Methomyl Research Articles

Enhancing soil health, microbial count, and hydrophilic methomyl and hydrophobic lambda-cyhalothrin remediation with biochar and nano-biochar

Pesticide contamination and soil degradation present significant challenges in agricultural ecosystems, driving extensive exploration of biochar (BC) and nano-biochar (NBC) as potential solutions. This study examines their effects on soil properties, microbial communities, and the fate of two key pesticides: the hydrophilic methomyl (MET) and the hydrophobic lambda-cyhalothrin (LCT), at different concentrations (1%, 3%, and 5% w w−1) in agricultural soil. Through a carefully designed seven-week black bean pot experiment, the results indicated that the addition of BC/NBC significantly influenced soil dynamics. Soil pH and moisture content (MC) notably increased, accompanied by a general rise in soil organic carbon (SOC) content. However, in BC5/NBC5 treatments, SOC declined after the 2nd or 3rd week. Microbial populations, including total plate count (TPC), phosphate-solubilizing bacteria (PSB), and nitrogen-fixing bacteria (NFB), showed dynamic responses to BC/NBC applications. BC1/NBC1 and BC3/NBC3 applications led to a significant increase in microbial populations, whereas BC5/NBC5 treatments experienced a decline after the initial surge. Furthermore, the removal efficiency of both MET and LCT increased with higher BC/NBC concentrations, with NBC demonstrating greater efficacy than BC. Degradation kinetics, modeled by a first-order equation, revealed that MET degraded faster than LCT. These findings underscore the profound impact of BC/NBC on pesticide dynamics and microbial communities, highlighting their potential to transform sustainable agricultural practices.

Pesticide residues in traditional and industrial honey marketed in Morocco and potential health risk

ABSTRACT This study evaluated the presence of the three pesticides methomyl (MET), carbendazim (CBZ) and chlorpyrifos-ethyl (CPE), as well as the degradation product of CPE (3,5,6-trichloro-2-pyridinol; TCP), in 44 honey samples from all 12 regions of Morocco. With a validated HPLC-UV method occurrence frequencies of 63.6% for MET, 54.5% for CBZ, 95.1% for CPE and 34.1% for TCP were obtained, even at concentrations higher than the maximum residue limits for MET, CPE and TCP. Based on the predominant pesticide, principal component analysis separated sampling regions into three groups. Risk assessment indicated that ingestion of these pesticides, alone or in combination, in honey did not pose a risk to consumers (HQ and HI < 1).

Removal of methomyl in water by leaves-generated biochar: Effect of metallic coating, kinetics, and important role of hydroxyl radical

Methomyl (MET) can exist as fatal water pollutant due to its high leachability, and solubility, which is urgently to be efficiently removed. This work investigated its removal in water by cost-effective biochar; in which, the efficiencies of leaves-generated biochar (BC) as non-modified adsorbent, and copper oxide coated BC (COBC) and hematite (Fe2O3) coated BC (MBC) as modified adsorbents were compared. At initial concentration of 20.0 mg/L in purified water, the respective removals by BC, COBC, and MBC were 21.3 %, 16.4 %, and 18.9 % within 360 min at 0.5 g/L dosage, which were increased to 33.8 %, 18.9 %, and 26.1 % at an increased dosage of 1.0 g/L. However, the removal efficiencies of combined method with non-modified, and the modified adsorbents were increased less. The removal was increased from 33.8 % to 47.0 % by increasing BC dosage to 1.5 g/L, and removal was further increased to 54.0 % when MET concentration was decreased to 10.0 mg/L. The removal of MET by BC was pH-dependent as it could be increased up to 80.0 % at pH 11.0; while, the influence of temperature was slight. With analyses of the effect of dissolved oxygen, and free-radical quenching experiment, both the adsorption, and hydroxyl radical (•OH) induced degradation were found responsible for removal. Finally, removal in tap water (TW) was investigated, which indicated that the leaves-generated BC was suitable for MET removal in real water.

Effects of methomyl on the intestinal microbiome and hepatic transcriptome of tilapia, and the modifying effects of mint co-culture

Methomyl (MET) is an oxime carbamate insecticide that can contaminate aquatic systems resulting in toxicological effects. It can harm some fish species possibly through the anti-oxidative, phagosome pathway. Mint is one of the most widely herbal plants exhibiting antioxidant activities. In this study, we investigated the impact of MET on the antioxidant system of Oreochromis niloticus in presence of mint as a floating bed. Results revealed that the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, and glutathione S-transferase significantly decreased and the GSH content significantly increased in the intestine. The hepatic peroxisome proliferator-activated receptor (PPAR) signalling pathway, carbon metabolism, renal phosphoinositide 3-kinase (PI3K)-Akt, mitogen-activated protein kinase (MAPK) signalling pathway, and phagosomes were significantly affected. Upon long-term exposure, circadian rhythm and phagosomes were enriched in the liver and kidney. However, mint increased the enriched pathways of Toll-like receptor, PPAR, p53, NF-kappa B, MAPK, oestrogen, and B cell receptor signalling pathways. MET with different concentrations destroyed the balance of gut microbiota, mint decreased Verrucomicrobia and Akkermansia for the maintenance resulted from MET. Cetobacterium had a positive impact on total nitrogen (TN), chemical oxygen demand (CODMn), and glutathione reductase (GR), while Akkermansia had a positive impact on feed conversion ratio (FCR), SOD and CAT, and the abundance of both decreased due to MET exposure. High mint density removed more concentrations of nitrogen and phosphorus in the tilapia cultivation wastewater. Therefore, planting with mint can alleviate the toxicological effects produced by MET, shape the intestinal microbiota, and strengthen the connection between water quality and the metabolic parameters.

Mixture effects of thiamethoxam and seven pesticides with different modes of action on honey bees (Aplis mellifera)

Even though honey bees in the field are routinely exposed to a complex mixture of many different agrochemicals, few studies have surveyed toxic effects of pesticide mixtures on bees. To elucidate the interactive actions of pesticides on crop pollinators, we determined the individual and joint toxicities of thiamethoxam (THI) and other seven pesticides [dimethoate (DIM), methomyl (MET), zeta-cypermethrin (ZCY), cyfluthrin (CYF), permethrin (PER), esfenvalerate (ESF) and tetraconazole (TET)] to honey bees (Aplis mellifera) with feeding toxicity test. Results from the 7-days toxicity test implied that THI elicited the highest toxicity with a LC50 data of 0.25 (0.20–0.29) μg mL−1, followed by MET and DIM with LC50 data of 4.19 (3.58–4.88) and 5.30 (4.65–6.03) μg mL−1, respectively. By comparison, pyrethroids and TET possessed relatively low toxicities with their LC50 data from the range of 33.78 (29.12–38.39) to 1125 (922.4–1,442) μg mL−1. Among 98 evaluated THI-containing binary to octonary mixtures, 29.59% of combinations exhibited synergistic effects. In contrast, 18.37% of combinations exhibited antagonistic effects on A. mellifera. Moreover, 54.8% pesticide combinations incorporating THI and TET displayed synergistic toxicities to the insects. Our findings emphasized that the coexistence of several pesticides might induce enhanced toxicity to honey bees. Overall, our results afforded worthful toxicological information on the combined actions of neonicotinoids and current-use pesticides on honey bees, which could accelerate farther comprehend on the possible detriments of other pesticide mixtures in agro-environment.

Exposure of Pisum sativum L. Seeds to Methomyl and Imidacloprid Cause Genotoxic Effects in Pollen-Mother Cells

Pesticides are commonly used in modern agricultural systems to protect the plants from pests. Even though they potentially increase the crop yield, they have undesirable toxic effects on the consumers of plant products and nontarget host plants. However, there are limited studies to demonstrate the cytological changes induced by pesticides on plant cells. In the present study, we assess the cytological changes induced by two most commonly used insecticides, methomyl (ME) and imidacloprid (IM), using Pisum sativum L. as model plant system. P. sativum seeds were exposed to various concentrations of ME and IM (0.1, 0.2, 0.3, 0.4 and 0.5%) for 1, 3, and 6 h, and their effects on seed germination (SG), radicle length (RL), mitotic index (MI), chromosomal aberrations frequency (CAF), and micronucleus frequency (MNF) were studied. The results indicate that these insecticides decrease MI in root-tip cells, and increase in the MNF in pollen-mother cells in a dose-dependent manner. Additionally, insecticide-treated groups showed a dose- and time-dependent increase in the percentage of aberrant meiotic cells. Clumped nuclei (CNU), stickiness (STC), bridges (BRs), laggards (LGs), secondary association (SA), and precocious separation (PS) were among the frequently observed anomalies. The findings of this study indicate that commonly used insecticides ME and IM have substantial genotoxic effects on the root-tip and pollen-mother cells of P. sativum L.

Effect of Methomyl on Growth, Antioxidant System of GIFT (Oreochromis niloticus), and Residue in the Presence of Water Spinach (Ipomoea aquatica Forsk).

This study was conducted to investigate the effect of methomyl (MET) on the growth and antioxidant system of GIFT (5.28 ± 0.12, n = 180) in the presence of water spinach (Ipomoea aquatica) aas a floating bed. Four treatment groups have been established, named control (0), 2, 20, and 200 μg/L MET. Results showed that at moderate temperatures such as 25°C to 30°C, tilapia's feed consumption increased and body weight improved. SOD, CAT, and GSH in the liver of GIFT indicated the significant increase under MET exposure. MET reduced the growth rate of GIFT, and water spinach reduced part of the water quality indexes in the MET (<200 μg/L) groups. Water spinach altered GIFT's hepatic oxidation system to some extent and effectively absorbed MET in water and transferred it to itself, and the degradation time was lower than the dietary standard time which termed as 15–20 days. Growing water spinach in farmed waters partially decomposes MET and prevents it from causing damage to GIFT's liver.

Appraisal of sub-chronic exposure to lambada-cyhalothrin and/or methomyl on the behavior and hepato-renal functioning in Oreochromis niloticus: Supportive role of taurine-supplemented feed

The existing study was designed to inspect the toxicological consequences of two pesticides; lambda-cyhalothrin (LCT) and methomyl (MTM) and their combination on Nile tilapia (Oreochromis niloticus) behaviors, oxidative stress, hepato-renal function indices and microarchitectural alterations. In addition, the efficiency of taurine (TUR) to rescue their toxicity was also considered. Juvenile O. niloticus were assigned into eight groups. The control and TUR groups were fed on a basal diet and TUR-enriched (10 g kg1) diet, respectively. The other groups were fed on a basal diet, and exposed to LCT (0.079 µg L–1), MTM (20.39 µg L–1 and (LCT + MTM). The last three groups were (LCT + TUR), (MTM + TUR), and (LCT + MTM + TUR) and fed on a TUR-enriched diet during exposure to LCT and/or MTM for 60 days. The exposure to LCT and/or MTM resulted in several behavioral alterations and stress via enhanced cortisol and nor-epinephrine levels. A significant elevation of serum 8-hydroxy-2- deoxyguanosine, aspartate and alanine aminotransferases, lactate dehydrogenase, Alkaline phosphatase, urea, creatinine was also observed in these groups. Furthermore, reduced antioxidant enzymes activities, including (catlase, glutathione peroxidase, and superoxide dismutase) with marked histopathological lesions in both liver and kidney tissues were detected. The up-regulated Bax and down-regulated Bcl-2 proteins were expressed in the liver and kidney tissues of LCT and/or MTM -exposed groups. Interestingly, all the observed alterations in behaviors, biochemical indices, and histo-architecture of renal and hepatic tissues were mitigated by TUR supplementation. The findings suggest that feeding O. niloticus dietary TUR may help to reduce the negative effects of LCT and/or MTM, and can also support kidney and liver health in O. niloticus, making it a promising aquaculture feed supplement.

Methomyl, imbraclaobrid and clethodim induced cytomixis and syncytes behaviors in PMCs of Pisum sativum L: Causes and outcomes

Cytomixis is a common phenomenon observed in meiotic cells such as anther which is influenced by various factors. Use of pesticides is a common practice in agriculture. However, it is not known whether pesticides can induce cytomixis in plant cells and induce genetic variation. To understand this, the present study was planned to assess the cytomixis and syncytes behaviors in PMCs of Pisum sativum L. Seeds of P. sativum (Family: Fabaceae) were treated with different concentrations of commonly used pesticides methomyl (ME), imbraclaobrid (IM) and clethodim (CL). Seeds were treated with various concentrations (0.1, 0.2, 0.3, 0.4 and 0.5% of ME, IM and CL prepared in water) for 1 and 3 h. Effect of pesticides on pollen fertility, frequency of cytomixis, and kind of cytomixis cells was assessed. In the cytomixis cells, the cytomictic channel (CC) and direct fusion (DF), and various stages of meiosis (PI, MI, AI and TI) with cytomixis cells were observed. In addition, frequency of syncytes cell and their various stages of meiosis I (PI, MI, AI and TI) in pollen mother cells (PMCs) was assessed. During the microsporogenesis in P. sativum, the occurrence of cytomixis and syncytes at various stages of meiosis I were seen. The formation of cytoplasmic channels and direct fusing of pollen mother cells (PMCs) were both seen to cause cytomixis, with the former being more common than the latter. The percentage of PMCs with cytomixis and syncytes cells increased with increase in the concentration of pesticides. The result of the present investigation indicates that commonly used pesticides ME, IM, and CL have a significant effect on pollen fertility, frequency of cytomixis, and kind of cytomixis cells, the cytomictic channel (CC) and direct fusion (DF), in addition, frequency of syncytes cell and their various stages of meiosis I (PI, MI, AI and TI) in pollen mother cells (PMCs) on P. sativum.

Effect of methomyl on water quality, growth performance and antioxidant system in liver of GIFT (Oreochromis niloticus) in the presence of peppermint (Mentha haplocalyx Briq.) as a floating bed.

This study was conducted to investigate the effect of methomyl (MET) on water quality, growth and antioxidant system of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) in the presence of peppermint as a floating bed. The concentration of NH3-N, NO2--N, NO3--N and TP in T3 (with 200 g wet peppermint) was significantly lower (P < 0.05) than that in T2 (100 g), T1 (50 g) and control, and the nutrient removal rates were 61.90%, 31.59%, 59.86% and 45.92% in 20 days, respectively. Juveniles GIFT (5.1 ± 0.2 g) were exposed to sub-lethal concentrations of 0.2, 2.0, 20 and 200 µg/L of MET for 45 days. After 6 weeks of a feeding trial, percentage weight gain (PWG), specific growth rate (SGR) and feed conversion ratio (FCR) were significantly decreased in 0.2, 2.0, 20 µg/L MET groups respectively and increased in the 200 µg/L MET group. Compared with the control, no significant changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were detected in the 0.2 µg/L group. The significant increase in activities of SOD, CAT and GPx was accompanied by a diminution in reduced glutathione (GSH) levels resulting with tilapia exposed to 2.0, 20, or 200 µg/L for 45 days. The highest rates observed in SOD, CAT, GPx were 157.63%, 164.05% and 167.46% of the control respectively, and the lowest inhibition rate in GSH was 66.42% of the control. Peppermint as a floating bed can alleviate the adverse effects of MET, such as growth retardation and oxidative stress.

Dietary Parsley Seed Mitigates Methomyl-Induced Impaired Growth Performance, Hemato-Immune Suppression, Oxidative Stress, Hepato-Renal Damage, and Pseudomonas aeruginosa Susceptibility in Oreochromis niloticus.

The present experiment investigated the potential protective role of parsley (Petroselinum crispum) seed meal (PSM) in alleviating methomyl (MET)-adverse impacts on growth, whole-body composition, hematological indicators, hepatorenal function, immune response, oxidative status, and disease resistance to Pseudomonas aeruginosa. For this purpose, 225 healthy Nile tilapia (Oreochromis niloticus) were allotted into five groups (45 fish/group in triplicate). One group was reared in clean water and fed a non-supplemented basal diet, while the other groups were exposed to 20.39 μg L−1 MET and fed a non-fortified basal diet or basal diets supplemented with 0.5, 1.0, or 2.0% of PSM for 60 days. The obtained data revealed significantly lower weight gain, feed intake, and specific growth rate, but higher feed conversion ratio and decreases in crude protein, lipid, and ash contents in the MET-exposed fish. Anemia, leukopenia, lymphocytopenia, and esonipenia were also obvious. Furthermore, MET-exposed fish had significantly higher serum levels of hepatic enzymes and renal damage products. Nevertheless, there was a significant depletion of enzymatic and non-enzymatic antioxidants and increased malondialdehyde, myeloperoxidase, and tumor necrosis factor-α levels in MET-exposed fish. The MET exposure significantly depressed lysozyme activity, nitric oxide, complement3, acetylcholinesterase activity, total proteins, globulin, and albumin levels in O. niloticus serum. Furthermore, pathological alterations in the liver and kidney were noted. The relative percentage of survival rate in MET-exposed fish was dramatically reduced on day 14 post-challenge with P. aeruginosa. The inclusion of PSM, on the other hand, greatly alleviated most of the MET-related negative effects. Taken together, the dietary intervention with PSM has a promising role in alleviating MET-deleterious impacts, rendering parsley seeds a viable aqua feed additive for O. niloticus.

Anti-insecticides activity in cell-lines model of Thunbergia laurifolia leaf extract aiming for functional drink

Thunbergia laurifolia has been used for folklore medicine and consumed as an herbal tea in Thailand ancient times. The aim of this study was to determine the influence of aqueous crude extracts of T. laurifolia leaves on endogenous antioxidant enzyme activity, lipid peroxidation indicated by malondialdehyde (MDA) production, and anti-insecticides property using three types of cells. Murine macrophage (RAW264.7), human embryonic kidney (HEK293), and human hepatocellular carcinoma (HepG2) cells, were treated with crude extract either combined, pre, and post-treatment exposure to chlorpyrifos (CP) and methomyl (MT). Cell viability was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test to find out anti-insecticide properties. Results indicated that crude extract increased catalase (CAT) and glutathione peroxidase (GPx) activities while decreasing malondialdehyde (MDA) levels in HEK293 and HepG2 cells and improved cells viability in all cell types induced by CP and MT toxins. The crude extract provided a protection and recovery effect on CP and MT insecticides better than atropine sulfate (AS) standard drug especially in HepG2 and HEK293 cells. Therefore, it was concluded that crude extract can improve antioxidant enzymes level and can be used as anti-insecticides. However, more investigation is needed to play it safe for functional drinks by processing in animal model further.

Insight into the degradation of methomyl in water by peroxymonosulfate

Methomyl (MET) is a carbamate pesticide frequently used in agriculture, globally. Its high solubility makes it a potential water pollutant. MET can be removed by peroxymonosulfate (PMS)-based advanced oxidation processes. This study explains MET degradation by PMS-Only, pyrite (PyR)-PMS and zero-valent iron (ZVI)-PMS systems. The degradation by PMS-Only, PyR-PMS and ZVI-PMS systems was 85.4%, 94.9% and 87.0%, respectively. The generation of reactive oxygen species (ROS) and their role in degradation was elucidated by electron paramagnetic resonance (EPR) and free-radical quenching analyses, respectively. EPR analysis indicated the presence of sulfate (SO4•−) and hydroxyl (•OH) radicals. The degradation in PMS-Only and ZVI-PMS systems was not significantly inhibited by tert-butyl alcohol (TBA) and methanol (MeOH), which suggests that the degradation in both systems was not majorly carried out by SO4•− and •OH. However, furfuryl acid (FFA) resulted in reduced degradation by applied systems, which showed that singlet oxygen (1O2) was mainly responsible for degradation in all systems. These results showed that MET was majorly degraded by non-radical PMS oxidation. PMS-Only system resulted in an almost equal degradation, compared with PyR-PMS and ZVI-PMS systems. So, detailed analysis was carried out for PMS-Only system. Hence, experiments were conducted to investigate the effect of PMS concentration, MET concentration, pH and temperature on the degradation by PMS-Only system, which showed that PMS-Only system was efficient from pH 5.0 to pH 9.0, and from 10.0 °C to 40.0 °C. Further, PMS-Only system has a potential for effective degradation in real waters because it resulted in 66.5%, 63.7% and 60.4% degradation in tap water, lake water and sewage water, respectively.

Green Tea Attenuates methomyl-Induced Cardiac Toxicity Through Modulating Oxidative Stress and Nuclear Factor kappa B Up- Regulation in Mice

ABSTRACT Methomyl (ME) is a carbamate insecticide that is causes a change in biochemical parameters and affects the oxidative state in the body through the production of free radicals. Herbal medicines derived from plant extracts are useful in treating many diseases, as they are considered natural antioxidants that have a protective role against toxins. This study aimed to evaluate the ability of green tea extract (GTE) to treat ME-induced cardiac toxicity in experimental animals. The experimental animals were divided into five groups. Blood and tissue were collected to estimate the biochemical parameters. ME caused significantly elevated levels of AST, LDH, NF-κB, and malondialdehyde. While a significant decrease was observed in levels of superoxide dismutase, a decrease in glutathione and glutathione-S-transferase was observed. Alterations in these biochemical markers were referred to oxidative stress-induced cardiac damage. The administration of GTE at a concentration (1.5%) to the ME treated group caused the tested biochemical parameters to appear close to those of the control group. GTE alleviates ME-induced oxidative stress in female albino mice. A higher concentration of GTE {1.5%} appears to have a better therapeutic effect than a lower concentration of extract {0.75%} in cardiac toxicity ME.

Assessing the combined toxicity of carbamate mixtures as well as organophosphorus mixtures to Caenorhabditis elegans using the locomotion behaviors as endpoints

Carbamate pesticides (CMs) and organophosphorus pesticides (OPs) have been widely used in agriculture and toxicologically affect non-target organisms. Although there are many reports about their toxicities, the combined behavioral toxicities of CM/OP mixtures on Caenorhabditis elegans have rarely been studied. In this study, body bend inhibition (BBI), head thrash inhibition (HTI), and swimming speed inhibition (SSI) by CMs and OPs were chosen as the toxicity endpoints. The locomotion behavioral toxicities of individual pesticides (carbofuran (CAR), methomyl (MET), chlorpyrifos (CPF), and triazophos (TAP)) and their binary mixtures on C. elegans were determined systematically and the toxicological interaction profiles of various CM/OP mixture rays constructed using the combination index. It was shown that four pesticides and their binary mixture rays have significant inhibitory effects on the locomotion behavior of C. elegans; that is, they produce locomotion behavioral toxicities and the toxicity of two OPs is higher than those of two CMs. The toxicological interactions in the binary CM and OP mixtures are different from each other. For example, one mixture ray (CAR-MET-R1) in the CM system on the SSI endpoint exhibits synergism at all concentration levels, another ray (CAR-MET-R3) displays low-dose synergism and high-dose additive action on BBI and HTI endpoints, and weak synergism at high-dose on SSI, and other rays perform additive action. Two rays (CPF-TAP-R1 and CPF-TAP-R2) in the OP mixture system display low-dose additive action and high-dose antagonism on the three endpoints. Another ray (CPF-TAP-R3) shows the additive action at all concentration levels. It can be concluded that it is not sufficient to evaluate the combined toxicity of binary CM/OP mixtures using only one concentration ratio ray and that it is necessary to examine multiple concentration ratios.

Evaluation The Effect of The Aqueous Extract of Green Tea on Renal Toxicity Induced by-Methomyl in Experimental Animals Model تقییم تاثر المستخلص المائی للشای الاخضر علی تسمم الکلی المستحدث بواسطه المیثومایل فی حیوانات التجارب

Methomyl (MET) [S-methyl N-(methylcarbamoyloxy) thioacetimidate ]C5H10N2O2S] is considered as one of the most important carbamate (oximes) pesticides that is extensively utilized around the world. Carbamate compounds were found to create an alteration in biochemical parameters and affect the oxidative status of the body through producing free radicals. Herbal medicines derived from plant extracts are useful in treatment of a variety of clinical disease, they are considered as natural antioxidants that have a protective role against toxicities. The purpose of the present investigation was to assess the ability of green tea extract (GTE) to protect kidney against methomyl induced toxicity in experimental animals. The insecticide caused significant elevation in urea, creatinine, NF-κB and malondialdehyde levels, and marked decrease in the levels of superoxide dismutase, reduced glutatione and glutathione –S-transferase. Alterations in these biochemical markers occurred were referred to kidney damage and the oxidative stress induced by MET. Co-administration of GTE of higher concentration (1.5%) in combination with MET brought the tested biochemical parameters to their normal levels. The study introduced novel findings regarding to the protective effect of GTE and their mixture against MET-induced toxicity in female albino mice.

Subacute and subchronic methomyl exposure induced toxic effects on intestines via oxidative stress in male albino rats: biochemical and histopathological study

The aim of the present study was to estimate the potential toxic effects of a subacute and a subchronic exposure to methomyl (MET) on some parts of the digestive system in male albino rats. Wistar rats were exposed daily by oral gavage to 4 mg/kg body weight (b.w.) of MET over 28 days in subacute experiments and to 1 mg/kg b.w. of MET for 90 consecutive days in subchronic exposure. Plasma levels of liver function indicators (ALT, AST, ALP and LDH) were significantly elevated after administration of MET to rats. MET had significant pro-oxidative effects on the intestines, as indicated by decreases in nonenzymatic (GSH) and enzymatic antioxidant (GPx, GST and CAT) parameters and significant increases in TBARS levels in both the duodenum and colon of rats. Microscopically, the duodenum and colon of rats exposed to MET showed severe pathological changes. It could be concluded that MET profoundly altered the structure and antioxidant status of intestinal rat tissue, which might lead to intestinal and digestive dysfunctions.

Protective Effects of Pelargonium graveolens Essential Oil on Methomyl-Induced Oxidative Stress and Spatial Working Memory Impairment in Association with Histopathological Changes in the Hippocampus of Male Wistar Rats.

Introduction:Methomyl (MET) is a carbamate insecticide, used in agriculture and public health to eliminate harmful insects. Besides its advantages in agriculture, it causes neurotoxic effects. The aim of this study was to evaluate the effect of MET on Spatial Working Memory (SWM), oxidative stress parameters, and histopathological changes in the hippocampus, as well as the possible protective role of Pelargonium graveolens Essential Oil (EO).Methods:Male Wistar rats were randomized into four groups of six animals: group I as the control that received the vehicle; group II received EO (75 mg/kg b.w), group III received MET (2 mg/kg b.w); and group IV received both MET and EO. The rats were administered the respective doses orally by gavage for 28 days. SWM was assessed using Y-maze on the day before the first treatment and day 28 after the last dose. They were sacrificed by decapitation and their brains were taken for assessing oxidative stress parameters and histopathological analysis.Results:MET treatment caused SWM deficits. Furthermore, drastic changes were observed in aspartate transaminase, alanine aminotransferase, and alkaline phosphatase activities. The level of malondialdehyde significantly increased, whereas antioxidant (glutathioneS-transferase and catalase) enzyme activities significantly decreased. The CA1 region of the hippocampus of rats exposed to MET revealed severe histological alterations. However, supplementation with EO improved SWM and partially restored the activities of antioxidant systems and prevented neuronal cell damage.Conclusion:P. graveolens EO has the potential in mitigating most of the adverse effects in the hippocampus and prevents SWM impairment induced by MET toxicity.

Teratogenicity and neurotoxicity effects induced by methomyl insecticide on the developmental stages of Bufo arabicus

Methomyl (MET) is a carbamate insecticide that has been widely used to protect the crop against insects as an alternative for organophosphorus insecticide. Thus the present study aims to evaluate the potential toxic effects of MET on the developmental stages of Bufo arabicus. Tadpoles were classified into three stages (25, 37, 40). Every stage was divided into two groups, control and MET-treated group (10 ppm for two weeks) after LC50 determination in acute toxicity test for 96 h. Control and MET-treated larvae were examined at the level of morphological, histological, skeleton deformities and immunohistochemical labeling of alpha-synuclein in the spinal cord and dorsal root ganglion. MET-exposed larvae showed hyperactivity, extreme agitation, abnormal swimming and kinking tail as compared to control. Alizarin Red S-Alcian blue staining showed scoliosis in MET-treated tadpoles at 25 and 37 stages; kyphosis, retarded tail regression and reduced ossification of the phalanges of digits for both fore-and hind limbs were noted in MET-exposed tadpoles at 40 stage as compared to control. Histopathological changes in myotomes, notochord and spinal cord were shown in MET-exposed tadpoles as compared to control. Immunohistochemical examination showed an over expression of alpha-synuclein either in the neurons of the spinal cord or in the dorsal root ganglion of MET-exposed tadpoles at stage 40 as compared to control. The present study concluded that MET insecticide induces malformation and teratogenicity effects which were accompanied by neurodegenerative effects for the neurons either in the spinal cord or in the dorsal root ganglion.

Assessing interactive mixture toxicity of carbamate and organophosphorus insecticides in the yabby (Cherax destructor).

Carbamate (CB) and organophosphorus (OP) pesticides are commonly detected in aquatic ecosystems and predominantly occur as mixtures of varying complexity. These pesticides inhibit the activity of total cholinesterase (ChE) and thus have the potential to interfere with behaviours that may be essential for the survival of aquatic species. Although the effects of individual ChE insecticides on aquatic species have been reported for decades, the neurotoxicity of mixtures is still poorly understood. This study examined the chronic toxicities of two OP insecticides (chlorpyrifos (CPF) and malathion (MAL)) and one carbamate insecticide (methomyl (METH)) in binary and ternary mixtures on the ChE activity of the yabby (C. destructor). Using the concentration addition approach to estimate mixture toxicity, the observed inhibition of ChE activity caused by all binary mixtures of CPF plus MAL, CPF plus METH and MAL plus METH was additive. In ternary mixtures, all combinations of CPF, MAL and METH were either additive or antagonistic depending on the relative ratios of these chemicals in the mixtures. The effect of mixtures of these three insecticides on C. destructor has not previously been assessed, and the data suggest that individual chemical risk assessments are likely to incorrectly estimate the effect of these insecticides on C. destructor in the aquatic environment where combinations of such chemicals occur.