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PubMed1997

Simultaneous determination of methylene violet, halogenated methylene violet and their photoproducts in the presence of DNA by high-performance liquid chromatography using an internal surface reversed-phase column.

A simple and rapid isocratic high-performance liquid chromatographic method for the analysis of methylene violet, a neutral phenothiazine dye, in the presence of DNA has been developed. These chromatographic conditions are also applicable to its N-demethylated, bromo and iodo analogs. The method utilizes an internal surface reversed-phase column and a mobile phase consisting of 20% acetonitrile in 50 mM phosphate buffer (pH 7.0) and detection at 280 nm. Under these conditions all five dyes are well resolved from one another and from the faster migrating DNA. The effects of organic modifiers, ionic strength and pH of the buffer on the capacity factors of the dyes have been investigated. The method has successfully been applied to detect the photoproducts of methylene violet and its bromo analog in the presence of DNA without removing the biopolymer from the reaction mixture.

Acetonitriles↗
PubMed1998

Vanadium haloperoxidases.

The nature of the oxidized halogen intermediate in vanadium bromoperoxidase has recently been shown to depend on the nature of the organic substrate. For example, in the presence of indoles, vanadium bromoperoxidase does not release a freely diffusible oxidized halogen intermediate (such as HOBr+/-BR2+/-Br3-). Regioselective investigations are, therefore, now feasible.

Binding Sites↗
PubMed2003

Effects of the brominated phenol, lanosol, on cytochrome P-450 and glutathione transferase activities in Haliotis rufescens and Katharina tunicata.

The relationship between biochemical transformation mechanisms and dietary preferences has been little studied among marine herbivores. Here we report on basal activities and kinetic parameters of steroid hydroxylase and glutathione transferase from digestive gland tissue of the marine molluscan generalist herbivores Haliotis rufescens and Katharina tunicata and the differential effects of the brominated phenol lanosol [1,2-dihydroxy-3,4-dibromo-5-(hydroxymethyl)-benzene] on the activity of these enzymes. Lanosol and other brominated aromatic compounds are prevalent among filamentous red algae frequently consumed by K. tunicata and have been shown to deter feeding in species of Haliotis. Animals were gavaged daily with 10 mg of lanosol per kg of wet mass for 3 days. Mean basal levels of estradiol and testosterone hydroxylase and glutathione transferase specific activities were higher in digestive gland tissue from H. rufescens relative to that of K. tunicata, and only K. tunicata glutathione transferase specific activity was affected by lanosol treatment. Apparent enzyme kinetic parameters (K(m) and V) for the substrate estradiol were higher in K. tunicata, and glutathione transferase from H. rufescens showed a higher efficiency of turnover compared with glutathione transferase from K. tunicata based on V/K(m) ratios. These results suggest a potential relationship between detoxification enzyme induction mechanisms and feeding behaviors among marine herbivores.

Animals↗
PubMed2001

High-performance liquid chromatography linked to inductively coupled plasma mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry for the simultaneous detection and identification of metabolites of 2-bromo-4-trifluoromethyl.

The use of HPLC coupled to inductively coupled plasma mass spectrometry (ICPMS) and orthogonal acceleration time-of-flight (oa-TOF) for the profiling, identification, and quantification of metabolites in rat urine following the administration of 2-bromo-4-trifluoromethylacetanilide is described. The metabolites present in the sample were separated by reversed-phase gradient chromatography with UV-diode array detection. The bulk of the eluent (90%) from the UV detector was directed to an ICPMS where bromine-containing metabolites were detected and quantified using ICPMS. The minor portion of the eluent (10%) was taken for oa-TOFMS for identification. By these means, the metabolites were identified as sulfate and glucuronide conjugates of a ring hydroxy-substituted metabolite, a N-sulfate, a N-hydroxylamine glucuronide, and N- and N-hydroxyglucuronides.

Anilides↗
PubMed1999

Detection of chlorinated and brominated byproducts of drinking water disinfection using electrospray ionization-high-field asymmetric waveform ion mobility spectrometry-mass spectrometry.

The lower limit of detection for low molecular weight polar and ionic analytes using electrospray ionization-mass spectrometry (ESI-MS) is often severely compromised by an intense background that obscures ions of trace components in solution. Recently, a new technique, referred to as high-field asymmetric waveform ion mobility spectrometry (FAIMS), has been shown to separate gas-phase ions at atmospheric pressure and room temperature. A FAIMS instrument is an ion filter that may be tuned, by control of electrical voltages, to continuously transmit selected ions from a complex mixture. This capability offers significant advantages when FAIMS is coupled with ESI, a source that generates a wide variety of ions, including solvent clusters and salt adducts. In this report, the tandem arrangement of ESI-FAIMS-MS is used for the analysis of haloacetic acids, a class of disinfection byproducts regulated by the US EPA. FAIMS is shown to effectively discriminate against background ions resulting from the electrospray of tap water solutions containing the haloacetic acids. Consequently, mass spectra are simplified, the selectivity of the method is improved, and the limits of detection are lowered compared with conventional ESI-MS. The detection limits of ESI-FAIMS-MS for six haloacetic acids ranged between 0.5 and 4 ng/mL in 9:1 methanol/tap water (5 and 40 ng/mL in the original tap water samples) with no preconcentration, derivatization, or chromatographic separation prior to analysis.

Acetates↗
PubMed2000

Investigation of the DsbA mechanism through the synthesis and analysis of an irreversible enzyme-ligand complex.

Approaching the molecular mechanism of some enzymes is hindered by the difficulty of obtaining suitable protein-ligand complexes for structural characterization. DsbA, the major disulfide oxidase in the bacterial periplasm, is such an enzyme. Its structure has been well characterized in both its oxidized and its reduced states, but structural data about DsbA-peptide complexes are still missing. We report herein an original, straightforward, and versatile strategy for making a stable covalent complex with a cysteine-homoalanine thioether bond instead of the labile cystine disulfide bond which normally forms between the enzyme and polypeptides during the catalytic cycle of DsbA. We substituted a bromohomoalanine for the cysteine in a model 14-mer peptide derived from DsbB (PID-Br), the membrane partner of DsbA. When incubated in the presence of the enzyme, a selective nucleophilic substitution of the bromine by the thiolate of the DsbA Cys(30) occurred. The major advantage of this strategy is that it enables the direct use of the wild-type form of the enzyme, which is the most relevant to obtain unbiased information on the enzymatic mechanism. Numerous intermolecular NOEs between DsbA and PID could be observed by NMR, indicating the presence of preferential noncovalent interactions between the two partners. The thermodynamic properties of the DsbA-PID complex were measured by differential scanning calorimetry. In the complex, the values for both denaturation temperature and variation in enthalpy associated with thermal unfolding were between those of oxidized and reduced forms of DsbA. This progressive increase in stability along the DsbA catalytic pathway strongly supports the model of a thermodynamically driven mechanism.

Alkylation↗
PubMed2002

Brominated flame retardants in archived serum samples from Norway: a study on temporal trends and the role of age.

The temporal trends and influence of age and gender on levels of selected brominated flame retardants (BFRs) in human serum have been assessed by analyzing archived samples from Norway. Serum from 40 to 50 year old men collected at six time periods during 1977 to 1999 and from eight groups of differing age and gender sampled in 1998 were pooled into six and eight samples, respectively. The BFRs were isolated using solid-phase extraction (SPE) and the serum lipids decomposed bytreatmentwith concentrated sulfuric acid directly on the polystyrene-divinylbenzene SPE column, prior to elution of the BFRs. Following diazomethane derivatization, the samples were analyzed by gas chromatography-electron capture mass spectrometry. Eight BFRs were quantified in the serum samples: 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154), 2,4,6-tribromophenol (TriBP), and tetrabromobisphenol A (TBBP-A). The serum concentrations of all the BFRs, increased during the entire period with the exception of TriBP, and the sum of the six polybrominated diphenyl ethers increased from 0.44 ng/g lipids in 1977 to 3.3 ng/g lipids in 1999. The BFR concentrations in the serum from the different age groups were relatively similar, except for the age group 0-4 years, which had 1.6-3.5 times higher serum concentrations. Women older than 25 years had lower serum concentrations of BFRs compared to the corresponding group of men. No trend related to age or gender, nor time during the period 1977 to 1999 was observed for TriBP. The present study indicates an ongoing increase in human exposure to BFRs, and the current body burden appears to be independent of age, except for infants (0-4 years old), who seem to experience elevated exposure.

Adolescent↗
PubMed2001

Brominated flame retardants in serum from U.S. blood donors.

Serum samples collected in 1988 from U.S. blood donors were analyzed for polybrominated diphenyl ethers (PBDEs) and polychlorinated and polybrominated biphenyls (PCBs and PBBs). The levels of the PBDEs are reported for the first time in serum from the U.S. population. The median concentrations and range of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47); 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153); 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE-183); and decabromodiphenyl ether (BDE-209) were 1.3 (<0.8-49); 0.54 (0.13-3.1); 0.24 (0.12-1.8); and <1 (<1-35) pmol/g lipid weight (l.w.), respectively. In addition we also measured detectable levels of nine additional PBDE congeners in many of the serum samples. The median concentrations and ranges of 2,2',4,4',5,5'-hexachloro- and hexabromobiphenyl (CB-153 and BB-153) were 190 (21-2600) and 19 (4.2-84) pmol/g l.w. The levels of PBDEs and CB-153 found in the U.S. samples were similar to background levels reported in the serum of Swedish hospital cleaners collected 10 years later, i.e., 1997. The BB-153 congener measured in the U.S. samples was not found in the Swedish samples. The difference in exposure to this congener could not be assessed in this study, although might be related to the 1973 BB-153 (FireMaster BP-6) animal and human contamination incident in the State of Michigan.

Blood Donors↗
PubMed2004

Brominated organic contaminants in the liver and egg of the common cormorants (Phalacrocorax carbo) from Japan.

The contamination profiles of brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs), biphenyls (PBBs), dibenzo-p-dioxins (PBDDs), and dibenzofurans (PBDFs) were determined in the liver and egg of common cormorants from Japan. PBDEs and PBBs were detected in all the samples; especially the former were detected at elevated levels. PBDDs/PBDFs were also detected in cormorants, albeit the concentrations were lower than those of the PBBs. The total concentration of PBDEs ranged from 330 to 2600 in the liver and from 600 to 3300 in the egg on a nanogram per gram of lipid basis. The concentration of PBBs was in the range from 3.0 to 33 (in the liver) and from 3.4 to 82 (in the egg) on a nanogram per gram of lipid basis. The 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) was the most predominant PBB congener in either organ, which corresponds to a major constituent of the BFR FireMaster BP-6. Concentrations of PBDDs/ PBDFs in the liver (range from 21 to 470) were slightly higher than in the egg (range from 31 to 160) on a picogram per gram of lipid basis. The results of this study imply that common cormorants accumulate a high level of PBDEs and PBBs. Comparing the concentrations of brominated organic compounds with those of chlorinated analogues, good relevance between PBBs and coplanar PCBs (r2 = 0.746 [liver] and 0.715 [egg]) was elucidated. To our knowledge, the present study demonstrates the first report of PBDEs, PBBs, and PBDDs/PBDFs in the common cormorant from Japan.

Animals↗
PubMed2006

Fate of pentabrominated diphenyl ethers in soil: abiotic sorption, plant uptake, and the impact of interspecific plant interactions.

Polybrominated diphenyl ethers (PBDEs) are potentially harmful and persistent environmental pollutants. Despite evidence that soils are a major sink for PBDEs, little is known regarding their behavior in this medium. An environmentally relevant level of a commercial penta-BDE mixture (75 microg kg(-1)) was added to topsoil, and the extractability of three congeners (BDE-47, -99, and -100) was monitored over 10 weeks in planted and unplanted treatments. The extractability of each congener decreased rapidly in the experimental soil due largely to abiotic sorption to soil particles, which was demonstrated by low PBDE recovery from sterilized and dry soils. Monoculture plantings of zucchini and radish did not affect the recovery of PBDEs from soil. However, PBDE recovery from mixed species plantings was nearly 8 times higher than that of unplanted and monoculture treatments, indicating that interspecific plant interactions may enhance PBDE bioavailablity in soil. Evidence for competitive interactions between the two species was revealed by reduced shoot biomass of zucchini plants in mixed treatments relative to pots containing only zucchini. Both plant species accumulated PBDEs in root and shoot tissue (<5 microg kg(-1) plant tissue). PBDE uptake was higher in zucchini, and translocation of PBDEs to zucchini shoots was congener-specific. Our results suggest that although abiotic sorption may limit the potential for human exposure to PBDEs in soil, plants may increase the exposure risk by taking up and translocating PBDEs into aboveground tissues and by enhancing bioavailability in soil.

Adsorption↗