(Table 2) Polybrominated diphenyl ether concentration in blubber samples from whales, seals and porpoises between 1986-2009

A selection of MeO-BDE and BDE congeners were analyzed in pooled blubber samples of pilot whale (Globicephala melas), ringed seal (Phoca hispida), minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), harbor porpoise (Phocoena phocoena), hooded seal (Cystophora cristata), and Atlantic white-sided dolphin (Lagenorhynchus acutus), covering a time period of more than 20 years (1986-2009). The analytes were extracted and cleaned-up using open column extraction and multi-layer silica gel column chromatography. The analysis was performed using both low resolution and high resolution GC-MS. MeO-PBDE concentrations relative to total PBDE concentrations varied greatly between sampling periods and species. The highest MeO-PBDE levels were found in the toothed whale species pilot whale and white-sided dolphin, often exceeding the concentration of the most abundant PBDE, BDE-47. The lowest MeO-PBDE levels were found in fin whales and ringed seals. The main MeO-BDE congeners were 6-MeO-BDE47 and 2'-MeO-BDE68. A weak correlation only between BDE47 and its methoxylated analog 6-MeO-BDE47 was found and is indicative of a natural source for MeO-PBDEs.

(Tables 1,2) Polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas) and ringed seal (Pusa hispida) liver microsomal protein content and EROD activity

The present study assessed and compared the oxidative and reductive biotransformation of brominated flame retardants, including established polybrominated diphenyl ethers (PBDEs) and emerging decabromodiphenyl ethane (DBDPE) using an in vitro system based on liver microsomes from various arctic marine-feeding mammals: polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas), and ringed seal (Pusa hispida), and in laboratory rat as a mammalian model species. Greater depletion of fully brominated BDE209 (14-25% of 30pmol) and DBDPE (44-74% of 90pmol) occurred in individuals from all species relative to depletion of lower brominated PBDEs (BDEs 99,100, and 154; 0-3% of 30pmol). No evidence of simply debrominated metabolites was observed. Investigation of phenolic metabolites in rat and polar bear revealed formation of two phenolic, likely multiply debrominated, DBDPE metabolites in polar bear and one phenolic BDE154 metabolite in polar bear and rat microsomes. For BDE209 and DBDPE, observed metabolite concentrations were low to nondetectable, despite substantial parent depletion. These findings suggested possible underestimation of the ecosystem burden of total-BDE209, as well as its transformation products, and a need for research to identify and characterize the persistence and toxicity of major BDE209 metabolites. Similar cause for concern may exist regarding DBDPE, given similarities of physicochemical and environmental behavior to BDE209, current evidence of biotransformation, and increasing use of DBDPE as a replacement for BDE209.

Multiresidue Analysis of Insecticides and Other Selected Environmental Contaminants in Poultry Manure by Gas Chromatography/Mass Spectrometry

An analytical method was developed for the simultaneous determination in poultry manure of 41 organic contaminants belonging to different chemical classes: pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers. Poultry manure was extracted with a modified QuEChERS method, and the extracts were analyzed by isotope dilution GC/MS. Recovery of these contaminants from samples spiked at levels ranging from 25 to 100 ng/g was satisfactory for all the compounds. The developed procedure provided LODs from 0.8 to 9.6 ng/g. The analysis of poultry manure samples collected on different farms confirmed the presence of some of the studied contaminants. Pyrethroids and polycyclic aromatic hydrocarbons were the main contaminants detected.

The domain structure of protoporphyrinogen oxidase, the molecular target of diphenyl ether-type herbicides

Protoporphyrinogen oxidase (EC 1–3-3–4), the 60-kDa membrane-bound flavoenzyme that catalyzes the final reaction of the common branch of the heme and chlorophyll biosynthesis pathways in plants, is the molecular target of diphenyl ether-type herbicides. It is highly resistant to proteases (trypsin, endoproteinase Glu-C, or carboxypeptidases A, B, and Y), because the protein is folded into an extremely compact form. Trypsin maps of the native purified and membrane-bound yeast protoporphyrinogen oxidase show that this basic enzyme (pI > 8.5) was cleaved at a single site under nondenaturing conditions, generating two peptides with relative molecular masses of 30,000 and 35,000. The endoproteinase Glu-C also cleaved the protein into two peptides with similar masses, and there was no additional cleavage site under mild denaturing conditions. N-terminal peptide sequence analysis of the proteolytic (trypsin and endoproteinase Glu-C) peptides showed that both cleavage sites were located in putative connecting loop between the N-terminal domain (25 kDa) with the βαβ ADP-binding fold and the C-terminal domain (35 kDa), which possibly is involved in the binding of the isoalloxazine moiety of the FAD cofactor. The peptides remained strongly associated and fully active with the Km for protoporphyrinogen and the Ki for various inhibitors, diphenyl-ethers, or diphenyleneiodonium derivatives, identical to those measured for the native enzyme. However, the enzyme activity of the peptides was much more susceptible to thermal denaturation than that of the native protein. Only the C-terminal domain of protoporphyrinogen oxidase was labeled specifically in active site-directed photoaffinity-labeling experiments. Trypsin may have caused intramolecular transfer of the labeled group to reactive components of the N-terminal domain, resulting in nonspecific labeling. We suggest that the active site of protoporphyrinogen oxidase is in the C-terminal domain of the protein, at the interface between the C- and N-terminal domains.

Double-level “orthogonal” dynamic combinatorial libraries on transition metal template

Dynamic combinatorial libraries are mixtures of compounds that exist in a dynamic equilibrium and can be driven to compositional self adaptation via selective binding of a specific assembly of certain components to a molecular target. We present here an extension of this initial concept to dynamic libraries that consists of two levels, the first formed by the coordination of terpyridine-based ligands to the transition metal template, and the second, by the imine formation with the aldehyde substituents on the terpyridine moieties. Dialdehyde 7 has been synthesized, converted into a variety of ligands, oxime ethers L11–L33 and acyl hydrazones L44–L77, and subsequently into corresponding cobalt complexes. A typical complex, Co(L22)22+ is shown to engage in rapid exchange with a competing ligand L11 and with another complex, Co(L22)22+ in 30% acetonitrile/water at pH 7.0 and 25°C. The exchange in the corresponding Co(III) complexes is shown to be much slower. Imine exchange in the acyl hydrazone complexes (L44–L77) is strongly controlled by pH and temperature. The two types of exchange, ligand and imine, can thus be used as independent equilibrium processes controlled by different types of external intervention, i.e., via oxidation/reduction of the metal template and/or change in the pH/temperature of the medium. The resulting double-level dynamic libraries are therefore named orthogonal, in similarity with the orthogonal protecting groups in organic synthesis. Sample libraries of this type have been synthesized and showed the complete expected set of components in electrospray ionization MS.

A general assay for antibody catalysis using acridone as a fluorescent tag.

A simple and highly sensitive catalysis assay is demonstrated based on analyzing reactions with acridonetagged compounds by thin-layer chromatography. As little as 1 pmol of product is readily visualized by its blue fluorescence under UV illumination and identified by its retention factor (Rf). Each assay requires only 10 microliters of solution. The method is reliable, inexpensive, versatile, and immediately applicable in repetitive format for screening catalytic antibody libraries. Three examples are presented: (i) the epoxidation of acridone labeled (S)-citronellol. The pair of stereoisomeric epoxides formed is resolved on the plate, which provides a direct selection method for enantioselective epoxidation catalysts. (ii) Oxidation of acridone-labeled 1-hexanol to 1-hexanal. The activity of horse liver alcohol dehydrogenase is detected. (iii) Indirect product labeling of released aldehyde groups by hydrazone formation with an acridone-labeled hydrazide. Activity of catalytic antibodies for hydrolysis of enol ethers is detected.

Pyrolysis and combustion study of flexible polyurethane foam

The thermal degradation of flexible polyurethane foam has been studied under different conditions by thermogravimetric analysis (TG), thermogravimetric analysis-infrared spectrometry (TG-IR) and thermogravimetric analysis-mass spectrometry (TG-MS). For the kinetic study, dynamic and dynamic+isothermal runs were performed at different heating rates (5, 10 and 20 °C min−1) in three different atmospheres (N2, N2:O2 4:1 and N2:O2 9:1). Two reaction models were obtained, one for the pyrolysis and another for the combustion degradation (N2:O2 4:1 and N2:O2 9:1), simultaneously correlating the experimental data from the dynamic and dynamic+isothermal runs at different heating rates. The pyrolytic model considered consisted of two consecutive reactions with activation energies of 142 and 217.5 kJ mol−1 and reaction orders of 0.805 and 1.246. Nevertheless, to simulate the experimental data from the combustion runs, three consecutive reactions were employed with activation energies of 237.9, 103.5 and 120.1 kJ mol−1, and reaction orders of 2.003, 0.778 and 1.025. From the characterization of the sample employing TG-IR and TG-MS, the results obtained showed that the FPUF, under an inert atmosphere, started the decomposition breaking the urethane bond to produce long chains of ethers which were degraded immediately in the next step. However, under an oxidative atmosphere, at the first step not only the urethane bonds were broken but also some ether polyols started their degradation which finished at the second step producing a char that was degraded at the last stage.