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PubMedDate not supplied

Effect of halogenated vinyl cysteine conjugates on renal tubular active transport.

Addition of halogenated vinyl cysteine conjugates to isolated rabbit kidney tubule suspensions resulted in a decrease in the active transport of para-aminohippuric acid (PAH) and tetraethylammonium bromide (TEA). At 10(-5) M vinyl cysteine conjugate, tubule to medium accumulation ratios (T/M) were similar to those of controls while at 10(-3) M the T/M values decreased to 1, indicating complete inhibition of active accumulation of PAH or TEA. The decreased active transport was not caused by inhibition of mitochondrial oxidation since incubations in the presence of 10(-3) M halogenated vinyl cysteine did not inhibit tubule O2 utilization or production of 14CO2 from [14C]glucose or [14C]succinate. A mechanism is proposed whereby toxicity may result from covalent binding of an active intermediate, produced by enzyme cleavage, to membrane associated nucleophilic groups thereby decreasing active transport.

Animals↗

PubMed1985

Predictive correlations for the toxicity of alkyl- and halogen- substituted phenols.

The structure-activity relationships between toxicity (log BR), monitored as cell population growth, and the log 1-octanol/water partition coefficient (log Kow) for a series of 20 alkyl- and halogen-substituted phenols have been examined. The equation log BR = 0.9455 log Kow -1.9190 has been found to be an excellent linear model for these compounds. It explains 93.8% of the variability in toxicity. Subdivision of the tested derivatives based on substituent field electronic effects reveals that those with electron-releasing effects, e.g. methyl or ethyl groups, are slightly less toxic than those with electron-withdrawing effects, e.g. halogen groups.

Electrons↗

PubMed2004

QSAR study on CA inhibitory activity of disulfonamides: effect of halogen substitution.

The paper deals with quantitative structure-activity relationship (QSAR) study on CA inhibitory activity (logIC(50)) of disulfonamides using a large series of distance-based topological indices. The study discusses effect due to halogen-substitution nearer (o-position) to -SO(2)NH(2) groups. The results have shown that halogen substitution at R(3) has pronounced effect on the inhibitory activity. Predictive power of the proposed models is discussed on the basis of regression data and cross-validation parameters.

Carbonic Anhydrase Inhibitors↗

PubMed2004

Halogenated aromatics from steel production: results of a pilot-scale investigation.

The potential environmental impact of emissions of halogenated aromatics from the steel industry is of growing concern. It has been suggested that electric arc furnaces are the only industrial source with constant or increasing emissions of dioxins to air. Here the results are reported from a pilot plant study on how scrap composition and various treatment alternatives affect the formation and release of chlorinated and brominated aromatics. The experiments were conducted with a statistical mixture design, and it is shown that scrap composition has a significant impact on the outcome. In contrast, the various treatment schemes examined--shredding, disassembly, and briquetting--did not affect the formation and release of halogenated aromatics. Parallel experiments with injection of adsorbents showed that it is possible to reduce emissions without substantial investments, and this option is recommended as a low-cost solution.

Air Pollution↗

PubMed2005

Halogenated compounds in a dated sediment core of the Teltow Canal, Berlin: time related sediment contamination.

To study the recent contamination history of DDT (1,1,1-trichloro-2,2-bis(chlorophenyl)ethane) and its metabolites, as well as methoxychlor (1,1,1-trichloro-2,2-bis(p-methoxyphenyl)ethane), chlorfenson (4-chlorophenyl-p-chlorobenzenesulfonate), and further halogenated aromatics, a sediment core was collected from the Teltow Canal in Berlin (Germany). The sampling site is located nearby a former industrial point source, where recently analyses on pre-samples have indicated high concentrations of halogenated organic compounds. The deposition time of the investigated sediments was determined by gamma-spectrometrical dating. Pollution trends of selected contaminants were attributed to a time period between 5 and 10 years. Concentration profiles reflect not only the recent pollution history of these compounds, but also the time-depending effects of the ban, restriction and termination of DDT-production in the German Democratic Republic (GDR). DDT and other chlorinated aromatic compounds were produced onsite until the late 1980s. Maximum values of 133 mg kg(-1) (dry weight) for p,p'-DDD (1,1-dichloro-2,2-bis(chlorophenyl)ethane) and approximately 100 mg kg(-1) (dry weight) for p,p'-DDMS (1-chloro-2,2-bis(chlorophenyl)ethane), main metabolites of the anaerobic degradation of DDT, were determined. The occurrence of all selected contaminants, most of which have been banned more than 10 years ago, demonstrate recent contamination pathways, and the necessity of a continuous long-term monitoring of the affected environment.

Berlin↗

PubMed2006

Measuring and modelling experimental densities and ultrasonic velocities of aromatic and halogenated environmental pollutants.

The potential environmental impact of aromatic and halogenated chemicals from the petrochemical and steel industry is of growning concern. The present paper deals with the modelling and experimental determination of density and speed of sound at the range 278.15-323.15 of six aromatic and halogenated compounds (Benzene, Toluene, Ethylbenzene, Fluorobenzene, 2-Fluorotoluene and Chlorobenzene). Fitting equations were applied to the data in order to correlate for later computer based design. The estimation of the studied properties was made by the application of different theoretical procedures. The Mchaweh-Nasrifar-Moshfeghian model (MNM), an equation of state based on the generalized van der Waals theory which combines the Staverman-Guggenheim combinatorial term of lattice statistics with an attractive lattice gas expression and the Free Length Theory showed a good response at the studied conditions.

Benzene Derivatives↗

PubMed2006

Quantitative structure-activity relationships for toxicity and genotoxicity of halogenated aliphatic compounds: wing spot test of Drosophila melanogaster.

Halogenated aliphatic compounds were evaluated for toxic and genotoxic effects in the somatic mutation and recombination test employing Drosophila melanogaster. The tested chemicals included chlorinated, brominated and iodinated; mono-, di- and tri-substituted; saturated and unsaturated alkanes: 1,2-dibromoethane, 1-bromo-2-chloroethane, 1-iodopropane, 2,3-dichloropropene, 3-bromo-1-propene, epibromohydrin, 2-iodobutane, 3-chloro-2-methylpropene, 1,2,3-trichloropropane, 1,2-dichloroethane, 1,2-dichlorobutane, 1-chloro-2-methylpropane, 1,3-dichloropropane, 1,2-dichloropropane, 2-chloroethymethylether, 1-bromo-2-methylpropane and 1-chloropentane. N-methyl-N-nitrosourea served as the positive and distilled water as the negative control. The set of chemicals for the toxicological testing was selected by the use of statistical experiment design. Group of unsaturated aliphatic hydrocarbons were generally more toxic than saturated analogues. The genotoxic effect was observed with 14 compounds in the wing spot test, while 3 substances did not show any genotoxicity by using the wing spot test at 50% lethal concentration. The highest number of wing spots was observed in genotoxicity assay with 1-bromo-2-chloroethane, 1,2-dichloroethane, 1,2-dibromoethane and 1-iodopropane. Nucleophilic superdelocalizability calculated by quantum mechanics appears to be a good parameter for prediction of both toxicity and genotoxicity effects of halogenated aliphatic compounds.

Animals↗

PubMed2004

Halogenated diterpenoids from the red alga Laurencia nipponica.

Chemical compositions of three collections of the red alga Laurencia nipponica from the western part of the Sea of Japan were studied. One of them contained a series of the previously known sesquiterpenoids. Another one gave C15 bromoallene ethers, predominantly. Finally, two new halogenated diterpenes, 15-bromoparguer-9(11)-ene-16-ol and 15-bromoparguer-7-ene-16-ol, were isolated from the third collection of the same species. Structures of these diterpenoids were established by 1D and 2D NMR (1H-1H COSY, DEPT, HMQC, HMBC and NOESY) along with molecular calculations for conformations having lowest energies and mass spectroscopy. Diversity and variability of halogenated secondary metabolites in L. nipponica were discussed.

Diterpenes↗

PubMed2001

Effect of bromide ions on genotoxicity of halogenated by-products from chlorination of humic acid in water.

Genotoxicity of halogenated by-products obtained by chlorination of humic acid in water was evaluated in the presence of bromide ions (Br-). After the halogenated humic acid solution was made to flow through CSP800 cartridge, absorbed substances were eluted with dimethyl sulfoxide or acetone, and subjected to mutagenicity assays and to analysis of trihalomethanes (THMs). Mutagenic activity was measured by Ames tests using S. typhimurium TA100 strain without metabolic activation, and by the frequencies of micronuclei formation using cultured Chinese hamster lung cells (CHL/IU) in vitro. A powerful effect of bromide ions in chlorinated humic acid solutions was observed on the reverse mutation and micronuclei formations. The formations of total THMs and more brominated THMs were also enhanced in the presence of bromide ions. The ratio of [Br-/Cl-] regulated the composition and concentrations of THMs intensely, and the rate of substitution of Br- was greater than that of chloride ions (Cl-). The increments of the mutagenicity and total THMs formed in chlorinated solutions were observed in parallel with the concentration of Br- or Cl-. From the observations, it was concluded that the increasing mutagenicity might be caused by the increasing chlorinated and/or brominated by-products.

Animals↗

PubMed1999

Quantitative structure-toxicity relationships for halogenated substituted-benzenes to Vibrio fischeri, using atom-based semi-empirical molecular-orbital descriptors.

Quantitative structure-toxicity relationships (QSTR's) are derived for an extensive series of halogenated benzenes, anilines, phenols, nitrobenzenes, toluenes and other substituted benzenes against Vibrio fischeri using a wide range of whole molecule and atom-based descriptors derived from semi-empirical molecular-orbital calculations. In terms of direct statistical correlation with toxicity it was found that the molar refractivity was the most important parameter, closely followed by the solvent accessible surface area of the compound. The accuracy of these descriptors in fitting the numerous fluoro- and chloro-mono-aromatic compounds was compared with bromine and iodine analogues, where the 'best' descriptors for the former were found in general to be less accurate for the latter in the case of multi-halogen substitution. The equations obtained were also used to classify the compounds into narcosis-based mechanisms of toxicity and those with respiratory uncoupling potential. A combination of the molar refractivity and the nucleophilic susceptibility of one of the meta ring carbons predicted the toxicity of the halo-benzenes and toluenes, along with anisoles, benzonitriles, nitrobenzenes and most of the anilines. The relevance of these descriptors to developing coherent and more generally applicable models for QSTR's of mono-aromatic compounds to other species in environmental toxicology is discussed.

Benzene Derivatives↗

PubMed2002

The effect of irradiation wavelength bandwidth and spot size on the scraping depth and temperature rise in composite exposed to an argon laser or a conventional quartz-tungsten-halogen source.

OBJECTIVES: The purpose of this study was to investigate the effect of the spectral distribution of the curing irradiation near the maximum excitation wavelength of the photo-initiator and the effect of the irradiation spot size on the scraping depth-of-cure and temperature rise in a resin composite for both an argon laser and a quartz-tungsten-halogen lamp. METHODS: Using bandpass filters, the spectral outputs of an argon laser and a quartz-tungsten-halogen lamp were restricted to pass selected wavelengths on to a commercial camphorquinone-based resin composite and the depth-of-cure, using scraping methods, was measured. The temperature rise in composite was measured for some of the above-mentioned sources. The spot sizes for both sources were varied and the scraping depth was measured. Lateral curing or the extent of curing away from the focused spot was also measured. RESULTS: For constant power density and exposure time, an irradiation spectral distribution closer to the photo-initiator excitation peak yielded a higher scraping depth than a broadband spectral distribution for both sources. Under similar conditions, the argon laser resulted in a lower temperature rise in the composite than the lamp. For the same total energy imparted to the resin composite, the scraping depth increased with reducing spot size of the curing irradiation. Furthermore lateral curing of the composite well beyond the irradiation spot size was observed. SIGNIFICANCE: The spectral and spatial characteristics of the curing irradiation need to be carefully considered as these affect the scraping depth-of-cure and temperature rise in a resin composite.

Argon↗

PubMed1992

The contribution of halogen atoms to protein-ligand interactions.

The three-dimensional structure of para-fluoro-D-phenylalanine (PFF) in its complex with the zinc protease carboxypeptidase A (CPA) has been determined at 2.0 A resolution by X-ray crystallographic methods. The structure reveals that the para-fluorobenzyl side chain of the inhibitor is buried in the S'1 hydrophobic pocket of the enzyme. Intriguingly, this ligand molecule inhibits CPA better than its amino acid analogues D-phenylalanine (D-Phe) and D-tyrosine (D-Tyr) by factors of 4 and 5, respectively. Moreover, the para-fluoro derivative is a better inhibitor than para-chloro- or para-bromo-D-phenylalanine by nearly a factor of 50. This result is consistent with binding enhancements realized in other protein complexes involving halogenated ligand molecules, regardless of whether the carbon-halogen group of the ligand makes specific polar interactions or non-specific hydrophobic interactions with its protein host. In the CPA-PFF complex, the fluorine atom of PFF does not make any direct polar contact with the enzyme, and the contact surface area of the protein-ligand interface is only slightly greater, although more hydrophobic, than that of D-Phe and D-Tyr. Therefore, we conclude that the slight binding enhancement measured for PFF relative to D-Phe and D-Tyr arises predominantly from increasing the hydrophobic character of the protein-ligand interface, and not solely from increasing the degree of protein-ligand contact.

Carboxypeptidases↗

PubMed2002

Natural halogenated fatty acids: their analogues and derivatives.

A comprehensive survey has been made of all fatty acids containing halogen atoms covalently bonded to carbon and which are deemed as naturally occurring. Generally thought to be minor components produced by many different organisms, these interesting compounds now number more than 300. Recent research, especially in the marine area, indicates this number will increase in the future. Sources of halogenated fatty acids include microorganisms, algae, marine invertebrates, and higher plants and some animals. Their possible biological significance has also been discussed

Animals↗

PubMed2002

Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds.

Some halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have natural sources but separating these compounds from their commercially synthesized counterparts is difficult. Molecular-level 14C analysis may be beneficial since most synthetic compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. As a baseline study, we measured, for the first time, the 14C abundance in commercial PCB and PBDE mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds were 14C-free except for the pesticide toxaphene. which had a modern 14C abundance, as did the brominated natural compound. The result for toxaphene was not surprising since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the 14C content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock.

Animals↗

PubMed2000

Pulse radiolytic oxidation of beta-carotene with halogenated alkylperoxyl radicals in a quaternary microemulsion: formation of retinol.

Pulse radiolytically generated halogenated alkylperoxyl radicals, namely CCl3OO*, CBr3OO*, CHCl2OO*, CHBr2OO*, etc. have been employed for a study of the oxidation of beta-carotene in a quaternary microemulsion. All these halogenated alkylperoxyl radicals produce a radical cation (absorption maximum at 840 nm), either via the initial formation of an adduct (absorption maximum at 740 nm), or by direct reaction. There was a considerable blue shift of both absorption peaks in the present system as compared to those earlier reported in non-polar as well as in micellar media. An additional intense absorption peak at approximately 345 nm was noted at a longer time scale and was stable up to 5 ms. On irradiation with a large number of electron pulses, a stable product with an absorption maximum at 315 nm appeared. On excitation at 315 nm, this product gave a fluorescence spectrum with an emission maximum at 525 nm. The absorption and fluorescence spectra of the stable product compared with those of retinol; this was further confirmed by HPLC analysis. A suitable mechanism has been proposed.

Animals↗

PubMed2003

Synthesis and spectroscopic investigations of iron(III) complexes with chlorides and dianionic, symmetrically halogen substituted phthalocyanines as ligands.

The synthesis of iron(III) complexes of general formula FeCl(R-pc), where R-pc are dianionic, symmetrically halogen substituted phthalocyanines at the positions 2,9,16,23 or 1,8,15,22, from the corresponding amino substituted derivatives is described (R=Cl, Br, I). The complexes are characterized by UV-visible and infrared spectra, powder X-ray diffraction and magnetic susceptibility measurements. The effect of substituents at the periphery and the basicity of the solvents used on the electronic spectra are discussed. The Q band of the electronic spectra for symmetrically halogen substituted derivatives are redshifted and the substituents at 2,9,16,23- positions are more effective in redshifting the Q bands than those at 1,8,15,22-positions. Depending upon the basicity of the solvents, the ligand-to-metal charge transfer (LMCT) transitions on Q band envelop shift to the higher energy region in the order of pyridine>DMF>DMSO. The infrared absorption signals for C-H and metal-ligand vibrations appear to be sharper for 1,8,15,22 substituted derivatives than for 2,9,16,23 substituted ones.

Anions↗

PubMed2003

Potent antibacterial activity of halogenated metabolites from Malaysian red algae, Laurencia majuscula (Rhodomelaceae, Ceramiales).

Red algae genus Laurencia (Rhodomelaceae, Ceramiales) are known to produce a wide range of chemically interesting secondary halogenated metabolites. This investigation delves upon extraction, isolation, structural elucidation and antibacterial activity of inherently available secondary metabolites of Laurencia majuscula Harvey collected from two locations in waters of Sabah, Malaysia. Two major halogenated compounds, identified as elatol (1) and iso-obtusol (2) were isolated. Structures of these compounds were determined from their spectroscopic data such as IR, 1H-NMR, 13C-NMR and optical rotation. Antibacterial bioassay against human pathogenic bacteria was conducted using disc diffusion (Kirby-Bauer) method. Elatol (1) inhibited six species of bacteria, with significant antibacterial activities against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp. while iso-obtusol (2) exhibited antibacterial activity against four bacterial species with significant activity against K. pneumonia and Salmonella sp. Elatol (1) showed equal and better antibacterial activity compared with tested commercial antibiotics while iso-obtusol (2) only equaled the potency of commercial antibiotics against K. pneumonia and Salmonella sp. Further tests conducted using dilution method showed both compounds as having bacteriostatic mode of action against the tested bacteria.

Anti-Bacterial Agents↗

PubMed2003

The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes.

AA8 Chinese hamster ovary cells were treated with halogenated nucleosides analogues of thymidine, namely CldU, 5-iodo-2'-deoxyuridine (IdU), and 5-bromo-2'-deoxyuridine (BrdU), following different experimental protocols. The purpose was to see whether incorporation of exogenous pyrimidine analogues into DNA could interfere with normal chromosome segregation. The endpoint chosen was endoreduplication, that arises after aberrant mitosis when daughter chromatids segregation fails. Treatment with any of the halogenated nucleosides for two consecutive cell cycles resulted in endoreduplication, with a highest yield for CldU, intermediate for IdU, and lowest for BrdU. The frequency of endoreduplicated cells paralleled in all cases the level of analogue substitution into DNA. Our results seem to support that thymidine analogue substitution into DNA is responsible for the triggering of endoreduplication. Besides, the lack of any effect on endoreduplication when CldU was present for only one S-period strongly suggest that it is the nature of template, and not nascent DNA, that plays a major role in chromosome segregation. Taking into account that topoisomerase II cleaves DNA at preferred sequences within its recognition/binding sites, the likely involvement of the enzyme is discussed.

Animals↗