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Claudiu T. Supuran - One of the best experts on this subject based on the ideXlab platform.
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synthesis and carbonic anhydrase isoenzymes i ii ix and xii inhibitory effects of dimethoxybromophenol derivatives incorporating cyclopropane moieties
Journal of Medicinal Chemistry, 2015Co-Authors: Murat Boztas, Meryem Topal, Abdullah Menzek, Muhammet Tanc, Yasin Cetinkaya, Ilhami Gulcin, Ertan şahin, Claudiu T. SupuranAbstract:Cyclopropylcarboxylic acids and esters and cyclopropylmethanols incorporating bromophenol moieties were investigated as inhibitors of the carbonic anhydrase enzyme (CA; EC 4.2.1.1). The cis- and trans-esters 5 and 6 were obtained from the reaction of 4-allyl-1,2-dimethoxybenzene (4) with ethyl diazoacetate, which after bromination with Br2 gave two isomeric monobromides (11 and 15), four isomeric dibromides (12, 13, 16, and 17), and two isomeric tribromides (14 and 18). The carboxylic acids 7, 8, and 19–26 were thereafter obtained by hydrolysis of the synthesized esters. All these bromophenol derivatives were tested against human (h) CA isoenzymes I and II (cytosolic, ubiquitous isoforms) and hCA IX and XII (transmembrane, tumor-associated enzymes). All tested bromophenols exhibited excellent inhibitory effects, in the low nanomolar range, with Ki values in the range of 0.54–59 nM against hCA I and in the range of 0.97–12.14 nM against hCA II, whereas they were low micromolar inhibitors against hCA IX and...
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Synthesis and Carbonic Anhydrase Isoenzymes I, II, IX, and XII Inhibitory Effects of Dimethoxybromophenol Derivatives Incorporating Cyclopropane Moieties
2015Co-Authors: Murat Boztaş, Yasin Çetinkaya, Meryem Topal, İlhami Gülçin, Abdullah Menzek, Ertan Şahin, Muhammet Tanc, Claudiu T. SupuranAbstract:Cyclopropylcarboxylic acids and esters and cyclopropylmethanols incorporating bromophenol moieties were investigated as inhibitors of the carbonic anhydrase enzyme (CA; EC 4.2.1.1). The cis- and trans-esters 5 and 6 were obtained from the reaction of 4-allyl-1,2-dimethoxybenzene (4) with ethyl diazoacetate, which after bromination with Br2 gave two isomeric monobromides (11 and 15), four isomeric dibromides (12, 13, 16, and 17), and two isomeric tribromides (14 and 18). The carboxylic acids 7, 8, and 19–26 were thereafter obtained by hydrolysis of the synthesized esters. All these bromophenol derivatives were tested against human (h) CA isoenzymes I and II (cytosolic, ubiquitous isoforms) and hCA IX and XII (transmembrane, tumor-associated enzymes). All tested bromophenols exhibited excellent inhibitory effects, in the low nanomolar range, with Ki values in the range of 0.54–59 nM against hCA I and in the range of 0.97–12.14 nM against hCA II, whereas they were low micromolar inhibitors against hCA IX and XII. The best hCA I inhibition was observed in new bromophenol derivative 20 (Ki = 0.54 nM). On the other hand, new bromophenol derivative 12 showed a powerful inhibition effect against hCA II (Ki = 0.97 nM)
Bingui Wang - One of the best experts on this subject based on the ideXlab platform.
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new nitrogen containing bromophenols from the marine red alga rhodomela confervoides and their radical scavenging activity
Food Chemistry, 2012Co-Authors: James B Gloer, Bingui WangAbstract:In addition to nine known bromophenol derivatives, five new nitrogen-containing bromophenols were isolated from an ethyl acetate extract of the marine red alga Rhodomela confervoides. By using spectro-scopic methods, the structures of the new compounds were identified as 3-(2,3-dibromo-4,5-dihydroxybenzyl)pyrrolidine-2,5-dione (1), methyl 4-(2,3-dibromo-4,5-dihydroxybenzylamino)-4-oxobutanoate (2), 4-(2,3-dibromo-4,5-dihydroxybenzylamino)-4-oxobutanoic acid (3), 3-bromo-5-hydroxy-4-methoxybenzamide (4), and 2-(3-bromo-5-hydroxy-4-methoxyphenyl)acetamide (5). All of these bromophenols showed potent scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals, with IC50 values ranging from 5.22 to 23.60 mu M. These compounds also displayed moderate activity against ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonate) radicals, with Trolox Equivalent Antioxidant Capacity values (TEAC) ranging from 2.11 to 3.58 mM. The results obtained in this study demonstrate that the bromophenols obtained from R. confervoides may have potential application in food and/or pharmaceutical fields as natural antioxidants. (C) 2012 Elsevier Ltd. All rights reserved.
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natural bromophenols from the marine red alga polysiphonia urceolata rhodomelaceae structural elucidation and dpph radical scavenging activity
Bioorganic & Medicinal Chemistry, 2007Co-Authors: Bingui WangAbstract:Three new natural occurring bromophenols, 3-(3-bromo-4,5-dihydroxyphenyl)-2-(3,5-dibromo-4-hydroxyphenyl)propionic acid (1), (E)-4-(3-bromo-4,5-dihydroxyphenyl)-but-3-en-2-one (2), and (3,5-dibromo-4-hydroxyphenyl) acetic acid butyl ester (3), together with one known bromophenol, 1,2-bis(3-bromo-4,5-dihydroxyphenyl)ethane (4), were isolated and identified from the marine red alga Polysiphonia urceolata. The structures of these compounds were elucidated by extensive analysis of ID and 2D NMR and IR spectra and MS data. Each of the isolated compounds was evaluated for scavenging alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical activity and all of them exhibited significant activity with IC50 values ranging from 9.67 to 21.90 mu M, compared to the positive control, a well-known antioxidant butylated hydroxytoluene (BHT), with IC50 83.84 mu M. (C) 2007 Elsevier Ltd. All rights reserved.
Barry Dellinger - One of the best experts on this subject based on the ideXlab platform.
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Formation of bromochlorodibenzo-p-dioxins and dibenzofurans from the high-temperature oxidation of a mixture of 2-chlorophenol and 2-Bromophenol.
Environmental science & technology, 2006Co-Authors: Catherine S. Evans, Barry DellingerAbstract:The homogeneous, gas-phase oxidative thermal degradation of a 50:50 mixture of 2-Bromophenol and 2-chlorophenol was studied in a 1 cm i.d., fused silica flow reactor at a concentration of 88 ppm, with a reaction time of 2.0 s, over a temperature range of 300 to 1000 °C. Observed products in order of decreasing yield included the following: dibenzo-p-dioxin (DD), 4-bromo-6-chlorodibenzofuran (4-B,6-CDF), phenol, 4,6-dibromodibenzofuran (4,6-DBDF), 2,6-dibromophenol, 4,6-dichlorodibenzofuran (4,6-DCDF), 2-bromo-4-chlorophenol, 2,4-dibromophenol, 2-chloro-4-bromophenol, 4-monobromodibenzofuran (4-MBDF), 4-monochlorodibenzofuran (4-MCDF), dibenzofuran (DF), 1-monobromodibenzo-p-dioxin (1-MBDD), 1-monochlorodibenzo-p-dioxin (1-MCDD), 2,4,6-tribromophenol, naphthalene, chloronaphthalene, bromonaphthalene, chlorobenzene, bromobenzene, and benzene. The results are compared and contrasted with previous results reported for the oxidations of pure 2-chlorophenol and 2-Bromophenol as well as results for the pyrolysi...
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Surface-mediated formation of PBDD/Fs from the high-temperature oxidation of 2-Bromophenol on a CuO/silica surface.
Chemosphere, 2005Co-Authors: Catherine S. Evans, Barry DellingerAbstract:Abstract As a model brominated hydrocarbon that may form brominated dioxins, we studied the surface-mediated, oxidative thermal degradation of 2-Bromophenol on a supported copper oxide catalyst in a 1 mm i.d., fused silica flow reactor at a constant concentration of 90 ppm over a temperature range from 250 to 550 °C. Observed products included: dibenzo- p -dioxin (DD), 1-monobromodibenzo- p -dioxin (1-MBDD), dibromodibenzo- p -dioxin (DBDD), tribromodibenzo- p -dioxin (TrBDD), 4-monobromodibenzofuran (4-MBDF), 2,4,6-tribromophenol, 2,4- and 2,6-dibromophenol, and polybrominated benzenes. The results are compared and contrasted with previous work on surface catalyzed oxidative thermal degradation of 2-chlorophenol as well as our own work with the surface-catalyzed pyrolytic thermal degradation of 2-Bromophenol. Typically 20 to 200× higher yields of PBDDs are observed for 2-Bromophenol than for the analogous PCDDs for 2-chlorophenol. However the anticipated PBDF, 4,6-DBDF, was not observed and 4-MBDF was observed at very low yields. Surprisingly, the maximum yields of PBDDs were observed at higher temperatures than under pyrolytic conditions. This is attributed to regeneration of the catalytic surface due to the presence of oxygen. Higher yields of polybrominated phenols and polybrominated benzenes were also observed than for the analogous chlorinated phenols and benzenes from the oxidation of 2-chlorophenol. This can be attributed to the ease of bromination over chlorination based on the higher abundance of bromine atoms present for 2-Bromophenol than chlorine atoms present for 2-chlorophenol.
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Formation of bromochlorodibenzo-p-dioxins and furans from the high-temperature pyrolysis of a 2-chlorophenol/2-Bromophenol mixture.
Environmental science & technology, 2005Co-Authors: Catherine S. Evans, Barry DellingerAbstract:The homogeneous, gas-phase pyrolytic thermal degradation of a 50:50 mixture of 2-Bromophenol and 2-chlorophenol was studied in a 1 cm i.d., fused silica flow reactor at a total concentration of 88 ppm, reaction time of 2.0 s, and temperatures from 300 to 1000 °C. Observed products included (in decreasing yield) naphthalene, dibenzo-p-dioxin (DD), phenol, dibenzofuran (DF), bromobenzene, chloronaphthalene, 4-bromo-6-chlorodibenzofuran (4-B,6-CDF), bromonaphthalene, benzene, 4,6-dichlorodibenzofuran (4,6-DCDF), chlorobenzene, 4-monobromodibenzofuran (4-MBDF), 4-monochlorodibenzofuran (4-MCDF), 1-monobromodibenzo-p-dioxin (1-MBDD), 2-chloro,4-bromophenol, 2,4-dibromophenol, and 2-bromo-4-chlorophenol. Unlike the case for the pyrolysis of pure 2-chlorophenol, 4,6-DCDF was observed, but the analogous 4,6-DBDF remained undetected similar to the individual results with 2-MBP. This indicates that the presence of bromine increases the concentration of chlorine atoms available for the formation of 4,6-DCDF. Due to ...
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Surface-mediated formation of polybrominated dibenzo-p-dioxins and dibenzofurans from the high-temperature pyrolysis of 2-Bromophenol on a CuO/silica surface.
Environmental science & technology, 2005Co-Authors: Catherine S. Evans, Barry DellingerAbstract:We studied the surface-mediated pyrolytic thermal degradation of 2-Bromophenol, a model brominated hydrocarbon that may form brominated dioxins in combustion and thermal processes, on silica-supported copper oxide in a 1 mm i.d., fused silica flow reactor at a constant concentration of 88 ppm over a temperature range of 250−550 °C. Observed products included dibenzo-p-dioxin (DD), 1-monobromodibenzo-p-dioxin (1-MBDD), dibromodibenzo-p-dioxin (DBDD), tribromodibenzo-p-dioxin (TrBDD), 4-monobromodibenzofuran (4-MBDF), dibenzofuran (DF), 2,4,6-tribromophenol, 2,4- and 2,6-dibromophenol, and polybrominated benzenes. These results are compared and contrasted with previous work on surface-catalyzed pyrolysis of 2-chlorophenol. Polybrominated dibenzofurans (PBDFs) are formed by the Langmuir−Hinshelwood mechanism, and the formation of polybrominated dibenzo-p-dioxins (PBDDs) is through an Eley−Rideal mechanism. Yields of PBDDs are at least 16× greater for 2-Bromophenol than for analogous PCDDs from 2-chlorophenol...
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Mechanisms of dioxin formation from the high-temperature oxidation of 2-Bromophenol.
Environmental science & technology, 2005Co-Authors: Catherine S. Evans, Barry DellingerAbstract:The homogeneous, gas-phase oxidative thermal degradation of 2-Bromophenol was studied in a 1 cm i.d., fused silica flow reactor at a concentration of 88 ppm, reaction time of 2.0 s, over a temperature range from 300 to 1000 degrees C. Observed products in order of yield were dibenzo-p-dioxin (DD) > 4,6-dibromodibenzofuran (4,6-DBDF) > 4-monobromodibenzofuran (4-MCDF), dibenzofuran (DF), 1-monobromodibenzo-p-dioxin (1-MBDD), naphthalene, bromonaphthalene, 2,4-dibromophenol, 2,6-dibromophenol, phenol, bromobenzene, and benzene. This result is in contrast to the oxidation of 2-chlorophenol, where the major product is 4,6-dichlorodibenzofuran (4,6-DCDF). 4,6-DBDF was observed in high yields in contrastto our previous results for the pyrolysis of 2-Bromophenol, where 4,6-DBDF was not detected. The increase in 4,6-DBDF yields is attributed to hydroxyl radical being the major chain carrier under oxidative conditions, which favors hydrogen-abstraction reactions that lead to formation of 4,6-DBDF. However, DD is still the highest yield product under oxidative conditions because of the relative ease of displacement of Br in the ring-closure reaction.
Krisztina Kónya - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of 8-Bromoflavone and its Buchwald-Hartwig Reaction
2016Co-Authors: Dávid Pajtás, Tamás Patonay, Krisztina KónyaAbstract:Simple and convenient synthesis of 8-bromoflavone was achieved, starting from 2-Bromophenol through 3’-bromo-2’-hydroxyacetophenone whose preparation was managed to be solved by optimized Fries rearrangement. The Buchwald-Hartwig reaction of 8-bromoflavone with different type of primary and secondary amines was carried out
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Synthesis of 8-Bromoflavone and Its Buchwald–Hartwig Reaction with Amines
Synthesis, 2015Co-Authors: Krisztina Kónya, Dávid Pajtás, Tamás PatonayAbstract:Simple and convenient synthesis of 8-bromoflavone was achieved, starting from 2-Bromophenol through 3’-bromo-2’-hydroxyacetophenone whose preparation was managed to be solved by optimized Fries rearrangement. The Buchwald-Hartwig reaction of 8-bromoflavone with different type of primary and secondary amines was carried ou
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Synthesis of 8-Bromoflavone and Its Buchwald-Hartwig Reaction with Amines
Synthesis, 2015Co-Authors: Dávid Pajtás, Tamás Patonay, Krisztina KónyaAbstract:Simple and convenient synthesis of 8-bromoflavone was achieved, starting from 2-Bromophenol through 3′-bromo-2′-hydroxyacetophenone whose preparation was managed to be solved by optimized Fries rearrangement. The Buchwald–Hartwig reaction of 8-bromoflavone with different type of primary and secondary amines was carried out.
Max M. Häggblom - One of the best experts on this subject based on the ideXlab platform.
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Detection and characterization of a dehalogenating microorganism by terminal restriction fragment length polymorphism fingerprinting of 16S rRNA in a sulfidogenic, 2-Bromophenol-utilizing enrichment.
Applied and environmental microbiology, 2004Co-Authors: Donna E. Fennell, Max M. Häggblom, Sung-keun Rhee, Youngbeom Ahn, Lee J. KerkhofAbstract:Terminal restriction fragment length polymorphism analysis of reverse-transcribed 16S rRNA during periods of community flux was used as a tool to delineate the roles of the members of a 2-Bromophenol-degrading, sulfate-reducing consortium. Starved, washed cultures were amended with 2-Bromophenol plus sulfate, 2-Bromophenol plus hydrogen, phenol plus sulfate, or phenol with no electron acceptor and were monitored for substrate use. In the presence of sulfate, 2-Bromophenol and phenol were completely degraded. In the absence of sulfate, 2-Bromophenol was dehalogenated and phenol accumulated. Direct terminal restriction fragment length polymorphism fingerprinting of the 16S rRNA in the various subcultures indicated that phylotype 2BP-48 (a Desulfovibrio-like sequence) was responsible for the dehalogenation of 2-Bromophenol. A stable coculture was established which contained predominantly 2BP-48 and a second Desulfovibrio-like bacterium (designated BP212 based on terminal restriction fragment length polymorphism fingerprinting) that was capable of dehalogenating 2-Bromophenol to phenol. Strain 2BP-48 in the coculture could couple reductive dehalogenation to growth with 2-Bromophenol, 2,6-dibromophenol, or 2-iodophenol and lactate or formate as the electron donor. In addition to halophenols, strain 2BP-48 appears to use sulfate, sulfite, and thiosulfate as electron acceptors and is capable of simultaneous sulfidogenesis and reductive dehalogenation in the presence of sulfate.
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reductive dehalogenation of brominated phenolic compounds by microorganisms associated with the marine sponge aplysina aerophoba
Applied and Environmental Microbiology, 2003Co-Authors: Youngbeom Ahn, Donna E. Fennell, Sung-keun Rhee, Lee J. Kerkhof, Ute Hentschel, Max M. HäggblomAbstract:Marine sponges are natural sources of brominated organic compounds, including bromoindoles, bromophenols, and bromopyrroles, that may comprise up to 12% of the sponge dry weight. Aplysina aerophoba sponges harbor large numbers of bacteria that can amount to 40% of the biomass of the animal. We postulated that there might be mechanisms for microbially mediated degradation of these halogenated chemicals within the sponges. The capability of anaerobic microorganisms associated with the marine sponge to transform haloaromatic compounds was tested under different electron-accepting conditions (i.e., denitrifying, sulfidogenic, and methanogenic). We observed dehalogenation activity of sponge-associated microorganisms with various haloaromatics. 2-Bromo-, 3-bromo-, 4-bromo-, 2,6-dibromo-, and 2,4,6-tribromophenol, and 3,5-dibromo-4-hydroxybenzoate were reductively debrominated under methanogenic and sulfidogenic conditions with no activity observed in the presence of nitrate. Monochlorinated phenols were not transformed over a period of 1 year. Debromination of 2,4,6-tribromophenol, and 2,6-dibromophenol to 2-Bromophenol was more rapid than the debromination of the monobrominated phenols. Ampicillin and chloramphenicol inhibited activity, suggesting that dehalogenation was mediated by bacteria. Characterization of the debrominating methanogenic consortia by using terminal restriction fragment length polymorphism (TRFLP) and denaturing gradient gel electrophoresis analysis indicated that different 16S ribosomal DNA (rDNA) phylotypes were enriched on the different halogenated substrates. Sponge-associated microorganisms enriched on organobromine compounds had distinct 16S rDNA TRFLP patterns and were most closely related to the δ subgroup of the proteobacteria. The presence of homologous reductive dehalogenase gene motifs in the sponge-associated microorganisms suggested that reductive dehalogenation might be coupled to dehalorespiration.
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Community analyses of sulfidogenic 2-Bromophenol-dehalogenating and phenol-degrading microbial consortia
FEMS Microbiology Ecology, 1999Co-Authors: Victoria K. Knight, Lee J. Kerkhof, Max M. HäggblomAbstract:Microbial consortia were enriched under sulfidogenic conditions using a common estuarine sediment inoculum with 2-Bromophenol or phenol as the sole the carbon source. Stable consortia were maintained over a 3-year period with repeated feeding and serial dilution into fresh medium. 2-Bromophenol was initially dehalogenated to phenol. Degradation of phenol was dependent on sulfate reduction and inhibited by molybdate, a specific inhibitor of sulfate reduction. Reductive dehalogenation of 2-Bromophenol, however, was not dependent on, or inhibited by sulfate. The 2-Bromophenol- and phenol-degrading sulfidogenic consortia were characterized using 16S rRNA restriction fragment length polymorphism analysis and unique clones were sequenced. Terminal restriction fragment length polymorphism of all individual clones and both microbial consortia indicated that all 16S rRNA types present in the consortia were cloned and characterized. Four phylotypes were identified from the 2-Bromophenol-utilizing consortium which based upon their 16S rRNA sequences clustered into three major groups: one sequence was related to the ϵ-subgroup of the Proteobacteria, two clones clustered within the sulfate-reducers (δ-subgroup of Proteobacteria), the fourth phylotype was divergent from previously described bacteria and was most closely related to the genus Planctomycetes. None of the clones from the 2-Bromophenol-degrading consortium are close to previously described aryl-dehalogenating bacteria which predominantly comprise the genera Desulfitobacterium and Desulfomonile. In contrast, the phenol-degrading consortium yielded only two clonal types. One was placed within the ϵ-sub-division of the Proteobacteria with Thiomicrospira denitrificans as its closest neighbor. The other clone was closest to the genus Cytophaga with Anaeroflexus maritimus as its closest neighbor.
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Dehalogenation and biodegradation of brominated phenols and benzoic acids under iron-reducing, sulfidogenic, and methanogenic conditions
Applied and environmental microbiology, 1997Co-Authors: Esteban Monserrate, Max M. HäggblomAbstract:The anaerobic biodegradation of monobrominated phenols and benzoic acids by microorganisms enriched from marine and estuarine sediments was determined in the presence of different electron acceptors [i.e., Fe(III), SO4(2-), or HCO3-]. Under all conditions tested, the bromophenol isomers were utilized without a lengthy lag period whereas the bromobenzoate isomers were utilized only after a lag period of 23 to 64 days. 2-Bromophenol was debrominated to phenol, with the subsequent utilization of phenol under all three reducing conditions. Debromination of 3-bromophenol and 4-bromophenol was also observed under sulfidogenic and methanogenic conditions but not under iron-reducing conditions. In the bromobenzoate-degrading cultures, no intermediates were observed under any of the conditions tested. Debromination rates were higher under methanogenic conditions than under sulfate-reducing or iron-reducing conditions. The stoichiometric reduction of sulfate or Fe(III) and the utilization of bromophenols and phenol indicated that biodegradation was coupled to sulfate or iron reduction, respectively. The production of phenol as a transient intermediate demonstrates that reductive dehalogenation is the initial step in the biodegradation of bromophenols under iron- and sulfate-reducing conditions.