation decreased HL-60 cell-HUVEC adhesion without showing any cytotoxicity. It also inhibited the cellular adhesion induced by lipid A, the active component of LPS, but it did not inhibit TNF-alpha or IL-1beta-induced cell adhesion. The result of surface plasmon resonance (SPR) analysis revealed that heptadepsin interacted with lipid A directly. Thus, heptadepsin, a novel naturally occurring cyclic heptadepsipeptide, was shown to inactivate LPS by direct interaction with LPS.     

60.

Study on Segmental Motion and Ion Binding in Polyelectrolyte Solutions by Ultrasonic Spectroscopy     

S. Koda  Y. Sugi  T. Sakurai  T. Matsuoka  H. Nomura 《Journal of solution chemistry》2004,33(6-7):747-760

The ultrasonic absorption spectra of aqueous solutions of polyacrylate (PA), polyphosphate (PP), and polystyrenesulfonate (PSS), neutralized by tetramethylammonium hydroxide (TMAOH), were measured. The effects of addition of tetramethylammonium chloride (TMACl) and sodium chloride (NaCl) to the polyelectrolyte solutions were investigated in the frequency range from 500 kHz to 100 MHz. Two ultrasonic relaxation processes due to the local segmental motions were observed. The relaxation frequency for TMAPP solution decreased as the ionic strength was increased by the addition of TMACl. For the other two polymer solutions, the ionic strength did not affect the relaxation spectra. The addition of NaCl led to an increase of the ultrasonic absorption, which was ascribed to ion binding. The ultrasonic absorption due to the ion binding was estimated by subtracting the contribution of the segmental motion from the measuring ultrasonic spectra. The volume changes accompanying the ion binding for polyacrylate and polyphosphate salts were estimated to be 5 and 8 cm³-mol^?1, respectively.     

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		CD379Br		CD381Br
$\text{ν}{}_2$		991.396 82 (18)		991.388 46 (17)		cm?1
$\text{ν}{}_5$		1055.469 00 (12)		1055.466 32 (12)		cm?1
$\text{μ}{}_0$		1.830 42 (52)		1.829 84 (47)		D
$\text{μ}{}_2$		1.829 93 (48)		1.829 57 (46)		D
$\text{μ}{}_5$		1.832 23 (60)		1.831 19 (56)		D

Isolation of heptadepsin, a novel bacterial cyclic depsipeptide that inhibits lipopolysaccharide activity

Lipopolysaccharide (LPS) is considered to cause various inflammatory reactions. We searched among microbial secondary metabolites for compounds that could inhibit LPS-stimulated adhesion between human umbilical vein endothelial cells (HUVEC) and human myelocytic cell line HL-60 cells. In the course of our screening, we isolated a novel cyclic depsipeptide, which we named heptadepsin, from the whole culture broth of Paenibacillus sp. The addition of heptadepsin prior to LPS stimulation decreased HL-60 cell-HUVEC adhesion without showing any cytotoxicity. It also inhibited the cellular adhesion induced by lipid A, the active component of LPS, but it did not inhibit TNF-alpha or IL-1beta-induced cell adhesion. The result of surface plasmon resonance (SPR) analysis revealed that heptadepsin interacted with lipid A directly. Thus, heptadepsin, a novel naturally occurring cyclic heptadepsipeptide, was shown to inactivate LPS by direct interaction with LPS.     

Study on Segmental Motion and Ion Binding in Polyelectrolyte Solutions by Ultrasonic Spectroscopy

The ultrasonic absorption spectra of aqueous solutions of polyacrylate (PA), polyphosphate (PP), and polystyrenesulfonate (PSS), neutralized by tetramethylammonium hydroxide (TMAOH), were measured. The effects of addition of tetramethylammonium chloride (TMACl) and sodium chloride (NaCl) to the polyelectrolyte solutions were investigated in the frequency range from 500 kHz to 100 MHz. Two ultrasonic relaxation processes due to the local segmental motions were observed. The relaxation frequency for TMAPP solution decreased as the ionic strength was increased by the addition of TMACl. For the other two polymer solutions, the ionic strength did not affect the relaxation spectra. The addition of NaCl led to an increase of the ultrasonic absorption, which was ascribed to ion binding. The ultrasonic absorption due to the ion binding was estimated by subtracting the contribution of the segmental motion from the measuring ultrasonic spectra. The volume changes accompanying the ion binding for polyacrylate and polyphosphate salts were estimated to be 5 and 8 cm³-mol^?1, respectively.