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1.
The aim of the work was to investigate the in vitro oxidation of diazinon and malathion, organophosphorous pesticides (OPs) containing phosphorthioate group, catalyzed by enzyme myeloperoxidase (MPO). The oxidation was performed in the presence of hydrogen peroxide. The products were identified as oxon derivatives (phosphates), where the sulfur atom from thioate group was substituted by an oxygen atom. No hydrolysis products were detected after enzyme - induced oxidation. The oxidation efficiency was controlled using acethylcholinesterase (AChE) bioassay for determination of oxon derivatives concentration. The influence of OPs concentration, incubation time of OPs with MPO, as well as MPO concentration on the yield of oxo forms was investigated. Kinetic constants of MPO in oxidation of malathion and diazinon were estimated. The maximum concentration of oxo forms was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO.  相似文献   

2.
The present paper deals with the investigations of optimal conditions for the myeloperoxidase (MPO) mediated oxidation of chlorpyrifos, azinphos-methyl and phorate, organophosphorous pesticides (OPs) containing phosphorothionate group, from thio- to oxo-forms, in the presence of hydrogen peroxide. The aim of the work was to apply this oxidation method in the AChE based bioanalytical tests for OPs determination. The maximum concentration of oxo-forms for all tested pesticides was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO in the presence of 50 μM H2O2. Optimal temperature for obtaining maximal concentration of oxo-forms was 37 °C. Only the parent compounds and their oxo-forms were identified chromatographically in the OPs samples after their exposure to MPO. Moreover, no hydrolysis products were detected in the time interval of 1 h after the MPO catalyzed reaction was stopped by catalase. The efficiency of OPs transformation from thio- to oxo-forms was measured using acethylcholinesterase (AChE) test, by comparison of percent of AChE inhibition before and after exposure to the oxidized sample.  相似文献   

3.
Organophosphorus pesticides (OPs) are of environmental significance due to their high toxicity to animals. Binding to plasma proteins may effective influence the toxicological properties of xenobiotics. In an attempt to evaluate the affinity of phenthoate (PTA) to bovine serum albumin (BSA) and inhibitory ability of bound PTA to acetylcholinesterase (AChE), we investigated the interactions between phenthoate (PTA) and bovine serum albumin (BSA) using tryptophan fluorescence quenching and subsequent inhibition on AChE activity by PTA. The results showed that PTA caused the fluorescence quenching of BSA because of the formation of a PTA-BSA complex. Quenching constants (Ksv), determined using the Sterns-Volmer equation to provide a measure of the binding affinity between PTA and BSA at 303, 306, 310 and 313 K were (3.4295 ± 0.0763) × 10−4, (3.2446 ± 0.0635) × 10−4, (3.0434 ± 0.0856) × 10−4 and (2.8262 ± 0.0569) × 10−4 M−1, respectively. The thermodynamic parameters, ΔH and ΔS were −25.04 kJ mol−1 and 168.94 J mol−1 K−1, respectively, which indicated that the electrostatic interactions played a major role in PTA-BSA association. The presence of BSA consistently reduced the inhibitory ability of PTA on AChE, with the relative activity being increased from 46.98 to 61.71% for the concentration range of BSA between 0 and 4.0 g L−1.  相似文献   

4.
In vitro inhibition of electric eel acetylcholinesterase (AChE) by single and simultaneous exposure to organophosphorus insecticides diazinon and chlorpyrifos, and their transformation products, formed due to photoinduced degradation, was investigated. Increasing concentrations of diazinon, chlorpyrifos and their oxidation products, diazoxon and chlorpyrifos-oxon, inhibited AChE in a concentration-dependent manner. IC50 (20 min) values, obtained from the inhibition curves, were (in mol/l): (5.1 ± 0.3) × 10−8, (4.3 ± 0.2) × 10−6 and (3.0 ± 0.1) × 10−8 for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively, while maximal diazinon concentration was lower than its IC50 (20 min). Calculated KI values, in mol/l, of 7.9 × 10−7, 9.6 × 10−6 and 4.3 × 10−7 were obtained for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively. However, 2-isopropyl-4-methyl-6-pyrimidinol (IMP) and 3,5,6-trichloro-2-pyridinol, diazinon and chlorpyrifos hydrolysis products, did not noticeably affect the enzyme activity at all investigated concentrations. Additive inhibition effect was achieved for lower concentrations of the inhibitors (diazinon/diazoxon ?1 × 10−4/1 × 10−8 mol/l i.e., chlorpyrifos/chlorpyrifos-oxon ?2 × 10−6/3 × 10−8 mol/l), while an antagonistic effect was obtained for all higher concentrations of the organophosphates. Inhibitory power of 1 × 10−4 mol/l diazinon irradiated samples can be attributed mostly to the formation of diazoxon, while the presence of non-inhibiting photodegradation product IMP did not affect diazinon and diazoxon inhibitory efficiencies.  相似文献   

5.
Trehalase, with the target to control insects, nematodes and fungi, is of increasing interest and has been investigated extensively in recent years. Validamycin compounds, as competitive trehalase inhibitors and lead compounds with broad applications have attracted substantial attention as well. In this study, the characterizations of termites trehalase were investigated and the inhibitory effects of validamycin compounds on the termites trehalase were studied as well. Results showed that the termites trehalase is presumably belonging to the acid trehalase with optimal pH of 3.3 and optimal temperature of 37 °C. It was investigated that the concentrations of validoxylamine A (VAA), validoxylamine B (VBB), validamycin A (VA) and validamycin B (VB) required for 50% inhibition IC50 of termites trehalase were calculated to be 14.73 mg l−1, 20.80 mg l−1, 3.17 × 103 mg l−1and 2.24 × 103 mg l−1, respectively. The inhibition kinetic constant Ki values for the above validamycin compounds were 3.2 × 10−6 mol l−1, 1.03 × 10−5 mol l−1, 4.02 × 10−4 mol l−1and 2.69 × 10−4 mol l−1, respectively. Validoxylamine A appeared to be the most potential termites trehalase inhibitor among the four compounds.  相似文献   

6.
Despite mounting concerns about amphibian population declines, information on impact of pesticides on physiological changes is meager. The present study deals the influence of an organophosphate pesticide—malathion on the lipid metabolism of Limnonectus limnocharis under laboratory conditions. Changes in the lipid metabolism were analyzed in the liver, muscle, ovary, and testis of frogs exposed to lethal (10.67 mg L−1 for 1, 2, 3, and 4 days) and sub-lethal (2.13 mg L−1 for 1, 5, 10, 15, 20, and 25 days) concentrations of malathion. Upon lethal concentration treatment, against the increase of fatty acids, glycerol, and lipase activities in all tested tissues, there was decrease in the total lipids content over different durations. On the other hand, exposure to sub-lethal concentration, the amount of total lipids content, free fatty acids, glycerol and lipase activity increased. Changes in the lipid metabolism due to lethal concentration of malathion exposure could depict the negative impact on the reproductive success, which would result in decline of amphibian population.  相似文献   

7.
The in vitro inhibition potency of some organophosphates (OPs) and carbamates (CAs) which are widely used to control plant-parasitic nematodes on acetylcholinesterase (AChE) of Meloidogyne javanica, Heterodera avenae and Tylenchulus semipenetrans, the major pathogens responsible for the damage of a wide range of crops in Al-Qassim region, Saudi Arabia was examined. AChE of H. avenae activity was 1.58- and 1.51-fold greater than that of T. semipenetrans or M. javanica, respectively. The order of inhibition potency of the tested compounds against T. semipenetrans AChE was: carbofuran > paraoxon > oxamyl > fenamiphos > phorate-sulfoxide > aldicarb, where the corresponding concentrations that inhibited 50% of the nematode AChE activity (I50) were 5 × 10−8, 7 × 10−7, 7.5 × 10−7, 2 × 10−6, 2 × 10−4 and 2 × 10−3 M, respectively. Paraoxon, fenamiphos and carbofuran exhibited high inhibition potency against M. javanica AChE where the I50 values were below 1 nM. Phorate-sulfoxide and aldicarb were potent inhibitors of M. javanica AChE with I50 values of 3.8 and 8 nM, respectively, while oxamyl exhibited low inhibition potency with I50 of 15 nM. Fenamiphos and paraoxon showed the highest I50 values of <100 μM against H. avenae followed by oxamyl (I50 < 1 mM), whereas paraoxon, carbofuran and aldicarb showed low potency with I50 values >1 mM. All the tested compounds exhibited high inhibition potency to AChE of M. javanica than T. semipenetrans or H. avenae. Except phorate-sulfoxide in M. javanica the inhibition pattern and implied mechanism for all the tested compounds for the three nematodes is suggested to be a linear mixed type (a combination of competitive and non-completive type).  相似文献   

8.
Valienamine, an aminocyclitol with similar configuration to α-glucose, has a strong inhibitory effect on α-glucosidase. α-Glucosidase plays an important role in insect carbohydrate metabolism. The inhibitory effect of valienamine on the enzymatic activity of honeybee (Apis cerana Fabr.) α-glucosidase was investigated. Our results show that valienamine inhibition of honeybee α-glucosidase was pH- and dose-dependent, but temperature-independent. Valienamine is shown to be a potent and competitive reversible inhibitor of honeybee α-glucosidase in vitro with an IC50 value of 5.22 × 10−5 M and Ki value of 3.54 × 10−4 M at pH 6.5, 45 °C. Valienamine has the potential to be developed into novel insecticides.  相似文献   

9.
A hydrophilic form of acetylcholinesterase (AChE) was purified from N-methyl carbamate susceptible (SA) and highly N-methyl carbamate-resistant (N3D) strains of the green rice leafhopper (GRLH), Nephotettix cincticeps Uhler. Both of purified AChE from SA and N3D strains displayed the highest activities toward acetylthiocholine (ATCh) at pH 8.5. In the SA strain, the optimum concentrations for ATCh, propionylthiocholine (PTCh), and butyrylthiocholine (BTCh) were about 1 × 10−3, 2.5 × 10−3, and 1 × 10−3 M, respectively. However, in the N3D strain, substrate inhibition was not identified for ATCh, PTCh, and BTCh to 1 × 10−2 M. The Km value in the SA strain was 51.1, 39.1, and 41.6 μM and that in the N3D strain was 91.8, 88.1, and 85.2 μM for ATCh, PTCh, and BTCh, respectively. The Km value in the N3D strain indicated about 1.80-, 2.25-, and 2.05-fold lower affinity than that of the SA strain for ATCh, PTCh, and BTCh, respectively. The Vmax value in the SA strain was 70.2, 30.5, and 4.6 U/mg protein and that in the N3D strain was 123.0, 27.0, and 14.5 U/mg protein for ATCh, PTCh, and BTCh, respectively. The Vmax value in the N3D strain was 1.75- and 3.15-fold higher for ATCh and BTCh than that in the N3D strain. However, it was 1.13-fold lower for PTCh. The increased activity of AChE in the N3D strain is due to the qualitatively modified enzyme with a higher catalytic efficiency. The bimolecular rate constant (ki) for propoxur was 27.1 × 104 and 0.51 × 104 M−1 min−1 in the SA and N3D strain and that for monocrotophos was 0.031 × 104 and 2.0 × 104 M−1 min−1 in the SA and N3D strain. AChE from the N3D strain was 53-fold less sensitive than SA strain to inhibition by propoxur. In contrast, AChE from the N3D strain was 65-fold more sensitive to inhibition by monocrotophos than AChE from the SA strain. This indicated negatively correlated cross-insensitivity of AChE to propoxur and monocrotophos.  相似文献   

10.
Multiwalled carbon nanotubes-polymeric methyl red film modified electrode (MWNT-PMRE) was made. The electrochemical behavior of carbendazim on modified electrode was studied with Cyclic Voltammetry, Linear Sweep Voltammetry, Stable Polarization Method and Chronocoulometry. The results indicated that the electrical oxidation of carbendazim on MWNT-PMRE in H2SO4 supporting electrolyte with concentration of 0.6 mol/L was irreversible and was mainly controlled by diffusion. Some parameters of the electrochemical process were evaluated. The impacts of experiment conditions on the electrochemical behavior of carbendazim were studied. A good linearity relationship between peak current and concentration of carbendazim in the range of 2.0 × 10−7-1.0 × 10−5 mol/L was found, of which the equation was Ip(A) = −1.149 × 10−5 − 2.301c (mol/L), the correlative coefficient R = −0.9953 and detection limit was 9.0 × 10−9 mol/L. The recovery was between 90.3% and 94.7%.  相似文献   

11.
The activity of the mutant CYPBM3 “21B3”, which is able to use hydrogen peroxide as the final electron acceptor, was evaluated against two major environmental pollutants; organochlorine and organophosphorus pesticides. This evolved CYP from Bacillus megaterium is able to transform a variety of structurally different pesticides. The catalytic parameters for two organochlorine; dichlorophen (kcat = 9.2 min−1, KM = 64.1 μM) and linuron (kcat = 226.5 min−1, KM = 468.2 μM), and two organophosphorus compounds; parathion (kcat = 10.9 min−1, KM = 59.3 μM) and chlorpyrifos (kcat = 9.2 min−1, KM = 226.5 μM) were determined giving catalytic efficiencies between 0.143 and 1.107 min−1 μM−1. CYPBM3 “21B3” has the ability to both activate and detoxify organophosphorus pesticides, as demonstrated by the chemical nature of the reaction products. The capacity to transform structurally diverse compounds together with the great stability, easy production and relatively inexpensive cofactors needed, makes CYPBM3 “21B3” an enzyme with a potential use on the environmental field.  相似文献   

12.
The features of two insecticides (chlorpyrifos and cypermethrin) binding to two blood proteins, bovine serum albumin (BSA), and bovine hemoglobin (BHb), were investigated via the fluorescence method. The results revealed that both insecticides caused the fluorescence quenching of BSA and the fluorescence enhancement of BHb. A new parameter (FE), i.e., the fluorescence intensity when adequate insecticide was added, was introduced to obtain the association constant (KA) and the number of binding sites (n). KA and n of chlorpyrifos and cypermethrin binding to BSA were 2.99 × 105 and 5.22 × 105 L mol−1, 1.25 and 0.78, respectively. KA and n of chlorpyrifos and cypermethrin binding to BHb were 2.94 × 104 and 2.48 × 104 L mol−1, 1.75 and 2.19, respectively. In conclusion, chlorpyrifos and cypermethrin could bind to BSA and BHb, and the binding of both insecticides to BSA was significantly stronger than that of insecticides to BHb. These could affect the distribution, metabolism, and excretion of insecticides.  相似文献   

13.
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14.
Effects of deltamethrin on voltage-sensitive calcium channels (VSCC) from rat brain (Cav2.2) expressed in Xenopus oocytes were assessed electrophysiologically. Deltamethrin reduced peak current of wild-type Cav2.2 in a stereospecific and concentration-dependent manner with an EC50 of 1 × 10−9 M. Phosphorylation of threonine 422 enhances voltage-sensitive calcium current, increases the probability that Cav2.2 will open under depolarizing conditions and antagonizes the inhibition of the channel by the betagamma subunit of heterotrimeric G-protein (Gβγ). Site-directed mutagenesis of threonine 422 to glutamic acid (T422E) results in a channel that acts as if it were permanently phosphorylated. Deltamethrin (10−7 M) significantly enhanced peak current via the T422E channel (1.5-fold) compared to the nontreated control and the increase was significantly greater than for either the wild-type (T422) or T422A (permanently unphosphorylated mutant) channels. The effect of deltamethrin on T422E Cav2.2 was stereospecific and concentration-dependent with an EC50 of 9.8 × 10−11 M. Thus, Cav2.2 is modified by deltamethrin but the resulting perturbation is dependent upon the phosphorylation state of threonine 422.  相似文献   

15.
In order to gain insight into the development of insecticides with novel modes of action, the effects of salicylidene aniline (a), salicylidene-4-chloroaniline (b), salicylidene-4-bromoaniline (c), and salicylidene-4-nitroaniline (d) on partially purified phenoloxidase (PO) from Pieris rapae L. were investigated. The results showed that the 4 compounds could inhibit PO activity, and the inhibitor concentrations leading to a loss of 50% activity (IC50) were estimated to be 0.025 mmol L−1, 0.732 mmol L−1, 0.471 mmol L−1, and 0.675 mmol L−1, respectively. Meanwhile, all the inhibitors showed reversible competitive inhibition, except (d), which showed reversible mixed inhibition. The KI values were determined as 0.106 mmol L−1, 10.059 mmol L−1, 8.390 mmol L−1, and 20.198 mmol L−1 for the four compounds, respectively. The UV-vis spectra of (a) and (d) in the presence of copper ions and the enzyme showed that (a) could directly chelate the copper ions of PO; however, (d) could neither chelate the additional copper ions nor the copper ions of PO.  相似文献   

16.
Malathion is an organophosphate (OP) pesticide that has been shown to induce oxidative stress in brain through the generation of free radicals and alteration of the cellular antioxidant defense system independent of its anticholinesterase effects. The aim of this study was to investigate the possible protective role of rolipram as a selective phosphodiesterase (PDE) type 4 inhibitor, on toxicity of malathion, by measuring the activities of brain mitochondrial and plasma peroxynitrite (ONOO−), glutathione peroxidase (GPx), superoxide dismutase (SOD), Mn-SOD, catalase (CAT), and lipid peroxidation (LPO) in rats. Effective doses of malathion (200 mg/kg/day) and rolipram (200 μg/kg/day) were administered alone or in combination for 7 days by intraperitoneal injection. At the end of the experiment, the brain mitochondria and plasma of the animals were separated. In the brain cells mitochondria and blood plasma, the LPO, ONOO−, and GPx were higher in the malathion group as compared with controls. Rolipram ameliorated all of malathion-induced changes. Plasma CAT decreased in malathion-treated animals while it increased in brain mitochondria comparing with controls. Co-administration of rolipram with malathion improved CAT in both brain mitochondria and plasma. Malathion and rolipram did not alter total SOD or Mn-SOD in the plasma while both caused a significant elevation in brain mitochondria. In conclusion, this model of study that we employed, in a large extent, characterized the relationships among malathion-induced neurotoxicity, mitochondrial dysfunction, and significant increase in systemic and local oxidative/nitrosative stress in plasma and brain, respectively. Intracellular cAMP-elevating agents like rolipram, may be considered beneficial for the protection or recovery of malathion-induced toxic damage in brain mitochondria and blood.  相似文献   

17.
In an attempt to find the biorational pesticides, we synthesized 12 pyridinyl derivatives of podophyllotoxin (PPT) and 4′-demthylepipodophylltoxin (4′-DMEP) in this study. Their structures and the α/β substitution at C-4 were confirmed by 1H NMR, IR, MS spectral analyses and elemental analysis. The insecticidal activities were tested against fifth-instar larvae of Pieris rapae and the third-instar larvae of Cullex pipiens pallens at concentrations of 250 and 10 μg ml−1. Four derivatives of PPT, 4.1, 4.2, 4.3 and 4.5, showed higher insecticidal activities against P. rapae than PPT, while three derivatives of PPT, 4.4, 4.5 and 4.6, displayed higher mosquito larvicidal activity than PPT, with LC50 values of 1.66, 3.96 and 1.54 mg l−1, respectively. Interestingly, we also found that the pyridine ring derivatives of PPT showed delayed insecticidal activity, which is different from traditional neurotic insecticides. The results suggest that 4′-OCH3 in the PPT derivatives is essential to keep the insecticidal activity and the insecticidal activities of pyridine ring derivatives of PPT are higher than that of the derivatives of 4′-DMEP, supporting PPT has the potential to be a lead structure of semi-synthetic insecticides.  相似文献   

18.
Recovery study was performed at regular intervals to establish the time course of 50% and 100% recovery in neurotransmitter enzyme (acetylcholinesterase, AChE, EC 3.1.1.7) and locomotor behaviour response of mosquito fish, Gambusia affinis exposed to lethal concentration (20.49 mg L−1) of an organophosphorous pesticide, monocrotophos (MCP) for 96 h. In vitro AChE activity studies indicated that MCP could cause 50% inhibition (I50) at 10.2 × 10−5 M. A positive correlation was observed between brain AChE activity and swimming speed during the recovery study. Also, the recovery response of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) as well as lipid peroxidation (LPO) as biomarkers of oxidative stress were assessed in viscera of G. affinis. The results showed that the MCP besides its inhibitory effect on target enzyme AChE activity and induction in antioxidant enzyme activities as a characteristic of oxidative stress, which can be used as biomarkers in the pesticide contaminated aquatic streams.  相似文献   

19.
Potential genotoxicity of sulcotrione 2-(2-chloro-4-(methylsulfonyl)benzoyl)-1,3-cyclohexanedione, a selective triketonic herbicide was evaluated on Vicia faba seedlings in hydroponic culture conditions. Sulcotrione (10−5, 10−4 and 2 × 10−4 M) treatments for 45 h, caused a dose dependent increase in micronuclei frequencies in root meristematic cells. Cytological analysis of root tips cells showed aneugenic effects of the sulcotrione on the plant root meristems. Sulcotrione induced chromosomal alterations at the lowest concentration used (10−5 M) when incubated for 42 h, indicating the potent mutagenic effect of this element. This is the first report for the genotoxicity of such a sulcotrione herbicide.  相似文献   

20.
The brown planthopper (BPH), Nilaparvata lugens Stål, is a primary insect pest of cultivated rice, and its effective control is essential for crop production. However, in recent years, outbreaks of the brown planthopper have occurred more frequently in China. In order to determine the causes and mechanisms of insecticide-induced BPH resurgence and perform population management, we conducted the following studies. By the topical application method, our results showed that, fenvalerate acted as stimulus of fecundity from 3.50 × 10−3 to 2.02 × 10−2 μg/female in the BPH. Apart from 7.00 × 10−3 μg/female, the number of hatched nymphs was increased gradually with an increase in application dose from 3.50 × 10−3 to 1.74 × 10−2 μg/female. After continuous selection with fenvalerate for 11 generations by the rice-stem dipping method, a resistant strain was achieved with medium resistance to fenvalerate (RR 39.22). Life table study indicated that the resistant strain (G4 and G8) showed reproductive advantages, including increased female ratio, copulation rate and fecundity. But the hatchability of resistant strain was lower. The survival rate and emergence rate were significantly lower in G4 and G8 resistant strain. Resistant strains in G4 and G8 showed a fitness advantage (1.04 and 1.11), and the number of offspring in G8 generation was higher than that in G4 generation. The significant difference detected between resistant insects (G4, G5, G8 and G9) and S-strain contains not only the effect of resistant selection but also the effect of continuous rearing itself. Hence it was concluded that the BPH had the potential to develop high resistance against fenvalerate and the induction of the nymphs by sublethal doses of fenvalerate was of importance in the BPH population management, particularly in the predicting. Further studies demonstrated that triphenyl phosphate (TPP) and diethyl maleate (DEM) had no synergism on fenvalerate. However, piperonyl butoxide (PBO) displayed significant synergism in susceptible strain (1.97) and resistant strain (2.73). We concluded that esterase and glutathione S-transferase play little role in fenvalerate detoxification. The increase of the P450-monooxygenases detoxification is an important mechanism for fenvalerate resistance. Because their resistant populations had a fitness advantage, we should pay close attention to the occurrence of BPH and use other functionally different insecticides to control the BPH.  相似文献   

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