A DFT study of determination of the reactive sites of the acetylcholine and its agonists: In the gas phase and dielectric medium

The reactive behavior of acetylcholine and its agonist molecules have been investigated using B3LYP hybrid density functional method at the 6‐311++G** basis set level, in the gas phase and aqueous phase. The calculations have been performed to obtain optimized geometries, relative reactivities, net atomic charges, HOMO, and LUMO energies. The solvent effect has been analyzed by using the continuum model (IPCM) and, the obtained results have shown that the all molecules have been stabilized more by solvent dielectric constant. For Ach and its analogues, it has been very well known that esteratic site and quaternary ammonium group which have reflected the difference in biological activity have been the two of the most important active site for interactions between molecule and its receptor. The structures of these analogues have provided an essential foundation for subsequent structure‐activity analysis of ligand binding at acetylcholine receptors, neuronal uptake inhibitors and transporters. Molecular modeling predictions will be important initial steps toward the development of novel pharmaceuticals in the fight acetylcholine‐related neurological disorders. This work is therefore expected to facilitate the design and development of new biologically active Ach analogues to treat Ach‐related neurological disorders and, specially is used to qualitative understanding of the reactivity and related properties and, so on can be used to a preselection of new ligands which at the moment is taken essentially from empirical knowledge. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Unprecedented Quassinoids with Promising Biological Activity from Harrisonia perforata

Perforalactone A ( 1 ), a new 20S quassinoid with a unique cagelike 2,4‐dioxaadamantane ring system and a migrated side chain, was isolated from the plant Harrisonia perforata together with two biosynthetically related new quassinoids. The structures of these natural products were elucidated by NMR spectroscopy, X‐ray diffraction analysis, computational modeling, and the CD excitation chirality method. The compounds exhibited notable biological properties, including insecticidal activity against Aphis medicaginis Koch and antagonist activity at the nicotinic acetylcholine receptor of Drosophila melanogaster. The structural features of these compounds may be related to their promising biological characteristics. Their biosynthesis and an alternative origin of quassinoid‐type natural products are also discussed.     

CGEMA and VGAP: a Colour Graphics Editor for Multiple Alignment using a Variable GAP penalty. Application to the muscarinic acetylcholine receptor

Summary Today, more than 40 protein amino acid (AA) sequences of membrane receptors coupled to guanine nucleotide binding proteins (G-proteins) are available. For those working in the field of medicinal chemistry, these sequences present a new type of information that should be taken into consideration. To make maximal use of sequence data it is essential to be able to compare different protein sequences in a similar way to that used for small molecules. A prerequisite, however, is the availability of a processing environment that enables one to handle sequences in an easy way, both by hand and by computer. In order to meet these ends, the package CGEMA (Colour Graphics Editor for Multiple Alignment) was developed in our laboratory. The programme uses a user-definable colour coding for the different AAs. Sequences can be aligned by hand or by computer, using VGAP, and both approaches can be combined. VGAP is a novel in-house written alignment programme with a variable gap penalty that also handles consecutive alignments using one sequence as a probe. In addition, secondary structure prediction tools are available.From the 20 protein sequences, available for the muscarinic acetylcholine receptor, 13 different sequences were selected, covering the subtypes m1 to m5. By comparing the sequences, two major groups are revealed that correspond to those found by considering the transducing system coupled to the various receptor subtypes. Different parts of the protein sequences are identified as characterizing the subtype and binding the ligands, respectively.     

The Effects of Structural Alterations in the Polyamine and Amino Acid Moieties of Philanthotoxins on Nicotinic Acetylcholine Receptor Inhibition in the Locust,Schistocerca gregaria

Alterations in the polyamine and amino acid (tyrosine) moieties of philanthotoxin-343 (PhTX-343) were investigated for their effects on the antagonism of nicotinic acetylcholine receptors (nAChRs) isolated from the locust (Schistocerca gregaria) mushroom body. Through whole-cell patch-clamp recordings, the philanthotoxin analogues in this study were shown to cause inhibition of the inward current when co-applied with acetylcholine (ACh). PhTX-343 (IC₅₀ = 0.80 μM at −75 mV) antagonised locust nAChRs in a use-dependent manner, suggesting that it acts as an open-channel blocker. The analogue in which both the secondary amine functionalities were replaced with methylene groups (i.e., PhTX-12) was ~6-fold more potent (IC₅₀ (half-maximal inhibitory concentration) = 0.13 μM at −75 mV) than PhTX-343. The analogue containing cyclohexylalanine as a substitute for the tyrosine moiety of PhTX-343 (i.e., Cha-PhTX-343) was also more potent (IC₅₀ = 0.44 μM at −75 mV). A combination of both alterations to PhTX-343 generated the most potent analogue, i.e., Cha-PhTX-12 (IC₅₀ = 1.71 nM at −75 mV). Modulation by PhTX-343 and Cha-PhTX-343 fell into two distinct groups, indicating the presence of two pharmacologically distinct nAChR groups in the locust mushroom body. In the first group, all concentrations of PhTX-343 and Cha-PhTX-343 inhibited responses to ACh. In the second group, application of PhTX-343 or Cha-PhTX-343 at concentrations ≤100 nM caused potentiation, while concentrations ≥ 1 μM inhibited responses to ACh. Cha-PhTX-12 may have potential to be developed into insecticidal compounds with a novel mode of action.     

Neuroinflammation Modulation via α7 Nicotinic Acetylcholine Receptor and Its Chaperone,RIC-3

Nicotinic acetylcholine receptors (nAChRs) are widely expressed in or on various cell types and have diverse functions. In immune cells nAChRs regulate proliferation, differentiation and cytokine release. Specifically, activation of the α7 nAChR reduces inflammation as part of the cholinergic anti-inflammatory pathway. Here we review numerous effects of α7 nAChR activation on immune cell function and differentiation. Further, we also describe evidence implicating this receptor and its chaperone RIC-3 in diseases of the central nervous system and in neuroinflammation, focusing on multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Deregulated neuroinflammation due to dysfunction of α7 nAChR provides one explanation for involvement of this receptor and of RIC-3 in neurodegenerative diseases. In this review, we also provide evidence implicating α7 nAChRs and RIC-3 in neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) involving neuroinflammation. Besides, we will describe the therapeutic implications of activating the cholinergic anti-inflammatory pathway for diseases involving neuroinflammation.     

人类乙酰胆碱酯酶（ACHE）与抑制剂小分子的对接研究

阿尔茨海默病（Alzheimer’s disease,AD）是一种中枢神经系统致死性神经原发性退行病变,是老年痴呆症中最常见的一种类型．乙酰胆碱酯酶抑制剂（AChEI）是目前治疗AD的主要药物．我们选择他克林、利伐斯的明、石杉碱甲、在研药物TV-3326、多奈哌齐和Anseculin,分别与AChE进行分子对接研究．结果表明：抑制剂与AChE结合能力的大小顺序为：他克林〈利伐斯的明〈石杉碱甲〈TV．3326〈多奈哌齐〈Anseculin,这与实验中测得ACHE1的IC50值反应活性大小一致．上述6类药物分子,Anseculin与AChE的相互作用能力最强．     

基于氮掺杂多孔碳的乙酰胆碱酯酶传感器检测残留农药甲拌磷

以制备的新型氮掺杂多孔碳为载体,玻碳电极(GC)为工作电极,构建了乙酰胆碱酯酶(ACh E)传感器,用于有机磷农药甲拌磷的检测研究。在1.0 mmol/L底物氯化乙酰胆碱溶液中的差分脉冲扫描结果表明,ACh E/GC电极上的峰电流为0.195 8μA,而ACh E/氮掺杂多孔碳/GC电极上的峰电流为0.841 4μA,说明氮掺杂多孔碳材料可有效固定ACh E,提高检测灵敏度。采用ACh E/氮掺杂多孔碳/GC电极对不同浓度甲拌磷进行测定,在6.0×10-10~1.2×10-6g/L浓度范围内,抑制率与甲拌磷浓度的负对数呈良好的线性关系(r2=0.998 5)。按照抑制率为10%计算,检出限为5.8×10-12g/L。采用加标回收法检测菠菜汁样品中的甲拌磷,回收率为91.7%~97.4%。     

An Enzyme Sensor For Determination of Acetylcholine and Choline In Rat Brain Extracts

Abstract

A choline enzyme sensor, recently developed by the authors, was used for choline and acetylcholine determination in rat brain extracts, using choline oxidase immobilized on cellulose triacetate membranes, and acetylcholinesterase in homogeneous solution. the method proved useful for assay of the acetylcholine content in a commercial pharmaceutical formulation used in ophthalmology.     

An Organic Cation-Selective Electrode: Potentiometric Determination of Acetylcholine Activity

Abstract

The performance characteristics of the first ion-selective electrode specifically designed for the quantitation of an organic cation are described. The liquid membrane electrode exhibits rapid and near Nernstian response to acetylcholine ion activity from 10^?1 to 10^?5 M. High selectivity over Na⁺, K⁺ and NH₄ ⁺ is observed.     

微柱高效液相色谱法测定大鼠脑微透析液中 的乙酰胆碱和胆碱

用所建立的微柱高效液相色谱分离、柱后固定化酶反应器酶解、电化学检测器检测的方法, 对用不同浓度异氟醚麻醉前后的大鼠脑微透析液中的乙酰胆碱和胆碱的浓度进行了测定。在 乙酰胆碱和胆碱的浓度为10～ 2 000 nmol/L 时,其浓度分别与各自相应峰高的线性 关系良好,两者的检测限(以信噪比为3计)均可达5 nmol/L 。微透析液中乙酰胆碱和胆碱的含量在大鼠清醒时最高,随着异氟醚吸入浓度的增加,乙酰胆碱和胆碱含量明显降低。在大鼠海马和脑皮层中乙酰胆碱浓度的降低与大鼠吸入异氟醚的浓度相关( P ＜