Larval Acetylcholinesterase Research Articles

Synthesis, characterization and larvicidal studies of ethyl 3-benzoyl-7-(piperidin-1-yl)indolizine-1-carboxylate analogues against Anopheles arabiensis and cheminformatics approaches

According to WHO, in 2021, there was an estimation of 247 million malaria cases from 84 malaria-endemic countries. Globally an estimated count of 2 billion malaria cases and 11.7 million deaths due to malaria were recorded in the past two decades. Further, the emergence of drug-resistant mosquitos threatens mankind. Therefore, the development of newer larvicidal agents is the need of the hour. This research identifies a new series of variably substituted indolizines for their effectiveness in controlling Anopheles arabiensis larvae through larvicidal activity. The series of Ethyl 3-benzoyl-7-(piperidin-1-yl)indolizine-1-carboxylate analogues (4a-j) were synthesized by reacting 4-(piperidin-1-yl)pyridine, phenacyl bromides with ethyl propiolate via 1, 3-dipolar cycloaddition and the green metrics of the process are reported. All the newly synthesized compounds were characterized by spectroscopic techniques such as 1H NMR,13C NMR, FT-IR, and HRMS. The larvicidal effectiveness of the newly synthesized compounds was assessed against Anopheles arabiensis. Among the compounds studied, namely 4c, 4d, 4e, and 4f, displayed the most notable larval mortality rates within the series, reaching 73%, 81%, 76%, and 71% respectively, in contrast with the negative control acetone. In comparison, the standard Temephos exhibited a mortality rate of 99% at the same concentration. Furthermore, computational approaches including molecular docking and molecular dynamics simulations identified the potential targets of the series compounds as the larval Acetylcholinesterase (AChE) enzyme and the Sterol Carrier Protein-2 (SCP-2) protein. However, it is essential for these computational predictions to undergo experimental validation. Communicated by Ramaswamy H. Sarma

Larvicidal and Antifeedant Effects of Copper Nano-Pesticides against Spodoptera frugiperda (J.E. Smith) and Its Immunological Response.

This study aimed to synthesize and evaluate the efficacy of CuO NPs (copper oxide nanoparticles) with varying test concentrations (10-500 ppm) against larvicidal, antifeedant, immunological, and enzymatic activities against larvae of S. frugiperda at 24 h of treatment. Copper nanoparticles were characterized by using a scanning electron microscope (SEM) and energy dispersive X-ray (EDaX) analysis. The EDaX analysis results clearly show that the synthesized copper nanoparticles contain copper as the main element, and the SEM analysis results show nanoparticle sizes ranging from 29 to 45 nm. The CuO NPs showed remarkable larvicidal activity (97%, 94%, and 81% were observed on the 3rd, 4th, and 5th instar larvae, respectively). The CuO NPs produced high antifeedant activity (98.25%, 98.01%, and 98.42%), which was observed on the 3rd, 4th, and 5th instar larvae, respectively. CuO NPs treatment significantly reduced larval hemocyte levels 24 h after treatment; hemocyte counts and sizes changed in the CuO NPs treatment compared to the control. After 24 h of treatment with CuO NPs, the larval acetylcholinesterase enzyme levels decreased with dose-dependent activity. The present findings conclude that CuO NPs cause remarkable larvicidal antifeedant activity and that CuO NPs are effective, pollution-free green nano-insecticides against S. frugiperda.

The aquatic macrophyte Salvinia molesta mitigates herbicides (glyphosate and aminomethylphosphonic acid) effects to aquatic invertebrates.

We evaluated the individual and combined effects of different environmentally representative concentrations of glyphosate (0, 25, 50, 75, and 100µgl-1) and aminomethylphosphonic acid (AMPA; 0, 12.5, 25, 37.5, and 50µgl-1) on the physiology of Aedes aegypti larvae, as well as the capacity of the aquatic macrophyte Salvinia molesta to attenuate those compounds' toxicological effects. Larvae of Ae. aegypti (between the third and fourth larval stages) were exposed for 48h to glyphosate and/or AMPA in the presence or absence of S. molesta. Glyphosate and AMPA induced sublethal responses in Ae. aegypti larvae during acute exposures. Plants removed up to 49% of the glyphosate and 25% of AMPA from the water, resulting in the exposure of larvae to lower concentration of those compounds in relation to media without plants. As a result, lesser effects of glyphosate and/or AMPA were observed on larval acetylcholinesterase, P450 reductase, superoxide dismutase, mitochondrial electron transport chain enzymes, respiration rates, and lipid peroxidation. In addition to evidence of deleterious effects by media contamination with glyphosate and AMPA on aquatic invertebrates, our results attest to the ability of S. molesta plants to mitigate the toxicological impacts of those contaminants.

Insecticidal and acetylcholinesterase inhibitory activities of Achillea biebersteinii essential oil and its nanoemulsion and major monoterpenes against Tribolium castaneum

• EO of Achillea biebersteinii was obtained and analyzed using (GC–FID) and (GC–MS). • Oil-in-water nanoemulsion was prepared and characterized from EO. • EO, nanoemulsion and monoterpenes were insecticidal and reduced T . castaneum progeny. • Botanicals significantly inhibited the larval acetylcholinesterase activity. • There is potential for using the test EO products as natural grain protectants. Essential oil (EO) was hydrodistilled from Achillea biebersteinii and analyzed using gas chromatography–flame ionization detection (GC–FID) and (GC–MS). Three monoterpenes, α-terpinene, p -cymene, and camphor were isolated as the main terpenes in the EO. Oil-in-water nanoemulsion (particle size 52.7 ± 4.4 nm) was prepared and characterized from EO through a hydrothermal approach. The EO products caused insecticidal effects and altered F 1 progeny of the red flour beetle, Tribolium castaneum (Herbst) in a dose and exposure time-dependent manner. The nanoemulsion was superior in bioactivity, followed EO. At 12.5 µl/cm 2 , nanoemulsion and EO caused 100% mortality of the second larvae after 4 days of exposure with reduction of F 1 progeny of 100.0 and 89.2%, respectively. At 50.0 µl/cm 2 , percentage mortality and reduction in progeny of EO products ranged between (61.4–100%) and (53.0–100%), respectively. Upon fumigation, nanoemulsion at 10 µl/L air caused 100% mortality of the second larvae after 4 days of exposure. At 20 µl/L air and 4 days after treatment, percentage mortality with the remainder botanicals ranging between 64.7 and 100. LC 50 ′s of products after 48 h exposure ranging between 6.7 and 58.1 µg/cm 2 in insecticidal bioassay, and between 3.6 and 26.3 µl/L upon fumigation. Botanicals caused a remarkable inhibition of acetylcholinesterase activity (AChE), where nanoemulsion (IC 50 = 14.22 mM), EO (IC 50 = 35.12 mM) and camphor (IC 50 = 23.93 mM) were superior as AChE inhibitors. There is a potential for using of A. biebersteinii EO, its nanoemulsion and monoterpenes as natural grain protectants after the required toxicological investigations.

Chemical profile, mosquitocidal, and biochemical effects of essential oil and major components of Dysphania ambrosioides against Culex quinquefasciatus Say

To seek new mosquito control agents while avoiding the environmental impacts and toxicity hazards of conventional pesticides, the essential oil of Dysphania ambrosioides was obtained by hydrodistillation and analysed using GC-FID and GC-MS. The compounds 1-methyl-4-(1-methylethyl)-2,3-dioxabicyclo[2.2.2]oct-5-ene (cis-ascaridole), 1-methyl-4-(1-methylethyl) benzene (р-cymene), and 1-isopropyl-4-methyl-1,3-cyclohexadiene (p-mentha-1,3-diene also known as α-terpinene) were identified as the major components. The EO and the major fractions showed remarkable mosquitocidal activity against third instar larvae and adults of Culex quinquefasciatus Say. The oil and fractions were assayed at 3.125, 6.25, 12.5, 25, and 50 μl/l. Mortality was time- and dose-dependent. At 24 h post-exposure at an assayed concentration of 50 μl/l, the larval and adult mortalities ranged between 80.11-100% and 91.22-100%, respectively. Strong larvicidal and adulticidal activities were recorded in the cases of the crude oil and cis-ascaridole. The LC50 values after 24 h of treatment ranged between 6.2-20.1 μl/l and 5.1-13.9 μl/l against larvae and adults, respectively. The corrected percentage mortalities increased over time with the tested plant oil and the major fractions relative to the control. The time required to achieve 50% mortality (LT50) decreased remarkably with all treatments. The tested EO and major fractions effectively inhibited larval acetylcholinesterase activity with IC50 values ranging from 8.44 to 64.80 mM compared with 2.08 × 10-3 mM for the reference standard, methomy. The results indicate the potential of developing natural mosquitocides against C. quinquefasciatus based on the tested EO and its major fractions. Graphical abstract.

Effects of Space Spray Application Methods on Fenitrothion Efficacy and Development of Resistance in Culex pipiens

Efficacy of fenitrothion as thermal fogging (TF) or ultra-low volume (ULV) applications against 6 successive generations of caged adult Culex pipiens and subsequent development of resistance in both adults and larvae were investigated in this study. In addition, larval acetylcholinesterase (AChE) activity was measured in each generation. Results indicated that the ULV application method was significantly more effective (P < 0.05) than TF against the adults in all treated generations. Selection pressure of TF and ULV applications on the adults after 5 generations resulted in larval resistance by ratios of 30.92- and 28.18-fold, respectively. A gradual decrease in the larval AChE activity was observed with increasing resistance as generations progressed. The AChE activity of susceptible larvae was higher than that of the F5 resistant generation in TF and ULV treatments by 6- and 8-fold, respectively. The results indicated that both the biological efficacy of fenitrothion and the rapidity of resistance development were affected by the application methods.

Azinphosmethyl exposure to grass shrimp (Palaemonetes pugio) life stages with emphasis on larval acetylcholinesterase activity.

Azinphosmethyl exposure to grass shrimp (Palaemonetes pugio) life stages with emphasis on larval acetylcholinesterase activity.

Mechanism of Abrupt Increase in Toxicity of Organophosphorothionates to Tiger Shrimp Larvae with Progress of Stages

To elucidate the cause of an abrupt increase in the toxicity of organophosphorus pesticides to tiger shrimp Penaeusjaponicus with the progress of larval stages, the toxicity of the pesticides to the shrimp larvae and the inhibition of larval acetylcholinesterase (AChE) by the pesticides, and the metabolism of fenitrothion(FS) in the larvae were studied at different stages, respectively. The toxicity of thiono-forms to the larvae increased abruptly with the progress of stages, whereas that of oxo-forms was unchanged from nauplius to postlarva. The susceptibility of larval AChE to each pesticide was almost unchanged in these stages. FS metabolic activity of zoea was very low, but the activity increased abruptly with their growth and resulted in the increase of fenitro-oxon which displays extremely high toxicity as compared with FS, i.e., the increase in the toxicity of thiono-forms to shrimp larvae with the progress of the stages must be due to the increase in the oxidative desulfuration activity.

Effect of salithion enantiomers on larval growth, carbohydrases, acetylcholinesterase, adenylate cyclase activities and cyclic adenosine 3',5'-monophosphate level of Musca domestica and Tribolium castaneum.

Dietary (R)(+)-salithion was a more potent insecticide (LC50 = 9.3 ppm) than the (S)(−)-enantiomer (LC50 = 63 ppm), correlating acetylcholinesterase (AChE) inhibition in vivo (I50 = 7.7 and 63 ppm) against Tribolium castaneum larvae. (S)(−)-Salioxon derived from (R)(+)-salithion had a stronger inhibitory activity (I50 = 8.8µm) than the (R)(+)-enantiomer (I50 = 22µm) in vitro against larval AChE. However, against Musca domestica female adults, a reversed tendency was observed: (S)(−)-salithion and (R)(+)-salioxon were more potent than (R)(+)-salithion and (S)(−)-salioxon in topical insecticidal and anticholinesterase activities in vivo and in vitro, respectively. Hence, the reversed stereospecificity between the T. castaneum larvicidal and M. domestica insecticidal activities of salithion enantiomers is due to a stereospecific difference in the intrincic potency of salioxon enantiomers as an AChE inhibitor with the two insects. A suppression of M. domestica larval growth, gut amylase and invertase activiti...

Acetylcholinesterase of Schistosoma mansoni: purification and characterization.

Larval acetylcholinesterase (acetylcholine acetylhydrolase) EC 3.1.3.7 of the trematode Schistosoma mansoni was characterized and purified by affinity chromatography. The enzyme was solubilized from sonicated cercarial tissue and showed a Km value of 1.83 mM and a Vmax value of 102 U/mg protein. It was characterized as a true AChE since it hydrolyses acetylthiocholine more than seven times faster than butyrylthiocholine, and since it was inhibited by high concentrations of substrate. The enzyme was purified by affinity chromatography on a Sepharose column of the inhibitor [N-(6-aminocaproyl-6-aminocaproyl)-m-aminophenyl] trimethyl ammonium. The purified enzyme eluted from the column by decamethonium bromide migrated as a single band of 500 kD on nondenaturing polyacrylamide gel electrophoresis (PAGE), whether stained for proteins or for enzymatic activity. Analysis by SDS-PAGE revealed two major polypeptide bands of 76 kD and 30 kD. By labeling the enzyme with 3H-DFP (di-isopropyl-fluorophosphate), the 30-kD polypeptide was shown to contain the active site of the enzyme, with an additional labeled band of 110 kD also being detected. On the basis of our data we suggest that the principal species of S. mansoni AChE is a tetramer of four subunit polypeptides each of MW ca. 110 kD which are not linked by disulfide bonds, and which are further cleaved into two fragments, one of MW 76,000 and one of MW 30,000, the latter bears the active site.

Purification and characterization of an ascidian larval acetylcholinesterase

Larval acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) of the ascidian Ciona intestinalis (L.) was purified by a two-step affinity chromatography procedure. Concanavalin A-Sepharose chromatography in batches provided the initial purification and was followed by chromatography on columns to which competitive inhibitors of acetylcholinesterase had been attached. The most efficient of these used m-carboxyphenylmethylammonium iodide coupled to Sepharose 4B via a hydrophobic 6-carbon spacer. In combination with the concanavalin A-Sepharose step, this affinity resin yielded recoveries of 30–39% with specific activities ranging from 580–730 units/mg protein, a total purification of 5000–7000-fold. Analysis of this product by polyacrylamide gel electrophoresis in the presence of SDS and β-mercaptoethanol revealed a single major polypeptide of M r 65 000–70 000. This protein was identified as the basic catalytic subunit of acetylcholinesterase by its coelectrophoresis with [ 3H]diisopropyl fluorophosphate-labeled enzyme. Sucrose density gradient studies demonstrated that the purified enzyme consisted of three distinct species that appeared to be qualitatively the same as those seen in crude extracts. The largest species (11 S) is possibly a tetramer of the basic catalytic subunit and the two smaller forms, the monomer and dimer. Purified enzyme was also used to produce anti-acetylcholinesterase antibody in rabbits. IgG prepared from the sera of immunized rabbits was shown to react completely (greater than 98%) with acetylcholinesterase from crude larval homogenates. This result also supports the conclusions that no qualitative selection occurred during the purification procedure and that the basic catalytic subunit is a fundamental component of all the larval acetylcholinesterases.