Although 193 states have committed to the Chemical Weapons Convention and 98% of the declared chemical weapons stockpiles have been destroyed so far, nerve agent poisoning remains a lingering threat. The recent dissemination of sarin in Syria, the assassination of Kim Jong-Nam in Malaysia, and the assault on Sergei Skripal in the United Kingdom underline the need for effective treatment. The current therapeutic options of a muscarinic receptor antagonist, an oxime, and an anticonvulsant have been unchanged for decades. Therefore, new therapeutic strategies, for example, bioscavengers and receptor-active substances, are promising concepts that have to be examined for their benefits and limitations. In order to facilitate rapid diagnosis in challenging clinical situations, point-of-care diagnostics and detection are of importance. Therapeutic guidance concerning the duration and success of the current oxime therapy via determination of the cholinesterase status can contribute to an optimal use of resources. In summary, the challenges of current and future therapies for nerve agent poisoning and key diagnostic devices will be discussed.
Extensive research on prenatal alcohol exposure has proven the potent teratogenicity of this substance of abuse. Children born to alcoholic mothers are often diagnosed with fetal alcohol syndrome (FAS). Those afflicted with FAS often have muscle weakness, muscle wasting, and atrophy. This study assessed the effects of prenatal alcohol exposure on the developing rat neuromuscular system.
A bnormal variants of plasma cholinesterase (ChE, EC. 3.1.1.8) are a rarity in this region and to date there is no reported case of suxamethonium sensitivity in the Malaysian population. We now report a case of a Malaysian Indian patient who received suxamethonium, developed prolonged apnoea and on investigation was found to be a homozygote for the silent gene. His family was screened for abnormal variants of plasma cholinesterase. The results are discussed.
Heavy metals with high chemical activity from sludge and waste release, agriculture, and
mining activity are a major concern. They should be carefully managed before reaching the
main water bodies. Excessive exposure to heavy metal may cause toxic effect to any types of
organism from the biomolecular to the physiological level, and ultimately cause death. Monitoring is the best technique to ensure the safety of our environment before a rehabilitation is
needed. Nowadays, enzyme-based biosensors are utilised in biomonitoring programmes as
this technique allows for a real-time detection and rapid result. It is also inexpensive and easy
to handle. Enzyme-based biosensors are an alternative for the preliminary screening of
contamination before a secondary screening is performed using high-performance technology.
This review highlights the current knowledge on enzyme-based biosensors, focusing on
cholinesterase for toxic metal detection in the environment.
The present study is aimed to evaluate the effects of sub-acute toxicity testing of copper sulphate (CuSO4), on behavioural, histological and biochemical changes of the Oreochromis mossambicus (black tilapia) blood tissues. The effects were assessed according to the previous results on sub-acute toxicity test after exposing fish to several concentrations (0.0, 2.5, 5.0, and 10.0 mg/L). The observations of scanning electron microscope, and transmission electron microscope studies revealed severe histopathological changes on the surface and the cellular changes in blood tissues, respectively. The morphological alterations in blood involved irregular structure of red blood cell and blood clot formation. CuSO4 affected the biochemical alteration of the blood cholinesterase also known as serum cholinesterase (ChE). Blood ChE inhibited up to 80% of activity when exposed to 10.0 mg/L CuSO4. The findings from this study can further improve the quality standards of aquaculture industry and the fundamental basis in selecting suitable strains among freshwater fish species to be used as bioindicator.
The release of pollutants, especially heavy metals, into the aquatic environment is known to have detrimental effects on such an environment and on living organisms including humans when those pollutants are allowed to enter the food chain. The aim of this study is to analyse the damage to Clarias gariepinus' liver caused by exposure to different concentrations of copper. In the present study, samples of C. gariepinus were exposed to sub-lethal copper sulphate (CuSO4) concentrations (from 0.2 to 20.0 mg/L) for 96 h. Physiological and behavioural alterations were observed with respect to their swimming pattern, mucus secretion and skin colour. Mortality was also observed at high concentrations of copper. Histopathological alterations of the liver were analysed under light, transmission and scanning electron microscopies. The liver of the untreated group showed normal tissue structures, while histopathological abnormalities were observed in the treated fish under light and electron microscopes with increased copper concentrations. Histopathological abnormalities include necrosis, melanomacrophage, hepatic fibrosis and congested blood vessels. In addition, the enzyme activity of liver cholinesterase (ChE) was also found to be affected by copper sulphate, as 100% of cholinesterase activity was inhibited at 20.0 mg/L. Thus, liver enzyme activity and histopathological changes are proven to be alternative sources for biomarkers of metal toxicity.
Introduction: Chemical pesticide is commonly used among vegetable family farmers in Sabah. There is no system to monitor adverse health effects. This study is to determine the blood cholinesterase activity and associated factors among vegetable family farmers. Methods: A cross sectional study has involved 163 farmers aged 18-60 years old. Validated questionnaire was used to assess the associated factors. Lovibond AF267 Cholinesterase Kit was used to determine the blood cholinesterase activity. Chi square test was used to determine the association between blood cholinesterase activity and socio demographic factors and work practices. Results: Approximately 23.3% of study sample had low blood cholinesterase activity. There were significant associations between low blood cholinesterase activity with older age group (p
Acetylcholinesterase (AChE) is usually used as an inhibitive assay for insecticides. A lesser
known property of AChE is its inhibition by heavy metals. In this work we evaluate an AChE
from brains of striped snakehead (Channa striatus) wastes from aquaculture industry as an
inhibitive assay for heavy metals. We discovered that the AChE was inhibited almost completely
by Hg2+, Ag2+ and Cu2+ during an initial screening. When tested at various concentrations, the
heavy metals exhibited exponential decay type inhibition curves. The calculated IC50 for the
heavy metals Hg2+, Ag2+, Pb2+, Cu2+ and Cr6+ were 0.08432, 0.1008, 0.1255, 0.0871, and 0.1771,
respectively. The IC50 for these heavy metals are comparable and some are lower than the IC50
values from the cholinesterases from previously studied fish. The assay can be carried out in less
than 30 minutes at ambient temperature.
Nerve crush injury is a well-established axonotmetic model in experimental regeneration studies to investigate the impact of various pharmacological treatments. Hericium erinaceus is a temperate mushroom but is now being cultivated in tropical Malaysia. In this study, we investigated the activity of aqueous extract of H. erinaceus fresh fruiting bodies in promoting functional recovery following an axonotmetic peroneal nerve injury in adult female Sprague-Dawley rats by daily oral administration. The aim was to investigate the possible use of this mushroom in the treatment of injured nerve. Functional recovery was assessed in behavioral experiment by walking track analysis. Peroneal functional index (PFI) was determined before surgery and after surgery as rats showed signs of recovery. Histological examinations were performed on peroneal nerve by immunofluorescence staining and neuromuscular junction by combined silver-cholinesterase stain. Analysis of PFI indicated that return of hind limb function occurred earlier in rats of aqueous extract or mecobalamin (positive control) group compared to negative control group. Regeneration of axons and reinnervation of motor endplates in extensor digitorum longus muscle in rats of aqueous extract or mecobalamin group developed better than in negative control group. These data suggest that daily oral administration of aqueous extract of H. erinaceus fresh fruiting bodies could promote the regeneration of injured rat peroneal nerve in the early stage of recovery.
A series of novel hybrid spiro heterocycles comprising pyrrolizine, spiroxindole and piperidine moieties was synthesized chemo-, regio- and stereoselectively in good yields from 1,3-dipolar cycloaddition reaction of a series of 1-acryloyl-3,5-bisarylmethylidenepiperidin-4-ones with azomethine ylides generated in situ from 5-choloroisatin and l-proline in methanol. These cycloadducts displayed significant cholinesterase inhibitory activity. Among the compounds screened, 8g and 8e, showed maximum inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinestrase (BChE) with IC50 values of 3.33 and 3.13μM, respectively.
In this study whole blood cholinesterase activities were determined (tintometric method) of agricultural pesticide users exposed to organophosphorus compounds in Indonesia, Malaysia, Sri Lanka and Thailand. Analysis of the data demonstrated a universal relationship between cholinesterase levels and the time between the last exposure to organophosphorus compounds and the day of blood collection for cholinesterase determination. It is suggested that it takes approximately 5 days before whole blood cholinesterase levels revert to their normal values. No relationship between whole blood cholinesterase levels and the sex of pesticide users was demonstrated except in Sri Lanka where female sprayers had lower values. It is suggested that these lower values are associated with the anaemic status of female agricultural workers. No relationship between whole blood cholinesterase level and age was demonstrated. The measurement of pre-exposure cholinesterase values is essential for comparison of values after pesticide application.
Novel thiazolopyrimidine derivatives have been synthesized via microwave assisted, domino cascade methodology in ionic liquid and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Among the newly synthesized compounds 6d, 6a, 6e and 6b displayed higher AChE inhibitory activity than standard drug, galanthamine, with IC50 values of 0.53, 1.47, 1.62 and 2.05μM, respectively. Interestingly, all the compounds except for 6m-r and 6x displayed higher BChE inhibitory potentials than galanthamine with IC50 values ranging from 1.09 to 18.56μM. Molecular docking simulations for 6d possessing the most potent AChE and BChE inhibitory activities, disclosed its binding interactions at the active site gorge of AChE and BChE enzymes.
Alzheimer's disease (AD) is a chronic neurodegenerative brain disease which is characterized by impairment in cognitive functioning. Orthosiphon stamineus (OS) Benth. (Lamiaceae) is a medicinal plant found around Southeast Asia that has been employed as treatments for various diseases. OS extract contains many active compounds that have been shown to possess various pharmacological properties whereby in vitro studies have demonstrated neuroprotective as well as cholinesterase inhibitory effects. This study, therefore aimed at determining whether this Malaysian plant derived flavonoid can reverse scopolamine induced learning and memory dysfunction in the novel object recognition (NOR) test and the elevated plus maze (EPM) test. In the present study, rats were treated once daily with OS 50 mg/kg, 100 mg/kg, 200 mg/kg and donepezil 1 mg/kg via oral dosing and were given intraperitoneal (ip) injection of scopolamine 1 mg/kg daily to induce cognitive deficits. Rats were subjected to behavioral analysis to assess learning and memory functions and hippocampal tissues were extracted for gene expression and immunohistochemistry studies. All the three doses demonstrated improved scopolamine-induced impairment by showing shortened transfer latency as well as the higher inflexion ratio when compared to the negative control group. OS extract also exhibited memory-enhancing activity against chronic scopolamine-induced memory deficits in the long-term memory novel object recognition performance as indicated by an increase in the recognition index. OS extract was observed to have modulated the mRNA expression of CREB1, BDNF, and TRKB genes and pretreatment with OS extract were observed to have increased the immature neurons against hippocampal neurogenesis suppressed by scopolamine, which was confirmed by the DCX-positive stained cells. These research findings suggest that the OS ethanolic extract demonstrated an improving effect on memory and hence could serve as a potential therapeutic target for the treatment of neurodegenerative diseases like AD.
Data on blood cholinesterase levels in the Malaysian population is lacking. The spectrophotometric method of Ellman was used to determine the red cell, plasma and whole blood cholinesterase (ChE) levels in 407 Malaysian blood donors. The mean+1SD for plasma ChE in females (n = 48) was 2.37 + 0.70 umol/min/ml and 2.76 + 0.75 umol/min/ml in males (n = 359). The mean plasma ChE in males was higher than in females (p < 0.001). The mean+1SD for red cell ChE in females was 9.01 + 1.20 umol/min/ml whereas in males it was 7.69 +1.30 umol/min/ml (the mean red cell ChE in females was higher than in males, p < 0.0001). The mean+1SD for whole blood ChE for females was 4.31+ 0.58 umol/min/ml and for males it was 4.95 + 0.71 umol/min/ml. The mean whole blood ChE in males was higher than in females (p < 0.0001). Sex influenced the plasma, red cell and whole blood ChE. In males the plasma ChE was affected by the race factor. The mean+1SD plasma ChE for the Malay, Chinese and Indian were 2.92 + 0.80, 2.73 + 0.71 and 2.61+ 0.73 respectively (p < 0.002). The age factor in males affected the red cell ChE with 7.88 + 1.32 in the (30-69) age group and 7.47 + 1.23 in the (15-29) age group (p < 0.005). The whole blood ChE in females was affected by blood groups. The mean+1SD whole blood ChE for blood groups A,B and O were 4.19 + 0.42, 3.93 + 0.46 and 4.49 + 0.62 respectively (p < 0.03). The significant difference is between the ChE of group B and O, but the ChE of group A could not be determined to be different from group B or O. These results serve as guidelines for our local population in the evaluation of cholinesterase levels with regard to pesticide poisoning, liver biosynthetic capacity and unusual sensitivity to succinylcholine.
From 1970 to 1984, 100 patients suffering from organophosphate poisoning were treated in the Intensive Care Unit at the University Hospital. These patients developed signs and symptoms of cholinergic over-activity and were treated with continuous intravenous atropine. Many of the patients also developed acute respiratory failure, which necessitated ventilatory support in the form of intermittent positive pressure ventilation. Other measures included the use of inotropes and nutritional support. Daily estimation of serum cholinesterase levels were useful in assessing degree of recovery of the patients from the effects of the organophosphates.
Surveys in a number of European and American populations have found the frequency of occurrence of the heterozygotes for the gene for the dibucaine-resistant variant of cholinesterase (E.C.3.1.1.8) to be relatively constant. Similar surveys in Oriental population have shown low incidence of the same gene. This study done on the multi-racial population consisting of 3 major groups shows an absence of the gene for the dibucaine resistant variant of cholinesterase. This is supported by the clinical experience in the use of suxamethonium as a single dose in more than 25,000 individuals.
Fogging activity has become one of the important methods in tackling dengue outbreaks nowadays. Despite this, it is an occupation that has known hazards namely noise and pesticides which can affect the body organs. Based on this knowledge, a cross sectional study was conducted to determine the association between hearing impairment and serum cholinesterase level among foggers from five randomly selected Health District Offices in Selangor. A total of 200 workers comprising of 100 workers exposed to fogging activity and another 100 workers not exposed were randomly selected for this study. Data was obtained through self administered questionnaire, audiometric testing and serum cholinesterase level measurement. The overall prevalence of hearing impairment was 16% with foggers having significant higher prevalence (24%) compared to the non foggers (8%) (χ2=9.52, p=0.002). Measurement of serum cholinesterase showed that exposed workers had lower level compared to the non exposed group. Similarly, those who have hearing impairment had also lower serum cholinesterase level although it was not statistically different. Among all studied factors, age and duration of exposure to fogging activities were statistically different with hearing impairment (p
Novel mono and bis spiropyrrolidine derivatives were synthesized via an efficient ionic liquid mediated, 1,3-dipolar cycloaddition methodology and evaluated in vitro for their AChE and BChE inhibitory activities in search for potent cholinesterase enzyme inhibitors. Most of the synthesized compounds displayed remarkable AChE inhibitory activities with IC50 values ranging from 1.68 to 21.85 μM, wherein compounds 8d and 8j were found to be most active inhibitors against AChE and BChE with IC50 values of 1.68 and 2.75 μM, respectively. Molecular modeling simulation on Torpedo californica AChE and human BChE receptors, showed good correlation between IC50 values and binding interaction template of the most active inhibitors docked into the active site of their relevant enzymes.
A phytochemical investigation on the ethyl acetate soluble fraction of Lonicera quinquelocularis (whole plant) led to the first time isolation of one new phthalate; bis(7-acetoxy-2-ethyl-5-methylheptyl) phthalate (3) and two new benzoates; neopentyl-4-ethoxy-3, 5-bis (3-methyl-2-butenyl benzoate (4) and neopentyl-4-hydroxy-3, 5-bis (3-methyl-2-butenyl benzoate (5) along with two known compounds bis (2-ethylhexyl phthalate (1) and dioctyl phthalate (2). Their structures were established on the basis of spectroscopic analysis and by comparison with available data in the literature. All the compounds (1-5) were tested for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities in dose dependent manner. The IC50 (50% inhibitory effect) values of compounds 3 and 5 against AChE were 1.65 and 3.43 µM while the values obtained against BChE were 5.98 and 9.84 µM respectively. Compounds 2 and 4 showed weak inhibition profile.