nitrophenols and 4-6-dinitro-o-cresol

Although they are widely used as insecticides, acaricides and fungicides in the agriculture or as raw materials in the dye industry, dinitrophenols (DNPs) are extremely noxious, death cases having been registered. These compounds produce cataracts, lower leucocyte levels, disturb the general metabolism and can cause cancer. It is also assumed that DNPs hinder the proton translocation through the mitochondrial inner membrane and therefore inhibit oxidative phosphorylation. Their fluorescence quenching properties can help understand and explain their toxicity. Fluorescence quenching of tryptophan was tested using different dinitrophenols such as 2,4-dinitrophenol (2,4-DNP), 4,6-dinitro-orthocresol (DNOC), 2-[(2,4-dinitrophenyl)amino]acetic acid (GlyDNP), 2-(1-methyl-heptyl)-4.6-dinitrophenyl crotonate (Karathan), 2-amino-5-[(1-((carboxymethyl)amino)-3-((2,4-dinitrophenyl)thio)-1-oxopropan-2-yl)amino]-5-oxopentanoic acid (SDN GSH), 2,4-dinitroanisole (2,4-DNA) and 2,4-dinitrobenzoic acid (2,4-DNB). 2,4-DNP and DNOC showed the highest tryptophan fluorescence quenching constant values, these being also the most toxic compounds. The electronic chemical potential value of the most stable complex of 2,4-DNP-with tryptophan is higher than the values of the electronic chemical potentials of complexes corresponding to the derivatives.

Topics: 2,4-Dinitrophenol; Anisoles; Dinitrocresols; Ethers; Germination; Linear Models; Models, Molecular; Nitrophenols; Nonlinear Dynamics; Quantitative Structure-Activity Relationship; Seeds; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Thermodynamics; Triticum; Tryptophan

The adsorption and degradation of 4,6-o-dinitrocresol (DNOC) and p-nitrophenol (PNP) in SWy-2 montmorillonite clay slurry were investigated. The pH and type of cation of the slurry were varied. Results showed that adsorption of DNOC and PNP increased at lower pH values, and when pH < pKa(4.4) of DNOC, DNOC was almost completely adsorbed on the clay under given experimental conditions. The specific cation also had a significant effect on adsorption, which was dramatically enhanced in the presence of K+ and NH4+, compared with the presence of Na+ or Ca2+. Anodic Fenton treatment (AFT) degradation of DNOC and PNP in the clay slurry was studied, and it was found that DNOC degradation rates were greatly affected by the initial pH and the types of electrolytes. Due to the higher adsorption, the degradation rate substantially decreased in the clay slurry system in the presence of K+ and low pH, with a large amount of DNOC residue remaining after 60 min treatment. AFT degradation of PNP was completed within 30 min treatment. Based on LC-MS data, a DNOC degradation pathway was proposed. Overall, the results showed the inhibition effect of adsorption on the degradation of nitroaromatic compounds in montmorillonite clay slurry by AFT, providing important implications for water and soil remediation.

Topics: Adsorption; Aluminum Silicates; Bentonite; Chromatography, Liquid; Clay; Dinitrocresols; Electrodes; Electrolytes; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Mass Spectrometry; Nitrogen; Nitrophenols; Sewage; Temperature; Time Factors; X-Ray Diffraction

Liquid chromatography with electrochemical detection has been used to determine various nitropesticides, DNOC, fenitrothion, and parathion (methyl and ethyl), and some of their main metabolites, 4-nitrophenol for parathion (methyl and ethyl) and 3-methyl-4-nitrophenol for fenitrothion, by using indirect detection. Analysis of them in river water samples has been performed without a preconcentration step. The recovery efficiencies of the tested compounds yielded values between 96 and 112% at the fortification level of 0.5 ppb in a river water sample, and their relative standard deviations were between 1 and 15%. The detection limits of these compounds ranged between 0.05 and 0.14 ppb.

Topics: Chromatography, High Pressure Liquid; Cresols; Dinitrocresols; Dinitrophenols; Electrochemistry; Fenitrothion; Indicators and Reagents; Insecticides; Methyl Parathion; Nitrophenols; Parathion; Pesticides; Spectrophotometry, Ultraviolet

Dinoseb is a herbicide known to inhibit photosystem II electron transfer like DCMU, triazine and phenolic-type herbicides. The mutant Din7 of the cyanobacterium Synechocystis sp. PCC 6803, selected for resistance to dinoseb, and the mutant Ins2, constructed by the insertion of the kanamycin resistance cassette into the drgA gene, were cross-resistant to other nitrophenolic herbicides (DNOC, 2,4-dinitrophenol) and to the cell inhibitor metronidazole but not to the photosystem II inhibitors DCMU or ioxynil. The Din7 mutant had the same characteristics of photosystem II inhibition by dinoseb as the wild type. This result suggested the existence of another site for dinoseb inhibition. The wild type cells modified dinoseb to a non-toxic product that gave an absorption spectrum similar to that of dithionite treated dinoseb containing reduced nitro groups. In contrast, the Din7 mutant did not modify dinoseb. These phenomena were controlled by the drgA gene encoding a protein which showed similarity to several enzymes having nitroreductase activity. The addition of superoxide dismutase to the medium relieved the toxic effect of dinoseb in wild type cells but not in Din7. It is proposed that in wild type cells of Synechocystis sp. PCC 6803 the DrgA protein is involved in detoxification of dinoseb via the reduction of the nitro group(s) and this process is accompanied by the formation of toxic superoxide anions. Mutations blocking the activity of the DrgA protein lead to the development of resistance to nitrophenolic herbicides and metronidazole.

Topics: 2,4-Dinitrophenol; Amino Acid Sequence; Cyanobacteria; Dinitrocresols; Drug Resistance, Microbial; Genes, Bacterial; Herbicides; Kinetics; Metronidazole; Molecular Sequence Data; Nitrophenols; Nitroreductases; Photosynthetic Reaction Center Complex Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Spectrophotometry

Topics: Antifungal Agents; Biphenyl Compounds; Cadaver; Cresols; Dinitrocresols; Fungicides, Industrial; Humans; Insecticides; Nitrophenols