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At least 19 recordsLinked to original sources
PubMed1984

Structure-activity relationships in the induction of hepatic drug metabolism by azo compounds.

Lipophilic azo compounds possessing 1-phenylazo-2-naphthol or 1-phenylazo-2-naphthylamine moieties induced cytochrome P-448 and related mono-oxygenase activities, UDP-glucuronyltransferase activity towards p-nitrophenol, glutathione-S-transferase activity towards 1-chloro-2,4-dinitrobenzene, aldehyde dehydrogenase, and menadione reductase activities. This pattern of induction by azo dyes is very similar to that by 3-methylcholanthrene. None of the hydrophilic azo compounds tested and none of the other lipophilic azo compounds tested including 4-phenylazo-1-naphthol induced these activities. It is suggested that the formation of a third six-membered ring fused to naphthalene in a phenanthrene-like arrangement by hydrogen bonding between the phenolic hydroxyl and azo nitrogen is required for induction.

Animals↗
PubMed1989

In vitro metabolic N-oxidation of azo compounds. I. Evidence for formation of azo N-oxides (azoxy compounds).

Certain azo compounds and their N-oxides have been prepared and characterized by spectroscopic methods. A HPLC method for the quantification of azo-N-oxide metabolites of those azo compounds is described. The enzymic N-oxidation of azo compounds in vitro has been demonstrated as a general metabolic pathway. In the case of the mixed aryl-alkyl azo compound, only one N-oxide was detected. The identity of N-oxide metabolites has been confirmed by CG/MS. Azo-N-oxidase activity was detected principally in the liver, but also in lung, heart and kidney whole organ homogenates. Studies using subcellular fractions showed that azo N-oxidase activity resides mainly in the hepatic microsomal fraction. The amount of N-oxide formed under optimised incubation conditions by hamster microsomal preparations is greatest with omega, omega'-azoxytoluene (AXT) and least with azoxybenzene (AXB); while omega-(phenylazoxy)toluene (PAXT) is intermediate.

Animals↗
PubMed2000

The comet assay in eight mouse organs: results with 24 azo compounds.

The genotoxicity of 24 azo compounds selected from IARC (International Agency for Research on Cancer) groups 2A, 2B, and 3 were determined by the comet (alkaline single cell gel electrophoresis, SCG) assay in eight mouse organs. We treated groups of four mice once orally at the maximum tolerated dose (MTD) and sampled stomach, colon, liver, kidney, bladder, lung, brain, and bone marrow 3, 8, and 24 h after treatment. For the 17 azo compounds, the assay was positive in at least one organ; (1) 14 and 12 azo compounds induced DNA damage in the colon and liver, respectively, (2) the genotoxic effect of most of them was greatest in the colon, and (3) there were high positive responses in the gastrointestinal organs, but those organs are not targets for carcinogenesis. One possible explanation for this discrepancy is that the assay detects DNA damage induced shortly after administration of a relatively high dose, while carcinogenicity is detected after long treatment with relatively low doses. The metabolic enzymes may become saturated following high doses and the rates and pathways of metabolic activation and detoxification may differ following high single doses vs. low long-term doses. Furthermore, considering that spontaneous colon tumors are very rare in rats and mice, the ability to detect tumorigenic effects in the colon of those animals might be lower than the ability to detect genotoxic events in the comet assay. The in vivo comet assay, which has advantage of reflecting test chemical absorption, distribution, and excretion as well as metabolism, should be effective for estimating the risk posed by azo dyes to humans in spite of the difference in dosage regimen.

Animals↗
PubMed1967

Pesticide transformation to aniline and azo compounds in soil.

The herbicide 3',4'-dichloropropionanilide decomposes in soil to carbon dioxide and 3,4-dichloroaniline. and two molecules of the latter compound are condensed to form 3,3',4,4'-tetrachloroazobenzene. Soil microorganisms are involved in both transformations.

Anilides↗
PubMed1995

Hepatic damage induced by perfusion of radical generating azo compound and its inhibition by vitamin E.

The damaging effect of perfusion of hydrophilic radical generating azo compound on the liver of normal and vitamin E-deficient rats and its inhibition by antioxidants were studied in order to increase understanding of the action of free radicals on biological tissues. The hepatic damage was evaluated from the release of cytosolic enzymes such as glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, mitochondrial oxidation metabolism and morphological change. Two kinds of hydrophilic azo compounds were used, one which decomposes spontaneously at a uniform rate to generate free radicals and the other which does not. The former induced hepatic damage in a dose-dependent manner, while the latter did not exert any damage. Both endogenous vitamin E in the membranes and a water soluble vitamin E analogue added simultaneously with a radical initiator suppressed the hepatic damage. These results show that the hepatic damage induced by perfusion of radical generating azo compound is caused not by the azo compound itself but by free radicals.

Alanine Transaminase↗
PubMed1989

In vitro metabolic N-oxidation of azo compounds. II. Some factors influencing N-oxidation.

Factors affecting the metabolism of azo compounds in vitro have been studied and conditions which allow maximal metabolism established. A species difference in the extent of N-oxidation was evident, the order of activity depending on the class of substrate used. With the bisaryl azo compound, the order of activity was rabbit greater than hamster greater than mouse greater than guinea pig greater than rat, while for the bisalkyl and mixed alkyl-aryl azo compounds, the order was hamster greater than guinea pig greater than mouse greater than rabbit greater than rat. The appropriate kinetic factors, Km and Vmax, for the N-oxidation of azobenzene (AB), omega,omega'-azotoluene (AT) and omega-phenylazotoluene (PAT) are reported. A sex difference in azobenzene N-oxidase activity was observed in rats but not in hamsters.

Animals↗
PubMed1984

Alterations of the intestinal microflora by diet, oral antibiotics, and Lactobacillus: decreased production of free amines from aromatic nitro compounds, azo dyes, and glucuronides.

F344 rats were fed compounds containing a nitro, azo, or amine-glucuronide group-2-nitronaphthalene (CAS: 581-89-5), 2-nitrofluorene (CAS: 607-57-8; 2-nitro-9H-fluorene), 4-phenylazo-2-naphthol (CAS: 6410-10-2; 1-[(4-nitrophenyl)azo]-2-naphthol), and 2-naphthylamine-N-D-glucuronide--and the formation of free amines was measured in the feces. The effects of diet (mean vs. grain), administration of antibiotic, and the feeding of Lactobacillus acidophilus were evaluated. Meat-fed rats given 2-nitronaphthalene had approximately 4 times higher concentration of free amines in their feces as compared to the concentration in grain-fed rats. In a similar experiment with 2-naphthylamine-N-D-glucuronide, the meat-fed animals had approximately 1.5 times more of the free amines and 50% less of the conjugates in their feces. When meat-fed animals were given L. acidophilus with 2-nitrofluorene or 2-naphthylamine-N-D-glucuronide, they had significantly lower free amines and higher concentrations of conjugates in their feces than did the meat-fed controls. Similarly, erythromycin or tetracycline decreased the fecal amine production in meat-fed animals that had received 2-nitrofluorene or 4-phenylazo-2-naphthol. In another experiment, erythromycin inhibited the production of free amines from 2-naphthylamine-N-D-glucuronide in rats fed a high-fat diet. Studies of fecal enzymes revealed lower levels of beta-D-glucuronidase, nitroreductase, and azoreductase in grain-fed rats and in meat-fed animals also given antibiotics or lactobacilli. These experiments showed that intestinal flora have the ability to convert exogenously administered aromatic nitro and azo compounds and an amine-glucuronide compound to free amines. The rate of these conversions was affected by diet and by oral administration of antibiotics and lactobacilli.

Amines↗
PubMed1996

EPR spin trapping study of the decomposition of azo compounds in aqueous solutions by ultrasound: potential for use as sonodynamic sensitizers for cell killing.

Sonodynamic therapy, a promising new approach to cancer treatment, is based on synergistic cell killing by combination of certain drugs (sonosensitizers) and ultrasound. Although the mechanism of sonodynamic action is not understood, the role of free radicals produced from sonosensitizers by ultrasound is implicated. In this work, we studied formation of free radicals during the decomposition of several water-soluble azo compounds by 50 kHz ultrasound in aqueous solutions. Using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) tertiary carbon-centered radicals from 2,2'-azobis (N,N'-dimethyleneisobutyramidine) dihydrochloride (VA-044), 2-(carbamoylazo)-isobutyronitrile (V-30), and 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) and .CH3 radicals from 1,1'-azobis (N,N'-dimethylformamide) (ADMF) were detected in argon-saturated solutions and the corresponding oxygen-centered radicals (alkoxyl and peroxyl) from VA-044, V-30, and AAPH were identified using the spin trap 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) in aerated sonicated solutions. No free radicals from 4,4'-dihydroxyazobenzene-3,3'-dicarboxylic acid, disodium salt (DHAB) could be found in either system. While VA-044 and AAPH could also be readily decomposed by heat (42.5 degrees C and 80 degrees C), V-30 decomposition only occurred in the ultrasound-exposed solutions. The most likely mechanism of decomposition of azo compounds by ultrasound is their thermolysis in the heated shell of the liquid surrounding cavitating bubbles driven by ultrasound and/or by pyrolysis inside these bubbles. Experiments using scavengers of .OH and .H, which are produced by sonolysis in aqueous solutions, demonstrated that these radicals are not involved in the ultrasound-mediated radical production from the azo compounds. Due to the known cytotoxic potential of free radicals produced from azo compounds, the use of these compounds as ultrasound sensitizers appears to be a promising approach for sonodynamic cell killing.

Azo Compounds↗
PubMed2002

Enhanced anaerobic degradation of polymeric azo compounds by Escherichia coli in the presence of low-molecular-weight redox mediators.

The effects of the redox mediator lawsone (2-hydroxy-1,4-naphthoquinone) on the ability of Escherichia coli to reduce anaerobically polymeric azo compounds were analysed. Two types of polymeric azo compounds were tested, that have been proposed as putative tools for the site-specific targeting of drugs to the colon. The first group of polymers consisted basically of linear chains of polymethacrylic acid or polymethylmethacrylate which were interrupted by subunits of 4,4'-bis(methacryloylamino)azobenzene. These polymers differed significantly in their hydrophilicity according to the relative proportion of polymethacrylic acid used for the polymerization procedure. The second group of polymers consisted of almost water-insoluble poly(ether-ester)azo polymers that were composed of 4-(6-hydroxyhexyl)oxy-phenylazobenzoate and 16-hydroxyhexadecanoate. The addition of lawsone to the anaerobically incubated cultures of E. coli resulted in a pronounced increase in the reduction rates of the water-soluble poly(methacrylate-co-4,4'-bis(methacryloylamino)azobenzene) and in a much smaller, but significant, increase in the reduction rates of the hydrophobic poly(ether-ester)azo polymers. An increase in the amount of azo groups resulted, for the hydrophobic poly(ether-ester)azo polymers, in an increased reduction rate in the presence of the redox mediator lawsone.

Azo Compounds↗
PubMed2003

[3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions.

We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily.

Journal Article↗
PubMed2002

Regio- and chemoselective catalytic transfer hydrogenation of aromatic nitro and carbonyl as well as reductive cleavage of azo compounds over novel mesoporous NiMCM-41 molecular sieves.

[reaction: see text] [corrected] Regio- and chemoselective reduction of nitroarenes and carbonyl compounds and reductive cleavage of azo compounds, including bulkier molecules, was achieved by the catalytic transfer hydrogenation method (CTH) using a novel nickel-containing mesoporous silicate (NiMCM-41) molecular sieve catalyst. In addition, the catalyst was also found to behave as a truly heterogeneous catalyst as the yield was practically unaffected.

Journal Article↗
PubMed1993

Spin trapping of nitric oxide (NO.) as aminoxyl radicals by its reaction with two species of short-lived radicals derived from azo compounds such as 2,2'-azobisisobutyronitrile and some aliphatic alcohols.

Aminoxyl radicals of the type R1N(O.)R2 are formed in the photochemical reaction between nitric oxide (NO.) and carbon-centered radicals R1. and R2.. R1. was formed from azo compounds such as 2,2'-azobisisobutyronitrile (AIBN): R1. = NC-C(CH3)2, 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN): R1. = CH3-CH(CH3)-CH2-C(CN)CH3, or 4,4'-azobis(4-cyanovaleric acid) (ACVA): R1. = HOOC-(CH2)2-C(CN) CH3. R2. was derived from aliphatic substances such as methanol, ethanol, or 2-propanol by homolytic abstraction of a hydrogen atom brought about by R1. from the azo compounds.

1-Propanol↗
PubMed1984

Induction of hepatic microsomal drug metabolism by azo compounds: a structure-activity relationship.

The structure-activity relationship of 40 azo compounds in their ability to induce cytochrome P-448 and associated monooxygenase activities, as well as UDP-glucuronyltransferase (UDPGT) activity, was investigated. Regardless of their structure, hydrophilic azo dyes and lipophilic azobenzene derivatives were not able to induce these enzyme activities. Only those lipophilic azo dyes with 1-azo-2-naphthol or 1-azo-2-naphthylamine moieties were able to induce cytochrome P-448 and related monooxygenase activities, as well as UDPGT activity. The extent of induction is comparable to or greater than that caused by 3-methylcholanthrene (3-MC). It is suggested that those azo dyes capable of inducing P-450 type cytochromes can form coplanar structures with three fused, 6-membered rings through intramolecular hydrogen bonding. These structures are analogous to polycyclic aromatic hydrocarbons that can also induce.

Animals↗