Acetyl- and butyrylcholinesterase inhibitory activities of sterols and phlorotannins from Ecklonia stolonifera

ABSTRACT:   As part of this study on the isolation of cholinesterase inhibitors from natural marine products, the bioactivity of the ethanolic extracts from 27 Korean seaweeds were screened using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory assays. Ecklonia stolonifera exhibited promising inhibitory properties against both AChE and BChE. Bioassay-guided fractionation of the active n -hexane and ethyl acetate (EtOAc) soluble fractions, obtained from the ethanolic extract of E. stolonifera , resulted in the isolation of the sterols; fucosterol ( 1 ) and 24-hydroperoxy 24-vinylcholesterol ( 2 ), from the n -hexane fraction and the phlorotannins; phloroglucinol ( 3 ), eckstolonol ( 4 ), eckol ( 5 ), phlorofucofuroeckol-A ( 6 ), dieckol ( 7 ), triphlorethol-A ( 8 ), 2-phloroeckol ( 9 ) and 7-phloroeckol ( 10 ), from the EtOAc fraction. Of these, compounds 2 , 9 and 10 were isolated from E. stolonifera for the first time. Compounds 4 – 7 , 9 and 10 exhibited inhibitory potential against AChE, with 50% inhibition concentration (IC₅₀) values of 42.66 ± 8.48, 20.56 ± 5.61, 4.89 ± 2.28, 17.11 ± 3.24, 38.13 ± 4.95 and 21.11 ± 4.16 μM, respectively; whereas, compounds 1 , 2 , 4 and 6 were found to be active against BChE, with IC₅₀ values of 421.72 ± 1.43, 176.46 ± 2.51, 230.27 ± 3.52 and 136.71 ± 3.33 μM, respectively. It has been suggested that the inhibition of these enzymes by the sterols and phlorotannins derived from marine brown algae could be a useful approach for the treatment of Alzheimer's disease.     

Effects of dietary caffeine on growth,body composition,somatic indexes,and cerebral distribution of acetyl‐cholinesterase and nitric oxide synthase in gilthead sea bream (Sparus aurata), reared in winter temperature

This study aims at examining the effect of caffeine administration on growth, feed efficiency, and consumption of sea bream (Sparus aurata), reared in winter temperatures. Moreover, it is questioned whether caffeine has a central action in the brain and its effects are partly mediated via central brain mechanisms. For this, we studied the influences of caffeine treatment on the cerebral pattern of the cholinergic neurotransmission and the novel neuromodulator nitric oxide (NO), by means of acetyl‐cholinesterase (AchE) and nitric oxide synthase (NOS) histochemistry. Five different diets containing 0.0, 0.1, 1.0, 2.0 and 5.0 g caffeine kg^?1 of diet were administrated to five groups of fish. Caffeine adversely affected sea‐bream growth at a concentration higher than 1 g kg^?1 diet and increased feed conversion ratio in the treatments of 2 and 5 g kg^?1 (P < 0.05). The daily consumption of feeds was similar to all groups, indicating that caffeine did not influence diet palatability. AChE‐ and NADPH‐diaphorase histochemistry showed densely labeled cells and fibers mainly in dorsal telencephalon, preoptic, pretectal, hypothalamic areas, optic tectum, reticular formation, cerebellum and motor nuclei. When compared with matched caffeine‐treated animals, no differences in the histochemical pattern and cell densities of cerebral AChE and NADPH‐diaphorase were found.     

The effects of physostigmine on the electroretinogram in the beagle dog

The purpose of the study was to correlate electroretinogram (ERG) parameters with increasing levels of plasma, erythrocyte and ocular tissue cholinesterase inhibition using the beagle dog as a model for human neurovisual toxicity. The anticholinesterase compound physostigmine was administered at various steady-state intravenous infusion rates based on pharmacokinetic estimates of plasma and red blood cell cholinesterase inhibition. The most sensitive parameter was the b-wave amplitude of the rod response, which was significantly depressed compared to pretreatment at all levels of acute cholinesterase depression. The overall maximal ERG response demonstrated a trend of declining a-and b-wave amplitudes, which corresponded with the increased levels of cholinesterase depression, but these differences were not significant. The depression of the electroretinogram rod and cone amplitudes appeared to parallel plasma cholinesterase inhibition more closely than erythrocyte cholinesterase activity. Ocular tissue cholinesterase activity was significantly depressed in the retina (70%), cornea (60%) and dorsal rectus extraocular muscle (46%). Electroretinography may be a useful physiological tool for evaluating the ocular toxicity of certain chemicals or pharmaceuticals associated with cholinesterase biomarker activity.Abbreviations AChE acetylcholinesterase - Amp amplitude - BuChE butyrylcholinesterase - C _p plasma level - C _ss steady-state plasma concentration - D _L loading dose - e ^–kt the rate of elimination over time (t) - ERG electroretinogram - k elimination rate constant - Lat latency - MBW metabolic body weight - O₁–O₅ consecutive oscillatory potential wavelets - PreTx pretreatment - R rate of infusion - R _Inf rate of infusion - V _d volume of distribution     

大型溞胆碱酯酶间接非竞争酶联免疫吸附定量分析法的建立

用达到电泳纯的大型溞(Daphniamagna)胆碱酯酶(cholinesterase,ChE)免疫BALB/c小鼠,得到效价达1∶8000的鼠抗大型溞ChE多克隆抗血清;通过优化抗原抗体反应条件,建立定量分析大型溞ChE含量的间接非竞争酶联免疫吸附法(indirectandnon‐competitiveenzyme‐linkedimmunosorbentassay).结果表明:此方法检测灵敏度为24ng爛mL-1;经免疫交叉反应鉴定,所获抗血清与5、10μg爛mL-1标准蛋白质和其他生物如花翅摇蚊、尖额溞、斑马鱼(脑、脑除外的整体)、家蚕、意大利蜜蜂、赤子爱胜蚯蚓、非洲爪蟾(蝌蚪)等来源的ChE交叉反应率分别为:<0畅25%、<0畅25%、 2畅13%、 10畅19%、3畅88%、 3畅56%、 2畅81%、 3畅93%、 5畅00%和2畅75%,具较高的特异性.说明用本试验得到的抗血清建立的间接非竞争酶联免疫吸附法可用于大型溞体内ChE含量的测定,以利于在农药暴露环境下大型溞体内ChE活性的精确检测.     

鸡实验性有机磷农药中毒血清酶活性及胆碱酯酶同工酶酶谱变化分析

选取临床健康、体重为0.8kg±0.07kg的三黄肉鸡60只,常规预饲6d后,随机分成对照组、急性试验组(皮下一次性注射氧乐果140mg/kg)、慢性试验组(皮下注射氧乐果35mg/kg,连续攻毒25d);每组20只饲喂。攻毒后采血,测定血清胆碱酯酶、碱性磷酸酶(SChE)、乳酸脱氢酶、谷丙转氨酶以及谷草转氨酶的活力以及血清胆碱酯酶同工酶的酶谱变化。结果表明,攻毒组SChE活性显著低于对照组,其他几种酶活性变化不大。同工酶区带中SChE1、2、3、5各组均100%出现,SChE4的出现率也大致相同,主要区别表现在FMB、SChE1′、SChE2′和SChE4区带。有机磷中毒的酶学诊断中将血清酶活力检测与SChE同工酶酶谱分析联合判断,可以提高诊断的特异性。     

红火蚁对辛硫磷敏感性及其乙酰胆碱酯酶活性的研究

用点滴法测定了辛硫磷对红火蚁不同品级的毒力,并用乙酰硫代胆碱-二硫双对硝基苯甲酸法（ASCh-DTNB法）测定了各品级乙酰胆碱酯酶(acetyl cholinesterase,AChE)的活性,以探明蚁群中不同品级个体对辛硫磷的敏感性差异及其与靶标酶的关系。毒力测定结果表明,处理后24h,辛硫磷对工蚁、兵蚁、有翅雄蚁、有翅雌蚁和蚁后的毒力（LC50值）分别为1.04、2.06、7.38、9.39和7.81 ug/ml,显示不同品级红火蚁对辛硫磷的敏感性差异非常大,其中工蚁最敏感,而有翅雌蚁蚁后敏感性最低。靶标酶活性测定结果表明,红火蚁不同品级个体中乙酰胆碱酯酶的活性存在极大差异,其中以有翅雄蚁的总活性最低,为0.0469 nmol/min?头,而以有翅雌蚁的最高,为14.8929 nmol/min?头。不同品级红火蚁对辛硫磷的敏感性与其乙酰胆碱酯酶活性不存在显著相关性（r=0.7456）。     

用于检测农药残留的胆碱酯酶酶源的研究进展

概述农药残留检测的现状,分析胆碱酯酶的分子类型、分布,不同来源的胆碱酯酶的特点及分离纯化方法,提出存在的问题,并展望其应用前景。     

敌敌畏和高脂对香猪肝肾及动脉损伤机理分析

为了探讨亚中毒剂量有机磷杀虫剂长期作用对猪体造成损害的机理,选择香猪作为实验动物,随机分为对照组、敌敌畏处理组和高脂处理组,饲养12个月后,分析香猪的肝、肾、动脉病理切片和相关酶活性变化.经预试验确定敌敌畏的亚中毒剂量为2.5 mg·(kg·2d)-1.以此剂量长期作用12个月后,敌敌畏能导致香猪严重的肝、肾细胞损伤,并使血清胆碱酯酶活性降低,对氧磷酯酶活性及其mRNA水平极显著下降(P＜0.01),但对大动脉组织结构、血脂水平和体质量的影响不明显.高脂处理组中,香猪的体质量明显增加(P＜0.05),同时血清胆碱酯酶活性、血清总胆固醇、高密度脂蛋白、低密度脂蛋白水平均上升(P＜0.05),对氧磷酯酶活性及其基因的表达量下降(P＜0.05).此外,大动脉血管壁内侧形成明显的脂质斑块和血栓;肝细胞受到一定损害,而肾组织受到的影响较小.研究结果提示,敌敌畏和高脂通过不同的途径刺激机体氧化应激反应,抑制对氧磷酯酶的活性;亚毒剂量的敌敌畏长期作用对肝肾造成的严重损害,提示应对猪场环境及饲料中的有机磷农药污染给予高度重视.     

Cholinesterase and Phosphatase Activities in Adults and Infective-stage Larvae of Levamisole-resistant and Levamisole-susceptible Isolates of Haemonchus contortus

Cholinesterase (ChE) and acid phosphatase (AP) activities, but not alkaline phosphatase activities, were detected in cytosolic and membrane-bound fractions of adult and infective-stage larvae of levamisole-resistant and levamisole-susceptible Haemonchus contortus. In contrast to other gastrointestinal nematodes, the ChE activity was higher in L₃ than in adults and, in both cases, was mainly associated with membranes. ChE activity was inhibited by Triton X-100 and was only detected in membrane-bound fractions when the detergent was removed. Differences between resistant and susceptible L₃ were observed in the response to inhibitors (cytosolic fraction) and in the enzymatic content (membrane-bound fraction). Phosphatase activity was detected at acidic pH in all fractions, being higher in the adult than in the L₃ stage. In the former, most of the enzyme was localized in the membrane-bound fractions, whereas in the latter it was mainly in cytosolic fractions. This difference could be correlated with the activity in the gut. In inhibition assays, a difference between cytosolic fractions from resistant and susceptible adults was observed in their response to 1 mmol/L tartaric acid.     

有机磷农药神经发育毒性作用机制研究进展

有机磷农药是目前使用最为广泛的一种化学合成杀虫剂,它所引起的毒性作用已成为全球关注的公共卫生问题.研究表明,有机磷农药的神经发育毒性作用主要与其不可逆地抑制乙酰胆碱酯酶进而导致乙酰胆碱在突触处的积累有关.而最近也提出了有机磷农药的其他非胆碱酯酶作用机制,这些作用机制涉及兴奋性氨基酸递质系统、多巴胺能神经递质系统、五羟色胺递质系统、cAMP反应单元结合蛋白信号通路和氧化应激等.针对有机磷农药神经发育毒性作用机制的研究现状进行综述.