Interaction of Human Alpha-2-Macroglobulin with Pesticide Aldicarb Using Spectroscopy and Molecular Docking.

BACKGROUND: Aldicarb is a carbamate pesticide commercially used in potato crop production. Once it enters human body, it interacts with diverse proteins and other substances. OBJECTIVE: Aldicarb is toxic to human health and it is also a cholinesterase inhibitor, which prevents the breakdown of acetylcholine in synapse. Human alpha-2-macroglobulin (α2M), is a large tetrameric glycoprotein of 720 kDa with antiproteinase activity, found abundantly in plasma. METHODS: In the present study, the interaction of aldicarb with alpha-2-macroglobulin was explored utilizing various spectroscopic techniques and molecular docking studies. RESULTS: UV-vis and fluorescence spectroscopy suggests the formation of a complex between aldicarb and α2M apparent by increased absorbance and decreased fluorescence with static quenching mode. CD spectroscopy indicates a slight change in the structure of alpha-2-macroglobulin. Docking studies confirm the interaction of aldicarb with Pro- 1391, Leu-1392, Lys-1393, Val-1396, Lys- 1397, Thr-1408, Glu-1409, Val-1410, Asp-282 and Glu-281 in the receptor binding domain at the C-terminal of the alpha 2 macroglobulin. DISCUSSION: In this work, aldicarb is shown to bind with alpha 2-macroglobulin at receptor binding domain which is the binding site for various extracellular and intracellular ligand too. Also, affecting the functional activity of the protein may lead to further physiological consequences. CONCLUSION: It is possible that aldicarb binds and compromises antiproteinase activity of α2M and binding properties by inducing changes in the secondary structure of the protein.

Fluorescence tuning behavior of carbon quantum dots with gold nanoparticles via novel intercalation effect of aldicarb.

A simple, sensitive and rapid fluorometric system has been developed for the detection of aldicarb (ALD) based on inner filter effect (IFE) of gold nanoparticles (AuNPs) on fluorescence (FL) intensity of carbon quantum dots (CQDs). Addition of CQDs into AuNPs, gets them aggregated due to electrostatic interaction resulting in quenching the FL intensity of CQDs. With addition of ALD into AuNPs, an intercalated layer was formed between them through Au-N and Au-S bond which reduced IFE of AuNPs. Hence, CQDs FL intensity recovered along with ALD concentration varying between 3.8 and 76 µg L-1 with lower detection limit of 3.02 µg L-1. The spiked real samples study in fruits, vegetables and soft drinks revealed that this sensing platform was repeatable and effective for real samples. The validation of proposed method indicates that the ALD sensor is promising and adaptable for everyday on spot environment and food safety monitoring.

In vivo efficacy of the Reactive Skin Decontamination Lotion (RSDL®) kit against organophosphate and carbamate pesticides.

In this study, we assessed the efficacy of the Reactive Skin Decontamination Lotion (RSDL®) Kit against parathion and aldicarb pesticide dermal exposure in a guinea pig model. The pesticides inhibit acetylcholinesterase (AChE) leading to signs and symptoms of hyperactivity of organs due to accumulation of acetylcholine. The RSDL Kit has been shown to physically remove and chemically degrade chemical warfare agents. Degradation occurs from a nucleophilic substitution reaction between an active ingredient in the RSDL lotion, potassium 2,3-butanedione monoximate (KBDO), with susceptible sites in these compounds. In the present study, guinea pigs dermally exposed to parathion and aldicarb were decontaminated with RSDL to mitigate the toxic effects of the pesticides. It is observed that animals exposed to 749 mg/kg of parathion (n = 3) died within 24 h without RSDL decontamination; however, RSDL-treated animals (n = 3) showed only mild signs of neurotoxicity. The RSDL-treated animals had an AChE inhibition of 0-58% while the untreated animals had up to 86% inhibition. Similarly, RSDL has been demostrated to prevent aldicarb neurotoxicity effects. The percent inhibition of AChE activity during the 24 h post challenge of 9 mg aldicarb/kg of animal weight ranged from 25% to 61% with severe signs of intoxication while only up to 5% with mild or no signs of intoxication in the case of RSDL-decontaminated animals. Generally, it has been shown that the toxic effects of the organophosphate and carbamate pesticides can be prevented via decontamination using the RSDL Kit.

Photocatalytic degradation of organic pollutant aldicarb by non-metal-doped nanotitania: synthesis and characterization.

The current study focused on pollution control by titania through photocatalytic degradation of aldicarb pesticide in aqueous medium. Titania, which is an efficient photocatalyst, can bring about degradation of aqueous organic pollutants under UV and visible light irradiation. Here, we prepared titania by sol-gel method from titanium tetraisopropoxide and doped non-metals like N and S from sources such as urea and thiourea, respectively. The prepared catalyst was characterized by XRD, UV-Vis.DRS, TEM, XPS, etc. Photocatalytic activity of the catalyst was evaluated from extend of degradation of aldicarb pesticide by measuring its concentration with the help of HPLC. It was found that the modified catalyst showed better photocatalytic degradation than pure titania in visible light.

[Dynamic behavior of aldicarb and its metabolites in cabbage by liquid chromatography-tandem mass spectrometry].

A liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) method was developed for the study of dynamic behavior of aldicarb and its metabolite residues in cabbage. Aldicarb was applied onto cultivated cabbages. The pesticides concentrations were measured periodically (between application and harvest) , and modeled to illustrate the dynamic behavior. The results showed that the liner ranges of aldicarb and its metabolites were from 0. 005 to 0. 2 mg/L, and the recoveries ranged from 78. 9% to 108. 5% with the relative standard deviations of 2. 03%- 8. 91% (n = 8). The aldicarb in cabbage increased at first with the first-order kinetic equation model of c = 0. 020(0.136t) with the correlation coefficient (r2) of 0. 888, and then decreased with the equation of c = 0. 65e(-059t) with the r2 of 0. 979 and the half-life of 29. 1 d. The reducing processes of aldicarb-sulfone and aldicarb-sulfoxide both matched the first-order kinetic equations (c = 23. 4e(-0.044t) and c = 4. 54e(-0.027t) with r2 of 0. 916 and 0. 972 respectively. To meet the limitation requirement of 0. 01 mg/kg, 70. 7, 226. 6 and 176. 3 d were respectively necessary for aldicarb, aldicarb-sulfone and aldicarb-sulfoxide. Final residues of aldicarb-sulfone and aldicarb-sulfoxide were still more than the limitation requirements, indicating that aldicarb should not be used in vegetables of growth cycle shorter than 120 d. This study provided theoretical basis for dynamic behavior of aldicarb residue and its safe use in vegetables.

Death by chumbinho: aldicarb intoxication-regarding a corpse in decomposition.

Chumbinho is the popular name given to carbamate aldicarb (Temik), an insecticide commonly used in agriculture and highly toxic (LD50 = 0.9 mg/kg oral in rats) that has been sold clandestinely in several regions of Brazil. Chumbinho is sold illegally as raticide and is available in a formulation of small black granules which are easily mixed with food for criminal purposes, its use often being attributed to accidents and suicides, hence the importance of its inclusion in the toxicology studies of suspicious deaths. With the corpse putrefaction, many pathological and toxicological anatomical parameters are damaged or lost. This study emphasizes the importance of the gastric content observation, which in this case has, despite the advanced putrefaction, recognized the presence of chumbinho and guide its toxicological confirmation.

Acetylcholinesterase biosensor for inhibitor measurements based on glassy carbon electrode modified with carbon black and pillar[5]arene.

New acetylcholinesterase (AChE) biosensor based on unsubstituted pillar[5]arene (P[5]A) as electron mediator was developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. The AChE from electric eel was immobilized by carbodiimide binding on carbon black (CB) placed on glassy carbon electrode. The working potential of 200mV was obtained in chronoamperometric mode with the measurement time of 180 s providing best inter-biosensors precision of the results. The AChE biosensor developed made it possible to detect 1×10(-11)-1×10(-6) M of malaoxon, 1×10(-8)-7×10(-6) M of methyl-paraoxon, 1×10(-10)-2×10(-6) M of carbofuran and 7×10(-9)-1×10(-5) M of aldicarb with 10 min incubation. The limits of detection were 4×10(-12), 5×10(-9), 2×10(-11) and 6×10(-10) M, respectively. The AChE biosensor was tested in the analysis of pesticide residuals in spiked samples of peanut and beetroot. The protecting effect of P[5]A derivative bearing quaternary ammonia groups on malaoxon inhibition was shown.

An enzyme-linked chemiluminescent immunoassay developed for detection of Butocarboxim from agricultural products based on monoclonal antibody.

In this study, four different haptens around the oxime moiety of Butocarboxim were designed and synthesised. Two of the haptens were conjugated with bovine serum albumin (BSA) to serve as the immunogen and all the haptens were conjugated with ovalbumin (OVA) for the coating antigen. The anti-Butocarboxim monoclonal antibody (Mab) was selected based on eight immunogen/coating antigen combinations. The first enzyme-linked chemiluminescent immunoassay (ELCIA) for determining Butocarboxim in agricultural products was developed. Under the optimised conditions, the detection limit for the ELCIA was 20 ng·mL(-1) and the linear range was 27-2700 ng·mL(-1). Analyte recoveries for extracts of spiked agricultural (apple and greengrocery) products and tap water ranged from 97.18% to 107.00%. The developed immunoassay has great potential to be developed as a test kit offering a simple and cost-effective approach (such as lateral flow test strip) for screening purposes and evaluating environmental exposure to Butocarboxim.

Cholinesterase sensor based on glassy carbon electrode modified with Ag nanoparticles decorated with macrocyclic ligands.

New acetylcholinesterase (AChE) sensor based on Ag nanoparticles decorated with macrocyclic ligand has been developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. AChE was immobilized by carbodiimide binding on carbon black (CB) layer deposited on a glassy carbon electrode. The addition of Ag nanoparticles decreased the working potential of the biosensor from 350 to 50 mV. The AChE sensor made it possible to detect 0.4 nM-0.2 µM of malaoxon, 0.2 nM-0.2 µM of paraoxon, 0.2 nM-2.0 µM of carbofuran and 10 nM-0.20 µM of aldicarb (limits of detection 0.1, 0.05, 0.1 and 10 nM, respectively) with 10 min incubation. The AChE sensor was tested for the detection of residual amounts of pesticides in spiked samples of peanut and grape juice. The protecting effect of new macrocyclic compounds bearing quaternary ammonia fragments was shown on the example of malaoxon inhibition.

MOF@activated carbon: a new material for adsorption of aldicarb in biological systems.

A new composite was synthesized by the hydrothermal method using a 3D coordination network [Ln2(C4H4O4)3(H2O)2]·H2O (Ln = Eu and Tb) and activated carbon. The coordination network is formed within the pores of the charcoal, allowing for the use of this material as a detoxifying agent.

Effect of ammonium on liquid- and gas-phase protonation and deprotonation in electrospray ionization mass spectrometry.

The electrospray ionization (ESI) is a complex process and there has been a long debate regarding the gas-phase effect on ion generation in the process. In this paper we investigated the effect of liquid chromatographic mobile phase additives (formic acid, aqueous ammonia and their combination) on the ESI signal intensities for a wide variety of compounds. The addition of a trace amount of aqueous ammonia to the common formic acid-methanol mobile phase significantly enhances the ESI signals of protonated molecules and suppresses the formation of sodium adduct ions. This effect is well observed for the compounds containing the -N-C=O group but not for those without N or O atoms. The ESI signal intensity of deprotonated molecules increases with increase in pH of the mobile phase for neutral compounds, such as substituted urea, whereas this trend is not observed for acidic compounds such as phenoxy acids. The mechanistic analysis regarding liquid- and gas-phase protonation and deprotonation is discussed.

A novel luminescent terbium-3-carboxycoumarin probe for time-resolved fluorescence sensing of pesticides methomyl, aldicarb and prometryne.

The luminescence arising from lanthanide cations offers several advantages over organic fluorescent molecules: sharp, distinctive emission bands allow for easy resolution between multiple lanthanide signals; long emission lifetimes (µs-ms) make them excellent candidates for time-resolved measurements; and high resistance to photo bleaching allow for long or repeated experiments. A time-resolved (gated) luminescence-based method for determination of pesticides methomyl, aldicarb and prometryne in microtiterplate format using the long-lived terbium-3-carboxycoumarin in 1:3 metal:ligand ratio has been developed. The limit of detection is 1.20×10(6), 5.19×10(5) and 2.74×10(6)ng L(-1) for methomyl, prometryne and aldicarb, respectively. The quantum yield (QY=0.08) of Tb(III)-3-carboxycoumarin was determined using 3-(2-benzothiazolyl)-7-diethylamino-coumarin (coumarin 6). Stern-volmer studies at different temperatures indicate that collisional quenching dominates for methomyl, aldicarb and prometryne. Binding constants were determined at 303, 308 and 313 K by using Lineweaver-Burk equation. A thermodynamic analysis showed that the reaction is spontaneous with negative ΔG. Effect of some relevant interferents on the detection of pesticides has been investigated.

Fluorescence and electrochemical sensing of pesticides methomyl, aldicarb and prometryne by the luminescent europium-3-carboxycoumarin probe.

This work describes the application of time resolved fluorescence in microtiterplates and electrochemical methods on glassy carbon electrode for investigating the interactions of europium-3-carboxycoumarin with pesticides aldicarb, methomyl and prometryne. Stern-volmer studies at different temperatures indicate that static quenching dominates for methomyl, aldicarb and prometryne. By using Lineweaver-Burk equation binding constants were determined at 303 K, 308 K and 313 K. A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined. A time-resolved (gated) luminescence-based method for determination of pesticides in microtiterplate format using the long-lived europium-3-carboxycoumarin has been developed. The limit of detection is 4.80, 5.06 and 8.01 µmol L(-1) for methomyl, prometryne and aldicarb, respectively. This is the lowest limit of detection achieved so far for luminescent lanthanide-based probes for pesticides. The interaction of the probe with the pesticides has been investigated using cyclic voltammetry (CV), differential pulse polarography (DPP), square wave voltammetry (SWV) and linear sweep voltammetry (LSV) on a glassy carbon electrode in I = 0.1 mol L(-1) p-toluenesulfonate at 25 °C. The diffusion coefficients of the reduced species are calculated. The main properties of the electrode reaction occurring in a finite diffusion space are the quasireversible maximum and the splitting of the net SWV peak for Eu(III) ions in the ternary complex formed . It was observed that the increase of the cathodic peak currents using LSV is linear with the increase of pesticides concentration in the range 5 × 10(-7) to 1 × 10(-5) mol L(-1). The detection limit (DL) were about 1.01, 2.23 and 1.89 µmol L(-1) for aldicarb, methomyl and prometryne, respectively. In order to assess the analytical applicability of the method, the influence of various potentially interfering species was examined. Influence of interfering species on the recovery of 10 µmol L(-1) pesticides has been investigated.

Aldicarb and carbofuran transport in a Hapludalf influenced by differential antecedent soil water content and irrigation delay.

Pesticide use in agroecosystems can adversely impact groundwater quality via chemical leaching through soils. Few studies have investigated the effects of antecedent soil water content (SWC) and timing of initial irrigation (TII) after chemical application on pesticide transport and degradation. The objectives of this study were to investigate the effects of antecedent soil water content (wet vs dry) and timing of initial irrigation (0h Delay vs 24h Delay) on aldicarb [(EZ)-2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime] and carbofuran [2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate] transport and degradation parameters at a field site with Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf) soils. Aldicarb and carbofuran were applied to plots near field capacity (wet) or near permanent wilting point (dry). Half of the dry and wet plots received irrigation water immediately after chemical application and the remaining plots were irrigated after a 24h Delay. The transport and degradation parameters were estimated using the method of moments. Statistical significance determined for SWC included averages across TII levels, and significance determined for TII included averages across SWC levels. For the dry treatment, aldicarb was detected 0.10 m deeper (P<0.01) on two of the four sampling dates and carbofuran was detected at least 0.10 m deeper (P<0.05) on all of the sampling dates compared to the wet treatment. Pore water velocity was found to be higher (P<0.10) in the dry vs wet treatments on three of four dates for aldicarb and two of four dates for carbofuran. Retardation coefficients for both pesticides showed similar evidence of reduced values for the dry vs wet treatments. These results indicate deeper pesticide movement in the initially dry treatment. For aldicarb and carbofuran, estimated values of the degradation rate were approximately 40-49% lower in the initially dry plots compared to the initially wet plots, respectively. When the initial irrigation was delayed for 24h, irrespective of antecedent moisture conditions, a 30% reduction in aldicarb degradation occurred. This study illustrates the deeper transport of pesticides and their increased persistence when applied to initially dry soils.

SNARE complex zero layer residues are not critical for N-ethylmaleimide-sensitive factor-mediated disassembly.

Membrane-anchored SNAREs assemble into SNARE complexes that bring membranes together to promote fusion. SNARE complexes are parallel four-helix bundles stabilized in part by hydrophobic interactions within their core. At the center of SNARE complexes is a distinctive zero layer that consists of one arginine and three glutamines. This zero layer is thought to play a special role in the biology of the SNARE complex. One proposal is that the polar residues of the zero layer enable N-ethylmaleimide-sensitive factor (NSF)-mediated SNARE complex disassembly. Here, we studied the effects of manipulating the zero layer of the well studied synaptic SNARE complex in vitro and in vivo. Using a fluorescence-based assay to follow SNARE complex disassembly in real time, we found that the maximal rate at which NSF disassembles complexes was unaffected by mutations in the zero layer, including single replacement of the syntaxin glutamine with arginine as well as multiple replacement of all four layer residues with non-polar amino acids. To determine whether syntaxin with arginine instead of glutamine in its zero layer can support SNARE function in vivo, we introduced it as a transgene into a Caenorhabditis elegans syntaxin-null strain. Mutant syntaxin rescued viability and locomotory defects similarly to wild-type syntaxin, demonstrating that SNARE complexes with two glutamines and two arginines in the zero layer can support neurotransmission. These findings show that residues of the zero layer do not play an essential role in NSF-mediated disassembly.

Adsorption kinetics and isotherms of pesticides onto activated carbon-cloth.

Adsorption of pesticides ametryn, aldicarb, dinoseb and diuron from aqueous solution onto high specific area activated carbon-cloth was studied. Kinetics of adsorption was followed by in situ UV-spectroscopy and the data were treated according to various rate models. The extent of adsorption was determined at the end of 125 min adsorption period. Rate constants and the extent of adsorption for the four pesticides were found to follow the order: dinoseb > ametryn > diuron > aldicarb. Adsorption isotherms were derived at 25 degrees C on the basis of batch analysis. Isotherm data were treated according to Langmuir and Freundlich models. The fits of experimental data to these equations were examined. The types of interactions between the surface and pesticide molecules were discussed.

Pulsed losses and degradation of aldicarb in a South Florida agricultural watershed.

The objectives of these studies were to characterize patterns of movement of aldicarb, aldicarb sulfoxide, and aldicarb sulfone from a typical canalized South Florida watershed and to evaluate aldicarb dissipation in surface water in situ within a citrus grove. Surface water samples were collected daily or every other day from the discharge point for the watershed beginning May 15, 2001, through August 15, 2002. Of 457 samples collected, aldicarb, aldicarb sulfoxide, and aldicarb sulfone were detected in 6, 1, and 13, respectively. Aldicarb was detected from February through May 2002, corresponding to the legal application season of January 1 through April 30 in Florida. Aldicarb concentrations ranged from <0.16 to 4.97 ng ml(-1). A single detection (0.99 ng ml(-1)) of aldicarb sulfoxide occurred in March 2001. The majority of aldicarb sulfone detections occurred during June and July, 2001, after the application season, and ranged from <0.22 to 0.89 ng ml(-1). The half-life for aldicarb in fortified, native surface water ranged from 1.86 to 3.64 days depending on the source of water and the presence of sediments. These results demonstrated the utility of sampling on a frequent basis (compared with monthly or quarterly) for better characterizing pesticide discharges, especially in flashy systems such as canal-drained watersheds within South Florida.

Determination of aldicarb, carbofuran and some of their main metabolites in groundwater by application of micellar electrokinetic capillary chromatography with diode-array detection and solid-phase extraction.

This paper describes a UV detection method for the pesticides aldicarb and carbofuran, and some of their main metabolites, aldicarb-sulfoxide, aldicarb-sulfone and 3-hydroxy-carbofuran, in ground waters. Micellar electrokinetic chromatography (MEKC) with diode-array detection was developed for their determination at 210 nm. The experimental study was performed using sodium dodecyl sulfate (SDS) at a concentration level of 140 mM, and a buffer of borax/HCl 20 mM at pH 8 which gives the best resolution with an analysis time of less than 20 min. Different instrumental parameters such as voltage (23 kV), injection time (12 s) and temperature (25 degrees C) were optimized. The detection limits were in the range 2-7.4 microg glitre(-1) by solid-phase extraction (SPE) with a subsequent evaporation step. Groundwater spiked samples were pre-concentrated off-line with graphite carbon and subsequently analyzed by MEKC with diode-array detection yielding average recoveries between 77 and 97% (n = 4) with RSD between 2-7%.

Construction of an acetylcholinesterase-choline oxidase biosensor for aldicarb determination.

In this study, acetylcholinesterase and choline oxidase were co-immobilized on poly(2-hydroxyethyl methacrylate) membranes and the change in oxygen consumption upon aldicarb introduction was measured. Immobilization of the enzymes was achieved either by entrapment or by surface attachment via a hybrid immobilization method including epichlorohydrin and Cibacron Blue F36A activation. Immobilized enzymes had a long-storage stability (only 15% activity decrease in 2 months in wet storage and no activity loss in dry storage). Aldicarb detection studies showed that a linear working range of 10-500 and 10-250 ppb aldicarb could be achieved by entrapped and surface immobilized enzymes, respectively. Enzymes immobilized on membrane surfaces responded to aldicarb presence more quickly than entrapped enzymes. Aldicarb concentrations as low as 23 and 12 ppb could be detected by entrapped and surface immobilized enzymes, respectively, in 25 min.

Biological effects of two insecticides on earthworms (Lumbricus terrestris L.) under laboratory conditions.

Earthworms (Lumbricus terrestris L.) were exposed to endosulfan and aldicarb for 2, 7, and 15 days and lethal concentrations were determined. Worms were then exposed to these concentrations (LC10, LC25, and LC50) of endosulfan and (LC10 and LC25) of aldicarb. Growth rate, total protein content, and insecticide residues were determined. Aldicarb was more toxic than endosulfan and both insecticides caused a significant reduction of growth rate and total protein content of earthworms. Residues remaining in the soil after 2 to 15 days ranged between 37.75% and 68.54% of applied concentration for endosulfan and between 10.13% and 67.71% of applied concentration for aldicarb. Less than 1% of soil concentration was detected in worms and accumulation was more important in the case of endosulfan. This study proposes the use of growth rate and total protein content as biomarkers for contamination by endosulfan and aldicarb.