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PubMed2005

In vitro cytotoxicity of selected chemicals commonly produced during fire combustion using human cell lines.

Fire combustion products contain a broad range of chemicals, which have a multitude of possible toxic interactions in humans. The aim of this study was to evaluate the cytotoxicity of selected substances commonly produced during fire combustion. A range of human cell lines and cultures including: skin fibroblasts, HepG2 (liver derived), and A549 (lung derived cells) were used to represent different human target organs. The colorimetric MTS assay (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) was used to detect the cytotoxic effects of selected substances including: acetic acid, ammonia, formaldehyde, hydrobromic acid, hydrochloric acid, hydrofluoric acid, potassium cyanide, sodium fluoride, sodium nitrite, sodium sulphide, and sulphurous acid. In this study, the NOAEC (No Observable Adverse Effect Concentration), IC(10) (10% inhibitory concentration), IC50 (50% inhibitory concentration), and TLC (Total Lethal Concentration) values were determined. The ratio between in vitro IC50 to in vivo human toxicity data (Lowest Lethal Dose-LDLo and Lowest Lethal Concentration--LCLo) was also established. Results indicated a strong relationship between IC50 values on the cell types used: fibroblast and A549 (R2: 0.92), A549 and HepG2 (R2: 0.72), fibroblast and HepG2 (R2: 0.69). Good correlation was obtained between the IC50 against LDLo and LCLo when an appropriate adjustment factor was implemented. Results of this study indicated that in vitro methods could be a potential technique for assessing the toxicity of fire combustion products.

Acetic Acid↗
PubMed1976

Effect of thiocyanate on nitrite estimation and the cleavage of nitrosamines.

Thiocyanate or bromide increased the colour formed by nitrite reacting with sulfanilic acid and naphthylethylenediamine. If the colour reagents were added together with thiocyanate (final concentration, M/10), the colour intensity was doubled. If sulfanilic acid was added three minutes before addition of naphthylethylenediamine, the relationship between nitrite concentration and colour production was more linear in the presence of thiocyanate. This effect was due to thiocyanate catalysing the diazotization of sulfanilic acid and inhibiting the reaction of nitrite with naphthylethylenediamine. Bromide and thiocyanate are similar in their catalytic effects on nitrosation, and hydrobromic acid in glacial acetic acid is an effective reagent for denitrosation of nitrosamine. Although thiocyanate catalysed denitrosation of nitrosamines, the effect was small except with nitrosomethylaniline, which had also been found to be denitrosated by sulfanilic acid. Thiocyanate could not be used generally for the destruction of nitrosamines; it was also found to be ineffective as an alternative to hydrobromic acid in the estimation of nitrosamines.

Acetates↗
PubMed1975

The purification of methylene blue and azure B by solvent extraction and crystallization.

Detailed schemes are described for the preparation of purified methylene blue and azure B from commercial samples of methylene blue. Purified methylene blue is obtained by extracting a solution of the commercial product in an aqueous buffer (pH 9.5) with carbon tetrachloride. Methylene blue remains in the aqueous layer but contaminating dyes pass into the carbon tetrachloride. Metal salt contaminants are removed when the dye is crystallized by the addition of hydrochloric acid at a final concentration of 0.25 N. Purified azure B is obtained by extracting a solution of commercial methylene blue in dilute aqueous sodium hydroxide (pH 11-11.5) with carbon tetrachloride. In this pH range, methylene blue is unstable and yields azure B. The latter passes into the carbon tetrachloride layer as it is formed. Metal salt contaminants remain in the aqueous layer. A concentrated solution oa azure B is obtained by extracting the carbon tetrachloride layer with 4.5 X 10(-4)N hydrobromic acid. The dye is then crystallized by increasing the hydrobromic acid concentration to 0.23 N. Thin-layer chromatography of the purified dyes shows that contamination with related thiazine dyes is absent or negligible. Ash analyses reveal that metal salt contamination is also negligible (sulphated ash less than 0.2%).

Azure Stains↗
PubMed2004

Application of ionic liquid halide nucleophilicity for the cleavage of ethers: a green protocol for the regeneration of phenols from ethers.

We have used the high nucleophilicity of bromide ion in the form of the ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]), for the nucleophilic displacement of an alkyl group to regenerate a phenol from the corresponding aryl alkyl ether. Using 2-methoxynaphthalene (1) as a model compound, we found that the combination of ionic liquid [bmim][Br] and p-toluenesulfonic acid with warming effected demethylation in 14 h, affording the desired product 2-naphthol (2) in good yield (97%). Various other protic acids (MsOH, hydrochloric acid (35%), dilute sulfuric acid (50%)) could be used as a proton source in this demethylation reaction. Under the same conditions, cleavage of alkyl alkyl ether 2-(3-methoxypropyl)naphthalene yielded mixture of corresponding 2-(3-bromopropyl)naphthalene and 2-(3-hydroxypropyl)naphthalene. Dealkylation of various aryl alkyl ethers could also be achieved using significantly reduced (i.e., stoichiometric) amounts of concentrated hydrobromic acid (47%) in the ionic liquid. Both procedures afforded the desired products in moderate to good yield; however, cleavage of aryl alkyl cyclic ether, 2,3-dihydrobenzofuran, resulted in low yield of the desired product o-2-bromoethylphenol. The convenience of this method for ether cleavage and its effectiveness using only a moderate excess of hydrobromic acid make it attractive as a green chemical method.

Journal Article↗
PubMed1999

Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) + (As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry.

A method for the selective quantitative determination of inorganic arsenic [As(III) + As(V)] in seafood was developed. In order to do so, various procedures for the solubilization and extraction of inorganic arsenic quoted in the literature were tested. None provided satisfactory recoveries for As(III) and As(V) in real samples. Consequently, a methodology was developed which included solubilization with HCl and subsequent extraction with chloroform. The arsenic was solubilized in 9 mol l-1 hydrochloric acid. After reduction by hydrobromic acid and hydrazine sulfate, the inorganic arsenic was extracted into chloroform, back-extracted into 1 mol l-1 HCl, dry-ashed, and quantified by hydride generation-atomic absorption spectrometry (HG-AAS). The analytical features of the method are as follows: detection limit, 3.07 ng g-1 As (fresh mass); precision (RSD), 4.0%; recovery, As(III) 99%, As(V) 96%. In the optimized conditions, other arsenic species--dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC) and tetramethylarsonium-ion (TMA+)--were not co-extracted. However, different percentages of minor species were extracted with chloroform: monomethylarsonic acid (MMA) 100%, and trimethylarsine oxide (TMAO) 3-10%. Real samples and reference materials of seafood (DORM-1, DORM-2, TORT-2, CRM-278 and SRM-1566a) were analyzed. The analysis of DORM-1 provided an inorganic arsenic value of 124 +/- 4 ng g-1 As, dry mass (dm), which is very close to the value obtained by other authors using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and ionic chromatography-hydride generation-atomic absorption spectrometry (IC-HG-AAS).

Arsenic↗
PubMed1988

O-demethylation of pyrilamine.

O-Demethylation of pyrilamine with l-propanethiol and potassium tert-butoxide gave hydroxytripelennamine, one of the major metabolites of tripelennamine. The reaction of pyrilamine with other demethylating agents has been explored and the products formed have been characterized. The reaction of pyrilamine with 48% hydrobromic acid yielded 2-(2-dimethylaminoethyl)aminopyridine. When a mild, neutral demethylating agent, Me3Sil, was used, 2,3-dihydroimidazopyridinium iodide was the sole product formed.

Acids↗
PubMed1997

[Reactive airway dysfunction syndrome and bronchiolitis obliterans after exposure to acid vapors].

A 37-year-old male non-smoker developed rapidly severe respiratory disease after a 3-hour exposure to hydrobromic acid fumes. An upper airway syndrome ensued with anosmia and aphonia as well as non-specific bronchial hyperreactivity, obstructive bronchiolitis (which led to a persistent respiratory volume of about 20% of the normal level with exercise-induced dyspnea) and obstructive bronchiolitis. Lung transplantation is currently being considered. When inhaled at irritant concentrations, certain toxic gases, such as chlorine, can lead to reflex apnea via laryngeal nerve reaction, limiting gas penetration into the bronchial tree. Other gases are cell toxins and can enter the deeper part of the lung before provoking irritating cough. This is what occurred for our patient who continued work in the polluted atmosphere until his severe cough obliged him to leave his job. This case is an example of cellular toxicity resulting from atmospheric gas fumes at low weakly-irritative concentrations, explaining the insidious nature of disease onset.

Adult↗
PubMed1982

Experiments on the protection of the thioether in methionine.

The decrease in the solubility of peptides when their methionine residues are replaced by methionine sulfoxides prompted the exploration of an alternative approach to the protection of the thioether in methionine side chains. Alkylation of tert.-butyloxycarbonyl methionine p-nitrophenyl ester with methyl p-toluenesulfonate yielded the crystalline derivative of methionine S-methyl p-toluenesulfonate which could be incorporated into peptide chains. Alternatively, methionine S-methyl p-toluenesulfonate (Mmt) residues could be generated by the action of methyl p-toulensulfonate on methionine containing peptides. The protecting group remained intact under the conditions of aminolysis and ammonolysis commonly used in peptide synthesis, and it was unchanged after the removal of other blocking groups with trifluoroacetic acid or diethylamine. On treatment with hydrobromic acid in acetic acid the toluenesulfonate anion was replaced by bromide ion, while hydrogenation resulted in the decomposition of the modified methionine side chain. In the process of deprotection Mmt residues could be smoothly converted to methionine residues by thiolysis. Thus, the protecting group functioned well in several respects but an increase in solubility (in dimethylformamide) on alkylation was observed only in a part of the peptide derivatives tested. Therefore, the value of the new approach for the protection of the methionine side chain in peptide synthesis remains to be established.

Alkylation↗
PubMed2001

Successive determinations of platinum(II) and selenium(IV) with 1,4-dibromo-2,3-diaminonaphthalene in aqueous micellar solutions.

Highly sensitive successive determinations for PtII and SeIV ions have been developed based upon reactions with 1,4-dibromo-2,3-diaminonaphthalene (Br2DAN), which forms a near-infrared (NIR) absorbing complex (epsilon = 1.2 x 10(5) l mol-1 cm-1 at 800 nm) and an emissive complex (ex. 386 nm, em. 604 nm) for PtII and SeIV ions, respectively, in acidic aqueous micellar solutions. In the presence of a cationic surfactant, cetyltrimethylammonium chloride, the detection limits for PtII and SeIV ions are 1.2 ng ml-1 (3 sigma) and 0.98 ng ml-1 (S/N = 3), respectively. Hydrobromic acid plays a key role to enhance the color development of the NIR-absorbing PtII complex. The influences of CuII and ZnII ions at the normal human serum levels are readily tolerated, and interference from FeIII ion at 35 mumol l-1 is circumvented by the addition of 50 mumol l-1 of polyaminocarboxylates, such as EDTA.

2-Naphthylamine↗
PubMedDate not supplied

Polyamides (nylon) composition analysis by capillary zone electrophoresis.

A new and simple method of analysis for polyamide composition is described. Polymer samples were decomposed to their corresponding monomers by hydrobromic acid (HBr) and the decomposed products were analyzed by capillary zone electrophoresis (CZE). Amines from polyamides were derivatized with fluorescamine and detected by UV at 280 nm. Aliphatic acids were detected by direct UV at 205 nm. Sample treatment is much simpler than published methods, and electropherograms show a good separation of decomposed products under the proper conditions.

Electrophoresis, Capillary↗
PubMed2005

Nutritive value of some agricultural wastes as affected by relatively low gamma irradiation levels and chemical treatments.

An experiment was carried out to study the changes in the values of in vitro organic matter digestibility (IVOMD) and metabolizable energy (ME) of wheat straw, sunflower seed shell, olive cake wood, date palm seeds and peanut shell after irradiation with various levels of gamma radiation (0, 20, 40, 60 kGy; kiloGray) or after spraying with different amounts of hydrobromic acid (HBr; 47%) and sodium hydroxide (NaOH): 0, 3, 6 ml HBr and 3, 6 g NaOH in 25 ml water/100 g DM. The results indicated that chemical treatments increased the IVOMD and ME values significantly for all samples treated except the date palm seeds. There was no significant effect of irradiation on IVOMD and ME. Combined treatments of irradiation and HBr or NaOH were also found to be ineffective in increasing the IVOMD and ME values.

Analysis of Variance↗
PubMed1997

A new procedure for the specific high-performance liquid chromatographic determination of hydroxyproline.

A procedure suitable for a selective high-performance liquid chromatographic (HPLC) analysis of the imino acid hydroxyproline in the presence of a large excess of amino acids is proposed. To deaminate the amino acids, the well-known reaction with nitrous acid is exploited. The N-nitroso derivatives of imino acids obtained are extracted in ethyl acetate, denitrosated by hydrobromic acid, and treated with dabsyl-chloride. The final HPLC separations are carried out on a reversed-phase column in a rapid isocratic run. The use of the cis isomer of hydroxyproline as an internal standard allows good reproducibility. As an application of the described method, the hydroxyproline content in samples containing collagen and an excess of bovine serum albumine (up to 20:1) is determined.

Animals↗
PubMed2006

Lead isotopes decipher multiple origins within single PM10 samples in the atmosphere of Paris.

The atmospheric concentration of lead (Pb) in France has strongly decreased since its legal reduction in gasoline in 2000. Pb-isotope ratios are effective tracers of its origin. Pb in atmospheric particulate matter with a diameter <10 microm (PM10) in Paris is shown to have a dual origin: (1) an intrinsic fraction (leached by hydrofluoric acid) forms the cores of particles and (2) a labile fraction (complexation with hydrobromic acid) represents generally >90 % (mass) of the bulk Pb and aggregates on pre-existing particles in the atmosphere. Characterisation of the emissions from different pollution sources, however, indicates that Pb is entirely contained in the labile fraction. Our results show that, in air, the intrinsic fraction is consistently more radiogenic (the degree of enrichment being greater in summer), hinting at different origins. The labile fraction clearly identifies industrial activity as its main source, but the intrinsic fraction may result from either a different industrial-pollution source or, more likely, from a natural end-member (i.e. pre-industrial sediment).

Air Pollutants↗
PubMed1996

Heterocyclic steroids: synthesis of steroidal selena, tellura, and thialactones of estrane series.

A successful approach in the synthesis of 3 beta-acetoxy-17a-selena-D-homo-1,3,5(10)-estratrien-17 -one (5), 3 beta-acetoxy-17a tellura-D-homo-1,3,5(10)-estratrien-17-one (6), and 3 beta-acetoxy-17a-thia-D-homo-1,3,5(10)-estratrien-17-one (7) was achieved from 3 beta-acetoxy-1,3,5(10)-estratrien-17-one (1). The Baeyer-Villiger reaction of 3 beta-acetoxy-1,3,5(10)-estratrien-17-one (1) with perbenzoic acid afforded 3 beta-acetoxy-17a-oxa-D-homo-1,3,5(10)-estratrien-17-one (2), which on reaction with hydrobromic acid gave 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-16-oic acid (3). Treatment of bromo acid (3) with thionyl chloride gave 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-17 acid chloride (4), whose reaction with Se and Te in the presence of sodium borohydride gave the desired products 5 and 6. Reaction of 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-17 acid chloride (4) with sodium sulfide gave the thia lactone derivative (7).

Molecular Structure↗
PubMed1996

[Synthesis of optically active (R)- and (S)-tai-ding-an(TDA) and their anti-HSV activity evaluation].

Tai-Ding-An (3-phthalimido-2-oxo-n-butyraldehyde bisthiosemicarbazone, TDA) is an antiviral drug first synthesized in this institute. In order to clarify the difference between the two enantiomeric isomers of TDA, (R)- and (S)-TDA were synthesized from (R)- and (S)-alanine, respectively, via the following steps: fusing with phthalic anhydride gave 2-phthalimido alanine(2a or 2b). The resulting acid was reacted with thionyl chloride to offer the corresponding acid chloride(3a or 3b), which was treated with diazomethane to give the diazoketone(4a or 4b). Bromination of the ketone with hydrobromic acid gave the key intermediate 3-phthalimido-2-oxo-1-bromobutanone (5a or 5b). Compound 5a or 5b was oxidized with DMSO to give 6a or 6b, which was directly condensed with thiosemicarbazide to afford the desired (R)- or (S)-TDA. (R)-TDA, (S)-TDA and (RS)-TDA have been tested in cell culture for anti-Herpes simplex virus I (HSV-1) and HSV-2 activities by plaque reducing method. All of them showed inhibitory effects on HSV-1 and HSV-2 replication with IC50 of 0.0296 mmol.L-1, 0.0359 mmol.L-1 and 0.0418 mmol.L-1 for HSV-1 and 0.88 mmol.L-1, 1.04 mmol.L-1 and 1.06 mmol.L-1 for HSV-2. Not much difference was found among these compounds either on IC50 or on therapeutic indexes.

Animals↗
PubMed1994

1-Aryl-1H-pyrazole-5-acetic acids with antiinflammatory, analgesic and other activities.

Reaction of methyl 4-methoxy-2-dimethylaminomethylene-3-oxobutanoate with arylhydrazines gave methyl 1-aryl-5-(methoxymethyl)-1H-pyrazole-4-carboxylates 1 in high yields. Esters 1 were hydrolyzed to the relative carboxylic acids, which were converted by heating to 1-aryl-5-(methoxymethyl)-1H-pyrazoles 3 in good yields. Reaction of 3 with hydrobromic acid afforded the intermediate 1-aryl-5-(bromomethyl)-1H-pyrazoles, which were converted with potassium cyanide to 1-aryl-1H-pyrazole-5- acetonitriles, whose hydrolysis gave the required 1-aryl-1H-pyrazole-5-acetic acids. Some acids 5 showed a strong antiinflammatory and analgesic activity in rats and mice, respectively, as well as moderate antipyretic and in vito platelet antiaggregating effects.

Acetates↗
PubMed2005

Syntheses and characterization of dicarbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media: spectroscopic, structural, and DFT analyses.

This work describes new synthetic routes to produce mixed carbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media. NaNO2, NOHSO4, and NO2(g) have been used to produce in situ nitrous acid as the primary source of NO+. Starting from the organometallic precursor fac-[MX3(CO)3]+, 1 (M = 99Tc, Re; X = Cl, Br), the formation of mixed dicarbonyl-mononitrosyl complexes was observed in aqueous hydrochloric and hydrobromic acid. Time-dependent analyses of the reactions by means of HATR-IR and 99Tc NMR spectroscopy in solution revealed the almost quantitative substitution of one CO ligand by NO+ and, thus, the formation of complexes with facial arrangement of the three pi-acceptor ligands. In the case of technetium, the monomeric complex (NEt4)[TcCl3(CO)2NO] (3a) and the dimeric, chloride-bridged, neutral complex [TcCl(mu-Cl)(CO)2NO]2 (4a) were produced. In the case of rhenium, the monomeric species (NEt4)[ReBr2X(CO)2NO] (X = Br (3b), NO3 (5)) was solely isolated. The X-ray structure of complexes 4a and 5 are discussed. The crystallographic analyses revealed the coordination of the NO+ group trans to the terminal chloride (4a) or the bromide (5), respectively. Crystal data: complex 4a (C4Cl4N2O(6)Tc2), monoclinic, Cc, a = 18.82(3) A, b = 6.103(6) A, c = 12.15(2) A, alpha = 90 degrees , beta = 105.8(2) degrees , gamma = 90 degrees , V = 1343(3) A(3), Z = 4; complex 5 (C10H20N3O(6)Br2Re), orthorhombic, P2(1)2(1)2(1), a = 10.2054(5) A, b = 12.5317(7) A, c = 13.9781(7) A, V = 1787.67(16) A(3), Z = 4. The isolated complexes and their potential facial isomers have been further investigated by density functional theory (DFT) calculations. The energy differences of the isomers are relatively small; however, the calculated energies are consistent with the formation of the observed and isolated compounds. The calculated bond lengths and angles of complex 5 are in good agreement with the data determined by X-ray diffraction. Experiments on the no-carrier-added level starting from fac-[99mTc(H2O)3(CO)3]+ revealed the formation of the complex fac-[99mTcCl(H2O)2(CO)2NO]+ in reasonable good yields. This aqueous-based, synthetic approach will enable the future evaluation of this novel, low-valent metal precursor for potential use in radiopharmacy.

Algorithms↗
PubMed1984

The primary structure of human liver manganese superoxide dismutase.

The complete amino acid sequence of manganese superoxide dismutase from human liver was determined. The sequence was deduced following characterization of the peptides obtained from tryptic, chymotryptic, and Staphylococcus aureus digests of the apoprotein. Chemical cleavage with dimethyl sulfoxide-hydrobromic acid was also carried out. The amino acid sequence listed below is made up of 196 amino acids and the two subunit polypeptides in the native enzyme appear to be identical. No homology was observed with copper/zinc containing class of superoxide dismutase. Lys-His-Ser-Leu-Pro-Asp-Leu-Pro-Tyr-Asp-Tyr-Gly-Ala-Leu-Glu-Pro-His-Il e -Asn-Ala-Gln-Ile-Met-Gln-Leu-His-His-Ser-Lys-His-His-Ala-Ala-Tyr-Val-Asn -Asn-Leu-Asn-Val-Thr-Gln-Glu-Lys-Tyr-Gln-Glu-Ala-Leu-Ala-Lys-Gly-Asp-Val -Thr-Ala-Gln-Ile-Ala-Leu-Gln-Pro-Ala-Leu-Lys-Phe-Asn-Gly-Gly-Gly-His-Ile -Asn-His-Ser-Ile-Phe-Trp-Thr-Asn-Leu-Ser-Pro-Asn-Gly-Gly-Gly-Gln-Pro-Lys -Gly-Glu-Leu-Leu-Glu-Ala-Ile-Lys-Arg-Asp-Phe-Gly-Ser-Phe-Asp-Lys-Phe-Lys -Gln-Lys-Leu-Thr-Ala-Ala-Ser-Val-Gly-Val-Gln-Gly-Ser-Gly-Trp-Leu-Gly-Phe -Asn-Lys-Gln-Arg-Gly-His-Leu-Gln-Ile-Ala-Ala-Cys-Pro-Asn-Gln-Asp-Pro-Leu -Gln-Gly-Thr-Thr-Gly-Leu-Ile-Pro-Leu-Leu-Gly-Ile-Asp-Val-Trp-Glu-His-Ala -Tyr-Tyr-Leu-Gln-Tyr-Lys-Asn-Val-Arg-Pro-Asp-Tyr-Leu-Lys-Ala-Ile-Trp-Asn -Val-Ile-Asn-Trp-Glu-Asn-Val-Thr-Glu-Arg-Tyr-Met-Ala-Cys-Lys-Lys.

Amino Acid Sequence↗