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PubMed2002

Lyngbyaloside B, a new glycoside macrolide from a Palauan marine cyanobacterium, Lyngbya sp.

A Palauan collection of the marine cyanobacterium Lyngbya sp., which had already afforded diverse peptide-based cytotoxins, also yielded a new glycoside macrolide exhibiting slight cytotoxicity. The compound was termed lyngbyaloside B (1) due to its structural analogy to the previously isolated lyngbyaloside (2). Lyngbyaloside B (1) appears to be only the third glycoside macrolide and second brominated compound of its kind from a marine cyanobacterium. Its gross structure was determined by a combination of NMR spectroscopy and mass spectrometric techniques. The relative stereochemistry for the 12 stereocenters is proposed on the basis of proton-proton spin-coupling constants and ROESY data.

Cyanobacteria↗
PubMed2005

Ozonation of the marine dinoflagellate alga Amphidinium sp.--implications for ballast water disinfection.

Ozone has been investigated for its potential to remove marine dinoflagellate algae from ships' ballast water. Dinoflagellate algae, Amphidinium sp. isolated from the Great Barrier Reef, Townsville, Australia were used as indicators since these produce a type of cyst that is difficult to inactivate, but are relatively easy to culture. The ozonation experiments have demonstrated a high ozone demand for inactivation of the algal cultures, which increases as the culture ages. The main ozone demand in seawater is due to its reaction with bromide to form bromine compounds. The non-bromide ozone demand has been estimated by measuring the residuals produced after various doses of ozone. The Amphidinium sp. show an unexpected response to both ozonation and bromination, with an instantaneous inactivation of the organisms for all doses that produced an oxidant residual in the seawater, followed by an effect of the disinfection residual. The standard design procedure of comparing Ct will not be effective for predicting the response of the organism to varying dose, C, and contact time, t, and a plot of ozone produced oxidant residual against organism inactivation for various contact times is proposed for design purposes. High doses of ozone (5-11 mg/L) and up to 6h of residual contact were required for a 4-log inactivation of the Amphidinium sp. Ozonation is likely to be a difficult technology to implement for organisms with this ozone requirement in combination with characteristics of ballast tanks, which contain areas of sediments high in detritus and areas of corrosion.

Animals↗
PubMed1983

Bromine levels in tissue lipids of rats fed brominated fatty acids.

Rats have been fed diets containing either 0.8% brominated corn oil or 0.5% of the ethyl ester of 9,10-dibromostearate or 9,10,12,13-tetrabromostearate. The brominated compounds were incorporated into semisynthetic diets and animals were observed after feeding periods of 5 days to 3 months. With the exception of adipose tissues, the highest concentration of lipid-bound bromine was observed after 5 days on the experimental diets. It was also observed that feeding of the dibromostearate resulted in the highest levels of lipid-bound bromine in heart, whereas the tetrabromostearate tended to result in higher levels of lipid-bound bromine in liver. Brominated corn oil produced more substantial changes than the brominated fatty acid esters, inducing fatty livers and enlarged yellow hearts. Microscopic examination indicated myocardial degeneration and occasional early necrosis.

Animals↗
PubMed2002

Sponge halogenated natural products found at parts-per-million levels in marine mammals.

Several unknown, abundant brominated compounds (BCs) were recently detected in the blubber of dolphins and other marine mammals from Queensland (northeast Australia). The BCs were interpreted as potential natural products due to the lack of anthropogenic sources for these compounds. This study investigated whether some of the BCs accumulated by diverse marine mammal species are identical with natural BCs previously isolated from sponges (Dysidea sp.) living in the same habitat. Isolates from sponges and mollusks (Asteronotus cespitosus) were compared with the signals detected in the mammals' tissue. Mass spectra and gas chromatography retention times on four different capillary columns of the isolates from sponges and mammals were identical in all respects. This proves that the chemical name of the compound previously labeled BC-2 is 4,6-dibromo-2-(2',4'-dibromo)phenoxyanisole and that the chemical name of BC-11 is 3,5-dibromo-2-(3',5'-dibromo,2'-methoxy)phenoxyanisole. Using a quantitative reference solution of BC-2, we established that the concentrations of the brominated metabolites found in the marine mammals are frequently >1 mg/kg. The highest concentration (3.8 mg/kg), found in a sample of pygmy sperm whale (Kogia breviceps), indicates that BC-2 is a bioaccumulative, natural organohalogen compound. This is supported by the concentrations of the BCs in our samples being equal to the highest concentrations of anthropogenic BCs in any environmental sample. The quantitative determination of BC-2 in blubber of marine mammals from Africa and the Antarctic suggests that BC-2 is widespread. These results are direct proof that marine biota can produce persistent organic chemicals that accumulate to substantial concentrations in higher trophic organisms.

Adipose Tissue↗
PubMed1996

Biological activity of 4-(4-bromophenyl)-thiosemicarbazide.

The two molecules (A and B) in the asymmetric unit of the title compound, C7H8BrN3S, display different conformation. In both molecules, the S atom is trans to the NH2 group. The Br atoms of the two molecules approach each other at a distance of 3.573(2) A. The crystal structure of the bromine compound is isomorphous with that of its chlorine analogue. In the crystal structure, intramolecular N-H...N and intermolecular N-H...S hydrogen bonds help stabilize the molecular packing. The increased antibacterial activity of the title compound compared to that of its chlorine analogue may be attributed to the increase in electron density on the hydrazinic end of the thiosemicarbazide chain.

Anti-Bacterial Agents↗
PubMed2000

Brominated anisoles and cresols in the red alga Polysiphonia sphaerocarpa.

The red marine alga Polysiphonia sphaerocarpa was extracted by a simultaneous steam distillation-solvent extraction technique and several brominated compounds were identified by gas chromatography-mass spectrometry. The compounds detected were 2,4-dibromoanisole, 2,4,6-tribromoanisole, 3-bromocresol, 3,5-dibromocresol, 3-bromo-4-hydroxybenzaldehyde, 3,5-dibromo-4-hydroxybenzaldehyde, 2-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol and 2,4,6-tribromophenol. This is the first time brominated anisoles and cresols have been detected in marine algae.

Anisoles↗
PubMed2003

Health effects of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs).

This article reviews the state of the science regarding the health effects of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). While thousands of articles have been published on the health effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs), little is know about the brominated and mixed chloro/bromo homologs. Available literature suggests that brominated compounds have similar toxicity profiles to their chlorinated homologs. However, further research investigating health effects will only be useful if exposure scenarios truly exist. Current exposure data is extremely limited, posing a major data gap in assessing potential risk of these chemicals. The rapid increase in the use of brominated flame retardants has raised the level of environmental concern regarding PBDDs/PBDFs as it is likely that human, as well as wildlife, exposure to brominated dioxins and furans will increase with their use.

Benzofurans↗
PubMed1987

Production of ethane, ethylene, and acetylene from halogenated hydrocarbons by methanogenic bacteria.

Several methanogenic bacteria were shown to produce ethane, ethylene, and acetylene when exposed to the halogenated hydrocarbons bromoethane, dibromo- or dichloroethane, and 1,2-dibromoethylene, respectively. They also produced ethylene when exposed to the coenzyme M analog and specific methanogenic inhibitor bromoethanesulfonic acid. The production of these gases from halogenated hydrocarbons has a variety of implications concerning microbial ecology, agriculture, and toxic waste treatment. All halogenated aliphatic compounds tested were inhibitory to methanogens. Methanococcus thermolithotrophicus, Methanococcus deltae, and Methanobacterium thermoautotrophicum DeltaH and Marburg were completely inhibited by 7 muM 1,2-dibromoethane and, to various degrees, by 51 to 1,084 muM 1,2-dichloroethane, 1,2-dibromoethylene, 1,2-dichloroethylene, and trichloroethylene. In general, the brominated compounds were more inhibitory. The two Methanococcus species were fully inhibited by 1 muM bromoethanesulfonic acid, whereas both Methanobacterium strains were only partly inhibited by 2,124 muM. Coenzyme M protected cells from bromoethanesulfonic acid but not from any of the other inhibitors.

Journal Article↗
PubMed1984

Relationship between the chemical structure and the mutagenic and carcinogenic potentials of five naphthofurans.

We have analyzed the relationship between the biological activities and chemical structure of five naphthofurans. The compounds studied included 2-nitro-7-methoxynaphtho[2,1-b]-furan (R 7000) (Compound A), 2-nitro-8-methoxynaphtho[2,1-b]-furan (Compound B), 2-nitronaphtho[2,1-b]furan (Compound C), 2-nitro-7-bromonaphtho[2,1-b]furan (Compound D), and 7-methoxynaphtho[2,1-b]furan (Compound E), the nonnitrated analogue of Compound A. The genotoxic activities of the compounds were studied in V79 cells using the micronucleus, sister chromatid exchange, and hypoxanthine-guanine phosphoribosyltransferase locus mutation tests. This allowed us to classify their mutagenic properties in the following order: A congruent to B much greater than C greater than D greater than E. However, in the in vivo short-term skin tests, the order in activities of the first three compounds is reversed, and the five compounds can be classified in decreasing rank of potency: C greater than B greater than A greater than or equal to E congruent to D. The two compounds tested for in vitro transformation, Compounds A and B, demonstrated a positive effect in both the C3H10T1/2 and the Syrian hamster embryo cell systems. The biological activities of Compounds A, B, C, and D appeared to be strongly linked to the presence of a NO2 group in position 2. These activities were enhanced or decreased by a methoxy group in position 7 or 8. Almost all activities were suppressed if the methoxy group in position 7 was replaced by a bromine (Compound D). The positive results obtained in the cell transformation assays and in the short-term skin tests indicate that Compounds A, B, and C are probably carcinogenic. Therefore, further in vivo studies should be accomplished before using the 2-nitronaphthofuran derivatives in human and animal treatments.

Animals↗
PubMed1976

[Affinity labeling of leucine aminopeptidase with new substrate analog inhibitors].

Substrate analogous compounds differing both in type and reactivity (diazonium group, chloro and mo ethyl ketone groups) and in the position of the reactive group at the inhibitor molecule were studied for their adequacy for affinity labelling of leucine amino-peptidase. The chloro methyl ketone derivatives of amino acids with free alpha-amino group are competitive inhibitors. Also, the more reactive bromine compound PheCh2br (Ki 1.2 mM) compared with the PheCH2C1 (Ki 0.3 mM) fails to give an irreversible inactivation of leucine amino-peptidase. The dipeptide derivatives Leu-PheCH2C1 and Phe-LeuCH2C1 also inhibit the enzyme activity up to 65%, but they are split at the peptide bond under reactivation of the enzyme. p-Diazophenylalanine methylketone Phe (pN+/2)CH3 and the two dipeptides Phe(pN+/2)-Phe and Phe(pN+/2)-Phe(pN+/2) with N-terminal diazonium groups afford an irreversible inactivation of leucine aminopeptidase in a time- and concentration-dependent reaction. The Phe-Phe(pN+/2) reactive only C-terminally, is less effective; the inhibition is partly reversible. The inactivation is strongly reduced by the competitive inhibitor Thr(but)-Phe-Pro. These effects are discussed with regard to the specific site of attack of the inhibitors in the active binding centre of leucine aminopeptidase. The synthesis of the three parasubstituted amino derivatives of phenylalanyl-phenylalanine Phe(pNH2)-Phe, Phe-Phe(pNH2) and Phe(pNH2)-Phe(pNH2) and their selective conversion to the respective diazonium peptides, retaining the aliphatic alpha-amino group, are discussed.

Affinity Labels↗
PubMed1986

Conformational analysis of the B and Z forms of the d(m5C-G)3 and d(br5C-G)3 hexamers in solution. A 300-MHz and 500-MHz NMR study.

The B and the Z forms of the DNA hexamers d(m5C-G)3 and d(br5C-G)3 were investigated by means of NMR spectroscopy. It is demonstrated that the low-salt form of d(m5C-G)3 is a B DNA structure. The form, which becomes increasingly predominant when increasing amounts of MgCl2 and/or methanol are added to the solution, has Z DNA characteristics. It is shown that the major geometrical features of the Z form of d(m5C-G)3 in the crystal structure are maintained in solution, with the dC residues S sugar conformation, gamma + and the base in the anti orientation and the dG residues N (except the 3'-terminal residue), gamma t and syn. Neither the Z form of the methylated nor that of the brominated compound resembles the Z' form, in which the deoxy guanosine sugar rings adopt a C1'-exo conformation. Substitution of m5C by br5C causes no perceptible conformational changes in either the B or in the Z forms.

Bromine↗
PubMed1989

Conformational analysis of brominated pA2'-5'A2'-5'A analogs. An NMR and model-building study.

NMR and model-building studies were carried out on pA2'-5'A2'-5'A and analogs in which one or more of the A residues were replaced by 8-bromoadenosine. Chemical shifts, coupling constants and NOE data were used to obtain structural information. The N/S equilibrium constant of the ribose rings as well as the phase angles and puckering amplitudes were determined from the experimental coupling constants with the aid of an improved version of the PSEUROT program. Chemical shifts in combination with NOE data were used to monitor base-base interactions and the orientation of the bases (syn or anti). The combined data suggest that different types of stacking interactions are present in the various compounds. Bromination of the first or second residue in the trimers results in a preference for N-type sugar and syn orientation of the base in these residues. When A(3) is brominated, an S-type sugar conformation together with a syn orientation of the base is favoured at the 2' terminus. Energy-minimized models of the different stacking interactions are presented which fit the present collection of data. The possible correlation between biological activity of these compounds and their conformation is briefly discussed.

Adenosine↗
PubMed1975

Trace analysis of organic volatiles in water by gas chromatography-mass spectrometry with glass capillary columns.

Traces of volatile organic materials in water have been concentrated by gas phase stripping and adsorption onto a porous polymer. A simple all-glass sampling device is proposed which allows efficient concentration at elevated temperatures. Sample transfer from absorbent into a gas chromatographic column is effected by a simple one-step procedure involving heat desorption. The capacity of the absorbent has been determined for a number of model substances which are found in water. Under the sampling conditions used, compounds being less volatile than benzene are usually quantitatively retained, with some exceptions. Separations were effected with highly efficient glass capillary columns. Water samples, collected from a small number of locations, included both tap water and untreated waters. A number of volatiles have been determined by gas chromatography-mass spectrometry in drinking water and in a river which flows through an industrialized area. The drinking water examined contains a large number of chlorinated and brominated compounds whereas the river water is largely free from this class of substances. Derivatives of camphor and terpenes have been identified in this particular river.

Absorption↗
PubMed2003

Differential effects of bromination on substrates and inhibitors of kynureninase from Pseudomonas fluorescens.

A series of brominated compounds has been synthesized and evaluated as substrates and inhibitors of kynureninase from Pseudomonas fluorescens. Both 3-bromo-L-kynurenine and 5-bromo-L-kynurenine were found to be substrates with similar k(cat) values to L-kynurenine, but the K(m) value for 3-bromo-L-kynurenine is very high (ca. 2 mM) compared to that for 5-bromo-L-kynurenine (11 microM) and L-kynurenine (25 microM). Both isomers of bromokynurenine react with kynureninase within the dead time of the stopped-flow instrument (ca. 1 ms) to form quinonoid intermediates with a lambda max of 494 nm that decay with rate constants of 300-600 s-1, similar to L-kynurenine. The two diastereomers of 5-bromodihydro-L-kynurenine were also prepared, and are more potent inhibitors than dihydro-L-kynurenines. (4R)-5-Bromodihydro-L-kynurenine is one of the most potent inhibitors of P. fluorescens kynureninase found to date (Ki = 55 nM) and also acts as a slow substrate; the (4S)-epimer, on the other hand, shows no measurable substrate activity, but it is a potent competitive inhibitor with a Ki value of 170 nM. In contrast, brominated analogs of (S)-(2-aminophenyl)-L-cysteine S,S-dioxide, (S)-(2-amino-4-bromophenyl)-L-cysteine S,S-dioxide and (S)-(2-amino-5-bromophenyl)-L-cysteine S,S-dioxide are competitive inhibitors of kynureninase, with Ki values of about 300 and 400 nm, respectively, about ten-fold higher than the value of 27 nM obtained for the parent compound. These results suggest that the binding modes of substrates and the various classes of inhibitors in the active site of kynureninase are different.

Binding, Competitive↗
PubMed2005

Brominated flame retardants in Alburnus alburnus from Cinca River Basin (Spain).

Thirty-two bleak fish (Alburnus alburnus) from three places along the Spanish River Cinca, a tributary of Ebro River, were collected for polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) determinations. Sampling sites corresponded to up- and downstream from Monzon, a heavily industrialized town draining to the river. Four different PBDE congeners (BDE-47, -153, -154 and -183) and HBCD were found at levels ranging from not detected (nd) to 573 ng/g wet weight for total PBDEs and from nd to 1643 ng/g wet weight for HBCD. The lowest values were found upstream of the industrialized area. Concentrations in fish were compared with previous data in sediment samples collected at the same sampling sites, and large fish to sediment ratios for these brominated compounds indicate that they are highly bioavailable. Moreover, PBDE and HBCD concentrations are correlated with fish length and weight indicating the bioaccumulation of these contaminants.

Animals↗
PubMed2005

Identification of brominated carbazoles in sediment cores from Lake Michigan.

During the analysis of brominated flame retardants in sediment cores taken from Lake Michigan, a group of unknown brominated compounds were observed. To identify their chemical structures, a variety of gas chromatographic mass spectrometric techniques were used. With the help of high-resolution and positive chemical ionization mass spectrometry, the molecular formula of the most abundant congener was established to be C12H5Br4N. On the basis of the electron impact and electron capture negative ionization mass spectra, this chemical was suspected of being a tetrabromocarbazole. The structure was confirmed by comparing the mass spectra and gas chromatographic retention times of an authentic standard of 1,3,6,8-tetrabromocarbazole with those of the most abundant unknown. The other unknown compounds may be other bromocarbazole congeners. The time trend determined by measuring these compounds as a function of depth in the Lake Michigan sediment cores indicated that the concentration of 1,3,6,8-tetrabromocarbazole peaked around 1920-1935. This is the first time that bromocarbazoles have been found in the environment.

Carbazoles↗
PubMed2004

Occurrence and bioavailability of polybrominated diphenyl ethers and hexabromocyclododecane in sediment and fish from the Cinca River, a tributary of the Ebro River (Spain).

Fish and sediments from four places along the Spanish River Cinca were analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The samples were collected up- and downstream from Monzón, a heavily industrialized town draining to the river. PBDEs and HBCD were found in sediments at levels ranging from 2 to 42 ng/g dry weight and from not detected (nd) to 514 ng/g dry weight, respectively. Twenty-three fish samples (Barbus graellsi) collected at the same places were also analyzed, showing levels from nd to 446 ng/g wet weight for PBDEs and from nd to 1172 ng/g wet weight for HBCD. The lowest values for both sediment and fish samples were found upstream of the industry. Of 40 congeners (from mono- to deca-BDEs) included in the analytical work, 8 PBDE congeners were detected in river sediments, whereas 17 different PBDEs were found in fish samples. Large fish-to-sediment ratios for these brominated compounds indicate that they are highly bioavailable, with the exception of deca-BDE which was only detected in sediment samples. Concentrations of PBDEs and HBCD were slightly higher in muscle tissues than in liver samples obtained from the same specimen of fish. Moreover, PBDE and HBCD concentrations are correlated with fish length indicating the bioaccumulation of these contaminants.

Animals↗