Effect of gamma irradiation on quality of kiwifruit (Actinidia deliciosa var. deliciosa cv. Hayward)

Ionizing radiation is able to inactivate the three pathogens of Botrytis cinerea, Diaporthe actinidiae, and Botryosphaeria dothidea in kiwifruit. Irradiated kiwifruits appeared softer compared to non-irradiated kiwifruits. The color and organic acid content of kiwifruits were minimally affected by the irradiation. Irradiated fruits showed a decrease in the total soluble solids content with increasing irradiation dose. Irradiation of kiwifruit up to 3 kGy had negative effects on vitamin C content and antioxidant activity, but it contributed to improving sensory quality.     

Hydrogen Exchange Mass Spectrometry of Related Proteins with Divergent Sequences: A Comparative Study of HIV-1 Nef Allelic Variants

Hydrogen exchange mass spectrometry can be used to compare the conformation and dynamics of proteins that are similar in tertiary structure. If relative deuterium levels are measured, differences in sequence, deuterium forward- and back-exchange, peptide retention time, and protease digestion patterns all complicate the data analysis. We illustrate what can be learned from such data sets by analyzing five variants (Consensus G2E, SF2, NL4-3, ELI, and LTNP4) of the HIV-1 Nef protein, both alone and when bound to the human Hck SH3 domain. Regions with similar sequence could be compared between variants. Although much of the hydrogen exchange features were preserved across the five proteins, the kinetics of Nef binding to Hck SH3 were not the same. These observations may be related to biological function, particularly for ELI Nef where we also observed an impaired ability to downregulate CD4 surface presentation. The data illustrate some of the caveats that must be considered for comparison experiments and provide a framework for investigations of other protein relatives, families, and superfamilies with HX MS.

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Graphical Abstract ?

     

Chemical Composition Analysis,Cytotoxic, Antimicrobial and Antioxidant Activities of Physalis angulata L.: A Comparative Study of Leaves and Fruit

Physalis angulata L. belongs to the family Solanaceae and is distributed throughout the tropical and subtropical regions. Physalis angulata leaf and fruit extracts were assessed for in vitro anticancer, antioxidant activity, and total phenolic and flavonoid content. The GC-MS technique investigated the chemical composition and structure of bioactive chemicals reported in extracts. The anticancer activity results revealed a decrease in the percentage of anticancer cells’ viability in a concentration- and time-dependent way. We also noticed morphological alterations in the cells, which we believe are related to Physalis angulata extracts. Under light microscopy, we observed that as the concentration of ethanolic extract (fruit and leaves) treated HeLa cells increased, the number of cells began to decrease.     

不同产地积雪草中的微量元素比较研究

用火焰原子吸收分光光度法测定了７个不同产地的中药材积雪草中８种微量元素Ｆｅ、Ｃｕ、Ｃｕ、Ｚｎ、Ｍｎ、Ｃｏ、Ｃｄ、Ｓｒ、Ｃｒ的含量,并进行了比较,结果表明中药材中微量元素含量因地而异。为药材道 地性研究,药理作用探讨及临床用药提供了依据。     

A Comparative Study of Biocathodes Based on Multiwall Carbon Nanotube Buckypapers Modified with Three Different Multicopper Oxidases

14 Single‐ and multi‐walled carbon nanotubes from different sources were characterized in detail, and the characteristics obtained were carefully analyzed. The carbon material with the highest capacitance, and also other superior properties (“Taunit‐M” from “NanoTechCenter”, Russia), was chosen for further modification and fabrication of buckypaper based electrodes. These electrodes were biomodified with plant and fungal laccases, as well as fungal bilirubin oxidase. The designed biocathodes were investigated in simple buffers and also in a complex physiological fluid (human serum). Biocathodes based on immobilized fungal laccase were bioelectrocatalytically inactive in chloride containing media at neutral pH. In spite of the quite high current densities realized using biodevices based on plant laccase and fungal bilirubin oxidase, the limited thermal stability of the enzymes renders the biocathodes inadequate for practical applications in implanted situations.     

Proton Controlled Supramolecular Assembly: A Comparative Structural Study of Bis(2-guanidinobenzimidazolo)nickel(II) with Bis(2-guanidinobenzimidazole)nickel(II) Nitrate and 2-guanidinobenzimidazole

Abstract

Previously studies have shown that when 2-guanidinobenzimidazole complexes with a number of transition metal ions it tautomerises so that, in contrast to the free ligand structure, no intermolecular hydrogen bonding between bound ligands occurs. In the present study it is demonstrated that ligand deprotonation to yield bis(2-guanidinobenzimidazolo)nickel(II) restores much of the original hydrogen bonding capability of the uncomplexed ligand. The structure of this neutral complex is compared to the previously reported structure of its diprotonated derivative, bis(2-guanidinobenzimidazole)nickel(II) nitrate, as well as to the structure of the uncomplexed ligand. In contrast to the dicationic species, the neutral complex exists in two enantiomeric forms that assemble to form an extended supramolecular lattice, containing channels through its structure. The walls of the channels are made up of ‘strings’ of complex molecules and are held in position by hydrogen bonding between the bound ligands and dimethyl sulfoxide (solvent) molecules as well as water molecules. Some of the solvent molecules lie within the channels and some outside. The hydrogen bonding motif responsible for chain formation differs from that found in the free ligand structure.     

一系列Ru(II)配合物电致化学发光性质的比较研究

比较研究了以C₂O₄^2－为共反应物时5个结构相关的Ru(II)配合物[Ru(bpy)₂L¹]^2＋, [Ru(bpy)₂L²]^2＋, [Ru(bpy)₂L³]^2＋, [Ru(phen)₂L¹]^2＋和[Ru(phen)₂L²]^2＋(其中bpy＝2,2′-联吡啶, phen＝1,10-邻菲啰啉, L¹＝4-羧基苯基咪唑[4,5-f][1,10]邻菲啰啉, L²＝3-羧基-4-羟基苯基咪唑[4,5-f][1,10]邻菲啰啉, L³＝3,4-二羟基苯基咪唑[4,5-f][1,10]邻菲啰啉)的电致化学发光(ECL)性质. 结果表明, 酚羟基的存在能有效地淬灭Ru(II)配合物[Ru(bpy)₂L²]^2＋, [Ru(bpy)₂L³]^2＋和[Ru(phen)₂L²]^2＋的ECL, 其它Ru(II)配合物的ECL量子效率与[Ru(bpy)₃]^2＋相差不大.     

Photoactive Branched and Linear Surface Architectures for Functional and Patterned Immobilization of Proteins and Cells onto Surfaces: A Comparative Study

Molecular architecture affects the properties of surface layers. Photosensitive silanes with branched architectures allow patterning and coupling of proteins and cells on surfaces while maintaining their biofunctional state. Attachment can be directed to the activated regions of irradiated substrates with high selectivity (see image of mouse fibroblasts).

     

Chemisorption of Platinum(II) and Platinum(IV) Chloride Complexes on Fibrous Sorbents Derived from Polyacrylonitrile Modified with Aminoguanidine

Sorption of platinum(II) and platinum(IV) chloride complexes on nitrogen-containing fibrous sorbents derived from polyacrylonitrile with aminoguanidine groups (GLIPAN-3) was studied as influenced by the temperature, platinum concentration in the solution, and pH of the solution. The kinetic sorption parameters and the sorption capacities of the sorbents in hydrochloric acid and chloride solutions were determined. The sorption mechanism and the composition of platinum compounds formed in the sorbent phase were suggested.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 729–735.Original Russian Text Copyright © 2005 by Simanova, Kuznetsova, Konovalov, Shchukarev.     

Antioxidant,Antimicrobial Activities and Fatty Acid Compositions of Wild Berberis spp. by Different Techniques Combined with Chemometrics (PCA and HCA)

Interest in medicinal plants and fruits has increased in recent years due to people beginning to consume natural foods. This study aims to investigate the total phenolic flavonoid content, antioxidant activity, condensed tannin content, oil content, and fatty acid compositions of five local breeds of Berberis spp. from Bayburt, Turkey, and their antioxidant and antimicrobial activities. The fatty acid composition of samples was performed with gas chromatography-mass spectrometry (GC-MS), and the total fatty acid content of samples was between 6.12% and 8.60%. The main fatty acids in Berberis spp. samples were α-linolenic acid (32.85–37.88%) and linoleic acid (30.98–34.28%) followed by oleic acid (12.85–19.56%). Two antioxidant assays produced similar results, demonstrating that extracts of wild B. vulgaris L. had the highest ferric reducing antioxidant power (FRAP) (621.02 μmol FeSO₄.7H₂O/g) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) (0.10 SC₅₀ mg/mL) values. According to principal component analysis (PCA), four components were determined. In addition, two main groups were determined according to hierarchical cluster analysis (HCA), and wild and culture of B. vulgaris L. were in different subgroups. This is the first original report about the fatty acid composition and oil content of Berberis spp. grown in Bayburt, Turkey. The obtained results indicate that B. integerrima Bunge and B. vulgaris, which have especially remarkable fatty acid content, antioxidant, and antimicrobial activity, could be potential sources for these properties in different areas of use.     

Isomeric Oligo(Phenylenevinylene)-Based Covalent Organic Frameworks with Different Orientation of Imine Bonds and Distinct Photocatalytic Activities

Imine-linked covalent organic frameworks (COFs) have been extensively studied in photocatalysis because of their easy synthesis and excellent crystallinity. The effect of imine-bond orientation on the photocatalytic properties of COFs, however, is still rarely studied. Herein, we report two novel COFs with different orientations of imine bonds using oligo(phenylenevinylene) moieties. The COFs showed similar structures but great differences in their photoelectric properties. COF-932 demonstrated a superior hydrogen evolution performance compared to COF-923 when triethanolamine was used as the sacrificial agent. Interestingly, the use of ascorbic acid led to the protonation of the COFs, further altering the direction of electron transfer. The photocatalytic performances were increased to 23.4 and 0.73 mmol g⁻¹ h⁻¹ for protonated COF-923 and COF-932, respectively. This study provides a clear strategy for the design of imine-linked COF-based photocatalysts and advances the development of COFs.     

Silver(I) and Copper(II) Catalysis for Oxidation of Histidine by Cerium(IV) in Acid Medium: A Comparative Kinetic Study

The catalytic effect of silver(I) and copper(II) ions on the oxidation of histidine by cerium(IV) in aqueous sulfuric acid solutions was studied spectrophotometrically at a constant ionic strength of 3.0 mol dm⁻³ and at 25°C. In both uncatalyzed and metal ions‐catalyzed paths, the reactions exhibited first‐order kinetics with respect to [Ce(IV)] and [catalyst], and fractional first‐order dependences with respect to [His] and [H⁺]. The oxidation rates increased as the ionic strength and dielectric constant of the reactions media increased. The catalytic efficiency of Ag(I) was higher than that of Cu(II). Plausible mechanistic schemes for both uncatalyzed and catalyzed reactions were proposed, and the rate laws associated with the suggested mechanisms were derived. In both cases, the final oxidation products of histidine were identified as 2‐imidazole acetaldehyde, ammonium ion, and carbon dioxide. The activation parameters associated with the second‐order rate constants were evaluated.     

Comparative study on the transition structures of (3,4) and (3,5) ene cyclizations: A theoretical approach

Possible transition structures (TSs) of (3,4) and (3,5) ene cyclizations of 7-methyl-1,6-octadiene and 7-methylocta-1,6-dien-3-one were constructed and optimized by DFT method. Product proportions were calculated using the relative energies of the transition structures and these results are found to be in good agreement with the experimental one. Variation of the product proportions was explained using some model TSs of intermolecular ene reactions. The change of the dihedral angle around the forming carbon–carbon bond in the model transition structures was found to play a crucial role in determining the overall selectivities of cyclized products.     

3D-QSAR Study on Diindolylmethane and Its Analogues with Comparative Molecular Field Analysis (CoMFA)

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新型5-(4-甲基硫代)吡唑磷酸酯的合成及生物活性研究

合成了12个5－（4－甲基硫代）吡唑磷酸酯及6个5－羟基吡唑新化合物，其结构^1H NMR和MS表征。杀虫，除虫及杀菌等生物活性的测试表明部分化合物具有较好的杀虫，除草或杀菌活性。     

Comparative Studies on Electrocatalytic Activities of Chemically Reduced Graphene Oxide and Electrochemically Reduced Graphene Oxide Noncovalently Functionalized with Poly(methylene blue)

This study compares the electrocatalytic activities of chemically reduced graphene oxide (crGO) and electrochemically reduced graphene oxide (erGO), which are both noncovalently functionalized with a polyaromatic dye, poly(methylene blue) (polyMB), toward the oxidation of β‐nicotinamide adenine dinucleotide (NADH). PolyMB‐crGO and polyMB‐erGO composites were obtained via electropolymerization of methylene blue on crGO and GO modified glassy carbon (GC) electrodes, respectively. Cyclic voltammetry (CV) results indicate that these two types of integrated electrodes reveal different electrocatalytic activities. PolyMB‐crGO integrated electrode possesses lower catalytic oxidation potential, suggesting higher catalytic activity. The present study is helpful for the understanding and screening of graphene‐based advanced carbon nanomaterials for potential electrochemical applications.     

Electronic Structures of O2 Molecules Chemisorbed on a（8,0） SWNT with Different Oxygen Contents：A Density Functional Theory Study

We report a theoretical study on the electronic structures of O2 chemisorbed on a(8,0) SWNT with different oxygen contents of 6.25,12.5 and 25%,respectively.On the basis of DFT calculations,we find that eight O2 molecules chemisorbed on the(8,0) SWNT aligned in the middle row of the circumference of the tube in proportional spacing way,is seen to become metallic,and a significant increase in conductivity is expected.There are different electronic structures of the functionalized systems related to different oxygen contents or O2 molecules' chemisorbed positions.