Use Of Azide Research Articles

Bacteria-targeted biomaterials: Glycan-coated microspheres to bind Helicobacter pylori

Gastric cancer is the third leading cause of cancer related deaths worldwide and Helicobacter pylori (H. pylori) persistent infection has been pointed as a causative agent of this disease. Current antibiotic based treatments to eradicate this bacterium fail in 20% of the patients, potentially leaving 140 million people in the world without alternative therapy. It is herein proposed the use of azide–alkyne coupling (“click chemistry”) to produce glycan-coated mucoadhesive microspheres that bind and remove the H. pylori adherent to the gastric mucosa through specific bacterial adhesin–glycan interactions. Glycan immobilization is performed via chitosan’s primary alcohol group, rather than the more reactive primary amines in order to preserve the amine groups that confer chitosan its mucoadhesiveness. It is shown that chitosan microspheres decorated with Lewis b glycans (Leb-Mic) bind specifically to H. pylori strains expressing the BabA adhesin (strains recognized as highly pathogenic) (∼230 bacteria/microsphere), are non-cytotoxic, are retained in the stomach of C57BL/6 mice for around 1.5h. Also, these Leb-Mic are able to prevent and remove H. pylori adhesion to gastric mucosa expressing the same glycan, in tissue sections from mice and human gastric mucosa (in vitro) and in fresh mice stomachs (ex vivo). These results provide proof-of-concept on the potential of glycan-decorated microspheres as an innovative therapeutic strategy against H. pylori and highlight the prospective of using targeted biomaterials to fight gastrointestinal infection. Statement of SignificanceGastric cancer has been associated with persistent infection by Helicobacter pylori, a bacterium that colonizes half of world population and whose available antibiotic treatment fails in 20% of cases. H. pylori adhesion to gastric epithelium is mediated between bacterial adhesins and glycans expressed in gastric mucosa.We demonstrate that these glycans can be immobilized in a controlled orientation into mucoadhesive chitosan microspheres, making them selective for different H. pylori strains. Efficacy studies (in vitro and ex vivo) with mice and human gastric mucosa that express the same glycan, revealed microspheres capacity to remove/prevent specific H. pylori adhesion, envisaging their future application as bacteria scavenging from stomach.This bacteria-binding strategy can be extrapolated to target other cells/bacteria using suitable ligands.

The use of azide–alkyne click chemistry in recent syntheses and applications of polytriazole-based nanostructured polymers

The rapid development of efficient organic click coupling reactions has significantly facilitated the construction of synthetic polymers with sophisticated branched nanostructures. This Feature Article summarizes the recent progress in the application of efficient copper-catalyzed and copper-free azide-alkyne cycloaddition (CuAAC and CuFAAC) reactions in the syntheses of dendrimers, hyperbranched polymers, star polymers, graft polymers, molecular brushes, and cyclic graft polymers. Literature reports on the interesting properties and functions of these polytriazole-based nanostructured polymers are also discussed to illustrate their potential applications as self-healing polymers, adhesives, polymer catalysts, opto-electronic polymer materials and polymer carriers for drug and imaging molecules.

ChemInform Abstract: Gold‐Catalyzed One‐Step Construction of 2,3‐Dihydro‐1H‐pyrrolizines with an Electron‐Withdrawing Group in the 5‐Position: A Formal Synthesis of 7‐Methoxymitosene.

What a ring formation! Bicyclic dihydropyrrolizines with an electron-withdrawing group (EWG) at the 5-position are formed in one step from linear azidoenynes under gold catalysis. This novel route involves the use of azide as a nitrene precursor, electronically-controlled regioselectivity, and the generation of destabilized 1-azapentadienium ions and their pericyclic reactions. This method was used for a formal synthesis of 7-methoxymitosene.

Gold‐Catalyzed One‐Step Construction of 2,3‐Dihydro‐1H‐Pyrrolizines with an Electron‐Withdrawing group in the 5‐position: A Formal Synthesis of 7‐Methoxymitosene

What a ring formation! Bicyclic dihydropyrrolizines with an electron-withdrawing group (EWG) at the 5-position are formed in one step from linear azidoenynes under gold catalysis. This novel route involves the use of azide as a nitrene precursor, electronically-controlled regioselectivity, and the generation of destabilized 1-azapentadienium ions and their pericyclic reactions. This method was used for a formal synthesis of 7-methoxymitosene.

Azide‐ and Alkyne‐Derivatised α‐Amino Acids

AbstractWith the emergence of the copper‐catalysed Huisgen cycloaddition the use of azide‐ and alkyne‐derivatised α‐amino acids has found widespread use within most chemistry disciplines. Despite a growing interest in these building blocks researchers are struggling to identify the best way for their synthesis. In this review we have compiled available methods for synthesising optically active azide‐ and alkyne‐derivatised α‐amino acids that can be prepared from readily available α‐amino acids. We highlight a number of commonly overlooked problems associated with existing methods and direct attention to unexplored possibilities.

ChemInform Abstract: Modification of Nucleic Acids Using [3 + 2]‐Dipolar Cycloaddition of Azides and Alkynes

AbstractReview: 336 refs.

Adding to the controversy: Continuously‐infused human C‐reactive protein reduces atherosclerosis in apolipoprotein E‐deficient mice

The role of C‐reactive protein (CRP) in atherosclerosis mouse models remains controversial, with studies showing both proatherogenic and no effects. We hypothesized that the discrepancies might relate to the use of azide‐ or endotoxin‐contaminated native (n) CRP, its episodic administration, to the use of CRP transgenic vs. non‐transgenic mice, or to biased sampling of the aorta in evaluating atherosclerotic lesions. We administered azide‐ and endotoxin‐free human nCRP (n=11) or placebo (n=11) to 12‐week‐old apolipoprotein E‐deficient (apoE−/−) male mice as a continuous infusion for 4 weeks (20.4 μg/day). Animals treated with nCRP developed fewer lesions (7.24 ± 1.59%) in the whole aorta than controls (9.90 ± 2.11%) (p= 0.0026; R2 = 0.3578). When aortic regions were analyzed separately, the extent of atherosclerotic lesions showed significant differences for nCRP‐treated vs. controls in the thoraco‐abdominal region (3.14 ± 1.27% vs. 4.67 ± 1.89%) (p = 0.0322; R2 =0.2004); but the differences were not significant in the aortic arch (3.71 ±1.15% vs. 4.63 ± 1.16%) (p = 0.0715; R2 = 0.1465), the iliac region (0.40 % ± 0.35 vs. 0.62; ± 0.30%) (p = 0.1247; R2 = 0.1086), or the aortic root (65.02 ± 7.81% vs. 64.71± 9.65%) (p= 0.9393; R2 = 0.0004). These comparisons show an unexpected reduction of atherosclerosis in nCRP‐treated mice. They also emphasize the methodological importance of examining the whole aorta, rather than arbitrarily selected regions, to gain a valid understanding of atherosclerosis in this model.

Opportunities and Limits of the Use of Azides in Industrial Production. Implementation of Safety Measures

Azides are very versatile precursors of organic synthesis functionalities such as amines, isocyanates, sulfonamides, triazoles, tetrazoles, triazolines, aziridines, amino acids and diazo compounds. In industry, one of the favourite starting materials for these syntheses is sodium azide which can generate hydrazoic acid whose toxicity and detonation potential is of major safety concern. However sodium azide is used daily in large tonnage in the air-bags of vehicles, in biologic institutes as a bactericide and in agriculture as a herbicide. In industrial synthesis, sodium azide is actually the starting material of herbicides, anti-HIV pharmaceuticals, anti-pain compounds and hypo tensors. This massive use of sodium azide represents severe toxicological and physical damage risks. The industrial synthesis under the scope of this presentation will be the manufacture of a tetrazole produced in several tens of tons per year. A risk assessment concluded that it would be necessary to conduct the reaction in a 'Bunker' and to minimise risks by absolutely avoiding generation of hydrazoic acid. This can be achieved by a careful design of the process and by strict organisational measures. Furthermore, the reaction equipment was designed to prevent any condensation of hydrazoic acid. One way to prevent its formation is to maintain the reaction medium under basic conditions at all times. This is achieved by using triethylamine hydrochloride as a buffer. In the applied reaction conditions it could be demonstrated that triethylamine was the refluxing compound at 130 °C and that a thermally stable triethyl ammonium azide was formed. The environmental problem could be resolved by incineration of the wastewaters. In conclusion, reactions with sodium azide are safe, they only need a stabilising agent. A search for such compounds could be an interesting but rather dangerous research project.

Nucleic acid binding of arylamines during the respiratory burst of human granulocytes

Following stimulation with phorbol myristate acetate, human granulocytes were found to incorporate a series of arylamines into cellular nucleic acid. No such binding occurred if the granulocytes were not induced to undergo the respiratory burst. The relative amount of covalent binding to cellular DNA and RNA was found to depend strongly on the chemical structure of the arylamine. 2-Aminofluorene gave the highest ratio of DNA/RNA binding, while 4-nitroaniline showed a very low ratio of DNA/RNA binding. 4-Nitroaniline may bind only to RNA, since the degree of binding to DNA was at the level of detectability. Two other substrates, 4-chloroaniline and 4-methylaniline, gave intermediary ratios of DNA/RNA binding. Studies on the possible role of the granulocyte enzyme myeloperoxidase in the activation and binding of these arylamines were conducted in vitro and also through the use of azide, an inhibitor of myeloperoxidase activity in cells. The results indicate that myeloperoxidase probably plays only a limited role in causing the covalent binding of arylamines to nucleic acid in human granulocytes. It is probable that other reactive oxygen species, which are not dependent upon myeloperoxidase for their production, are necessary for the bioactivation of some arylamines, especially for substrates such as 4-nitroaniline. A free-radical mechanism for arylamine bioactivation, and its potential role in arylamine toxicity, was presented in the context of the current scientific literature.

Use of azide and hydrogen peroxide as an inhibitor for endogenous peroxidase in the immunoperoxidase method.

We describe a simple and effective method for inhibition of endogenous peroxidase activity in the immunoperoxidase technique. Specimens are pre-treated with a mixture of azide and hydrogen peroxide, which is then followed by an indirect immunoperoxidase procedure. Comparison studies showed no significant loss of antigenicity or morphological details by this pre-treatment. The method is most useful for evaluating cell-specific antigens on specimens that have abundant endogenous peroxidase activity, such as blood and bone marrow.

An enantioselective synthesis of the carzinophilin degradation product (2s,3s) 4-amino-2,3-dihydroxy-3-methylbutyric acid

An efficient, enantioselective synthesis of (2S,3S) 4-amino-2,3-dihydroxy-3-methylbutyric acid (1) is described. The sequence includes the direct use of azide to selectively open a secondary epoxy alcohol formed under Payne rearrangement conditions.

Evaluation of mutagenicity and other adverse effects of occupational exposure to sodium azide

The ubiquitous use of sodium azide has resulted in widespread occupational exposure to it in both laboratory and industrial settings, despite a lack of knowledge of the risks which may be involved. Explosive, toxic, and mutagenic hazards have been shown at even low-dose exposures. These effects occur in many species, from cellular damage through pathology of whole systems, and human fatalities have been reported. The advantages to its availability for applicable uses precludes reaching a “no exposure” level, but efforts to decrease unnecessary exposure can reduce its risk; therefore a quantitative procedure for determining human exposure is necessary. However, for various reasons present methods for this type of evaluation of azide are unsatisfactory, and minimizing hazard is dependent upon good laboratory hygiene and motivated personnel. The increasing use of azide and proportionally increasing occupational and accidental exposure in the future warrants the undertaking of chronic exposure studies, which hopefully will result in more explicit guidelines for human protection.

Use of azide to enhance the sensitivity of colorimetric immobilized-glucose-oxidase methods for glucose.

Journal Article Use of azide to enhance the sensitivity of colorimetric immobilized-glucose-oxidase methods for glucose. Get access R Q Thompson, R Q Thompson Search for other works by this author on: Oxford Academic Google Scholar C J Patton, C J Patton Search for other works by this author on: Oxford Academic Google Scholar S R Crouch S R Crouch Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 28, Issue 3, 1 March 1982, Pages 556–557, https://doi.org/10.1093/clinchem/28.3.556 Published: 01 March 1982

Problems Associated with the Use of Azide as an Inhibitor of Microbial Activity in Soil

Problems associated with the use of sodium or potassium azide as an inhibitor of microbial activity in soil include erroneous CO(2) evolution readings, shifts in inhibitor concentration, rise in soil pH, and explosion hazard.

The oxidation of bilayer dispersions of unsaturated phosphatidylcholines by decomposing potassium peroxychromate

The oxidation of aqueous dispersions of unsaturated phosphatidylcholines by products released during the decomposition of potassium peroxychromate has been investigated. The rate and extent of oxidation have been measured by loss of unsaturated fatty acids and related to the rate of decomposition of peroxychromate as monitored by pH titrimetry and chromate analysis. The loss of oleic and linoleic acid from egg lecithin dispersions was similar in systems containing between 0.062 and 2 g peroxychromate and was limited to less than 50% of the total unsaturated residues of the substrate. Studies of the rate of oxidation suggested that the mechanism of reaction involved the progressive oxidation of the substrate dependent on the continuous supply of relatively short-lived oxidising species. The use of azide as a singlet oxygen quencher and 2,5-dimethyl- and 2,5-diphenylfurans as singlet oxygen traps did not prevent oxidation of the phospholipid.

Azide as a Broadspectrum Soil Treatment for Vegetable Crops1

Abstract Azide as NaN3 or KN3 impregnated on clay granules gave excellent control of yellow nutsedge (Cypetus esculentus L.) compared to methyl isothiocyanate combined with chlorinated C3 hydrocarbons (Vorlex) or a non-hand weeded control. Nematode control was obtained with all treatments. Significant yield responses from the use of azide were obtained with all crops.

On the reaction of sulfenyl iodide derivatives with azide

Based on the suggested mechanism of the Raschig catalytic iodine-azide reaction the use of azide for the azotometric estimation of sulfenyl iodide groups is proposed. In the Raschig reaction reduction of iodine to iodide and oxidation of azide to elementary nitrogen is specifically catalyzed by bivalent sulfur compounds; the reaction is usually formulated to proceed via hypothetical sulfenyl iodide derivatives. This has been explored with the use of available, relatively stable sulfenyl iodide derivatives. The -SI group oxidizes azide to nitrogen stoichiometrically: 1 mole of a sulfenyl iodide consumes 2 moles of sodium azide and yields 3 moles of elementary nitrogen. The specificity and limitations of the method are discussed.

Use of Azide with Optochin Disk for Rapid Identification of Pneumococci

Use of Azide with Optochin Disk for Rapid Identification of Pneumococci