Marked production of ginsenosides Rd, F2, Rg3, and compound K by enzymatic method

The hydrolysis of protopanaxadiol-type saponin mixture by various glycoside hydrolases was examined. Among these enzymes, crude preparations of lactase from Aspergillus oryzae, beta-galactosidase from A. oryzae, and cellulase from Trichoderma viride were found to produce ginsenoside F(2) [3-O-(beta-D-glucopyranosyl)-20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol], compound K [20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol], and ginsenoside Rd {3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol}, respectively, from protopanaxadiol-type saponin mixture in large quantities. Moreover, the crude preparation of lactase from Penicillium sp. having a high producing activity of ginsenoside Rh(1) (6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol) from protopanaxatriol-type saponin mixture gave ginsenoside Rd as a main product, ginsenoside Rg(3) {3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-20(S)-protopanaxadiol}, and compound K from protopanaxadiol-type saponin mixture. The hydrolytic pathways of ginsenosides Rb(1), Rb(2), and Rc to ginsenosides Rd, Rg(3), and F(2), and compound K by crude preparations of four glycoside hydrolases were also studied. This is the first report on the enzymatic preparation of an intestinal bacterial metabolite, ginsenoside F(2), in quantity, and a considerable amount of a minor saponin, ginsenoside Rg(3), from a protopanaxadiol-type saponin mixture.     

Mechanochemical synthesis of chromium tris(2-ethylhexanoate) and evaluation of its catalytic activity in the reaction of ethylene trimerization

A method was developed for synthesis of chromium(III) tris(2-ethylhexanoate) by the mechanochemical interaction of chromium(III) chloride with sodium 2-ethylhexanoate without a solvent, followed by heating of the reaction mixture. The influence exerted by the conditions of the mechanical activation and the subsequent thermal treatment on the course of the processes and some properties of activated mixtures was studied. Chromium(III) tris(2-ethylhexanoate) can be isolated from the reaction mixture in a ～75% yield. Both the activated reaction mixture and the target product obtained exhibit a high catalytic activity and selectivity in the reaction of ethylene trimerization.     

Enzymatic preparation of ginsenosides Rg2, Rh1, and F1

During investigation of the hydrolysis of a protopanaxatriol-type saponin mixture by various glycoside hydrolases, crude preparations of beta-galactosidase from Aspergillus oryzae and lactase from Penicillium sp. were found to produce two minor saponins, ginsenoside Rg(2) [6-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl)-20(S)-protopanaxatriol] and ginsenoside Rh(1) (6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), respectively, in high yields. Moreover, a naringinase preparation from Penicillium decumbens readily gave an intestinal bacterial metabolite, ginsenoside F(1) (20-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), as the main product, with a small amount of 20(S)-protopanaxatriol from a protopanaxatriol-type saponin mixture. Also, a hesperidinase from Penicillium sp. selectively hydrolyzed ginsenoside Re into ginsenoside Rg(1). This is the first report on the enzymatic preparation of minor saponins, ginsenosides Rg(2) and Rh(1), and of an intestinal bacterial metabolite, ginsenoside F(1), with high efficiency from a protopanaxatriol-type saponin mixture.     

Powder coating mixture of a novel anxiolytic, Y-23684: dissolution characteristics and bioavailability.

A powder coating mixture was investigated with a view toward improving the dissolution property of the anxiolytic 2-(4-chlorophenyl)-5,6-dihydro-[1]benzo-thiepino-[5,4-c]-pyrida zin-3(2H)-one 7-oxide (1), which was barely water soluble. The powder coating mixture in various ratios of 1 and cornstarch was prepared in an automated mortar. Among these mixtures, at the optimum ratio of 1 and cornstarch (2:1, 67% drug content), the powder coating mixture gave a maximized effect for solubilizing 1 on the bases of stability and solubility. Conventional granules were made from the 67% powder coating mixture. The granules showed an excellent absorption profile in beagle dogs. The mechanism of the solubilizing effect resulting from a pharmaceutical process was also discussed.     

In situ synthesis of platelet graphite nanofibers from thermal decomposition of poly(ethylene glycol)

Platelet graphite nanofibers (PGNFs) were synthesized by in situ thermal decomposition from a mixture containing poly(ethylene glycol) (PEG) serving as the carbon source and nickel chloride (NiCl(2)) serving as the catalytic precursor. The mixture was conducted by thermal treatment under a nitrogen atmosphere at 750 degrees C and results found PGNFs with high purity and a uniform diameter distribution formed without hydrocarbon gases in the process. Observations using field-emission scanning electron microscopy and high-resolution transmission electron microscopy revealed PGNFs with a high degree of graphitization, well-ordered graphene layers, and uniform diameters of 10-20 nm. Thermogravimetry-differential scanning calorimetry-mass spectrometry was employed to study the thermal decomposition phenomena of the mixture (PEG/NiCl(2)) before the thermal process. The analysis clarified the in situ synthesis growth mechanism of PGNFs from the mixture.     

Selective extraction of higher fullerenes using cyclic dimers of zinc porphyrins

Higher fullerenes (>/=C76) were selectively extracted from a fullerene mixture obtained from a combustion-based industrial production source by cyclic dimers of beta-unsubstituted porphyrin zinc complexes 2C5-2C7 with C5-C7 alkylene spacers as host molecules. Results of single extraction of the fullerene mixture with 2C5-2C7 together with a beta-substituted analogue of 2C6 (1C6) and spectroscopic titration of 2C6 and 1C6 with C60, C70, and C96 indicated that the host selectivity toward higher fullerenes is much dependent on the structure of the porphyrin units and the size of the host cavity. Sequential three-stage extraction of the fullerene mixture with the best-behaved 2C6 resulted in considerable enrichment in very rare fullerenes C102-C110 (<0.1 abs %) up to 82 abs % (C76-C114, 99 abs %) (356 nm) of total fullerenes.     

Molecular simulation of the binary mixture of 1-1-1-2-tetrafluoroethane and carbon dioxide

The refrigerant 1-1-1-2-tetrafluoroethane (R134a) is being phased out in Europe from 2011. This requires the adoption of alternatives, and the mixture of R134a with carbon dioxide (CO(2)) is a promising candidate. However, limited experimental data currently stymie evaluation of its performance in industrial applications. In this paper, we employ atomistic force fields and the configurational-bias Monte Carlo technique to study the vapour-liquid equilibrium of this mixture. We also characterize the microscopic structure of the mixture, which is not readily available from experiments. At 272 K and 11.55 bar, the average coordination number of the first solvation shell of R134a is 11 and that of CO(2) is eight. CO(2) does not alter the structure of R134a, but its structure is slightly changed, due to the presence of R134a. All pair interactions are sensitive to pressure and are more structured at lower pressure. CO(2) prefers to form clusters of two in the mixture and highly extended or percolating clusters are not found.     

Formation of Tetrahydrofuran Derivatives and Acetonylation of Alkenes Using Carbon Radicals Derived from Manganese(III) Oxidation of Diketene

Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed.     

3-氨基-4-硝基呋咱和3,3’-二硝基-4,4’-偶氮呋咱的合成研究

3-氨基-4-硝基呋咱(ANF)及其衍生物是一类重要的含能材料. ANF的制备首先以乙二醛、盐酸羟胺和氢氧化钠为原料, 经过两步反应制得3,4-二氨基呋咱(DAF), 采用新的氧化体系过氧化氢/甲烷磺酸/钨酸钠混合物(H2O2/CH3SO3H/ Na2WO4)代替原氧化体系过氧化氢/硫酸/过硫酸铵混合物[H2O2/H2SO4/(NH4)2S2O8]氧化DAF以67%的产率获得了ANF. 然后在单电子氧化体系高锰酸钾/盐酸混合物作用下ANF发生氧化反应以54.7%的产率得到3,3’-二硝基- 4,4’-偶氮呋咱(DNAzF). 研究表明过氧化氢/甲烷磺酸/钨酸钠混合物是制备氨基硝基单/多呋咱非常有效的氧化体系.     

Selective determination of surface density of bromide ion through XAFS and its application to verification of a criterion of an ideal mixing of surfactant mixture

The mole fraction of chloride ion of dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) mixture in the adsorbed film XHC was estimated not only by the thermodynamic analysis of the surface tension data but also by analyzing the Br K-edge jump of the XAFS spectrum under the total reflection condition (TRXAFS method). The phase diagrams of adsorption (PDA) at several surface tensions from the two methods were in good agreement. On the basis of the PDA obtained, it was clearly shown that the criterion of an ideal mixing for the DTAB-DTAC system is not given by the linear relation between the total molality of surfactant mixture m and XHC, m = m0B + (m0C - m0B)XHC, but by the one between m2 and XHC, m2 = (m0B)2 + [(m0C)2 - (m0B)2]XHC. Furthermore, it was demonstrated that the theoretical approach that provides the latter relation draws a distinction between the criteria for an ionic surfactant mixture without a common ion and that for an ionic surfactant mixture with a common ion.     

Spectrophotometric analysis of simultaneous protolysis equilibria

Simultaneous protolysis equilibria can be spectrophotometrically analysed easily by means of absorbance diagrams. The dissociation constants K(1) and K(2) can be determined directly from distinct points on the absorbance diagram by correlation with a photometric titration plot of absorbance vs. pH. Furthermore, from the absorbance diagram the ratio K (2)K (1) can be evaluated from the ratio of corresponding sides, and pH-measurement is not necessary. The titration systems of a mixture of 2-nitroso-l-naphthol-4-sulphonic acid with P-nitrophenol, and a mixture of P-nitrophenol with o-nitrophenol have been analysed by these methods, and are described as examples.     

Selection between pinching-type and supramolecular polymer-type complexes by alpha-cyclodextrin-beta-cyclodextrin hetero-dimer and hetero-cinnamamide guest dimers

Novel supramolecular complexes have been prepared from an alpha-cyclodextrin-beta-cyclodextrin hetero-dimer (alpha-CD-beta-CD hetero-dimer) and hetero-cinnamamide guest dimers, G-t-Boc and G-NH2, having adamantyl groups in aqueous solutions. On addition of the competitive guest, the supramolecular structure formed by a mixture of the alpha-CD-beta-CD hetero-dimer and G-t-Boc was found to be different from that of a mixture of the alpha-CD-beta-CD hetero-dimer and G-NH2 by the 1H NMR spectroscopy, the ROESY NMR spectroscopy, and the circular dichroism spectroscopy. The size of the supramolecular complex from the mixture of the alpha-CD-beta-CD hetero-dimer and G-NH2 is larger than that from the mixture of the alpha-CD-beta-CD hetero-dimer and G-t-Boc, which was proved by the pulse field gradient spin-echo NMR and the atomic force microscopy. These results suggest that the mixture of the alpha-CD-beta-CD hetero-dimer and G-t-Boc formed a pinching-type complex, and the mixture of the alpha-CD-beta-CD hetero-dimer and G-NH2 formed a supramolecular polymer-type complex.     

A modification of the Doong-Yang model for gas mixture adsorption using the lewis relationship

The Doong-Yang model, which is used for predicting gas mixture adsorption equilibrium from pure-component isotherms of the Dubinin type, is modified by incorporating the Lewis relationship. The modified model is tested against experimental data for four binary systems, including a like-component (or nearly ideal) mixture, CH(4) + C(2)H(6), a moderately nonideal mixture, CO(2) + C(2)H(4), and two highly nonideal mixtures, CO(2) + C(3)H(8) and CO(2) + H(2)O. Comparisons are made with the ideal adsorbed solution (IAS) theory and the Bering model. Results show that the proposed model is the best for the like-component mixture and the moderately nonideal mixture. In contrast, for the highly nonideal mixtures, the original Doong-Yang model is the only one among the four models that can predict CO(2) + C(3)H(8) adsorption correctly. The IAS theory and the Bering model have similar predictions and are suitable only for like-component mixtures. The new model requires a simple numerical iteration but is easy to use; no new parameters are required. Theoretical reasons are given for the fact that the original Doong-Yang model is best for nonideal mixtures, whereas the modified Doong-Yang model is best for ideal mixtures.     

Simultaneous de novo identification of molecules in chemical mixtures by doubly indirect covariance NMR spectroscopy

The detailed characterization of complex molecular mixtures plays a key role in many areas of modern Chemistry. Here we report a novel NMR spectroscopic method that deconvolutes a complex mixture of organic molecules simultaneously into individual components and depicts their chemical structure without requiring physical separation of the components. Doubly indirect covariance spectroscopy is introduced and applied to 2D (13)C-(1)H HSQC and 2D (1)H-(1)H COSY spectra, which results in a (13)C-(13)C 2D spectrum with unprecedented high resolution. This reconstituted spectrum is indeed a carbon-connectivity map that can be directly analyzed with basic graph theory to obtain the skeletal structures of individual mixture components or their fragments. The method is demonstrated for a model mixture and a natural product mixture extracted from cancer cells. Its suitability for automation makes this approach attractive for the analysis of a broad range of mixtures of natural or synthetic products.     

Separation of a CaCl2-HCl Model Mixture on Neutral Nanoporous Hypercrosslinked Polystyrene under Static and Dynamic Conditions

The distribution of CaCl₂ and HCl (separately and in a mixture) between the aqueous and nanoporous hypercrosslinked polystyrene sorbent phases was studied under static conditions. It was shown that virtually the whole pore volume of the sorbent was accessible to HCl, whereas CaCl₂ was largely excluded from small pores. It was found that the distribution isotherms of the electrolytes between the phases changed significantly in going from the pure electrolytes to their mixture. Under dynamic (chromatographic) conditions, the elution profiles of CaCl₂ and HCl (separately and in a mixture) were studied. It was shown that the components of the mixture competed for the pore space of the sorbent: small HCl molecules were displaced from large pores and the interstitial space into small pores inaccessible to CaCl₂. (This is why the retention of HCl in the chromatography column significantly increased as the concentration of the mixture grew; that is, both the efficiency and selectivity of separation increased as the column became loaded heavier.) It was found that the degree of hydration of ions decreased as the concentration of the solution increased.     

Computational Study of Adsorption and Separation of CO(2), CH(4), and N(2) by an rht-Type Metal-Organic Framework

In this work, a computational study is performed to evaluate the adsorption-based separation of CO(2) from flue gas (mixtures of CO(2) and N(2)) and natural gas (mixtures of CO(2) and CH(4)) using microporous metal organic framework Cu-TDPAT as a sorbent material. The results show that electrostatic interactions can greatly enhance the separation efficiency of this MOF for gas mixtures of different components. Furthermore, the study also suggests that Cu-TDPAT is a promising material for the separation of CO(2) from N(2) and CH(4), and its macroscopic separation behavior can be elucidated on a molecular level to give insight into the underlying mechanisms. On the basis of the single-component CO(2), N(2), and CH(4) isotherms, binary mixture adsorption (CO(2)/N(2) and CO(2)/CH(4)) and ternary mixture adsorption (CO(2)/N(2)/CH(4)) were predicted using the ideal adsorbed solution theory (IAST). The effect of H(2)O vapor on the CO(2) adsorption selectivity and capacity was also examined. The applicability of IAST to this system was validated by performing GCMC simulations for both single-component and mixture adsorption processes.     

Investigation of the Compatibility of a Multi-Component TN Liquid Crystal Mixture and a Multi-Component Cholesteric Liquid Crystal Mixture by DSC

The phase transition curves of a multi-component TN liquid crystal mixture (TN 88-1) and a multi-component cholesteric liquid crystal mixture (Ch 88-2) were plotted by using a differential scanning calorimeter. The phase transition temperature and phase transition heat were obtained from the DSC curves. The results show that the components of TN 88-1 are compatible and they can form a stable mixture with CB 15 chiral liquid crystal. The components of Ch 88-2 are not compatible and Poly (MMA-BMA) can greatly improve their compatibility. This revised version was published online in July 2006 with corrections to the Cover Date.     

Atropisomeric myristinins: selective COX-2 inhibitors and antifungal agents from Myristica cinnamomea

The first naturally occurring atropisomeric flavans, myristinins B (2), C (2a), E (4), and F (4a), together with their corresponding trans-isomers, myristinins A (1) and D (3), were isolated from the CH(2)Cl(2) extract of Myristica cinnamomea fruits. Compounds 1, the mixture of 2 and 2a, and the mixture of 4 and 4a, exhibited antifungal activity against Candida albicans with IC(50) values ranging from 5.9 to 8.8 microg/mL, and they selectively inhibited the enzyme cyclooxygenase-2 (COX-2).     

Molecular insight into the high selectivity of double-walled carbon nanotubes

Combining experimental knowledge with molecular simulations, we investigated the adsorption and separation properties of double-walled carbon nanotubes (DWNTs) against flue/synthetic gas mixture components (e.g. CO(2), CO, N(2), H(2), O(2), and CH(4)) at 300 K. Except molecular H(2), all studied nonpolar adsorbates assemble into single-file chain structures inside DWNTs at operating pressures below 1 MPa. Molecular wires of adsorbed molecules are stabilized by the strong solid-fluid potential generated from the cylindrical carbon walls. CO(2) assembly is formed at very low operating pressures in comparison to all other studied nonpolar adsorbates. The adsorption lock-and-key mechanism results from perfect fitting of rod-shaped CO(2) molecules into the cylindrical carbon pores. The enthalpy of CO(2) adsorption in DWNTs is very high and reaches 50 kJ mol(-1) at 300 K and low pore concentrations. In contrast, adsorption enthalpy at zero coverage is significantly lower for all other studied nonpolar adsorbates, for instance: 35 kJ mol(-1) for CH(4), and 14 kJ mol(-1) for H(2). Applying the ideal adsorption solution theory, we predicted that the internal pores of DWNTs have unusual ability to differentiate CO(2) molecules from other flue/synthetic gas mixture components (e.g. CO, N(2), H(2), O(2), and CH(4)) at ambient operating conditions. Computed equilibrium selectivity for equimolar CO(2)-X binary mixtures (where X: CO, N(2), H(2), O(2), and CH(4)) is very high at low mixture pressures. With an increase in binary mixture pressure, we predicted a decrease in equilibrium separation factor because of the competitive adsorption of the X binary mixture component. We showed that at 300 K and equimolar mixture pressures up to 1 MPa, the CO(2)-X equilibrium separation factor is higher than 10 for all studied binary mixtures, indicating strong preference for CO(2) adsorption. The overall selective properties of DWNTs seem to be superior, which may be beneficial for potential industrial applications of these novel carbon nanostructures.