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A palladium-catalyzed allenamide carbopalladation/allylation with active methine compounds has been developed. Various indoles and isoquinolinones bearing a quaternary carbon center were achieved with good efficiency, a broad substrate scope and good functional group tolerance. This reaction underwent cascade oxidative addition, carbopalladation, and allylic alkylation, and two new C-C bonds were formed in one pot.

The crude β-xylosidase from Aureobasidium pullulans CBS 135684 was immobilized on the surface of the modified spent expanded perlite via (3-aminopropyl) triethoxy-silane and glutaraldehyde cross-linking reaction. Over 80% of the initial free enzyme activity was detected on the bound enzyme. The immobilized β-xylosidase (204.7 ± 6.5 U g-1 of perlite) exhibited transxylosylation activity when sugars from black liquor xylan hydrolysate and a variety of alcohols (C1-6) were used as donor and acceptor molecules, respectively, yielding a number of alkyl xylosides. The synthesized hexyl xyloside exhibited some interesting properties comparable with those of a commercial hexyl glucoside, including an antioxidant activity (IC50 = 8.9 ± 2.0 mg mL-1), wetting time (43 s), and critical micelle concentration value (252 mmol L-1). Optimization for hexyl xyloside synthesis was performed via statistical analysis using a Box and Behnken design. The maximum predicted yield of hexyl xyloside (499.0 ± 1.1 mg g-1 xylan hydrolysate) was obtained with 10% (w/v) xylan hydrolysate, 10 U g-1 immobilized β-xylosidase, and 13% (v/v) hexanol at 70 °C, pH 6.0 for 4 h, and it was validated by the following experimental yield (498.9 ± 4.8 mg g-1 xylan hydrolysate). The maximum production yield remained relatively stable after the immobilized enzyme was reused for 12 cycles with a 471.5 ± 15.1 mg g-1 hexyl xyloside yield (94.4% of the first cycle). Thus, the immobilized β-xylosidase has a high potential as a robust catalyst for application in alkyl xyloside production.

Oxidative stress is the major cause of renal fibrosis in the progression of DN. Connexin43 (Cx43) exerts an anti-fibrosis effect on diabetic kidneys. The current study aimed to investigate whether astaxanthin (AST) could ameliorate the pathological progression of DN by upregulating Cx43 and activating the Nrf2/ARE signaling, which is a pivotal anti-oxidative stress system, to strengthen the cellular anti-oxidative capacity and diminish fibronectin (FN) accumulation in HG-induced glomerular mesangial cells (GMCs). Our hypothesis was verified in GMCs and the kidneys from db/db mice by western blot, immunofluorescence, immunohistochemistry, immunoprecipitation, dual luciferase reporter assay and reactive oxygen related detection kits. Results showed that AST simultaneously upregulated the Cx43 protein level and promoted the Nrf2/ARE signaling activity in the kidney of db/db mice and HG-treated GMCs. However, Cx43 depletion abrogated the Nrf2/ARE signaling activation induced by AST. AST reduced the interaction between c-Src and Nrf2 in the nuclei of GMCs cultured with HG, thereby enhancing the Nrf2 accumulation in the nuclei of GMCs. Our data suggested that AST promoted the Nrf2/ARE signaling by upregulating the Cx43 protein level to prevent renal fibrosis triggered by HG in GMCs and db/db mice. c-Src acted as a mediator in these processes.

Pyroligneous acids (PA) from hardwood, softwood, and bamboo significantly disinfected encephalomyocarditis virus (EMCV). Twenty-five kinds of phenolic derivatives in the PAs were identified and quantified. The total amounts of phenolic compounds in bamboo PA is higher than those in the PAs from softwood and hardwood. Phenol, 2-methoxyphenol, 2-methoxy-4-methylphenol, and 2-methoxy-4-ethylphenol are the most abundant compounds in the PAs examined. The activities of all the phenolic compounds against the encephalomyocarditis virus were assessed. The number of phenolic hydroxyl groups significantly affects the antiviral activity, and catechol and its derivatives exhibit higher viral inhibition effects than other phenolic derivatives. In addition, substituents affect the antiviral activity of the compounds. Phenolic compounds with a methyl group show higher activities than with a methoxyl group (e.g., 2-methylphenol > 2-methoxyphenol). Moreover, the relative position of functional groups also plays a key role...

The pyrolysis product, wood vinegar (WV), from Japanese larch exhibited strong antiviral activity against the encephalomycarditis virus (EMCV). Catechol, 3-methyl-, 4-methyl-, 4-ethyl-, and 3-methoxycatechol, and 2-methyl-1,4-benzenediol were identified as the major antiviral compounds. The viral inhibition ability of these compounds was affected by the structure and position of the substituent group attached to the aromatic skeleton. The IC50 of catechol was 0.67 mg mL−1 and those of its derivatives were

A novel strategy, based on surface-initiated grafting polymerization and post-polymerization thiol-yne click chemistry, with Ir(ppy)3 as a sole photoredox catalyst, under visible light irradiation is developed. The “livingness” of the grafting polymerization is demonstrated by the linear increase of the graft yield with irradiation time and the block grafting polymerization. Then, acetenyl groups of poly(propargyl methacrylate) (PPMA) grafting chains are reacted with pentaerythritoltetra-(3-mercaptopropionate) via the thiol-yne click reaction. The successful introduction of reactive thiol groups onto the low-density polyethylene-graft-poly(propargyl methacrylate) (LDPE-g-PPMA) films is demonstrated by Fourier transform IR (FTIR) and X-ray photoelectron spectra (XPS) spectroscopy, and the thiol-ene click reaction with N-(1-pyrenyl) maleimide.

Cu/Ni nanoparticles (NPs) with stable fluorescence and excellent water dispersion were synthesized through a facile aqueous solution method with a similar Kirkendall effect. Ultraweak chemiluminesc...

An ultraweak chemiluminescence (CL) was observed when sodium hydrosulfite (NaHSO(3)) reacts with hydrogen peroxide (H(2)O(2)) and was enhanced 70 times by adding 10 pmol benzo[a]pyrene-7,10-quinone (7,10-BaPQ). The CL reaction is fast, and it reached maximum intensity in 0.1 s, and then decayed to baseline in 3 s. Mechanism of NaHSO(3)-7,10-BaPQ-H(2)O(2) system were investigated by CL spectrum, radical scavengers and electron spin resonance (ESR). Hydroxyl radical ((•)OH), super oxide anion radical ((•)O(2)(-)), and sulfite radical ((•)SO(3)(-)) were generated in the NaHSO(3)-7, 10-BaPQ-H(2)O(2) system. Reduction of 7,10-BaPQ by (•)O(2)(-) radical gave excited semiquinone, which showed strong CL emission when decayed to its ground state. Maximum CL emission wavelength was located at 440 nm, which may belong to the excited semiquinone. This CL system was developed as post column detection of high performance liquid chromatography for the determination of 7,10-BaPQ. Linearity ranged from 50 fmol to 20 pmol (R(2) = 0.9995) with limit of detection of 30 fmol (S/N = 3). The proposed method was used to determine 7,10-BaPQ in airborne particulates. Average atmospheric concentrations of 7,10-BaPQ in Kanazawa in December 2010 and Wajima in October 2007 were 2.0 and 1.6 pg/m(3), respectively.

Chemiluminescence (CL) phenomenon of hydrogen peroxide with potassium permanganate in the presence of sodium hydrogen carbonate was reported. Effects of the surfactant on the CL system were investigated. Nonionic surfactants could effectively increase the CL signal. Radical scavengers and organic reagents such as nitro blue tetrazolium chloride (NBT), cytochrome c, sodium azide, ascorbic acid, thiourea, tert-butanol and dimethyl sulphoxide were used to study the emitting species. CL emission spectrum was recorded and the results showed that the maximal emission wavelengths of NaHCO3-H2O2-KMnO4 system were 440 and 634 nm. The mechanism was discussed based on electron spin resonance (ESR) spectra, fluorescence spectra and UV-vis absorption spectra. The addition of rhodamine B or uranine into this CL system enhanced the CL signal. It was due to part of the energy transfer from singlet oxygen and excited triplet dimers of two CO2 molecules to rhodamine B or uranine. The CL could be induced by excited rhodamine B or uranine.

The plots of logarithms of relative rates of ISCN addition to alkenes versus alkene IPs and versus alkene HOMO energies reveal that the alkene relative reactivity depends upon both electronic and steric effects of the substituents. Steric effects are related not only to the degree of substitution on the C C bond but also to the relative position, size, and branching of alkyl substituents.

Plots of logarithms of relative reaction rates of chromyl chloride oxidation and of chromic acid oxidation of alkenes (log krel values) versus alkene ionization potentials (IPs) and versus their highest occupied molecular orbital energy levels (HOMOs) demonstrate excellent correlations. Each plot has a similar appearance and shows a single line with a positive slope. The results indicate that the rate-determining step of each title reaction involves an electrophilic attack on the alkene π-bond without significant steric effects; this supports a proposed 2 + 3 cycloaddition mechanism and disfavors a proposed stepwise 2 + 2 cycloaddition mechanism. Comparison is made with other d0 transition metal complexes that oxidize alkenes. Copyright © 2004 John Wiley & Sons, Ltd.

Investigations of the title reaction, carried out by plotting logs of the relative reaction rates vs IPs, vs HOMOs, and vs LUMOs, reveal multiple nearly parallel lines of correlation with small negative slopes in each. Overall, the natural grouping into monosubstituted and disubstituted alkenes gives better correlations than that obtained by using all alkenes. Comparison with analogous plots for other reactions indicates that the mechanism for this reaction has similarities to that for hydroboration, the major difference being that the lines in the plots for hydroboration have positive slopes, indicating an electrophilic rate-determining step involving the pi electrons, while those for the title reaction have small negative slopes, indicating a nucleophilic rate-determining step. Of the two reaction mechanisms proposed for the title reaction, only one has a nucleophilic attack at the complexed alkene as the rate-determining step, and therefore, this work supports that reaction mechanism.

A set of convenient conditions for the title reaction is used to determine directly relative reactivities of alkenes with widely-varying steric requirements. Previous determinations did not use one set of conditions for all alkenes, but developed parameters in order to compare alkene reaction rates run in different solvents and in different concentrations; such an indirect reactivity comparison can introduce errors. Relative rates established under this common set of reaction conditions are compared to those previously calculated by using correction parameters. Comparison reveals that the approximate method overestimated effects of some groups attached to C C, such as methyl and chloro.

In this work, a chemiluminescence (CL) reaction between hydrogen peroxide (H(2)O(2)) and sodium hydrosulfite (NaHSO(3)) was developed. Hydroxyl radical ((•)OH) and sulfite radical ((•)SO(3)(-)) were the main intermediates generated in the NaHSO(3)-H(2)O(2) CL system. Inhibition effects of radical scavengers such as thiourea, chloride ion, nitro blue tetrazolium chloride (NBT), and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) indicated the existence of these two radicals. Singlet oxygen ((1)O(2)) and excited sulfur dioxide (SO(2)*) were emitting species involved in NaHSO(3)-H(2)O(2) CL system. (1)O(2) were confirmed by 1,4-diazobicyclo[2,2,2]octane (DABCO) and sodium azide (NaN(3)), which were specific (1)O(2) scavengers. In addition, electron spin resonance (ESR) spectra clearly show the existence of (1)O(2) and (•)OH. Alcoholic solvent, especially n-butanol, enhanced the ultraweak CL emission more than 40 times. The enhancing effect of alcoholic solvent on NaHSO(3)-H(2)O(2) CL system was ascribed to the formation of solvent cage, which can accelerate the reaction rate and protect the emitting species from quenching by water. The CL emission of the NaHSO(3)-n-butanol-H(2)O(2) system was measured by cutoff filters. The maximum wavelength was located around 490 nm, which belongs to (1)O(2). The wide peak from 400 to 600 nm is the characteristic peak of SO(2)*.

In this research, a highly sensitive chemiluminescence method based on a sodium hydrosulfite (NaHSO3)–hydrogen peroxide (H2O2) reaction for the determination of 1-hydroxypyrene (1-OHP) was developed. The response of this system was linear in the range from 0.5 to 50 pmol (R2 = 0.9983). The limit of detection for 1-OHP was 100 fmol (S/N = 3). 1-OHP in airborne particulates was well separated from interfering compounds using an ODS column with 75% methanol as the mobile phase in isocratic mode. The proposed method was successfully applied to determine the 1-OHP in airborne particulates collected in Kanazawa, Japan. The average concentration of 1-OHP in the atmosphere was 2.0 pg/m3 (9.2 fmol/m3).

In the present work, a strongly chemiluminescence (CL) from the mixing of hydrogen peroxide (H(2)O(2)), hydrogen carbonate (HCO(3)(-)) and CdSe/CdS quantum dots (QDs) was observed. The addition of trace amount of L-ascorbic acid into the CL system caused significant quenching luminescence intensity. Based on this phenomenon, a flow injection CL analysis system for the determination of l-ascorbic acid was developed. The CL reaction conditions, such as mixing orders and concentrations of CL reagents, flow rates, pH, and particle size of quantum dots have been optimized. The CL intensity and the concentration of L-ascorbic acid have a good linear relationship in the ranges of 1.0x10(-7)-1.0x10(-4)molL(-1) (R(2)=0.9916). The limit of detection for L-ascorbic acid is 6.7x10(-9)molL(-1) (S/N=3). This method has been successfully applied to determine L-ascorbic acid in human serum. The recoveries for the real samples were from 83% to 111% and the variance coefficient was

Plots of the logarithms of relative rates of homogeneous catalytic hydrogenation of alkenes (log k(rel) values) by using Wilkinson's catalyst versus their ionization potentials (IPs) and versus their lowest unoccupied molecular orbital energy levels (LUMOs) display good-to-excellent correlations. The correlations indicate that the rate-determining step of this reaction is a nucleophilic addition to the alkene double bond, which is dependent upon both electronic effects and steric effects. This conclusion is in agreement with only two of three previously proposed mechanisms for the reaction, effectively ruling out one in which the rate-determining step involves electrophilic addition to the alkene. Characteristics of the analysis using these correlations are compared and contrasted with other additions to alkenes, such as the Wacker oxidation, to probe patterns in transition state characteristics.

Plots of log k(rel) versus IP or versus HOMO for the title reactions are presented; similarities and differences among the reactions are discussed. The Cl2 and Br2 data each show a single line of correlation with positive slope for all alkenes regardless of the steric requirements; increasing substitution at the double bond increases the reaction rate, indicating an electrophilic reaction. Each plot of the I2 data calculated for adsorption exhibits a natural separation into groups of similarly substituted alkenes, in which increased substitution reduces the rate. Within each group, a good-to-excellent correlation is observed, with a lower IP generally corresponding to a higher relative rate. The results indicate that the relative magnitude of the steric requirements about the double bond is similar to that of the electronic effects in iodination. Plot shapes for iodination are compared to those of other reactions, such as hydroboration, oxymercuration, complexation with Ag+, and complexation with MeHg+.