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PubMed2003

Study of tropaeolin degradation by iron--proposition of a reaction mechanism.

The degradation of tropaeolin by iron was studied under oxidizing and inert atmospheres. The products were identified by various chromatographic and spectroscopic methods. Under inert atmosphere, the proposed model of mechanism is based on the adsorption of tropaeolin by the sulfonate function on the solid iron, followed by a reduction of the [bond]Nz[double bond]N[bond] bond with formation of 1-amino-2-naphthol and sulfanilic acid. These two intermediaries were reduced to 1,2-dihydroxynaphthalene and benzene with NH(4)(+) and HSO(3)(-) liberation. Under oxidizing atmosphere, besides the reductions of tropaeolin, water and ferric ions, the existence of a homogeneous degradation was found. This process was explained (on the basis of surface iron potential monitoring) by a stepwise reduction of oxygen giving hydrogen peroxide. The initial stages of the mechanism were similar to those under inert atmosphere, but the degradation of the 1,2-dihydroxynaphthalene continued giving 1,2-naphthalenedione, then various polar monocyclic compounds leading to three unidentified volatile final products.

Azo Compounds↗
PubMed2007

One-pot procedure for diazo transfer and azide-alkyne cycloaddition: triazole linkages from amines.

[reaction: see text] A one-pot reaction for Cu(II)-catalyzed diazo transfer and Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (sometimes called click reaction) is reported. 1,4-Disubstituted 1,2,3-triazoles are obtained in excellent yields from a variety of readily available amines without the need for isolation of the azide intermediates. The reaction has a broad scope and is especially practical for the synthesis of multivalent structures because compounds substituted with multiple azides are potentially unstable.

Alkynes↗
PubMed1979

Comparison of the effects of insulin and insulin-like agents on different aspects of adipocyte metabolism.

The effect of insulin, spermine, cysteine, and diamide on glucose transport, glucose oxidation, and lipolysis were compared using isolated rat adipocytes. Each agent exerted insulin-like effects on glucose transport and glucose oxidation, whereas spermine and cysteine, but not diamide, inhibited lipolysis. Furthermore, the relative potencies of these agents on the various insulin responsive processes were markedly different. Thus, although these agents have much in common with insulin, the differences in relative potencies suggest that at least some of the insulin-like properties of these compounds may not be exerted through the same mechanisms as insulin.

Adipose Tissue↗
PubMed2003

Novel catalytic photochemical and hydrothermal treatment processes for acid dye wastewater.

The purpose of the present study was to evaluate the catalytic effect of a heteropoly acid, namely H4SiW12O40, on aqueous Acid Orange 7, a well-known, representative textile monoazo dye applied to nylon fabrics, in sub-critical water (T = 160 degrees C-290 degrees C; P = 0.6-3.0 MPa, pH = 2.6) and under near-UV-VIS light irradiation (isopropanol: water ratio = 1:10: pH = 2.8). SiW12O40-catalyzed photochemical Acid Orange 7 bleaching was also explored in the presence of two dye assisting chemicals as well as in simulated acid dye wastewater at its natural, acidic pH under otherwise identical reaction conditions. Though less explored than TiO2-mediated, heterogeneous photocatalytic treatment, heteropolyacid-catalyzed thermal and/or photoatalytic re-mediation could be an attractive alternative for the degradation of refractory, colored compounds using relatively mild wet oxidation operating conditions or even natural solar light.

Azo Compounds↗
PubMed1979

[Biologically active azomethines. Delépine reaction with 1-chloromethylisatin; preparation of some 1-aminomethylisatinazomethines (author's transl)].

The authors describe the synthesis of I-aminomethylisatin (3) from [I-chloromethylisatin] (1) by means of the Delépine reaction. On condensation with aromatic aldehydes, 3 yields the azomethines 5--7. The azomethine 5 is converted into the corresponding thiosemicarbazone 9. Testing for mitodepressive activity showed that the compounds 5--7 are active. On testing in vitro for tuberculostatic effects, the compound 9 proved exceptionally potent.

Antitubercular Agents↗
PubMed1998

Mutagenicity of isomeric alkanediazotates, precursors for ultimate alkylating species of carcinogenic N-nitroso compounds.

Alkanediazohydroxides are common key intermediates in carcinogenesis and mutagenesis of N-nitroso compounds, which are widely found in human environment. Mutagenicity of (E)- and (Z)-potassium alkanediazotates, as precursors of corresponding alkanediazohydroxides were evaluated to investigate the effect of geometric isomerism and also the effect of alkyl groups on their biological activity. Mutagenicity of N-nitroso-N-alkylureas which spontaneously produce alkanediazohydroxides after non-enzymatic hydrolysis were also tested in comparison to that of the corresponding diazotates and other activated chemical species of N-nitrosamines. When the mutagenicity was assayed in three microbial strains, Salmonella typhimurium TA1535, and Escherichia coli WP2 and WP2 uvrA, the order of mutagenic potency of the compounds with the same alkyl group was as follows; (E)-diazotates > (Z)-diazotates > nitrosoureas. The effect of alkyl groups on the mutagenic potency was different in Salmonella strain and in E. coli strains, and this result could be explained by the efficiency of O6-alkylguanine-DNA alkyltransferase. In each bacterial strain, this effect of alkyl groups was similar in mutagenicity induced by (E)- and (Z)-diazotates, N-nitroso-N-alkylureas and other activated N-nitrosodialkylamines such as alpha-hydroxy nitrosamines. The geometrical isomerism affected the mutagenicity of (E)- and (Z)-potassium alkanediazotates, and the result suggested that alkanediazohydroxides react through diazonium ions in a cage rather than through free alkyldiazonium ions which have no geometrical isomerism. Our results confirmed that (E)-potassium alkanediazotates, (Z)-potassium alkanediazotates and N-nitroso-N-alkylureas all decomposed through diazohydroxides, and that alkanediazohydroxides are the active alkylating species of N-nitroso compounds, and also that the geometrical isomerism is important for carcinogenic N-nitroso compounds to show their biological activity.

Alkylating Agents↗
PubMed1975

The effect of acid proteinase inhibitors on chicken pepsin.

1. The activity of chicken pepsin was partially inhibited by dimethyl-(2-hydroxy-5-nitrobenzyl)sulphonium bromide, but was unaffected by p-bromophenacyl bromide. 2. In the presence of Cu2+, diazoacetylnorleucine methyl ester completely inactivated chicken pepsin with the incorporation of 1 mol/mol. The mechanism of the reaction was similar to that with pig pepsin. 3. Chicken pepsin was completely inactivated by 2-diazo-4-bromoacetophenone in the presence of Cu2+. 4. Chicken pepsin was almost completely inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane at 25 degrees C, 3-4mol of inhibitor/mol being incorporated. The reaction at 10 degrees C was investigated briefly. 5. Calf chymosin was inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane at 10 degrees C, the incorporation of 1 mol/mol being required for complete inhibition. 6. The characteristics of the reactions of chicken pepsin with the above compounds were compared with those of other acid proteinases.

Acetophenones↗
PubMed1981

Carcinogenic, Mutagenic, and Comutagenic Aromatic Amines in Human Foods.

Three recent topics related to possible exposure of humans to mutagenic and carcinogenic aromatic amines and related compounds in foods are reviewed. A food additive, AF-2,2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, was first demonstrated to be mutagenic in Escherichia coli WP-2 and then proved to be carcinogenic in experimental animals. This is an example of prediction of the carcinogenicity of a compound from results of short-term microbial tests. Pyrolysates of amino acids, proteins, and foods high in a protein contain many heterocyclic aromatic amine compounds. For example, a tryptophan pyrolysate contains two derivatives ofamino-gamma-carboline(pyridoindole), and a glutamicd acid pyrolysate contains two derivatives of djipyridoimidazole. These compounds are strong frameshift mutagens in Salmonella typhimurium. Some of them were carcinogenic in an in vitro transformation test and were also carcinogenic when injected sc into hamsters and rats and when given orally to mice. Carcinogenic aromatic amines, such as aniline, and o-toluidine and yellow OB were demonstrated to be mutagenic in the presence of the beta-carboline, norharman, with S-9 mix. Diphenylnitrosamine was also mutagenic in the presence of norharman, which is present in tobacco tar and broiled food. These mutagenicities of aniline, o-toluidine, yellow OB, and diphenylnitrosamine are discussed in relation to an evaluation of compounds as environmental carcinogens from the results of short-term microbial tests.

Animals↗