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Food Chemistry Feb 2016A wide variety of azo dyes are generally added for coloring food products not only to make them visually aesthetic but also to reinstate the original appearance lost... (Review)
Review
A wide variety of azo dyes are generally added for coloring food products not only to make them visually aesthetic but also to reinstate the original appearance lost during the production process. However, many countries in the world have banned the use of most of the azo dyes in food and their usage is highly regulated by domestic and export food supplies. The regulatory authorities and food analysts adopt highly sensitive and selective analytical methods for monitoring as well as assuring the quality and safety of food products. The present manuscript presents a comprehensive review of various analytical techniques used in the analysis of azo dyes employed in food industries of different parts of the world. A brief description on the use of different extraction methods such as liquid-liquid, solid phase and membrane extraction has also been presented.
Topics: Azo Compounds; Chromatography, Liquid; Food Industry; Mass Spectrometry
PubMed: 26304415
DOI: 10.1016/j.foodchem.2015.07.085 -
Mutation Research Apr 1983Azo dyes are widely used in textile, printing, cosmetic, drug and food-processing industries. They are also used extensively in laboratories as either biological stains... (Review)
Review
Azo dyes are widely used in textile, printing, cosmetic, drug and food-processing industries. They are also used extensively in laboratories as either biological stains or pH indicators. The extent of such use is related to the degree of industrialization. Since intestinal cancer is more common in highly industrialized countries, a possible connection may exist between the increase in the number of cancer cases and the use of azo dyes. Azo dyes can be reduced to aromatic amines by the intestinal microflora. The mutagenicity of a number of azo dyes is reviewed in this paper. They include Trypan Blue, Ponceau 3R, Pinceau 2R, Methyl Red, Methyl Yellow, Methyl Orange, Lithol Red, Orange I, Orange II, 4-Phenylazo-Naphthylamine, Sudan I, Sudan IV, Acid Alizarin Violet N, Fast Garnet GBC, Allura Red, Ponceau SX, Sunset Yellow, Tartrazine, Citrus Red No. 2, Orange B, Yellow AB, Carmoisine, Mercury Orange, Ponceau S, Versatint Blue, Phenylazophenol, Evan's Blue and their degraded aromatic amines. The significance of azo reduction in the mutagenesis and carcinogenesis of azo dyes is discussed.
Topics: Animals; Azo Compounds; Biotransformation; Carcinogens, Environmental; Chemical Phenomena; Chemistry; Humans; Intestinal Neoplasms; Intestines; Mutagens
PubMed: 6339890
DOI: 10.1016/0165-1110(83)90035-0 -
Critical Reviews in Microbiology 1992Azo dyes are widely used in the textile, printing, paper manufacturing, pharmaceutical, and food industries and also in research laboratories. When these compounds... (Review)
Review
Azo dyes are widely used in the textile, printing, paper manufacturing, pharmaceutical, and food industries and also in research laboratories. When these compounds either inadvertently or by design enter the body through ingestion, they are metabolized to aromatic amines by intestinal microorganisms. Reductive enzymes in the liver can also catalyze the reductive cleavage of the azo linkage to produce aromatic amines. However, evidence indicates that the intestinal microbial azoreductase may be more important than the liver enzymes in azo reduction. In this article, we examine the significance of the capacity of intestinal bacteria to reduce azo dyes and the conditions of azo reduction. Many azo dyes, such as Acid Yellow, Amaranth, Azodisalicylate, Chicago Sky Blue, Congo Red, Direct Black 38, Direct Blue 6, Direct Blue 15, Direct Brown 95, Fast Yellow, Lithol Red, Methyl Orange, Methyl Red, Methyl Yellow, Naphthalene Fast Orange 2G, Neoprontosil, New Coccine, Orange II, Phenylazo-2-naphthol, Ponceau 3R, Ponceau SX, Red 2G, Red 10B, Salicylazosulphapyridine, Sunset Yellow, Tartrazine, and Trypan Blue, are included in this article. A wide variety of anaerobic bacteria isolated from caecal or fecal contents from experimental animals and humans have the ability to cleave the azo linkage(s) to produce aromatic amines. Azoreductase(s) catalyze these reactions and have been found to be oxygen sensitive and to require flavins for optimal activity. The azoreductase activity in a variety of intestinal preparations was affected by various dietary factors such as cellulose, proteins, fibers, antibiotics, or supplementation with live cultures of lactobacilli.
Topics: Animals; Azo Compounds; Bacteria; Coloring Agents; Diet; Humans; Intestines; Molecular Structure; Oxidation-Reduction
PubMed: 1554423
DOI: 10.3109/10408419209114557 -
Organic & Biomolecular Chemistry Apr 2019This review describes catalytic asymmetric cycloaddition reactions of silyl-protected enoldiazo compounds for the construction of highly functionalized carbo- and... (Review)
Review
This review describes catalytic asymmetric cycloaddition reactions of silyl-protected enoldiazo compounds for the construction of highly functionalized carbo- and heterocycles which possess one or more chiral center(s). The enoldiazo compound or its derivative, donor-acceptor cyclopropene, form electrophilic vinylogous metal carbene intermediates that combine stepwise with nucleophilic dipolar reactants to form products from [3 + 1]-, [3 + 2]-, [3 + 3]-, [3 + 4]-, and [3 + 5]-cycloaddition, generally in high yield and with exceptional stereocontrol and regioselectivity.
Topics: Azo Compounds; Catalysis; Copper; Cycloaddition Reaction; Molecular Structure; Stereoisomerism
PubMed: 30924829
DOI: 10.1039/c9ob00478e -
Current Topics in Medicinal Chemistry 2018The development of new antimicrobial drugs is a very challenging task owing to the rapidly developing drug resistance among the existing drugs. The hybridization of... (Review)
Review
The development of new antimicrobial drugs is a very challenging task owing to the rapidly developing drug resistance among the existing drugs. The hybridization of active and novel compounds is a commonly used approach to combat this situation. The azo linkage (N=N) is successfully used to link two bioactive moieties to enhance the therapeutic effects. The hybrid derivatives linked by azo linkage have shown their activity by acting on target proteins in microorganisms, cell wall inhibitors, DHPS inhibitors, RNA Editing Ligase 1 inhibitors, the general protein secretory (Sec) pathway inhibitors, neuraminidase inhibitors, etc. The current review covers the general enzymes and regulatory pathways in microorganisms targeted by diazenyl compounds and recent developments pertaining to diazenyl derivatives as antimicrobial agents during the last five years. This information will prove useful to the researchers for the development of novel antimicrobial agents by slight modifications in active derivatives with improved activities.
Topics: Animals; Anti-Infective Agents; Azo Compounds; Enzyme Inhibitors; Humans; Microbial Sensitivity Tests
PubMed: 29412106
DOI: 10.2174/1568026618666180206093107 -
Nature Protocols Mar 2010This protocol describes the aerobic oxidation of aromatic anilines to aromatic azo compounds using gold (Au) nanoparticles supported on TiO(2) as a catalyst. Yields...
This protocol describes the aerobic oxidation of aromatic anilines to aromatic azo compounds using gold (Au) nanoparticles supported on TiO(2) as a catalyst. Yields above 98% are achieved under a few bars of oxygen pressure. It should be noted that the use of stoichiometric amounts of environmentally unfriendly reagents, e.g., transition metals and nitrites, commonly used in current syntheses of azo compounds, is avoided using this approach. The protocol is illustrated with the synthesis of parent azobenzene from aniline, and this reaction takes 22 h. Au on TiO(2) can also be used as a hydrogenation catalyst, making it possible to prepare azo compounds directly from nitroaromatics through a two-step (hydrogenation followed by aerobic oxidation), one-pot, one-catalyst reaction. In addition, the catalytic process is efficient for the synthesis of symmetric and a range of asymmetric aromatic azo compounds from the mixtures of two anilines substituted with electron-donor and electron-acceptor substituents.
Topics: Amines; Azo Compounds; Catalysis; Coloring Agents; Gold; Hydrocarbons, Aromatic; Isomerism; Nitro Compounds
PubMed: 20203657
DOI: 10.1038/nprot.2009.242 -
Molecules (Basel, Switzerland) May 2017Some novel (phenyl-diazenyl)phenols - were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against...
Some novel (phenyl-diazenyl)phenols - were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl groups on the azobenzene rings. The aim of this work was to evaluate the consequent changes of the antimicrobial activity and to validate the hypothesis that, for these compounds, a plausible mechanism could involve an interaction with protein receptors, rather than an interaction with membrane. All newly synthesized compounds were analyzed by ¹H-NMR, DSC thermal analysis and UV-Vis spectroscopy. The in vitro minimal inhibitory concentrations (MIC) of each compound was determined against Gram-positive and Gram-negative bacteria and . Compounds and showed the highest activity against and , with remarkable MIC values of 10 µg/mL and 3 µg/mL, respectively. Structure-activity relationship studies were capable to rationalize the effect of different substitutions on the phenyl ring of the azobenzene on antimicrobial activity.
Topics: Anti-Infective Agents; Azo Compounds; Bacteria; Fungi; Microbial Sensitivity Tests; Molecular Structure; Quantitative Structure-Activity Relationship
PubMed: 28587076
DOI: 10.3390/molecules22060875 -
Journal of Chromatography. B,... May 2018Lipophilicity as key molecular descriptor of potential biological activity for selected derivatives of azo dyes was determined mathematically, by using relevant software...
Lipophilicity as key molecular descriptor of potential biological activity for selected derivatives of azo dyes was determined mathematically, by using relevant software packages and by reversed-phase thin-layer chromatography (RPTLC) on C18 and cyano modified carriers in mixtures of water/n-propanol and water/acetone. The obtained chromatographic parameters, R and m, of the examined azo dyes were correlated with the standard measure of lipophilicity, log P, important pharmacokinetic predictors and selected toxicity parameters applying linear regression analysis. Thereby, good correlations for each applied system were obtained (average correlation coefficient, r, 0.944, 0.885 and 0.919). Also, the correlations between the studied parameters of azo dyes were examined applying two multivariate methods (Cluster Analysis and Principal Component Analysis). It was shown that the polarity of the substituent, and to a lesser extent its electronic effects has the greatest influence on the studied parameters of the azo dyes derivatives. Multivariate methods pointed out the similarity of the chromatographic retention constant, R, with the parameters of lipophilicity, unlike the chromatographic parameter m, which exhibits better agreement with the toxicity parameters.
Topics: Azo Compounds; Chromatography, Liquid; Hydrophobic and Hydrophilic Interactions; Linear Models; Principal Component Analysis
PubMed: 29604612
DOI: 10.1016/j.jchromb.2018.03.035 -
Drug Metabolism Reviews 1991Azo dyes are consumed and otherwise utilized in varying quantities in many parts of the world. Such widely used chemicals are of great concern with regard to their... (Review)
Review
Azo dyes are consumed and otherwise utilized in varying quantities in many parts of the world. Such widely used chemicals are of great concern with regard to their potential toxicity and carcinogenic properties. Their metabolism has been studied extensively and is significant for detoxication and metabolic activation. Both oxidative and reductive pathways are involved in these processes. The majority of azo dyes undergo reduction catalyzed by enzymes of the intestinal microorganisms and/or hepatic enzymes including microsomal and soluble enzymes. The selectivity of substrate and enzyme may to a large extent be determined by the oxygen sensitivity of reduction since a normal liver is mainly aerobic in all areas, whereas the microorganisms of the lower bowel exist in an anaerobic environment. However, it should be pointed out that the pO2 of centrilobular cells within the liver is only a fraction that of air, where pO2 = 150 torr. Therefore, an azo dye reduction experiment performed aerobically may not be an accurate predictor of reductive metabolism in all areas of the liver. Many of the azo dyes in common use today have highly charged substituents such as sulfonate. These resist enzymic attack and for the most part are poorly absorbed from the intestinal tract, providing poor access to the liver, the major site of the mixed-function oxidase system. Lipophilic dyes, such as DAB, which are often carcinogenic, readily access oxidative enzymes and are activated by both mixed-function oxidase and conjugating systems. Reduction of the carcinogenic dyes usually leads to loss of carcinogenic activity. By contrast, most of the highly charged water-soluble dyes become mutagenic only after reduction. Even then, most of the fully reduced amines required oxidative metabolic activation. An outstanding example is the potent human bladder carcinogen benzidine, which derives from the reduction of several azo dyes. Many problems regarding mutagenic and carcinogenic activation remain to be solved. At the present time, it is apparent that both oxidative and reductive pathways yield toxic products. Toxicologic assessment of azo dyes must consider all pathways and particularly the oxygen sensitivity of azoreduction. This is critical in the treatment of waste from chemical plants where there is a great need for soil bacteria which catalyze reduction aerobically. Consideration of secondary pathways are also of great concern. For example, azoreduction of carcinogenic dyes such as DAB removes carcinogenic activity although oxidative metabolism of the primary amines yield mutagenic products. Such apparent dilemmas must be dealt with when considering metabolism/toxicity relationships for azo dyes.
Topics: Animals; Azo Compounds; Bacteria; Biotransformation; Carcinogens; Coloring Agents; Humans; Inactivation, Metabolic; Mutagenesis; Oxidation-Reduction
PubMed: 1935573
DOI: 10.3109/03602539109029761 -
Biophysical Chemistry Jul 2022Microbial decolorization of azo dyes, mediated by an enzymatic mechanism is an intricate cost-effective, and eco-friendly treatment method of genotoxic azo pollutants....
Microbial decolorization of azo dyes, mediated by an enzymatic mechanism is an intricate cost-effective, and eco-friendly treatment method of genotoxic azo pollutants. Scientists are on the constant lookout for microbes, enzymes, and mechanisms that could aid remediation of the environment at a fast pace. Alcaligenes faecalis subsp. phenolicus MB207 is one such bacteria, consisting of azoreductase (AzoR) and laccase/multicopper oxidase enzyme responsible for sulphonated mono-azo dye (Methyl orange) and di-azo dye (Congo red) degradation. AzoR degrades dyes by a ping-pong setup while multicopper oxidase achieves this through a non-specified radical approach. We have coupled experimental analysis with bioinformatics for deciphering intricacies of this procedure in tiny scale enzymatic machines of this biotope. The degradation assays were followed by molecular docking of the enzyme-substrate complexes. Key anchoring bonds were detected and mapped H-bonding, electron exchange, ionic interactions, as well as hydrophobic interactions, provided insights into dye-enzyme and NADH-enzyme binding. This study establishes a foundation of the molecular basis of dye interaction with azoR and multicopper oxidase in A. facealis subsp. phenolicus MB207.
Topics: Alcaligenes; Amlodipine Besylate, Olmesartan Medoxomil Drug Combination; Azo Compounds; Biodegradation, Environmental; Coloring Agents; Molecular Docking Simulation
PubMed: 35397247
DOI: 10.1016/j.bpc.2022.106806