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PubMed2002

Analysis of beta-lactam antibiotics by high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using bromoform.

The novel identification method for a heat-unstable antibiotic, FC/TA-891 and its active metabolite (FCE22101) by high-performance liquid chromatography (HPLC)-atmospheric pressure chemical ionization mass spectrometry (APCI-MS) employing bromoform as an ionization acceleration solvent, was applied to eight penicillins and 13 cephalosporins which are groups of beta-lactam antibiotics. The conditions of HPLC-APCI-MS were examined with ampicillin. Bromoform or chloroform was added to the mobile phase in HPLC to compare the difference between bromine and chlorine adducted ions. For all penicillins except sulbenicillin, both chlorine adducted and bromine adducted ions were observed with a flow injection method. The results indicated that the relative sensitivity ratios of bromine adducted ions to [M-H](-) were higher than those of chlorine adducted ions. These bromine adduct ions could be clearly distinguished from other ions due to its isotopical ratio (1:1), leading to an easy identification of the compounds. For 13 cephalosporins, bromine adducted ions were detected in nine compounds, and chlorine adducted ions were detected in four compounds. The separation of four antibiotics was investigated with an HPLC column to apply this technique to the actual analysis. The capability was equal as in the flow injection method and it found that this technique, i.e. APCI-MS with bromoform could be applicable in the separation analysis.

Anti-Bacterial Agents↗
PubMed2005

Fast isolation of hydrophobic organic environmental contaminants from exposed semipermeable membrane devices (SPMDs) prior to GC analysis.

Semipermeable membrane devices (SPMD) represent a passive sampling technology that is becoming widely used for monitoring of surface waters pollution. While "classic" procedures employ dialysis to recover target compounds from exposed SPMDs, in the present study analytes were isolated from cut membrane together with sequestering medium (triolein) using hexane as an extraction solvent. This approach allowed us to reduce the time needed for accomplishment of isolation step from 48 h to only 1 h. Automated gel permeation chromatography (GPC) clean-up is employed in the following step to separate triolein from analytes fraction. Musk compounds (MCs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and several other persistent organochlorine compounds (OCs) were determined in the respective fraction by GC method employing selective detectors (MSD, ECD). As shown in a series of analyses of SPMDs deployed in various aquatic ecosystems, high recoveries and good repeatability of results together with a possibility to obtain the information on the pollution of sampling site at the day of sample arrival to laboratory make this newly implemented procedure an interesting alternative to time consuming dialysis.

Chromatography, Gas↗
PubMed1999

Enhancement of electron-capture detection of methyl bromide in air by iodination.

An instrumentally simple and cost-effective method for the direct analysis of methyl bromide in ambient air is described. The method is based on the separation of sample components by gas chromatography, the conversion of methyl bromide to methyl iodide by reaction with an inorganic iodide salt, and the detection of the methyl iodide thereby produced by an electron-capture detector. Of the 20 different inorganic salts investigated here for conversion of methyl bromide to methyl iodide, zinc iodide was found to provide the greatest conversion efficiency. In addition, zinc iodide was found to provide high conversion efficiency at a modest reaction temperature, thereby minimizing both the thermal decomposition of compounds within the reaction volume and the level of column bleed introduced to the detector. The reactions of several other brominated and chlorinated organic compounds with zinc iodide have also been characterized. The successful application of this instrument to the quantitative determination of methyl bromide in a local background air sample is then demonstrated.

Air↗
PubMed1982

Bromination of guanosine and cyclic GMP confers resistance to metabolic processing by B cells.

The metabolic fates of 8-bromoguanosine (8BrGuo) and 8-bromoguanosine-3'5'-cyclic monophosphate (8Br-cGMP) were examined in cultures of murine B lymphocytes. These compounds exert striking immunostimulatory effects upon bone marrow-derived lymphoid cells in vitro. Both 8BrGuo and 8Br-cGMP were resistant to metabolic processing by these cells. That purine metabolic pathways are intact and operant in B cells was demonstrated by the ready degradation and phosphorylation of native guanosine and cyclic GMP. Inaccessibilty of the substrate to the relevant enzymes was ruled out as an explanation by the observation that the brominated compounds also were resistant to processing in broken cell preparations. Moreover, 8BrGuo did not interfere with the cellular machinery for metabolizing native guanosine. The implications of these observations for studying the actions of purine nucleotides, cyclic nucleotides, and their enzymatic processing in B cells are discussed.

Animals↗
PubMed2002

PBCDD and PBCDF from incineration of waste-containing brominated flame retardants.

Brominated organic flame retardants comprise a large, heterogeneous group of compounds that are useful but also potentially damaging to the environment. In this investigation, three common brominated flame retardants were co-combusted with an artificial municipal solid waste in a pilot-scale fluidized bed incinerator. Combustion conditions ensured degradation of the flame retardants, but stable brominated organic compounds such as polybrominated dibenzo-p-dioxins and polybrominated dibenzofurans were formed in the cooling flue gases. The incineration of fuels that contain both chlorine and bromine leads to the formation of a complex mixture of polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans. More bromination than chlorination was observed in these experiments, and the chlorination levels increased when bromine was added to the fuel. The most favored reactions led to the formation of dibromodichlorodibenzo-p-dioxin and dibromodichlorodibenzofuran. Theoretical calculations show that there is more Br2 than Cl2 in the flue gas when the two halogens are present at equimolar levels, because chlorine is mainly found in the form of HCl. This may explain the higher bromination level. BrCl is also present, which drives the chlorination observed when bromine is added.

Benzofurans↗
PubMed2004

Effects of the substitution positions of Br group in intercalative ligand on the DNA-binding behaviors of Ru(II) polypyridyl complexes.

Two new polypyridyl ligands containing substituent Br at different positions in the phenyl ring, PBIP [PBIP=2-(4-bromophenyl)imidazo[4,5-f]1,10-phenanthroline], OBIP [OBIP=2-(2-bromophenyl)imidazo[4,5-f]1,10-phenanthroline] and their Ru(II) complexes, [Ru(phen)2PBIP]2+ 1, [Ru(phen)2OBIP]2+ 2 (phen=1,10-phenanthroline), have been synthesized and characterized. The binding strength of the two complexes to calf thymus DNA (CT DNA) was investigated with spectrophotometric methods, viscosity measurements, as well as equilibrium dialysis and circular dichroism spectroscopy. The theoretical calculations for these two complexes were also carried out applying the density functional theory (DFT) method. The experimental results show that the Br group substituting H at different positions of the phenyl ring in the intercalated ligand has significant effects on the spectral properties and the DNA-binding behaviors of Ru(II) complexes. Both the complexes can bind to CT DNA in intercalative mode and interact with CT DNA enantioselectively. Moreover, complex 1 can bind to CT DNA more strongly than complex 2, and complex 2 can become a much better candidate as an enantioselective binder to CT DNA than complex 1. The theoretical calculations show that both intercalative ligands, PBIP and OBIP, in these two complexes are essentially planar, and the obtained electronic structures of the complexes can be used to explain reasonably some of their experimental regularities or trends. Such experimental and theoretical information will be useful in design of novel probes of nucleic acid structures.

Animals↗
PubMed1987

Comparison of antinicotinic activity by neosurugatoxin and the structurally related compounds.

Neosurugatoxin (NSTX) which contains two sugars (myoinositol and xylopyranose) and bromine in the chemical structure, has been shown previously to be a selective antagonist of nicotinic receptors in guinea pig ileum and in murine brain. To study the role of sugar moiety and bromine in the antinicotinic activity by NSTX, we have examined the action of NSTX (compound I) and the structurally related compounds (compound II, III and IV) on the nicotine-induced contraction of guinea pig isolated ileum and on specific [3H]nicotine binding in rat forebrain membranes. Among four compounds examined, compound I was the most potent in inhibiting the nicotine-induced contraction of guinea pig isolated ileum (pA2 = 9.1 +/- 0.1, pD2' = 8.0 +/- 0.1) and also in inhibiting specific [3H]nicotine binding in rat forebrain (IC50 = 83 +/- 9 9 nM). Compared to compound I, compound II and III which are devoid of one and two sugars, respectively, in the chemical structure of compound I were 2 or 3 times less potent in the antinicotinic activity in both tissues, and compound IV which lacks bromine in addition to two sugars was two orders of magnitude less potent. Thus, the present study demonstrates that bromine rather than sugar moiety in the chemical structure of compound I (NSTX) is an important determinate of its high affinity for nicotinic receptors.

Animals↗
PubMed2003

Effects of temperature on the production of hydrogen peroxide and volatile halocarbons by brackish-water algae.

Marine algae produce volatile halocarbons, which have an ozone-depleting potential. The formation of these compounds is thought to be related to oxidative stress, involving H2O2 and algal peroxidases. In our study we found strong correlations between the releases of H2O2 and brominated and some iodinated compounds to the seawater medium, but no such correlation was found for CHCl3, suggesting the involvement of other formation mechanisms as well. Little is known about the effects of environmental factors on the production of volatile halocarbons by algae and in the present study we focused on the influence of temperature. Algae were sampled in an area of the brackish Baltic Sea that receives thermal discharge, allowing us to collect specimens of the same species that were adapted to different field temperature regimes. We exposed six algal species (the diatom Pleurosira laevis, the brown alga Fucus vesiculosus and four filamentous green algae, Cladophora glomerata, Enteromorpha ahlneriana, E. flexuosa and E. intestinalis) to temperature changes of 0-11 degrees C under high irradiation to invoke oxidative stress. The production rates, as well as the quantitative composition of 16 volatile halocarbons, were strongly species-dependent and different types of responses to temperature were recorded. However, no response patterns to temperature change were found that were consistent for all species or for all halocarbons. We conclude that the production of certain halocarbons may increase with temperature in certain algal species, but that the amount and composition of the volatile halocarbons released by algal communities are probably more affected by temperature-associated species shifts. These results may have implications for climatic change scenarios.

Eukaryota↗
PubMed1997

Haloperoxidase activity of manganese peroxidase from Phanerochaete chrysosporium.

Manganese peroxidase (MnP) from Phanerochaete chrysosporium exhibits haloperoxidase activity at low pH. In the presence of hydrogen peroxide, MnP oxidizes bromide and iodide as measured by the formation of tribromide and triiodide complexes and the halogenation of various organic substrates. The optimum pHs for bromide and iodide oxidation are 2.5 and 3.0, respectively. Transient-state kinetic studies show that the reaction between MnP compound I and bromide or iodide occurs via a single two-electron step process, obeying second-order kinetics. The second-order rate constants for MnP compound I reduction by bromide and iodide are (4.1 +/- 0.2) x 10(3) and (1.1 +/- 0.1) x 10(5) m-1 s-1, respectively, at pH 3.0. MnP brominates a variety of aromatic substrates, including veratryl (3,4-di-methoxybenzyl) alcohol (I) to produce of 2-bromo-4,5-dimethoxybenzyl alcohol (II). MnP also hydrobrominates cinnamic acid (VI) to produce 2-bromo-3-hydroxyphenylpropionic acid (VII). With 3,4-dimethoxycinnamic acid (III) as the substrate, two bromination products are identified: trans-2-bromo-1-(3, 4-dimethoxyphenyl) ethylene (IV) and 2-bromo-3-(3, 4-dimethoxyphenyl)-3-hydroxypropionic acid (V). MnP also brominates 1,3-dicarbonyl compounds such as monochlorodimedone and malonic acid. Incubation of MnP with bromide and H2O2 in the absence of organic substrates results in enzyme inactivation. MnP binds halides to produce characteristic optical difference spectra. From these spectra, apparent dissociation constants at pH 3.0 are determined to be 0.13, 20, and 45 mm for fluoride, chloride, and bromide, respectively.

Basidiomycota↗
PubMed1998

Synthesis of some new biologically active 2,3-disubstituted quinazolin-4-ones.

The facile synthesis of 2-(2'-4-anisoylvinyl)-3-arylquinazolin-4-ones (2a, b) involves the condensation of 2-toluidine or 4-phenylenediamine with the corresponding 2-[2'-(4-anisoylvinyl)]-4H-3,1-benzoxazine-4-one (1). Reaction of compound 2 with aldehydes, bromine, alcohols, hydrazine hydrate, urea and thiourea are discussed. The former structure of the products have been characterized by elemental analysis and spectral data. Preliminary screening of some selected compounds for antimicrobial activity is reported.

4-Quinolones↗
PubMed1992

Antitumor activity evaluation of bromine-substituted analogues of ifosfamide. I. Stereodifferentiation of biological effects and selection of the most potent compounds.

The series of 9 compounds, including 3 racemates and 6 enantiomers of bromine-substituted analogues of ifosfamide (bromo-, chlorobromo- and dibromofosfamides) have been evaluated for antitumor activity against L1210 leukemia, Lewis lung carcinoma and B16 melanoma in mice. Effective and curative doses of tested compounds were estimated on the basis of computer-assisted elaboration of the dose-effect curves obtained from experimental data. Two oxazaphosphorine drugs, ifosfamide and its congener cyclophosphamide, were used as referentials. Elementary toxicity studies were conducted in parallel in healthy animals and lethal doses were determined. Selection of the most potent compounds was based on the comparison of their therapeutic indices, calculated from the ratio of lethal to effective doses. In effect four compounds which have been shown therapeutically more effective than both referential drugs, were selected for further evaluation in mice bearing advanced tumours. Stereodifferentiation of evaluated biologic effects favouring S(-) isomers was observed in all three groups of compounds. Preliminary observation was also made indicating significant lethality reduction after per os administration of selected agents, which was not paralleled by diminution of their antitumor effectivity.

Animals↗