Metabolism of eupatilin in rats using liquid chromatography/electrospray mass spectrometry

Eupatilin (5,7-dihydroxy-3',4',6-trimethoxy flavone) is an active ingredient of an ethanol extract of Artemisia asiatica (DA-9601) that is used in the treatment of gastritis. In vitro and in vivo metabolism of eupatilin in the rats has been studied by LC-electrospray mass spectrometry. Rat liver microsomal incubation of eupatilin in the presence of NADPH and UDPGA resulted in the formation of four metabolites (M1-M4). M1, M2, M3 and M4 were tentatively identified as 3'- or 4'-O-demethyl-eupatilin glucuronide, eupatilin glucuronide, 6-O-demethyleupatilin and 3'- or 4'-O-demethyl-eupatilin, respectively. Those metabolites from in vitro study were also characterized in bile, plasma or urine samples after an intravenous administration of eupatilin to rats. In rat bile, plasma and urine samples, eupatilin glucuronide (M2) was a major metabolite, whereas M3, M4 and M4 glucuronide (M1) were the minor metabolites.     

Roles of terminal groups of oligomer electrolytes in determining photovoltaic performances of dye-sensitized solar cells

The effect of terminal groups of oligomer electrolytes on the photovoltaic performance of dye-sensitized solar cells (DSSCs) have been systematically investigated to show that the terminal group plays a critical role in determining the concentration of I(3)(-), ionic conductivity, flatband potential and consequently the energy conversion efficiency.     

Evaluation of biological monitoring markers using genomic and proteomic analysis for automobile emission inspectors and waste incinerating workers exposed to polycyclic aromatic hydrocarbons or 2,3,7,8,-tetracholrodedibenzo-p-dioxins

In this study, we investigated the effects of PAHs and dioxin on mRNA and plasma protein expression using genomic and proteomic analysis for automobile emission inspectors and waste incineration workers. About 54 workers from automobile emission inspection offices, 31 workers from waste incinerating company and 84 unexposed healthy subjects were enrolled in this study. Urine and air samples were collected and analyzed by HPLC and GC/MS. Comet assays were carried out to evaluate any DNA damage in mononuclear and polynuclear cells. A significant difference in Olive tail moments in mononuclear cells was observed between exposed and control subjects (P < 0.0001). To examine the differences of the gene expression profile in automobile emission inspectors and waste incineration workers, radioactive complementary DNA microarrays were used to evaluate changes in the expression of 1,152 total genes. The gene expression profiles showed that 11 genes were up-regulated and 4 genes were down-regulated in waste incinerating workers as compared with controls. Plasma proteins were analyzed by 2-dimentional electrophoresis with pH 3-10 NL IPG Dry strip. The protein expression profiles showed that 8 proteins were up- regulated and 1 protein, haptoglobin, was down- regulated in automobile emission inspectors and waste incineration workers. Serum paraoxonase/ arylesterase was found only in the plasma of waste incineration workers. The expression of genes and proteins involved in oxidative stress were up-regulated in both automobile emission inspectors and waste incineration workers. Several proteins, such as transthyrethin, sarcolectin and haptoglobin, that were highly up- or down-regulated, could serve as biological monitoring markers for future study.     

Photocatalytic decomposition of orange II over TiO2-loaded on SBA-15 prepared using a microwave process

SBA-15 mesoporous material was prepared by microwave-hydrothermal method and was used as support in TiO₂-loaded SBA-15 photocatalysts. The physical properties of these particles were investigated. We also examined the activity of these samples as photocatalysts for the decomposition of orange II. Titania loaded on a silica matrix decreases the surface area of the support as expected for TiO₂ incorporation. For TiO₂-loaded SBA-15 photocatalysts, the IR absorption at ∼960 cm⁻¹ commonly accepted as the characteristic vibration of the Ti-O-Si bond. The photocatalytic activity increases with an increase of the TiO₂ loading.     

Complexation mechanism of olefin with silver ions dissolved in a polymer matrix and its effect on facilitated olefin transport

Remarkable separation performance of olefin/paraffin mixtures was previously reported by facilitated olefin transport through silver-based polymer electrolyte membranes. The mechanism of facilitated olefin transport in solid membranes of AgCF3SO3 dissolved in poly(N-vinyl pyrrolidone) (PVP) is investigated. In silver polymer electrolyte membranes, only free anions are present up to the 2:1 mole ratio of [C=O]:[Ag], and ion pairs start to form at a ratio of 1:1, followed by higher-order ionic aggregates above a ratio of 1:2. At silver concentrations above 3:1, the propylene permeance increases almost linearly with the total silver concentration, unexpectedly, regardless of the silver ionic constituents. It was also found that all the silver constituents, including ion pairs and higher order ionic aggregates, were completely redissolved into free anions under the propylene environment; this suggests that propylene can be a good ligand for the silver cation. From these experimental findings, a new mechanism for the complexation reaction between propylenes and silver salts in silver-polymer electrolytes was proposed. The new mechanism is consistent with the linearity between the propylene permeance and the total silver concentration regardless of the kind of the silver constituents. Therefore, the facilitated propylene transport through silver-polymer electrolytes may be associated mainly with the silver cation weakly coordinated with both carbonyl oxygen atoms and propylene.     

Immobilization of antibody fragment for immunosensor application based on surface plasmon resonance

Biosurface fabrication using the Fab′ fragment of immunoglobulin (IgG) was carried out by self-assembly (SA) technique. The pepsin-digested monoclonal antibody (Mab) against bovine insulin containing the F(ab′)₂ fragment and residual proteins was separated using affinity chromatography and dialysis. To prevent the nonspecific binding of F(ab′)₂ onto gold (Au) substrate, the native disulfide bridge was reduced using dithiothreitol (DTT) to convert F(ab′)₂ into Fab′, which made the immobilization to be carried out via the native thiol (–SH) group. The fabricated biosurface using SA technique showed the formation of stable thin film through AFM topography. Through the concentration change of DTT and Fab′, the absorption characteristics against the Au surface were investigated using surface plasmon resonance (SPR) with the flow cell. The amount of immobilized antibody fragment and the antigen binding capacity were regulated with respect to the reduction state and concentration of F(ab′)₂. Based on the biosurface of the fabricated Fab′, the insulin-detection was carried out by the measurement of SPR. The proposed antibody surface could successfully detect the bovine insulin at the concentration from 100 ng/mL to 10 μg/mL.     

Determination of interferon-gamma in Chinese hamster ovary cell culture supernatant by coupled-column liquid chromatography

A robust tandem HPLC method coupling size-exclusion (Shodex Asahipak GS-320HQ) and reversed phase (Vydac 218TP54) columns with ultraviolet detection was developed for quantitative determination of interferon-gamma (IFN-gamma) in Chinese hamster ovary cell culture supernatant. The 2D-HPLC system was linked up by a 6-port 2-position low hold-up volume switch valve. Compared to a commercial ELISA kit for IFN-gamma, the coupled column LC approach was able to detect and quantify soluble IFN-gamma, regardless of the glycoprotein's molecular/conformational variability and sample background. Each LC-LC analysis took 90 minutes inclusive of column regeneration. The relative standard deviation of measurements (n = 5) was less than 3%. The limit of detection (LOD) was determined to be 0.35 microg IFN-gamma.     

Effect of the donor-bridge energy gap on the electron-transfer mechanism in donor-bridge-acceptor systems

The effect of the energy gap between donor and bridge states in the electron transfer of a double mutant photosynthetic purple bacterial reaction center is thoroughly investigated using a recently introduced modified on-the-fly filtered propagator important path integral formalism. By decomposition of the reduced density matrix of a system coupled to a dissipative environment, partial contributions of incoherent hopping, coherent superexchange, and partially coherent hopping transport to the overall electron or charge transfer are evaluated. Within the tight-binding donor-bridge-acceptor model, the three mechanisms coexist for a wide range of donor-bridge energy gap values, and the governing mechanism changes from incoherent hopping to partially coherent hopping and eventually to coherent superexchange as the donor-bridge energy gap becomes large.