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At least 217 records · Page 12Linked to original sources
PubMed1982

[Effect of exogenous amino acids on myocardial contraction and metabolism of nitro-compounds in the myocardium during anoxia].

Anoxic perfusion of an isolated rat heart resulted in contractility disorder, increased production of ammonia, alanine, glutamine and lowered levels of glutaminic and asparaginic acids, while the total pool of free amino acids and taurine remained unchanged. Subsequent reoxygenation partly recovered cardiac contractility. When 3.5 mM glutaminic acid or 5 mM arginine was added to the perfusate, the anoxic contracture was less pronounced, and the heart maintained a higher pressure than would be common for anoxia, while reoxygenation resulted in virtually complete recovery of contractility. Both amino acids did not basically affect ammonia synthesis, but enhanced its binding in heart tissue, i. e. glutamine and urea synthesis, the reactions requiring increased ATP spending. The findings suggest that the mechanism of exogenous amino acids' action in anoxic conditions is based on substrate phosphorylation rather than their ability to bind ammonia.

Amino Acids↗
PubMed2000

Analysis of nitro musk compounds and their amino metabolites in liquid sewage sludges using NMR and mass spectrometry.

A method using HRGC ion trap MS/MS for measuring simultaneously amino metabolites and the parent compounds, the nitro musks, an important group of organic fragrance components found in sewage sludges, was developed. The monoamino metabolites were synthesized and characterized by 1H/13C NMR and mass spectroscopy. Among the nitro musks, musk ketone was the major compound, found at an average concentration of 5 microg/kg of dry mass (dm) whereas musk xylene was detected in only one sample (30 microg/kg dm). Three amino metabolites were identified, namely, 1-tert-butyl-3,5-dimethyl-4-amino-2,6-dinitrobenzene, 1,1,3,3,5-pentamethyl-4-nitro-6-aminoindane, and 4-acetyl-1-tert-butyl-3,5-dimethyl-2-nitro-6-aminobenzene, the corresponding reduction products of the nitro musks xylene, moskene, and ketone. These metabolites were present in partly higher concentrations in the sludges than the corresponding nitro musk compounds. Musk xylene and musk moskene were mainly found as their monoamino metabolites, underlining the importance of anaerobic reduction processes in the sewage treatment plant.

Amino Acids↗
PubMed1987

Mode of action of nitro-heterocyclic compounds on Escherichia coli.

The inhibitory and bactericidal activities of several different nitro-heterocyclic compounds, such as nitrofuran, nitronaphthofuran, nitrobenzofuran, nitroimidazole and nitrothiazole, were assessed in vitro. All these substances except nitroimidazole were active against Escherichia coli, though to different degrees. Under anaerobic test conditions the antibacterial activity increased slightly. Nitroreductase-deficient mutants, however, were highly resistant to all nitro-compounds, indicating that only when the nitro-group is reduced to these agents get into an active antibacterial form. SOS repair-deficient strains were much more susceptible to the nitro-containing substances than repair-proficient counterparts, indicating that damage to bacterial DNA is the essential mechanism of antibacterial activity of all nitro-heterocyclic compounds.

Escherichia coli↗
PubMedDate not supplied

[Reduction of nitro-substituted compounds by native and immobilized Escherichia coli cells].

Reduction of nitro-substituted compounds, 1,4-benzodiazepine-2-ones, dibenzo[b,f]-1,4-diazepines, quinolones, and quinoxalinones, by Escherichia coli cells was studied. Physicochemical methods demonstrated the formation of corresponding amines. 4-(p-Nitrophenyl)-1H-6-R-quinolones-2 were nor reduced by Escherichia coli cells. Regiospecific reduction of 2,4-dinitro-5H-11-(p-R-phenyl)-dibenzo[b,f]-1,4-diazepines and 4-(2'-R-3',5'-dinitro)-benzoyl-3,4-dihydroquinoxalinones-2 was shown to result in the formation of 2-nitro-4-amino-5H-11-(p-R-phenyl)-dibenzo[b,f]-1,4-diazepines and 4-(2'-R-3'-nitro-5'-amino)-benzoyl-3,4-dihydroquinoxalinones-2, respectively. Methods for microbiological reduction of nitro compounds and immobilization of Escherichia coli cells into carrageenan and its modified forms were elaborated.

Cells, Immobilized↗
PubMed1982

Microbial detection of mutagenic nitro-organic compounds in filtrates of coal fly ash.

The presence of mutagenic nitro-organic compounds on coal fly ash was indicated by the greatly reduced microbial mutagenicity of the ash filtrates with nitroreductase-deficient strains of Salmonella typhimurium compared to their corresponding parental strains. Addition of the liver S-9 microsomal enzyme preparation significantly increased the mutagenic activities of the ash extracts. Extracts of fly ash mutagens were prepared with horse serum, dimethyl sulfoxide, or azeotropic benzene/methanol mixture. The data were normalized to net revertants per 10(8) Salmonella typhimurium cells per milligram of ash used. This normalization procedure is essential for interpretation of comparative results. Both four-way and three-way analyses of variance were used to simultaneously evaluate the differences between solvent extracts, fly ash mutagen, S-9 activation, and nitroreductase-deficient strains and their parental strains. Of the three extraction systems tested, benzene/methanol azeotropic mixture was generally found to have the highest extraction power, and horse serum was the lowest. The results show that overall 87.5% (+/- 1.8 SE) of the mutagenic activity of the fly ash was associated with nitro-organic compounds.

Animals↗
PubMed1997

Ultrasound in natural products synthesis: applications to the synthesis of histrionicotoxin via nitroalkanal acetals.

Ultrasound promoted the Kornblum reaction of silver nitrite or sodium nitrite with haloalkyl acetals to afford the corresponding C-nitro compounds. The acetalprotected nitro compounds were used as reactants in a 'double Henry' reaction to produce the key intermediate nitrocyclohexane diol with a masked aldehyde side chain. The nitrodiol was then subjected to an ultrasound-promoted one-pot/single operation sequence involving a reduction deprotection followed by a cyclization-reduction. The entire sequence provided the core spiropiperidine substructure of the histrionicotoxins.

Acetals↗
PubMed1989

Evaluation of the nephrotoxicity of aromatic nitro-amino compounds by urinary enzyme activities.

Nephrotoxicity of some aromatic nitro-amino compounds were evaluated by urinary enzyme activities and renal histopathological changes. Male Fischer 344 rats were intraperitoneally injected with aniline, p-aminophenol, acetyl-p-aminophenol, p-chloroaniline, p-chloronitrobenzene, p-anisidine, or p-nitroaniline at 1.0 mmol/kg. In the rats injected with p-aminophenol, necrosis of renal tubular epithelial cells and remarkable elevation of urinary N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyltranspeptidase (gamma-GTP) activities were observed. Injection with p-chloroaniline caused significant elevation of the urinary NAG and gamma-GTP activities. p-Anisidine and p-nitroaniline induced swelling of the tubular epithelial cells and a significant elevation in urinary NAG activities in rats, which was also caused by p-chloronitrobenzene. However, administration of aniline or acetyl-p-aminophenol did not change either the urinary enzymes or renal histopathology. These results indicate that p-aminophenol is a highly nephrotoxic substance, and that nephrotoxicity of p-chloroaniline, p-chloronitrobenzene, p-anisidine and p-nitroaniline exceed that of acetyl-p-aminophenol which has been known to cause a renal damage.

Acetylglucosamine↗
PubMed2005

[Electrochemical reduction characteristics of nitro-benzene compounds at the copper electrode and the influence of pH on reduction].

The electrochemical reduction characteristics of nitro-benzene compounds were investigated using cyclic voltammetry technique. The reductive reactivity of the nitro-benzene compounds at the copper electrode was evaluated, the reduction mechanisms of the nitrobenzene compounds at the copper electrode and the influences of pH on them were also discussed in this paper. The experimental results show that nitro-benzene compounds is capable of reducing directly at the copper electrode, and the reduction peaks were at - 0.58V and - 1.32V or so (vs. SCE). Both acidity and basicity favor reduction of nitro-group at the copper electrode: the elimination reaction is easy to occur in the alkaline medium with the formation of nitroso-group; in the acid medium the probability of the reaction between the obtained electrons nitro group and hydrogen ions raises, which causes magnification of the current through the solution; in addition, the growth of hydrogen atoms in number favors the occurring of the addition and substitution reactions at the electrode. pH strongly influenced the electrochemical reduction characteristics of the nitrobenzene compounds at the copper electrode, and it mainly depends on the properties of the substituents on the benzene ring, their configurations and numbers, and their location versus nitro group on the benzene ring. The results provide a theoretical and experimental basis for investigating the reduction mechanisms by the catalyzed iron inner electrolysis process.

Catalysis↗
PubMed2002

N-oxidation of drugs associated with idiosyncratic drug reactions.

Circumstantial evidence strongly suggests that most idiosyncratic drug reactions are due to reactive metabolites of drugs rather than due to the drugs themselves. Many of the drugs that are associated with idiosyncratic drug reactions contain nitrogen. There are many possible reasons for this association. One is simply that many drugs, especially CNS active drugs, contain nitrogen. In addition, nitrogen is relatively easy to oxidize because of its lone pair of electrons and many nitrogen-containing compounds readily undergo redox cycling, which can generate reactive oxygen species. There are several nitrogen-containing function groups that are especially associated with adverse reactions. These include aromatic amines, nitro compounds (nitro compounds are reduced to the same reactive intermediates as are formed by oxidation of the corresponding aromatic amine), hydrazines and compounds that can be oxidized to iminoquinone and related compounds. A greater attention to the issue of reactive metabolites during drug development would likely lead to safer drugs; however, not all drugs that form reactive metabolites are associated with a high incidence of idiosyncratic drug reactions. In addition to the presence of such a group, other factors, such as dose and electron density of the compound, appear to play a role in whether the drug containing such functional groups will be associated with a relatively high incidence of idiosyncratic drug reactions.

Biotransformation↗
PubMed1994

9-Methoxytariacuripyrone, a naturally occurring nitro-aromatic compound with strong mutagenicity in Salmonella typhimurium.

9-Methoxytariacuripyrone, a nitro-aromatic compound isolated from Aristolochia brevipes showed strong mutagenic activity in strain TA98, TA100 and some YG strains of Salmonella typhimurium with and without S9 mix. Incubation with cytosol resulted in a heavy increase in mutagenicity. When incubated with microsomes the activity was dramatically decreased. The results are discussed in view of the enzymes possibly involved in activation and detoxification of the compound. The role of the basic structure on the mutagenicity mediated through the nitro group was also considered.

Animals↗
PubMed1987

Frameshift mutagenesis by nitracrine analogues in wild-type, uvrB, polA and recA strains of Salmonella typhimurium, with and without plasmid pKM101.

The mutagenic potential of 9-[(3-dimethylaminopropyl)amino]-acridine and its 1-, 2-, 3- and 4-nitro derivatives was studied in several strains of Salmonella typhimurium carrying the frameshift marker hisC3076. The strains all carried deep rough (rfa) mutations, and were either wild-type with respect to DNA repair capacity or carried recA, uvrB, polA1 or polA3 (amber) mutations. Derivatives with and without plasmid pKM101 were also studied. The des-nitro compound resembled 9 aminoacridine and other simple intercalating compounds. Both toxicity and mutagenesis were apparently unaffected by the uvrB and recA mutations or by the presence of plasmid pKM101. However, mutagenicity was reduced by the polA1 mutation, and virtually eliminated by the polA3 mutation. The drug was substantially more toxic in the latter, slightly more toxic in the former, of these polA- strains. Plasmid pKM101 enhanced mutagenesis and protected from toxicity in both polA1- and polA3- strains, although it did not restore either of these parameters to the level in the wild-type strain. The 2-nitro compound was generally similar to the des-nitro compound, except that it was considerably more toxic and apparently non-mutagenic in the recA-bearing strain. By contrast, mutagenicity of the 3- and 4-nitro compounds was enhanced by the uvrB mutation and by the presence of the plasmid. These compounds were highly toxic but non-mutagenic in the recA- strain, and showed some increased toxicity in polA1- and polA3- strains. The 1-nitro compound has been previously found to cross-link DNA. Unlike well-characterised cross-linkers such as mitomycin C it was highly mutagenic in the uvrB- strain, and this mutagenesis was enhanced by plasmid pKM101, but eliminated by the recA mutation. At high doses, where the drug was completely toxic towards uvrB- or recA-carrying strains, it became mutagenic in the DNA-repair-proficient strains. This 'high-dose' mutagenesis was enhanced by plasmid pKM101, but reduced by the polA1 mutation and almost eliminated by the polA3 mutation. Although there are several possible interpretations of these data, they are compatible with the suggestion that the lesion induced by high doses (but not by low doses) of nitracrine is a cross-link, but that this is not the major mutagenic lesion.

Aminoacridines↗
PubMed1996

A comparative study of five nitro musk compounds for genotoxicity in the SOS chromotest and Salmonella mutagenicity.

Five nitro musk compounds widely used in cosmetics and detergents were examined for DNA-damaging and mutation-inducing properties. For this purpose two short-time assays were used, the SOS chromotest and the Salmonella/mammalian microsome test. Musk ambrette showed mutagenicity in Salmonella typhimurium TA 100 requiring metabolic activation by rat liver postmitochondrial supernatant (S9) but it lacked mutagenicity in the absence of S9 and genotoxicity in the SOS chromotest. Musk xylene, musk ketone, musk moskene and musk tibetene showed neither mutagenicity nor genotoxicity in the presence and absence of S9.

Alkaline Phosphatase↗
PubMed1994

Photochemical generation of nitric oxide from nitro-containing compounds: possible relation to vascular photorelaxation phenomena.

We examined the production of nitric oxide (NO) from various nitro-containing compounds (500 microM and 100 microM solutions in Krebs buffer, pH 7.4). Sealed vials containing solutions of NaNO2, N-nitro-L-arginine, 4-nitrophenol, BAY K 8644, or N-nitro-L-arginine methyl ester were stored in the dark, under normal room light, or were exposed to ultraviolet light (365 nm), for 30 min (24 degrees C). NO was measured in the vial headspace after 30 min, using a sensitive assay previously established in our laboratory. Production of NO was found to be dependent on the intensity of light exposure for all compounds, and the highest degree of light-induced production of NO was found for NaNO2 and BAY K 8644 solutions. Since NO is a relaxant of smooth muscle, these results help explain the increased sensitivity to relaxation by UV light of vascular and other types of smooth muscle in the presence of NaNO2, BAY K 8644 and N-nitro-L-arginine, as observed by other investigators.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗