Home About us Contact
|
Home About us Contact | ||
|
|
||
Organophosphorus Compounds (organophosphoru + compound)
Selected AbstractsNew ways to break an old bond: the bacterial carbon,phosphorus hydrolases and their role in biogeochemical phosphorus cyclingENVIRONMENTAL MICROBIOLOGY, Issue 10 2007John P. Quinn Summary Phosphonates are organophosphorus molecules that contain the highly stable C,P bond, rather than the more common, and more labile, C,O,P phosphate ester bond. They have ancient origins but their biosynthesis is widespread among more primitive organisms and their importance in the contemporary biosphere is increasingly recognized; for example phosphonate-P is believed to play a particularly significant role in the productivity of the oceans. The microbial degradation of phosphonates was originally thought to occur only under conditions of phosphate limitation, mediated exclusively by the poorly characterized C,P lyase multienzyme system, under Pho regulon control. However, more recent studies have demonstrated the Pho-independent mineralization by environmental bacteria of three of the most widely distributed biogenic phosphonates: 2-aminoethylphosphonic acid (ciliatine), phosphonoacetic acid, and 2-amino-3-phosphonopropionic acid (phosphonoalanine). The three phosphonohydrolases responsible have unique specificities and are members of separate enzyme superfamilies; their expression is regulated by distinct members of the LysR family of bacterial transcriptional regulators, for each of which the phosphonate substrate of the respective degradative operon serves as coinducer. Previously no organophosphorus compound was known to induce the enzymes required for its own degradation. Whole-genome and metagenome sequence analysis indicates that the genes encoding these newly described C,P hydrolases are distributed widely among prokaryotes. As they are able to function under conditions in which C,P lyases are inactive, the three enzymes may play a hitherto-unrecognized role in phosphonate breakdown in the environment and hence make a significant contribution to global biogeochemical P-cycling. [source] Toxicity of azinphos-methyl to various development stages of the codling moth Cydia pomonella (Lepidoptera: Tortricidae)PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2007Haim Reuveny Abstract The response to azinphos-methyl of different life-stages of the codling moth Cydia pomonella (L.) was studied. A similarity in response to azinphos-methyl (LC50, LC90) was observed in neonate larvae obtained from the first and second generations of field populations. Mortality rates for neonate larvae of a field population cross-bred with a laboratory colony were lower (by a factor of 1.2,2.2) in comparison with field neonate larvae. The mortality rate of larvae from a laboratory colony exposed to artificial diet containing azinphos-methyl gradually decreased at older instars. The mortality rates of fifth-instar larvae were remarkably low when exposed to artificial diet mixed with azinphos-methyl or when topically treated with the insecticide. One- to three-day-old females were more sensitive than males of the same age, whereas the opposite was observed in 14,to 17-day-old adults. Mortality rates of 14- to 17-day-old adults were higher than those under 10 days old. No significant difference in sensitivity to the organophosphorus compound was noticed between the sexes of 7- to 10-day-old adults. Neonate larvae of the codling moth can serve as a target life-stage for various groups of pesticides, and the importance of using such a stage as a standardized methodology for monitoring resistance in the codling moth is discussed. Copyright © 2006 Society of Chemical Industry [source] Diastereomers (RC,SP)- and (RC,RP)- S -methyl P -(3-azidopropyl)- N -[(1R)-1-phenylethyl]phosphonamidothioateACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Lilu Guo Diastereoisomers of the title organophosphorus compound, C12H19N4OPS, denoted RCSP, (I), and RCRP, (II), were structurally characterized and compared. Asymmetric phosphorus compounds are of interest with regard to the use of these systems as possible protein probes via the stereoselective delivery of an azide group tethered to the P atom into key protein regions. The diastereomers were produced in a 1:1 mixture and isolated by chromatography. Although both isomers crystallize in the same space group with superficially similar cell constants, conformational and packing differences are pronounced. Despite the conformational differences, strong intermolecular hydrogen bonding links both isomers into chains parallel to the a axis [N...O = 2.8609,(18) and 2.966,(3),Ĺ in (I) and (II), respectively], with C,H..., interchain interactions of ca 3.5,Ĺ. [source] Paraoxonase 1 (PON1) polymorphisms and risk for essential tremorEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2010E. García-Martín Background:, The polymorphic enzyme human serum paraoxonase 1 (PON1), encoded by the gene PON1 (chromosome 7q21.3), plays a major role in the metabolism of organophosphorus compounds. We investigated the possible association between the PON1 genotype and allelic variants of the polymorphisms Leu55Met and Glu192Arg, and the risk for essential tremor (ET). Methods:, We studied the frequency of the PON1 genotypes and allelic variants in 201 patients with ET and 220 healthy controls using a PCR-RLFP method. Results:, The frequencies of the PON1 genotypes and allelic variants of the polymorphisms Leu55Met and Gln192Arg did not differ significantly between patients with ET and controls. These polymorphisms were unrelated with the age of onset of ET. Conclusions:,PON1 polymorphisms are not related with the risk for ET. [source] Green, Palladium-Catalyzed Synthesis of Benzylic H -Phosphinates from Hypophosphorous Acid and Benzylic AlcoholsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2008Laëtitia Coudray Abstract Benzylic alcohols cross-couple directly with concentrated H3PO2 by using Pd/xantphos (1 or 2 mol-%). Depending on the substrate, DMF at 110 °C or t -AmOH at reflux with a Dean,Stark trap can be used. A broad range of benzylic alcohols react successfully to give moderate to good yields of the products. The preparation of other organophosphorus compounds (phosphinic and phosphonic acids) is also demonstrated. Asymmetric reaction with (R)-1-(2-naphthyl)ethanol provids the corresponding H -phosphinic acid in 77,% ee. The methodology provides a green, PCl3 -free route to benzylic- H -phosphinic acids.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of the new adducts of imines and enamines with PH acids and their derivatives,HETEROATOM CHEMISTRY, Issue 2 2009Andrey A. Prishchenko Nucleophilic or radical addition of esters of trivalent organophosphorus acids with PH fragments to various imines and enamines is proposed as convenient methods for the synthesis of new substituted aminomethyl organophosphorus compounds with three-, four-, and five-coordinated phosphorus. Also the new functionalized derivatives of these compounds with acyl and methanesulfonyl moieties are synthesized, and some properties of the obtained compounds are presented. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:70,80, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20513 [source] Studies on organophosphorus compounds: Synthesis and reactions of [1,2,4,3]triaza-phospholo[4,5- a]quinoxaline derivativeHETEROATOM CHEMISTRY, Issue 5 2008Hassan M. Moustafa 2,4-Bis-(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's reagent) (1) reacted with 2-hydrazino-3-methyl-quinoxaline (2) to give [1,2,4,3]-triazaphospholo[4,5- a]quinoxaline derivative 3. The Mannich reaction using different amines on compound 3 gave Mannich bases 4a,d. Also, compound 3 reacted with formaldehyde to give the corresponding 2-hydroxymethyl derivative 5, which upon reaction with thionyl chloride gave the corresponding chloromethyl derivative 6. Treatment of compound 6 with some thiols yielded the corresponding sulfides 7a,d. Acylation of compound 3 gave acylated compounds 8a,b. Compound 9, which was prepared through the reaction of compound 3 with ethyl cyanoacetate, was investigated as a starting material for the synthesis of some new heterocyclic systems 10,13. Also, reaction of compound 9 with carbon disulfide and 2 equivalents of methyl iodide in a one-pot reaction yielded the corresponding ketene-S,S-acetal 14, which in turn reacted with bidentates to give some new heterocycles 15,17. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:520,529, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20473 [source] Studies on low-coordinated nitrogen, phosphorus, sulfur, and selenium compoundsHETEROATOM CHEMISTRY, Issue 4 2001Naoki Inamoto The major studies of my laboratory on heteroatom chemistry are briefly outlined and include the following topics: (1) novel radical reactions to kinetic stabilization of organosulfur and selenium compounds, (2) novel reactions of organophosphorus compounds, (3) reaction of the S atom to stabilization of o-thioquinonemethides, (4) N-nitrosoimines stabilized by heterocycles to hypervalent sulfur compounds, and (5) phosphinidenes (R-P) to kinetic stabilization of low-coordinated organophosphorus compounds. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:183,194, 2001 [source] Minireview: does in-vitro testing of oximes help predict their in-vivo action after paraoxon exposure?JOURNAL OF APPLIED TOXICOLOGY, Issue 6 2009D. E. Lorke Abstract K-oximes have recently been developed in the search for efficacious broad-band reactivators of acetylcholinesterase (AChE) inhibited by organophosphorus compounds (OPC). Before clinical use, their toxicity and efficacy need to be assessed, and there is clear demand for simple in vitro tests that can predict in vivo performance. This article summarizes our in vitro data obtained for conventional and experimental oximes in human and rat blood exposed to the OPC paraoxon and correlates them with our in vivo results. The intrinsic AChE inhibitory activity of oximes, as reflected by their in vitro IC50, is strongly correlated with their LD50 (rat): oximes with a high IC50 (K-27, K-48, pralidoxime and obidoxime) also show a high LD50 and are thus relatively non-toxic, whereas oximes K-105, K-108 and K-113 have a low IC50, a low LD50 and are far more toxic. The IC50 is also correlated with the in vivo capacity to protect from paraoxon-induced mortality: oximes with a higher IC50 reduce the relative risk of death more. In contrast, the protective ability as assessed in vitro by the slope of the IC50 shift (tan,), is not correlated with in vivo protection from paraoxon-induced mortality: the best in vivo protectors (K-27 and K-48) show a much lower tan, value (around 2) than K-110 and K-113 (tan, around 10), which hardly reduce the relative risk of death after paraoxon exposure. The partition coefficient logP of the individual oximes is inversely correlated with their IC50 and with their LD50 and is therefore an indicator of toxicity: strongly hydrophilic oximes tend to be less toxic than less hydrophilic ones. These data highlight the good predictive value of in vitro IC50 testing for in vivo toxicity and the limited practical significance of in vitro assessment of protective potency. Copyright © 2009 John Wiley & Sons, Ltd. [source] Simple radioactive assay for the estimation of DNA breaksJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2002R. Sreekumaran Nair Abstract The intactness of DNA is an important part of the normal cellular structure. Any change to the DNA in the form of breaks leads to a change in the integrity, which in turn leads to abnormality in the cellular activity. Many discrepancies have been reported among the various methods of detecting DNA damage. Here, a simple, sensitive and reproducible method has been developed for the detection of DNA breaks by radioactive labelling of 5, broken ends. The method was evaluated by studying chemically induced DNA damage by using both organochloride (2,4-dichlorophenoxyacetic acid and lindane) and organophosphorus (sevin and phosphamidon) compounds at different concentrations. Phosphamidon, one of the organophosphorus compounds studied, showed complete degradation of the DNA after treatment. Radioactive analysis of phosphamidon showed higher counts at the lowest concentration (20 µg) of the chemical when compared with the control (2752 scintillation counts per minute, scm). Studies on the chemically induced DNA breaks by radiolabelling revealed that the cumulative effect of the organophosphorus and organochloride compounds showed maximum counts in all the samples (the highest being 2904 scm) when compared with the organophosphorus and organochloride compounds studied separately (the highest being 1881 and 2260 scm, respectively). Radiolabelling studies on the blood samples of 23 pesticide workers by the newly developed assay showed a significant positive correlation (0.893) between the number of years of exposure and the scintillation counts. A maximum of 11 702 scm (for 18 years of exposure) and a minimum of 1682 scm (for 4 years of exposure) were recorded compared with 1253 scm for the negative control. This method can be used effectively for estimation of the DNA breaks, irrespective of its nature. Copyright © 2002 John Wiley & Sons, Ltd. [source] Effect of octanol:water partition coefficients of organophosphorus compounds on biodistribution and percutaneous toxicity,,JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2006Steven E. Czerwinski Abstract Knowledge of partition coefficient (log P) data can play a critical role in understanding the pharmacokinetic and pharmacodistributive properties of toxic organophosphorus (OP) compounds. Using a recently published gas chromatographic method, the octanol:water log P values for the compounds tabun (GA), sarin (GB), cyclosarin (GF), and O -ethyl- S -(2-diisopropylaminoethyl) methylphosphonothiolate (VX) were determined to be 0.384 ± 0.033, 0.299 ± 0.016, 1.038 ± 0.055, and 0.675 ± 0.070, respectively. Based on these data, the log P value of the fluorophosphonate fragment, common to GB, soman (GD), and GF, was determined to be ,2.256 ± 0.273. The predictive value for absorption and distribution of the determined log P values was compared to measured values. The time to onset of local fasciculations (47.3, 29.0, 8.8, 8.5, and 6.3 min, respectively) in guinea pigs exposed percutaneously to equilethal doses of GA, VX, GF, GB, or GD was used as an indicator of dermal penetration. There was a good correlation (r = 0.95) between the measured log P value and the rate of onset of local fasciculations. Assuming a direct correspondence, equilibrium tissue:blood log P may be estimated from octanol:water log P. Comparison of the estimated and directly measured tissue:blood log P revealed a correlation of 0.8 for GD in liver, muscle, and adipose tissue. Our results demonstrate the use of log P data to both predict absorption and determine the distribution of OP compounds in tissues. This facilitates further estimates of in vivo OP effects from in vitro experiments. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:241,246, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20140 [source] Regio- and Stereo-selective Bioreduction of Diketo- n -butylphosphonate by Baker's YeastCHINESE JOURNAL OF CHEMISTRY, Issue 11 2002Ke Wang Abstract A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxyalkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of ,, ,-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Homer-Wadsworth-Emmons (HWE) reaction of the biotransformation products. [source] | ||||||||||