The effects of new cytochalasins from Phomopsis sp. and the derivatives on cellular structure and actin polymerization

The effects of ten 10-phenyl-[11]cytochalasins produced by Phomopsis sp. including novel compounds having 5,7- or 6,7-glycol structures and their derivatives, on the cell morphology and actin distribution in C3H-2K cells, as well as on lymphocyte capping and actin polymerization, were examined. The structure-activity relationship reported in the previous papers has been confirmed. The novel glycol type compounds showed little or no activity, suggesting the importance of the perhydroisoindol-1-one nucleus for the manifestation of the cytochalasin actions.     

Asymmetric selective polymerization of racemic 1,2-diphenylethyl methacrylate with the ethylmagnesium bromide-(−)-sparteine complex

Asymmetric selective (or stereoelective) polymerization of racemic 1,2-diphenylethyl methacrylate (DPEMA) with ethylmagnesium bromide (EtMgBr)-(?)-sparteine catalyst was studied in toluene at ?78°C. In the polymerization (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized DPEMA was greater than 90%. Optically pure (R) monomer was recovered at about 70% polymer yield. Poly(DPEMA) obtained with EtMgBr-(?)-sparteine complex was highly isotactic. It was found in the polymerization of optically active DPEMA that optical rotation of poly(DPEMA) was dependent on the tacticity and that isotactic and syndiotactic poly(DPEMA)s showed opposite optical rotations. Circular dichroism spectra of the optically active polymers were measured.     

Essential structure of co-pigment for blue sepal-color development of hydrangea

Blue sepal-color of Hydrangea macrophylla might be due to a supramolecular metal-complex pigment consisting of delphinidin 3-glucoside (1), co-pigments (5-O-caffeoylquinic acid (2), and/or 5-O-p-coumaroylquinic acid (3)) and Al³⁺ in an aqueous solution around pH 4.0. To clarify the mechanism of blue sepal-color development of hydrangea, we tried to reproduce the blue color in vitro by mixing 1 with designed synthetic co-pigments in the presence of Al³⁺ at pH 4.0. We at first succeeded in clarifying the essential functional structure in the co-pigment that could form the stable blue solution. Here, we present the structure of the blue pigment caused by an Al-complex coordinating of 1 at ortho-dihydroxyl groups of the B-ring, 1-hydroxy, 1-carboxylic acid, and the carbonyl residue in the ester at 5-position of 2 and/or 3. The hydrophobic interaction between the aromatic acyl residue at 5-position and the nucleus of 1 may also contribute to stabilize the complex.     

Enantioselective phenyl transfer to aldehydes using 1,1′-bi-2-naphthol-3,3′-dicarboxamide as chiral auxiliary

N,N,N′,N′-Tetra-n-butyl-BINOL-3,3′-dicarboxamide 5d was found to promote phenyl transfer from ethylphenylzinc to both aromatic and aliphatic aldehydes with high enantioselectivity up to 96% ee in tert-butyl methyl ether.     

Origin of enhancement in open-circuit voltage by adding ZnO to nanocrystalline SnO2 in dye-sensitized solar cells

SnO2 + ZnO working electrodes for dye-sensitized solar cells were made by mixing a nanocrystalline SnO2 colloidal dispersion with ZnO or Zn(CH3COO)2. Addition of ZnO or Zn(CH3COO)2 enhanced the open-circuit voltage (V(oc)) of the cells with respect to cells containing only SnO2. Dependence of the electron lifetime in the electrodes on short-circuit photocurrent density (J(sc)) gave evidence against the assumption that the suppression of back electron transfer to the electrolyte is the origin for the V(oc) enhancement by addition of Zn. V(oc) dependence on temperatures indicated a decrease in the combined capacitance of the mixed electrode. The slope of the V(oc) dependence versus the logarithm of J(sc) indicated that the contribution of unpinning of the band to the enhancement of V(oc) could be neglected. From the cyclic voltammograms of the electrodes, the combined capacitance of the mixed electrode was 1 order of magnitude smaller than that of SnO2. The decrease in the combined capacitance in the mixed electrode could be explained by the decrease in the chemical capacitance of SnO2, thus the shift of the conduction band position toward the vacuum level. X-ray photoelectron spectra of Sn 3d(5/2) peaks showed a shift toward lower binding energy with an increasing amount of added Zn. This was attributed to an increase in the surface potential toward the negative direction, which might have resulted from a dipole moment formed by Zn on the surface of SnO2.     

Electronic structure of brain: structure-activity relationships between electronic structure and neurotransmitters based on molecular hardness concept

In order to understand the relation between the electronic structure of neurotransmitters and the brain, a model of the brain based on absolute hardness (eta) and absolute electronegativity (chi) is described. It was found that the coordinate r(chi, eta) of electronic structures of neurotransmitters obtained using the parameters eta and chi can be graphically classified into three groups: catecholamine type (group I), gamma-aminobutanoic acid (GABA) type (group II), and acetylcholine (ACh) type (group III) in the eta-chi diagram. The results suggest that the brainstem and neocortex in the brain are chemically soft and hard, respectively, because they show that the myelinated nerve is chemically soft and the unmyelinated nerve is chemically hard. If one calculates the r(chi, eta) to understand which group a drug belongs to, one can predict the target receptors of the drug from the eta-chi diagram. Using eta-chi maps, one is then able to design medications like antidepressants, tranquilizers, and ACh agonists.     

Rapid chemiluminescence measurements by digital processing of signals and smoothing by fourier transform

Smoothing by Fourier transform of data obtained with a laboratory-built rapid injection device is shown to be useful for peak-height measurements of the chemiluminescence rapidly produced by luminol catalyzed by hemin (t_{$\text{1}\text{2}$} = 0.28 s); the observation time was 0.25 s. An algorithm prepared for the smoothing of data comprising a single peak is three times faster than the corresponding fast Fourier transform program and permits real-time processing. The principles of the rapid measurement are also applied to slower luminol chemiluminescence continuing for >40 s; the measurement needed just 0.5 s.     

Nuclear magnetic resonance studies of isoprenyllithium derived from 1,1-diphenyl-n-butyllithium-3,4-d5, and isoprene

The equimolar reactions of 1,1-diphenyl-n-butyllithium-3,4-d₅ (RLi) with isoprene (I) and isoprene-1,4-d₄ (Id) were carried out in benzene-d₆ quantitatively to give isoprenyllithiums, RILi and RIdLi, respectively. From the NMR spectrum of the RILi it was proposed that the isoprene unit had cis-1,4, cis-4,1 and some unknown structures in benzene-d₆. When RILi was prepared in the presence of about one equivalent of THF to RILi, the anion was considered to include an isoprene unit in cis-1,4, trans-1,4, cis-4,1, and probably 3,4 structures. The same anion was obtained even if an equimolar THF was added afterward to the RILi prepared in benzene-d₆ The RLi was reproduced by the reverse reaction from RILi, when a large excess of THF was added or the temperature of the solution was elevated. The results obtained were correlated with those of anionic polymerizations of isoprene by lithium initiators.     

Selective colorimetric determination of p-haloaniline in a mixture witho-haloaniline by the reaction with chloranil

Summary p-Haloanilines react with chloranil to develope an intense color (_max: 545 nm), whileo-haloanilines do not. This difference in reaction has been applied to the selective determination ofp-haloanilines in a mixture witho-haloaniline.

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Zusammenfassung p-Halogenaniline geben mit Chloranil eine intensive Farbreaktion (_max= =545 nm), während die entsprechenden o-Verbindungen dies nicht tun. Auf dieser Grundlage wurde eine selektive Bestimmungsmethode für p-halogenierte Aniline in Gemischen mit o-halogenierten Anilinen ausgearbeitet.

     

Asymmetric polymerization of triphenylmethyl methacrylate by optically active anionic catalysts

Triphenylmethyl methacrylate (TrMA) was polymerized with two types of asymmetric anionic catalyst, lithium (R)-N-(1-phenylethyl)anilide (LiAn) and (-)-sparteine–butyllithium complex (Sp–BuLi), at ?78°C. Both catalysts yielded optically active polymers. The polymers obtained with LiAn in toluene and tetrahydrofuran (THF) showed specific rotations [α] of from ?50° to ?90° (in THF). The [α] of the polymer obtained with Sp–BuLi in toluene was positive and increased with polymer yield reaching above +300°s, whereas the polymer obtained in THF showed a low [α] (ca. +7°). Gel permeation chromatograms of both polymers obtained with LiAn and Sp–BuLi in THF exhibited rather narrow molecular weight distributions, whereas those obtained in toluene showed at least two or three components with markedly different molecular weights. The circular dichroism (CD) spectrum of the polymer obtained with Sp–BuLi showed strong positive peaks at 208 and 232 nm and a weak band at 250–280 nm; the polymer produced with LiAn showed a similar spectrum with opposite sign. The poly(methyl methacrylate)s derived from these poly(TrMA)s were highly isotactic but showed negligible rotations ([α] ± 2° in toluene). The polymer of high molecular weight showed clear polarization under a polarizing microscope and the low polymer obtained with LiAn appeared to show flow birefringence in chloroform at room temperature.