Appendix 2-5: Rejected ecotox bibliography for Chlorpyrifos



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Macex (R) concentrations tested from 0.06 to 1.0 gL(-1) (or mgkg(-1) in the mouse test), no genotoxicity was observed in the prokaryotic or eukaryotic test organisms. However, at Macex (R) concentrations of 0.5 gL(-1) and above a significant decrease in the mitotic index (P <= 0.05) in the V. faba was observed. Micronucleus formation was likewise increased in the test organism at concentrations starting at 2.0 gL(-1). Conclusions These data allow us to classify this natural formicide preparation as a product with no geno-environmental-impact when applied at recommended concentrations.
Keywords: Pesticide genotoxicity, Formicide, Vicia faba, Micronucleus assay, Ames
ISI Document Delivery No.: 935UL

254. Cowman, D. F. and Mazanti, L. E. Ecotoxicology of "New Generation" Pesticides to Amphibians. 2000: 233-267.


Rec #: 2280
Keywords: REFS CHECKED,REVIEW
Call Number: NO REFS CHECKED (ACP,ATZ,AZ,CBF,CBL,CPY,DDVP,DM,DMDP,DMT,DQTBr,DU,DZ,EFV,ES,FNT,FNV,GYP,HXZ,MLN,MLT,MP,MYC,MZB,Maneb,Naled,OML,PMR,PPX,PQT,PRT,PSM,RTN,TFN,TMP,TPR), NO REVIEW (ACP,ATZ,AZ,CBF,CBL,CPY,DDVP,DM,DMDP,DMT,DQTBr,DU,DZ,EFV,ES,FNT,FNV,GYP,HXZ,MLN,MLT,MP,MYC,MZB,Maneb,Naled,OML,PMR,PPX,PQT,PRT,PSM,RTN,TFN,TMP,TPR)
Notes: Chemical of Concern: ACP,ATZ,AZ,CBF,CBL,CPY,DBN,DDVP,DM,DMDP,DMT,DQTBr,DU,DZ,EFV,EPRN,ES,FNT,FNTH,FNV,GYP,HXZ,MCPA,MLN,MLT,MP,MSMA,MYC,MZB,Maneb,Naled,OML,PIM,PMR,PPX,PQT,PRN,PRT,PSM,RTN,TBT,TFN,TMP,TPR,TRL

255. Crane, A. L.; Klein, K., and Olson, J. R. Bioactivation of chlorpyrifos by CYP2B6 variants. 2012; 42, (12): 1255-1262.


Rec #: 58369
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: 1. Chlorpyrifos (CPF), an organophosphorus (OP) pesticide, is bioactivated by cytochrome P450s (CYPs) to the active metabolite chlorpyrifos oxon (CPF-O). Given that human CYP2B6 has the highest intrinsic clearance (CL(int)) for CPF bioactivation, CYP2B6 polymorphisms may impact human susceptibility to CPF at real world environmental and occupational CPF exposure levels. 2. CYP2B6.4,.5,.7, and. 18 were over-expressed in mammalian COS-1 cells to assess the impact of CYP2B6 variants on the K(m) and V(max) for bioactivation of CPF. Cell lysates were incubated with CPF (0-100 mu M) and the production of CPF-O was measured via HPLC analysis. CYP2B6 content was determined by western blot. 3. CYP2B6.18 had neither detectable protein nor activity levels. The V(max) value for each remaining variant was significantly higher than wild-type (CYP2B6.1, V(max) 4.13 x 10(4) pmol/min/nmol CYP2B6), with CYP2B6.4,.5, and.7 having V(max) values of 4.52 x 10(5), 1.82 x 10(5), and 9.60 x 10(4) pmol/min/nmol CYP2B6, respectively. The K(m) values for these variants ranged from 0.39 to 1.09 mu M and were not significantly different from wild-type. All active variants examined had significantly higher CL(int) than CYP2B6.1. 4. Variants of CYP2B6 have altered capacity to bioactivate CPF and may affect individual susceptibility by altering the V(max) for CPF-O formation.
Keywords: Biotransformation, toxicokinetics, pesticide metabolism, cytochrome
ISI Document Delivery No.: 033PS

256. Crane, Alice L; Klein, Kathrin; Zanger, Ulrich M, and Olson, James R. Effect of Cyp2b6*6 and Cyp2c19*2 Genotype on Chlorpyrifos Metabolism. 2012 Mar 11; 293, (1-3): 115-122.


Rec #: 38949
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: Chlorpyrifos (CPF) is a widely used organophosphorus (OP) pesticide. CPF is bioactivated by cytochrome P450s (CYPs) to the potent cholinesterase inhibitor chlorpyrifos oxon (CPF-O) or detoxified to 3,5,6-trichloro-2-pyridinol (TCPy). Human CYP2B6 has the highest reported Vmax)/Km (intrinsic clearance--CL(int)) for bioactivation while CYP2C19 has the highest reported CL(int) for detoxification of CPF. In this study, 22 human liver microsomes (HLMs) genotyped for common variants of these enzymes (CYP2B6*6 and CYP2C19*2) were incubated with 10 μM and 0.5 μM CPF and assayed for metabolite production. While no differences in metabolite production were observed in homozygous CYP2C19*2 HLMs, homozygous CYP2B6*6 specimens produced significantly less CPF-O than wild-type specimens at 10 μM (mean 144 and 446 pmol/min/mg, respectively). This correlated with reduced expression of CYP2B6 protein (mean 4.86 and 30.1 pmol/mg, for CYP2B6*6 and *1, respectively). Additionally, CYP2B6*1 and CYP2B6*6 were over-expressed in mammalian COS-1 cells to assess for the first time the impact of the CYP2B6*6 variant on the kinetic parameters of CPF bioactivation. The Vmax for CYP2B6*6 (1.05×105 pmol/min/nmol CYP2B6) was significantly higher than that of CYP2B6*1 (4.13×104 pmol/min/nmol CYP2B6) but the K(m) values did not differ (1.97 μM for CYP2B6*6 and 1.84 μM for CYP2B6*1) resulting in CL(int) rates of 53.5 and 22.5 nL/min/nmol CYP2B6 for *6 and *1, respectively. These data suggest that CYP2B6*6 has increased specific activity but reduced capacity to bioactivate CPF in HLMs compared to wild-type due to reduced hepatic protein expression, indicating that individuals with this genotype may be less susceptible to CPF toxicity. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Keywords: EC 1.14.14.1
Keywords: 2921-88-2
Keywords: Animals
Keywords: Polymorphism, Single Nucleotide
Keywords: COS Cells
Keywords: Microsomes, Liver -- metabolism
Keywords: Humans
Keywords: Bupropion -- metabolism
Keywords: Cholinesterase Inhibitors -- metabolism
Keywords: 34841-39-9
Keywords: Insecticides
Keywords: Recombinant Proteins -- metabolism
Keywords: Biotransformation
Keywords: CYP2C19 protein, human
Keywords: Aryl Hydrocarbon Hydroxylases -- genetics
Keywords: Oxidoreductases, N-Demethylating -- metabolism
Keywords: Male
Keywords: Amino Acid Substitution
Keywords: Insecticides -- metabolism
Keywords: Oxidoreductases, N-Demethylating -- genetics
Keywords: EC 1.5.-
Keywords: Homozygote
Keywords: Recombinant Proteins
Keywords: S-mephenytoin N-demethylase
Keywords: Aryl Hydrocarbon Hydroxylases
Keywords: Hydroxylation
Keywords: Chlorpyrifos
Keywords: Cholinesterase Inhibitors
Keywords: Aryl Hydrocarbon Hydroxylases -- metabolism
Keywords: 0
Keywords: Kinetics
Keywords: Microsomes, Liver -- enzymology
Keywords: Bupropion
Keywords: Cercopithecus aethiops
Keywords: Oxidoreductases, N-Demethylating
Keywords: Female
Keywords: Chlorpyrifos -- metabolism
Date completed - 2012-04-09
Date created - 2012-02-20
Date revised - 2012-12-20
Language of summary - English
Pages - 115-122
ProQuest ID - 922498212
Last updated - 2013-01-19
British nursing index edition - Toxicology, March 11, 2012, 293(1-3):115-122
Corporate institution author - Crane, Alice L; Klein, Kathrin; Zanger, Ulrich M; Olson, James R
DOI - MEDL-22281205; 22281205; 1879-3185 eng

257. Crawford, Kevin D; Weinstein, John E; Hemingway, Ronald E; Garner, Thomas R; Globensky, Gavin, and Crawford, Kevin D. A Survey of Metal and Pesticide Levels in Stormwater Retention Pond Sediments in Coastal South Carolina. 2010 Jan; 58, (1): 9-23.


Rec #: 44269
Keywords: FATE
Notes: Chemical of Concern: CPY
Abstract: Abstract: During the summer of 2007, sediment samples were collected from 16 stormwater detention ponds and 2 reference ponds located in coastal South Carolina. The sediments were analyzed for more than 30 pesticides with current and historical uses, six polybrominated diphenyl ethers (PBDEs), and seven metals. The results are compared with established screening assessment parameters, with copper found to be the contaminant of highest concern. Lead levels were found to correlate well with pond drainage area, while copper and zinc levels correlated with both pond drainage area and pond surface area. Chlorpyrifos levels were found to correlate with pond surface area. Our results also show that ponds draining commercial areas were likely to have higher levels of zinc and lead in the sediments compared to other pond classes.
Keywords: Q5 01503:Characteristics, behavior and fate
Keywords: Historical account
Keywords: Heavy metals
Keywords: ENA 12:Oceans & Estuaries
Keywords: SW 3030:Effects of pollution
Keywords: ANW, USA, South Carolina
Keywords: Copper
Keywords: Freshwater
Keywords: Lead
Keywords: Ponds
Keywords: Environmental Studies
Keywords: Polybrominated diphenyl ethers
Keywords: Agricultural Chemicals
Keywords: USA, South Carolina
Keywords: Stormwater runoff
Keywords: Zinc
Keywords: Ethers
Keywords: Drainage Area
Keywords: X 24330:Agrochemicals
Keywords: Toxicology
Keywords: Aqualine Abstracts; Environment Abstracts; Water Resources Abstracts; ASFA 3: Aquatic Pollution & Environmental Quality; Pollution Abstracts; Oceanic Abstracts; Toxicology Abstracts
Keywords: O 4060:Pollution - Environment
Keywords: Sediment pollution
Keywords: Marine
Keywords: Metals
Keywords: Drainage
Keywords: Surface area
Keywords: AQ 00008:Effects of Pollution
Keywords: Brackish
Keywords: Sediments
Keywords: Chlorpyrifos
Keywords: polybrominated diphenyl ethers
Keywords: Coastal zone
Keywords: P 1000:MARINE POLLUTION
Keywords: Pesticides
Keywords: summer
Keywords: Contaminants
Keywords: surface area
Date revised - 2011-12-01
Language of summary - English
Location - USA, South Carolina; ANW, USA, South Carolina
Pages - 9-23
ProQuest ID - 909766873
SubjectsTermNotLitGenreText - Sediment pollution; Coastal zone; Stormwater runoff; Heavy metals; Pesticides; Sediments; Toxicology; Lead; Ponds; Chlorpyrifos; polybrominated diphenyl ethers; Drainage; Surface area; Zinc; Copper; Contaminants; Polybrominated diphenyl ethers; Historical account; Metals; summer; surface area; Agricultural Chemicals; Ethers; Drainage Area; USA, South Carolina; ANW, USA, South Carolina; Freshwater; Brackish; Marine
Last updated - 2011-12-09
Corporate institution author - Crawford, Kevin D; Weinstein, John E; Hemingway, Ronald E; Garner, Thomas R; Globensky, Gavin
DOI - OB-d0df2094-4c9a-48df-ada9mfgefd107; 12598027; CS1021577; 0090-4341; 1432-0703 English

258. Croom, Edward L; Wallace, Andrew D; Hodgson, Ernest, and Croom, Edward L. Human Variation in Cyp-Specific Chlorpyrifos Metabolism. 2010 Oct 29; 276, (3): 184-191.


Rec #: 40239
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: Chlorpyrifos, an organophophorothioate insecticide, is bioactivated to the neurotoxic metabolite, chlorpyrifos-oxon (CPO) by cytochromes P450 (CYPs). To determine the variability in chlorpyrifos bioactivation, CPO production by human liver microsomes from 17 individual donors was compared relative to phenotype and genotype. CPO production varied over 14-fold between individuals in incubations utilizing 20 mu M chlorpyrifos as substrate, while CPO production varied 57-fold in incubations with 100 mu M chlorpyrifos. For all but two samples, the formation of the less toxic metabolite, 3,5,6-trichloro-2-pyridinol (TCP), was greater than CPO production. TCP production varied 9-fold in incubations utilizing 20 mu M chlorpyrifos as substrate and 19-fold using 100 mu M chlorpyrifos. Chlorpyrifos metabolism by individual human liver microsomes was significantly correlated with CYP2B6, CYP2C19 and CYP3A4 related activity. CPO formation was best correlated with CYP2B6 related activity at low (20 mu M) chlorpyrifos concentrations while CYP3A4 related activity was best correlated with CPO formation at high concentrations (100 mu M) of chlorpyrifos. TCP production was best correlated with CYP3A4 activity at all substrate concentrations of chlorpyrifos. The production of both CPO and TCP was significantly lower at a concentration of 20 mu M chlorpyrifos as compared to 100 mu M chlorpyrifos. Calculations of percent total normalized rates (% TNR) and the chemical inhibitors ketoconazole and ticlopidine were used to confirm the importance of CYP2B6, CYP2C19, and CYP3A4 for the metabolism of chlorpyrifos. The combination of ketoconazole and ticlopidine inhibited the majority of TCP and CPO formation. CPO formation did not differ by CYP2B6 genotype. Individual variations in CPO production may need to be considered in determining the risk of chlorpyrifos poisoning.
Keywords: ticlopidine
Keywords: Environment Abstracts; Toxicology Abstracts
Keywords: Microsomes
Keywords: Pharmacy And Pharmacology
Keywords: Poisoning
Keywords: Metabolites
Keywords: Genotypes
Keywords: Ketoconazole
Keywords: ENA 02:Toxicology & Environmental Safety
Keywords: Chlorpyrifos
Keywords: Insecticides
Keywords: Cytochrome
Keywords: Pesticides
Keywords: Neurotoxicity
Keywords: Liver
Keywords: Cytochrome P450
Keywords: X 24330:Agrochemicals
Keywords: Metabolism
Date revised - 2011-10-01
Language of summary - English
Pages - 184-191
ProQuest ID - 808661221
SubjectsTermNotLitGenreText - ticlopidine; Chlorpyrifos; Microsomes; Insecticides; Neurotoxicity; Poisoning; Liver; Metabolites; Cytochrome P450; Genotypes; Ketoconazole; Metabolism; Cytochrome; Pesticides
Last updated - 2011-12-13
Corporate institution author - Croom, Edward L; Wallace, Andrew D; Hodgson, Ernest
DOI - OB-15ac0000-dfa5-4a64-8924csaobj202; 13783341; 0300-483X English

259. Croom, Edward Lee and Hodgson, Ernest. Human Hepatic Expression of Cyp2b6: Developmental Pattern and in Vitro Bioactivation of Chiorpyrifos. 2009.


Rec #: 51819
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: Chlorpyrifos is a widely used organophosphorothioate insecticide. Known human exposures to chlorpyrifos range from low dietary levels to the intentional ingestion of concentrated chlorpyrifos solutions as a means of suicide. Chlorpyrifos derives its in vivo toxicity through bioactivation by the cytochromes P450 (CYPs) to the neurotoxic metabolite, chlorpyrifos-oxon (CPO). Chlorpyrifos-induced toxicity occurs when the level of CPO produced exceeds the capacity to detoxify CPO before acetylcholinesterase inhibition occurs. Several human esterases detoxify CPO, the most efficient being the serum esterase, paraoxonase 1 (PON1). The capacity of PON1 to detoxify CPO is understood to depend on genotype, age and diet. PON1 expression can be developmentally delayed not plateauing until at least six months of age. The ability to produce CPO has not been as well studied in humans and there are questions regarding the impact of age, genetic variation on chlorpyrifos bioactivation. To assess CPO production variability, a series of in vitro metabolism studies were conducted with individual human liver microsomes incubated with chlorpyrifos. CPO production varied over 14-fold and was predicted by CYP2B6 activity but no relationship with CP2B6 genotype was observed. CYP expression can change substantially during development. However, CYP2B6 ontogeny has been poorly characterized. Earlier reports suggested a general lack of CYP2B6 expression in neonatal and fetal liver samples. CYP2B6 levels in 220 individual human liver microsomal samples ranging from 10 weeks gestation to 17 years were semi-quantitatively measured by western blot. CYP2B6 protein expression was determined to be significantly higher after the neonatal period and the percent of samples with detectable CYP2B6 protein increased from a low of 60% detectable in the first-trimester to over 90% detectable in samples from donors over 11 years of age. CYP2B6 is highly efficient at producing CPO.
Start Page: 110
ISSN/ISBN: 9781124264752
Keywords: 0383:Surgery
Keywords: Hepatic expression
Keywords: Bioactivation
Keywords: CYP2B6
Keywords: 0758:Developmental biology
Keywords: Liver microsomes
Keywords: Insecticide
Keywords: 0383:Toxicology
Keywords: Health and environmental sciences
Keywords: CYP isoforms
Keywords: Cytochromes P450
Keywords: Chiorpyrifos
2009
Hepatic expression
9781124264752
CYP2B6
Bioactivation
Liver microsomes
Insecticide
0383: Toxicology
66569
0383: Surgery
n/a
English
759199415
Chiorpyrifos
Copyright ProQuest, UMI Dissertations Publishing 2009
2167983291
2012-07-10
0758: Developmental biology
49384871
Health and environmental sciences
CYP isoforms
3425966
Croom, Edward Lee
Cytochromes P450 English

260. Crossan, Angus N; Kennedy, Ivan R, and Crossan, Angus N. Calculation of Pesticide Degradation in Decaying Cotton Gin Trash. 2008 Oct; 81, (4): 355-359.


Rec #: 45519
Keywords: FATE
Notes: Chemical of Concern: CPY
Abstract: Abstract: Pesticide residues were measured in stockpiled cotton gin trash (CGT) over a 2-year period. Samples were analysed by GC/MS/MS and interpretation of the results was aided by the presence of DDE residues, remnant from prior DDT use. Fourteen pesticide residues from current agricultural practice were detected in CGT. Several of these, including indoxacarb, profenofos, chlorpyrifos, propargite, bifenthrin, ethion and cyhalothrin, were more persistent than expected on the basis of published data for soil dissipation. The results showed a complex pattern of pesticide residue decay over time because of the simultaneous decomposition of the CGT matrix.
Keywords: Cyhalothrin
Keywords: Data processing
Keywords: agricultural practices
Keywords: Cotton
Keywords: Degradation
Keywords: Pesticide residues
Keywords: P 5000:LAND POLLUTION
Keywords: DDE
Keywords: Decomposition
Keywords: ENA 02:Toxicology & Environmental Safety
Keywords: Chlorpyrifos
Keywords: Soil
Keywords: Guanylate cyclase
Keywords: Agricultural practices
Keywords: Toxicology Abstracts; Pollution Abstracts; Environment Abstracts
Keywords: Insecticides
Keywords: Nitrous oxide
Keywords: Pesticides
Keywords: DDT
Keywords: Decay
Keywords: X 24330:Agrochemicals
Date revised - 2010-01-01
Language of summary - English
Pages - 355-359
ProQuest ID - 21253795
SubjectsTermNotLitGenreText - Chlorpyrifos; Soil; Guanylate cyclase; Agricultural practices; Cyhalothrin; Data processing; Cotton; Pesticide residues; Pesticides; DDT; DDE; Decomposition; agricultural practices; Degradation; Insecticides; Nitrous oxide; Decay
Last updated - 2011-12-14
British nursing index edition - Bulletin of Environmental Contamination and Toxicology [Bull. Environ. Contam. Toxicol.]. Vol. 81, no. 4, pp. 355-359. Oct 2008.
Corporate institution author - Crossan, Angus N; Kennedy, Ivan R
DOI - MD-0010968715; 11766972; 0007-4861; 1432-0800 English

261. Crow, J. A.; Bittles, V.; Borazjani, A.; Potter, P. M., and Ross, M. K. Covalent inhibition of recombinant human carboxylesterase 1 and 2 and monoacylglycerol lipase by the carbamates JZL184 and URB597. 2012; 84, (9): 1215-1222.


Rec #: 58419
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: Carboxylesterase type 1 (CES1) and CES2 are serine hydrolases located in the liver and small intestine. CES1 and CES2 actively participate in the metabolism of several pharmaceuticals. Recently, carbamate compounds were developed to inhibit members of the serine hydrolase family via covalent modification of the active site serine. URB597 and JZL184 inhibit fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively; however, carboxylesterases in liver have been identified as a major off-target. We report the kinetic rate constants for inhibition of human recombinant CES1 and CES2 by URB597 and JZL184. Bimolecular rate constants (k(inact)/K(i)) for inhibition of CES1 by JZL184 and URB597 were similar [3.9 (+/- 0.2) x 10(3) M(-1) s(-1) and 4.5 (+/- 1.3) x 10(3) M(-1) s(-1), respectively]. However. k(inact)/K(i) for inhibition of CES2 by JZL184 and URB597 were significantly different [2.3 (+/- 1.3) x 10(2) M(-1) s(-1) and 3.9 (+/- 1.0) x 10(3) M(-1) s(-1), respectively]. Rates of inhibition of CES1 and CES2 by URB597 were similar; however. CES1 and MAGL were more potently inhibited by JZL184 than CES2. We also determined kinetic constants for spontaneous reactivation of CES1 carbamoylated by either JZL184 or URB597 and CES1 diethylphosphorylated by paraoxon. The reactivation rate was significantly slower (4.5x) for CES1 inhibited by JZL184 than CES1 inhibited by URB597. Half-life of reactivation for CES1 carbamoylated by JZL184 was 49 +/- 15 h, which is faster than carboxylesterase turnover in HepG2 cells. Together, the results define the kinetics of inhibition for a class of drugs that target hydrolytic enzymes involved in drug and lipid metabolism. (C) 2012 Elsevier Inc. All rights reserved.
Keywords: Carboxylesterase, Monoacylglycerol lipase, Carbamate, Bimolecular rate
ISI Document Delivery No.: 017DL

262. Crow, J. Allen; Middleton, Brandy L.; Borazjani, Abdolsamad; Hatfield, M. Jason; Potter, Philip M., and Ross, Matthew K. Inhibition of carboxylesterase 1 is associated with cholesteryl ester retention in human THP-1 monocyte/macrophages. 2008 Oct; 1781, (10): 643-654.


Rec #: 3000
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Cholesteryl esters are hydrolyzed by cholesteryl ester hydrolase (CEH) yielding free cholesterol for export from macrophages. Hence, CEH has an important regulatory role in macrophage reverse cholesterol transport (RCT). CEH and human carboxylesterase 1 (CES1) appear to be the same enzyme. CES1 is inhibited by oxons, the bioactive metabolites of organophosphate (OP) pesticides. Here, we show that CES1 protein is robustly expressed in human THP-1 monocytes/macrophages and its biochemical activity inhibited following treatment of cell lysates and intact cells with chlorpyrifos oxon, paraoxon, or methyl paraoxon (with nanomolar IC50 values) or after immunodepletion of CES1 protein. CES1 protein expression in cells is unaffected by a 24-h paraoxon treatment, suggesting that the reduced hydrolytic activity is due to covalent inhibition of CES1 by oxons and not down-regulation of expression. Most significantly, treatment of cholesterol-loaded macrophages with either paraoxon (a non-specific CES inhibitor) or benzil (a specific CES inhibitor) caused enhanced retention of intracellular cholesteryl esters and a Ç£foamyÇ¥ phenotype, consistent with reduced cholesteryl ester mobilization. Thus, exposure to OP pesticides, which results in the inhibition of CES1, may also inhibit macrophage RCT, an important process in the regression of atherosclerosis. Atherosclerosis/ Cholesteryl ester hydrolase/ Carboxylesterase/ Cholesterol metabolism/ Organophosphate/ Benzil

263. Crow, Jallen; Bittles, Victoria; Herring, Katye L; Borazjani, Abdolsamad; Potter, Philip M; Ross, Matthew K, and Crow, JAllen. Inhibition of Recombinant Human Carboxylesterase 1 and 2 and Monoacylglycerol Lipase by Chlorpyrifos Oxon, Paraoxon and Methyl Paraoxon. 2012 Jan 1; 258, (1): 145-150.


Rec #: 39169
Keywords: HUMAN HEALTH
Notes: Chemical of Concern: CPY
Abstract: Abstract: Oxons are the bioactivated metabolites of organophosphorus insecticides formed via cytochrome P450 monooxygenase-catalyzed desulfuration of the parent compound. Oxons react covalently with the active site serine residue of serine hydrolases, thereby inactivating the enzyme. A number of serine hydrolases other than acetylcholinesterase, the canonical target of oxons, have been reported to react with and be inhibited by oxons. These off-target serine hydrolases include carboxylesterase 1 (CES1), CES2, and monoacylglycerol lipase. Carboxylesterases (CES, EC 3.1.1.1) metabolize a number of xenobiotic and endobiotic compounds containing ester, amide, and thioester bonds and are important in the metabolism of many pharmaceuticals. Monoglyceride lipase (MGL, EC 3.1.1.23) hydrolyzes monoglycerides including the endocannabinoid, 2-arachidonoylglycerol (2-AG). The physiological consequences and toxicity related to the inhibition of off-target serine hydrolases by oxons due to chronic, low level environmental exposures are poorly understood. Here, we determined the potency of inhibition (IC50 values; 15min preincubation, enzyme and inhibitor) of recombinant CES1, CES2, and MGL by chlorpyrifos oxon, paraoxon and methyl paraoxon. The order of potency for these three oxons with CES1, CES2, and MGL was chlorpyrifos oxon>paraoxon>methyl paraoxon, although the difference in potency for chlorpyrifos oxon with CES1 and CES2 did not reach statistical significance. We also determined the bimolecular rate constants (k|>inact/KI) for the covalent reaction of chlorpyrifos oxon, paraoxon and methyl paraoxon with CES1 and CES2. Consistent with the results for the IC50 values, the order of reactivity for each of the three oxons with CES1 and CES2 was chlorpyrifos oxon>paraoxon>methyl paraoxon. The bimolecular rate constant for the reaction of chlorpyrifos oxon with MGL was also determined and was less than the values determined for chlorpyrifos oxon with CES1 and CES2 respectively. Together, the results define the kinetics of inhibition of three important hydrolytic enzymes by activated metabolites of widely used agrochemicals.
Keywords: Pharmacy And Pharmacology
Keywords: Statistics
Keywords: Acetylcholinesterase
Keywords: Monoglycerides
Keywords: Carboxylesterase
Keywords: Enzymes
Keywords: Metabolites
Keywords: Toxicity
Keywords: Paraoxon
Keywords: Esters
Keywords: Agrochemicals
Keywords: Chlorpyrifos
Keywords: Triacylglycerol lipase
Keywords: Insecticides
Keywords: Cannabinoids
Keywords: serine hydrolase
Keywords: Kinetics
Keywords: 2-Arachidonylglycerol
Keywords: Pharmaceuticals
Keywords: X 24330:Agrochemicals
Keywords: Toxicology Abstracts
Keywords: Serine
Date revised - 2012-03-01
Language of summary - English
Pages - 145-150
ProQuest ID - 919309362
SubjectsTermNotLitGenreText - Statistics; Acetylcholinesterase; Monoglycerides; Enzymes; Carboxylesterase; Metabolites; Paraoxon; Toxicity; Esters; Agrochemicals; Chlorpyrifos; Triacylglycerol lipase; Insecticides; Cannabinoids; serine hydrolase; Kinetics; 2-Arachidonylglycerol; Pharmaceuticals; Serine
Last updated - 2012-03-22
Corporate institution author - Crow, JAllen; Bittles, Victoria; Herring, Katye L; Borazjani, Abdolsamad; Potter, Philip M; Ross, Matthew K
DOI - OB-f79f27ee-a168-47aa-a7e1csamfg201; 16208784; 0041-008X English

264. Crowe, K. M.; Bushway, A. A.; Bushway, R. J., and Davis-Dentici, K. Microbial degaradation of phosmet on blueberry fruit and in aqueous systems by indigenous bacterial flora on lowbush blueberries (Vaccinium angustifolium). 2007; 72, (8): M293-M299.


Rec #: 58449
Keywords: NO EFFECT
Notes: Chemical of Concern: CPY
Abstract: Abstract: Phosmet-adapted bacteria Isolated from lowbush blueberries (Vaccinium angustifolium) were evaluated for their ability to degrade phosmet on blueberry fruit and in minimal salt solutions. Microbial metabolism of phosmet by isolates of Enterobacter agglomerans and Pseudomonas fluorescens resulted in significant reductions (P < 0.05; 33.8%)
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