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PubMed1999

Oxidation of hypotaurine to taurine with photochemically generated singlet oxygen: the effect of azide.

Hypotaurine is oxidized to taurine by singlet oxygen (1O2) generated with methylene blue used as a photosensitizer. The oxidation rate increases in the presence of deuterium oxide as expected for the involvement of 1O2. Addition of the 1O2 quencher azide also produced an activating effect in contrast with the expected inhibition. Azidyl radicals produced by the oxidation of azide by the horseradish peroxidase/hydrogen peroxide system stimulate the oxidation of the added hypotaurine. It is concluded that azide competes with hypotaurine for 1O2 generating the azidyl radical which is a strong one-electron oxidant transfer of the radical to hypotaurine. The hypotaurine radical is then converted into taurine, possibly through the disulfone intermediate. Formation of the sulfonic hydroperoxide is the possible intermediate in the absence of azide. The finding that the azidyl radical efficiently oxidizes hypotaurine to its metabolic product taurine raises the expectation of hypotaurine being a valuable scavenger of endogenous and exogenous radicals.

Azides↗

PubMed2002

Sodium azide reduces the thermotolerance of respiratively grown yeasts.

The effect of sodium azide in heat shock-induced cell death was studied in Debaryomyces vanrijiae, Candida albicans, and Saccharomyces cerevisiae yeasts. The results presented demonstrate that the azide addition induced a drastic decrease in the thermotolerance of glucose-grown D. vanrijiae. In contrast, glucose-grown S. cerevisiae and C. albicans cells treated with NaN(3) became more resistant to heat shock than control cells. Nevertheless, in galactose medium the decrease of thermotolerance of S. cerevisiae and C. albicans cells was observed in the presence of sodium azide. It was suggested that the decreasing effect of sodium azide on thermotolerance takes place only when the yeast cell is incapable of using fermentation for ATP synthesis and obtains energy via oxidative phosphorylation.

Culture Media↗

PubMed1979

Azide-induced mutagenesis in gram-negative bacteria is recA-and lexA-independent.

Azide-induced mutagenesis was investigated in Salmonella typhimurium and Escherichia coli. Azide was highly effective in inducing mutation in uvrB, uvrB recA and uvrB recB mutants of S. typhimurium. The mutagenic effect of azide was also observed in uvrA lexA mutants of E. coli K12 and E. coli B/r. These results suggest that azide-induced mutagenesis is due to mis-replication of DNA.

Azides↗

PubMed1979

Mutagenesis of Saccharomyces cerevisiae by sodium azide activated in barley.

Concentrated dialysate of the extract prepared from barley seeds treated with sodium azide increased up to 100--200 times the frequency of forward mutations to cycloheximide resistance in the excision-deficient UV-sensitive heploid strain rad2-5 of Saccharomyces cerevisiae, when applied to growing cells in complete medium at pH 4.2. Only a slight increase of mutation frequency (less than 4 times) was found in the haploid RAD+ strain treated in the same way as well as in haploid RAD+ and rad2-5 strains treated directly by sodium azide. In contrast with the barley-activated sodium azide, UV irradiation was more effective in the induction of cycloheximide resistance in the RAD+ strain than in the RAD2-5 mutant. The dialysate from azide-treated barley seeds, applied at both pH 4.2 and pH 9, also significantly increased the frequency of locus-specific suppressor mutations to isoleucine independence and -- to a lesser extent -- reversions and/or gene conversions in the trp5 locus in growing cells of the diploid strain D7. The dialysate was also mutagenic in resting cells of strains D7 and rad2-5 but with lower effectiveness.

Azides↗

PubMed1980

The effects of sodium azide on mammalian cells cultivated in vitro.

Sodium azide acted cytostatically to cytotoxically on 2 lines of mammalian cells. After application of the substance in an acid environment the highest cytostatic effect was noted. The results of the DNA-synthesis inhibition test suggest that sodium azide does not damage the DNA of the observed fibroblasts with any of the tested modes of application. In Chinese hamster cells neither 20-h treatment in medium nor 60-min treatment in an acid environment gave rise to significantly increased occurrence of 6-TG-resistant mutations. The results of the DNA-synthesis inhibition test, as well as the mutagenicity testing, do not suggest the possibility that treatment with sodium azide might induce DNA damage in the observed human and Chinese hamster cells. The cytostatic effect of sodium azide on the fibroblasts studied is probably not accompanied by a genotoxic effect.

Animals↗

PubMed1981

Effects of L-cysteine and O-acetyl-L-serine in the synthesis and mutagenicity of azide metabolite.

The ability of L-cysteine to inhibit azide-metabolite synthesis and mutagenicity is investigated in Salmonella typhimurium TA1530 and cys E6 strains. L-cysteine specifically inhibits the synthesis of the mutagenic azide metabolite as other compounds containing SH group did not affect the production of this metabolite. Azide mutagenicity is completely inhibited by L-cysteine at a concentration (5 mumoles/plate) where the metabolite mutagenicity was not affected. O-Acetyl-L-serine can reverse the L-cysteine mediated inhibition of the metabolite synthesis and thus mutagenicity in the same strains. These results suggest that O-acetyl-L-serine may be required to synthesize the azide metabolite or its precursor.

Azides↗

PubMed1995

Cytocompatibility of calf pericardium treated by glutaraldehyde and by the acyl azide methods in an organotypic culture model.

Glutaraldehyde (GTA) is used to cross-link collagen-based biomaterials, but these materials are often cytotoxic. In order to overcome this problem, we have proposed the use of the acyl azide methods with either hydrazine or diphenylphosphoryl azide (DPPA) as reagents. In this paper we determine the cytocompatibility of acyl azide- and GTA-treated pericardium in vitro, by an organotypic chick aorta culture technique developed for the evaluation of the propensity of vascular cells (both endothelial and smooth muscle cells) to migrate and grow on the surface of biomaterials. We first examined pericardium stabilization as a function of GTA concentration and time, so that we could minimize residual GTA molecules in the material. Treatment for 72 h with 0.05% GTA was optimal for thermal stabilization of the pericardium with a denaturation temperature (Td) of 86.8 degrees C, providing similar results to treatment with 0.6% GTA for 4 h (Td = 85.1 degrees C). Pericardium treated in this way was, however, poorly cytocompatible with little vascular cell migration and growth when compared with tissues treated by the acyl azide methods. The best results were obtained with 0.5% DPPA; treated tissues showed a high level of cross-linking (Td = 82.4 degrees C) and three-fold increases in cell growth and migration over those in a non-toxic control.

Animals↗

PubMed1988

Interaction of organic azides with purified camel glutathione S-transferase.

A series of organic azides was synthesized and was tested as inhibitors of purified camel glutathione S-transferases. Enzymes purified from camel liver, lung, and kidney were inhibited reversibly by these compounds in a concentration-dependent pattern. The liver glutathione S-transferase was more sensitive to inhibition by most of these compounds and the lung enzyme was the least affected. The most effective reversible inhibitors of the tested organic azides for the purified camel liver enzyme were alkyl and allyl azides. The inhibition occurred immediately upon adding the inhibitors and remained constant during a further 30-min incubation period. The tested organic azides were found to inhibit the glutathione S-transferase catalyzed conjugation of glutathione with both 1-chloro-2,4-dinitrobenzene and 4-nitrobenzyl chloride and the kinetics of these inhibitions was qualitatively different, being competitive with some inhibitors and noncompetitive with others.

Animals↗

PubMed2005

A biosensor based on catalase for determination of highly toxic chemical azide in fruit juices.

In this work, an amperometric biosensor based on catalase enzyme was developed for the determination of azide. The principle of the measurements was based on the determination of the decrease in the differentiation of oxygen level which had been caused by the inhibition of catalase in the bioactive layer of the biosensor by azide. Firstly, the optimum conditions for the inhibitor biosensor were established. In the optimization studies of the biosensor, the most suitable catalase and gelatin amounts and glutaraldehyde ratio were determined. Optimum catalase activity, optimum gelatin amount and glutaraldehyde percentage were 5000 Ucm(-2), 5.94 mgcm(-2) and 2.5%, respectively. Characterization studies of the biosensor such as optimum pH and optimum temperature were carried out. The repeatability experiments were done and the average value (x), standard deviation (S.D.) and variation coefficient (C.V.) were calculated as 98.6 microM, +/-4.16 microM and 4.23%, respectively. A good linear relationship with a correlation coefficient of 0.9902 was obtained over the concentration range of 25 microM to 300 microM azide. After the optimization and characterization studies the proposed biosensor was applied to the determination of azide in certain fruit juices.

Azides↗

PubMed2006

N-glycoside neoglycotrimers from 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl azide.

2,3,4,6-Tetra-O-acetyl-beta-D-glucopyranosyl azide is available on large scale from D-glucose by means of a three-step sequence involving acetylation, activation as the glycosyl bromide, and stereospecific displacement with azide anion. The azide functionality then serves as a convenient anchor upon which to introduce new functionality, usually with retention of the beta-stereochemistry. Here we report the synthesis of an amide-linked N-glycosyl trimer, by employing a Staudinger-aza-Wittig process on the azide, as well as a hybrid N-glycosyl triazole-amide-linked trimer in which the sugars are separated by 1,2,3-triazole heterocycles. Both of these neoglycotrimers are isolated in good yield with high beta-selectivity in each case.

Azides↗

PubMed2004

Application of iodine-azide reaction for detection of amino acids in thin-layer chromatography.

The iodine-azide reaction was employed to TLC detection of sulphur-containing derivatives of protein and some non-protein amino acids. The derivatization reaction with phenyl isothiocyanate (PITC) took place directly on the plate before the developing step. Subsequently, the plates were sprayed with a mixture of sodium azide and starch solution in NP-TLC and in the case of RP-TLC sodium azide solution with starch incorporated into mobile phase and then exposed to iodine vapour. The spots became visible as white spots on violet-grey background. The obtained detection limits of PTC-derivatives have been compared with other visualizing techniques commonly used in TLC practice (UV254 and iodine vapour). The iodine-azide system has been proved to be the most favourable and enabled to detect quantities per spot in the range of 1-60 pmol (HPTLC) and 3-100 pmol (TLC).

Amino Acids↗

PubMed2005

Detection of mercaptopyridines and mercaptopyrimidines in planar chromatography with iodine-azide reaction as a detection system.

Reaction between iodine and azide ion induced by mercaptopyridines and mercaptopyrimidines was utilized as a detection system in TLC and HPTLC. The developed plates were sprayed with a freshly prepared mixtures of sodium azide and starch solution adjusted to pH 5.5, and exposed to iodine vapour. The spots became visible as white spots on violet-grey background. The iodine-azide detection system has been proved to be the most favourable and enabled to detect quantities per spot in the range of 1-20 pmol (HPTLC) and 1-60 pmol (TLC). The iodine-azide tests were compared with other visualizing techniques commonly used in planar chromatography (iodine vapour and UV254). The developed method was applied to detection of thiopental in biological samples.

Azides↗

PubMed2005

Determination of thiopental in urine sample with high-performance liquid chromatography using iodine-azide reaction as a postcolumn detection system.

The reaction between iodine and azide ions induced by thiopental was utilized as a postcolumn reaction for chromatographic determination of thiopental. The method is based on the separation of thiopental on an Nova-Pak CN HP column with an acetonitrile-aqueous solution of sodium azide as a mobile phase, followed by spectrophotometric measurement of the residual iodine (lambda=350 nm) from the postcolumn iodine-azide reaction induced by thiopental after mixing an iodine solution containing iodide ions with the column effluent containing azide ions and thiopental. Chromatograms obtained for thiopental showed negative peaks as a result of the decrease in background absorbance. The detection limit (defined as S/N=3) was 20 nM (0.4 pmol injected amount) for thiopental. Calibration graphs, plotted as peak area versus concentrations, were linear from 40 nM. The elaborated method was applied to determine thiopental in urine samples. The detection limit (defined as S/N=3) was 0.025 nmol/ml urine. Calibration graphs, plotted as peak area versus concentrations, were linear from 0.05 nmol/ml urine. Authentic urine samples were analyzed, thiopental was determined at nmol/ml urine level.

Acetonitriles↗

PubMed1978

Substitution reactions of a water-soluble metalloporphyrin with azide and 1,1,3,3-tetramethyl-2-thiourea.

The substitution reactions of tetrakis-(4-N-methylpyridyl)porphinecobalt (III) (CoIIITMpyP) with azide and with 1,1,3,3-tetramethyl-2-thiourea (TMTU) have been studied as a function of pH at 25 degrees and an ionic strength of 0.5 M. The mechanistic pathway proposed for thiocyanate [1] and pyridine [2] is applicable to these ligands as well once allowance is made for two attacking forms of azide, N3- and HN3. A TMTU axial substituent has about the same influence on the rate of further ligand substitution as does SCN- and a much larger influence than does azide. Similar behavior between bound SCN- and bound TMTU is also shown in electron-transfer reactions with Ru(NH3)62+. Whereas both sulfur-containing ligands enhance the rate relative to the diaquo complex, the azide complex undergoes reduction an order of magnitude more slowly than does the diaquo complex.

Azides↗

PubMed2002

Characterization of the azide-dependent bacteriorhodopsin-like photocycle of salinarum halorhodopsin.

The photocycle of salinarum halorhodopsin was investigated in the presence of azide. The azide binds to the halorhodopsin with 150 mM binding constant in the absence of chloride and with 250 mM binding constant in the presence of 1 M chloride. We demonstrate that the azide-binding site is different from that of chloride, and the influence of chloride on the binding constant is indirect. The analysis of the absorption kinetic signals indicates the existence of two parallel photocycles. One belongs to the 13-cis retinal containing protein and contains a single red shifted intermediate. The other photocycle, of the all-trans retinal containing halorhodopsin, resembles the cycle of bacteriorhodopsin and contains a long-living M intermediate. With time-resolved spectroscopy, the spectra of intermediates were determined. Intermediates L, N, and O were not detected. The multiexponential rise and decay of the M intermediate could be explained by the introduction of the "spectrally silent" intermediates M1, M2, and HR', HR, respectively. The electric signal measurements revealed the existence of a component equivalent with a proton motion toward the extracellular side of the membrane, which appears during the M1 to M2 transition. The differences between the azide-dependent photocycle of salinarum halorhodopsin and pharaonis halorhodopsin are discussed.

Absorption↗

PubMed2000

Stereoselective synthesis of 1,2-cis- and 2-deoxyglycofuranosyl azides from glycosyl halides.

Protected 1,2-cis glycofuranosyl azides with alpha-D-ribo, beta-D-arabino and 2-deoxy-2-fluoro-beta-D-arabino configurations were efficiently prepared from the appropriate 1,2-trans glycosyl halides bearing non-participating 0-2 substituent by inversion with sodium azide under phase transfer catalytic conditions (80-85% yields, 90-96% de). The same method failed to result in sufficiently good beta-selectivity starting from 2-deoxy-3,5-di-O-(p-toluoyl)-alpha-D-ery-thro-pentofuranosyl chloride (5alpha) (40% de). The selectivity in favour of the protected 2-deoxy-beta-D-erythro-pentofura-nosyl azides was greatly improved (74-80% de) by treating 5alpha and its p-chlorobenzoyl analog 6alpha with cesium or potassium azide in dimethylsulfoxide at room temperature (83-85% yields).

Azides↗

PubMed2003

General methods for the synthesis of glycopyranosyluronic acid azides.

Per-O-acetylated D-glycopyranoses derived from both mono- and disaccharides were first converted to glycosyl iodides and subsequently reacted with an azide source to achieve the stereoselective synthesis of beta-D-glycosyl azides after deacetylation. Low-temperature (4 degrees C) TEMPO oxidation of the monosaccharides provided the corresponding uronic acids, which were purified as the free acids. Oxidation of the lactosyl- and cellobiosyl azides resulted in diacid formation. However, 4',6'-O-benzylidene protection enabled selective oxidation of the C-6 hydroxyl. 2-Acetamido-2-deoxy-D-glycopyranosyl azides were also prepared and converted to uronic acids completing the library synthesis.

Azides↗

PubMed2000

Syntheses of amphiphilic glycosylamides from glycosyl azides without transient reduction to glycosylamines.

Protected glycosyl azides react with acyl chlorides in the presence of triphenylphosphine to afford glycosylamides in high yields, at room temperature. Starting from the beta-glycosyl azides, the reaction is highly stereoselective and occurs with retention of configuration, whereas the alpha-azido anomers display a lower stereoselectivity giving rise to alpha/beta mixtures of glycosylamides. The reaction was applied to several monosaccharidic azides and to lactosyl azide with various acyl chlorides; it was shown to be of general use for preparing 1,2-trans beta-glycosylamides.

Amides↗