Isolation and evaluation of the radical-scavenging activity of the antioxidants in the leaves of an edible plant, Mallotus japonicus

The antioxidative properties of a hot water extract of the leaves of Mallotus japonicus were evaluated. The extract had a high phenolic content and strong antioxidative activity, compared with green tea, rooibos tea, and red wine. Six phenolic compounds were isolated as antioxidative components by HPLC. They were identified as mallotinic acid, mallotusinic acid, corilagin, geraniin, rutin, and ellagic acid. These antioxidative compounds were subjected to DPPH radical-scavenging, superoxide radical-scavenging, and hydroxyl radical-scavenging assays, and compared with other antioxidative compounds. Four of the compounds, mallotinic acid, mallotusinic acid, corilagin and geraniin, exhibited much stronger antioxidative activity than gallic acid, rutin, ellagic acid, quercetin, and chlorogenic acid, and were as active as epigallocatechin gallate (EGCG), a strong antioxidant in green tea. Mallotus japonicus leaves are an excellent source of strong natural antioxidative materials.     

Rapid homogeneous immunoassay of peptides based on bioluminescence resonance energy transfer from firefly luciferase

A sensitive homogeneous immunoassay is needed in the field of clinical diagnostics. Here we propose a rapid and potentially sensitive homogeneous immunoassay of peptide epitope based on the bioluminescence resonance energy transfer (BRET). A GST peptide tag fused to the N-terminus of firefly luciferase, and Cy3 or Cy3.5-labeled anti-peptide antibody were prepared to detect BRET from the hybrid luciferase to the fluorolabeled antibody. By measuring the spectral change due to BRET, the amount of c-myc peptide was successfully determined in a short period.     

Structure and electrochemical properties of carbon films prepared by a electron cyclotron resonance sputtering method

This paper describes the characterization, electrochemical properties, and applications of carbon films prepared by the electron cyclotron resonance (ECR) sputtering method. The ECR-sputtered carbon film was deposited within several minutes at room temperature. The optimized sputtering conditions significantly change the film structure, which includes many more sp3 bonds (sp3/sp2 = 0.702) than previously reported film (sp3/sp2 = 0.274)1 with an extremely flat surface (0.7 A). The ECR-sputtered carbon films exhibit excellent electrochemical properties. For example, they have nearly the same potential window in the positive direction as that of high-quality, boron-doped diamond (moderately doped, 10(19)-10(20) boron atoms/cm3)2 and an even wider potential window in the negative direction with a low background current, high stability, and suppression of fouling by electroactive species without pretreatment. The electron-transfer rates at ECR-sputtered carbon films are similar to those of glassy carbon (GC) for Ru(NH3)(6)(2+)/(3+) and Fe(CN)(6)(3-)/(4-), whereas they are much slower than those of GC for Fe2+/3+, dopamine oxidation, and O2 reduction due to weak interactions between electroactive species and the ECR-sputtered carbon film surface. Such a response can be attributed to the ultraflat surface and low surface O/C ratios of ECR-sputtered carbon films. ECR-sputtered carbon film is advantageous for measuring biochemicals with high oxidation potentials because of its wide potential window and high stability. Highly reproducible and well-defined cyclic voltammograms were obtained for histamine and azide ions with a peak potential at 1.25 and 1.12 V vs Ag/AgCl, respectively. The film is very stable for continuous voltammetry measurements in 10 microM bisphenol A, which usually fouls the electrode surface with oxidation products.     

Permeability properties of isometrically temperature-responsive poly(acrylic acid)-graft- oligo(N-isopropylacrylamide) gel membranes

A series of temperature-responsive hydrogels were prepared by grafting oligo(N-isopropylacrylamide) (ONIPAAm) chains onto a crosslinked poly(acrylic acid) (PAAc) network, intending an application to drug delivery systems (DDS). Cloud points and swelling ratios of the obtained PAAc-graft-ONIPAAm gels were measured as a function of temperature under various pH conditions. At pH > 4.5, the clear cloud points were observed at 31–33°C, which were almost the same values as that of poly(N-isopropylacrylamide) (PNIPAAm), whereas swelling/shrinkage phenomenon was not observed in the temperature range 25–45°C. It seemed that grafted ONIPAAm chains underwent the coil-to-globule transition, while the crosslinked PAAc network remained unchanged, due to the anionic charges on the main chains. In the presence of NaCl in the buffer solution, the phase transition temperature was slightly lowered. To assess the applicability of these temperature-responsive PAAc-graft-ONIPAAm gels to DDS, permeability of theophylline through the gel membranes was measured as a function of temperature. At a temperature below the cloud point, the permeability of theophylline was low, whereas it was high at an elevated temperature above the cloud point. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1027–1034, 1998     

Ionically conductive polymer gel electrolytes prepared from vinyl acetate and methyl methacrylate for electric double layer capacitor

In order to obtain highly conductive polymer electrolytes for an electric double layer capacitor, three kinds of polymer gel electrolytes were prepared. Vinyl acetate (VAc) and methyl methacrylate (MMA) were copolymerized with divinyl adipate (DA) and ethylene glycol dimethacrylate (EGDMA), respectively, in propylene carbonate (PC) containing tetraethylammonium tetrafluoroborate (TEATFB) to form network polymer gel electrolytes. MMA was also copolymerized with butylene glycol DMA for comparison. The polymer gel electrolytes obtained were characterized by means of thermogravimetry, complex impedance analysis, and cyclic voltammetry for use in the electric double layer capacitor. The ionic conductivities of the polymer gel electrolytes were dependent on the TEATFB concentration, temperature, and crosslinking degree. The polymer gel electrolytes in the VAc‐DA system exhibited higher room temperature conductivities (10⁻² S/cm) than those in the MMA‐EGDMA system. Further, the polymer gel electrolytes in the VAc‐DA system showed good electrochemical stability windows ranging from −4.0 to 4.0 V versus Ag. Thermal analysis revealed that the polymer gel electrolytes in both systems were stable up to 150°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 12–18, 2000     

Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure

Ionic conduction of oxygen in the ceria-samarium oxide system was investigated as a function of temperature, partial pressure of oxygen and the oxide composition, together with its crystal structure, density and defect structure. The ionic conductivity of (CeO₂)_1–x(SmO_1.5)_x was the highest in ZrO₂-, ThO₂- and CeO₂-based oxide systems. The system CeO₂-SmO_1.5 consisted of the solid solution with a fluorite structure atx<50 at.%. The ionic transference number was nearly unity between 600 and 900°C. With an increase in Sm₂O₃ content, the ionic conductivity gradually decreased due to a decrease in mobility of oxygen ions. The samarium oxide-doped ceria was less reducible than pure and alkaline earth oxide-doped ceria.     

Macrophage Polarization Related to Crystal Phases of Calcium Phosphate Biomaterials

Calcium phosphate (CaP) materials influence macrophage polarization during bone healing. However, the effect of the crystal phase of CaP materials on the immune response of bone remains unclear. In this study, the effect of the crystal phases of CaP materials on the regulation of macrophage polarization was investigated. Human THP-1 cells and mouse RAW 264 cells were cultured with octacalcium phosphate (OCP) and its hydrolyzed form Ca-deficient hydroxyapatite to assess the expression of pro-inflammatory M1 and anti-inflammatory M2 macrophage-related genes. OCP inhibited the excessive inflammatory response and switched macrophages to the anti-inflammatory M2 phenotype, which promoted the expression of the interleukin 10 (IL10) gene. In contrast, HL stimulated an excessive inflammatory response by promoting the expression of pro-inflammatory M1 macrophage-related genes. To observe changes in the microenvironment induced by OCP and HL, inorganic phosphate (Pi) and calcium ion (Ca²⁺) concentrations and pH value in the medium were measured. The expression of the pro-inflammatory M1 macrophage-related genes (tumor necrosis factor alpha (TNFα) and interlukin 1beta (IL1β)) was closely related to the increase in ion concentration caused by the increase in the CaP dose. Together, these results suggest that the microenvironment caused by the crystal phase of CaP materials may be involved in the immune-regulation capacity of CaP materials.     

Effect of flavonol glycoside in mulberry (Morus alba L.) leaf on glucose metabolism and oxidative stress in liver in diet‐induced obese mice

BACKGROUND: Mulberry therapies on type 2 diabetic patients or streptozotocin‐induced diabetic rats have been reported to improve fasting blood glucose levels. We investigated the effects of dietary consumption of mulberry‐leaf powder and purified quercetin 3‐(6‐malonylglucoside), the quantitatively major flavonol glycoside in mulberry leaves, on glucose and lipid metabolism in high‐fat diet‐induced obese mice. Male C57BL/6J mice aged 8 weeks were assigned to three groups (control, mulberry leaf powder (MLP), and quercetin 3‐(6‐malonylglucoside) (Q3MG)) and treated with their respective diets for 8 weeks. RESULTS: We found that dietary supplementation of 10 g MLP kg^?1 or 1 g Q3MG kg^?1 in high‐fat diet effectively suppressed blood glucose levels. We also noted increased expression of glycolysis‐related genes and suppression of thiobarbituric acid reactive substances concentrations in the liver of Q3MG group compared to control mice. CONCLUSION: Dietary consumption of Q3MG, the quantitatively major flavonol glycoside in mulberry leaves, improved hyperglycemia in obese mice and reduced oxidative stress in the liver. Copyright © 2010 Society of Chemical Industry