Embryonic cholinesterase activity during morphogenesis of the mouse genital tract

Summary In the genital tract of male and female mouse embryos cholinesterase activity is described that is independent from innervation. The enzyme activity is localized in the mesenchyme at the junction of Wolffian and Müllerian ducts with the urogenital sinus. During male development prostate buds and vesicular glands grow out into the cholinesterase-active mesenchyme. During female development the active mesenchyme participates in the downgrowth of the vaginal anlage. Ultrastructurally the cholinesterase activity is localized in the perinuclear cisterna and in smooth endoplasmic reticulum of the mesenchymal cells. The enzyme activity disappears with definitive differentiation of the tissue. The embryonic cholinesterase is a component of a primitive muscarinic system. Its relation to the morphogenetic action of testosterone and its possible general functions are discussed.     

Synthesis and bioevaluation of new tacrine-cinnamic acid hybrids as cholinesterase inhibitors against Alzheimer’s disease

Small molecule cholinesterases inhibitor (ChEI) provides an effective therapeutic strategy to treat Alzheimer’s disease (AD). Currently, the discovery of new ChEI with multi-target effect is still of great importance. Herein, we report the synthesis, structure–activity relationship study and biological evaluation of a series of tacrine-cinnamic acid hybrids as new ChEIs. All target compounds are evaluated for their in vitro cholinesterase inhibitory activities. The representatives which show potent activity on cholinesterase, are evaluated for the amyloid β-protein self-aggregation inhibition and in vivo assays. The optimal compound 19, 27, and 30 (human AChE IC₅₀?=?10.2?±?1.2, 16.5?±?1.7, and 15.3?±?1.8?nM, respectively) show good performance in ameliorating the scopolamine-induced cognition impairment and preliminary safety in hepatotoxicity evaluation. These compounds deserve further evaluation for the development of new therapeutic agents against AD.     

Inhibition of Ache: Structure-Activity Relationship Among Conformational Transition of Trp84 and Bimolecular Rate Constant

Abstract

In this study the authors attempt to correlate kinetic constants for carbamylation of AChE, by a series of carbamate inhibitors, with the conformational positioning of Trp84 in transition state complexes of the same carbamates with Torpedo AChE, as obtained by computerized molecular modelling. They present evidence for changes in the distance of the carbamates from the center of the indole ring which can be correlated with the bimolecular rate constants for inhibition. As a result the greater the distance from Trp84, the smaller the bimolecular inhibition constant value, k₁ (= k₂/K_a), becomes. In conclusion, the value of the biinolecular rate constant for selected AChE inhibitors (structural changes that have been hypothesised or natural alkaloids of unknown activity) which possess similar size and rigidity, can be obtained. Under these conditions energy minimization alone seems to be sufficient even to accurately predict protein-substrate interactions that actually occur. Modelling studies also suggest that conformational re-orientation of Trp84 in the transition state could produce an overall movement of the Cys67-Cys94 loop.     

α-bisabolol β-D-fucopyranoside as a potential modulator of β-amyloid peptide induced neurotoxicity: An in vitro & in silico study

Alzheimer’s disease (AD) is a multifaceted neurodegenerative disorder affecting the elderly people. For the AD treatment, there is inefficiency in the existing medication, as these drugs reduce only the symptoms of the disease. Since multiple pathological proteins are involved in the development of AD, searching for a single molecule targeting multiple AD proteins will be a new strategy for the management of AD. In view of this, the present study was designed to synthesize and evaluate the multifunctional neuroprotective ability of the sesquiterpene glycoside α-bisabolol β-D-fucopyranoside (ABFP) against multiple targets like acetylcholinesterase, oxidative stress and β-amyloid peptide aggregation induced cytotoxicity. In silico computational docking and simulation studies of ABFP with acetylcholinesterase (AChE) showed that it can interact with Asp74 and Thr75 residues of the enzyme. The in vitro studies showed that the compound possess significant ability to inhibit the AChE enzyme apart from exhibiting antioxidant, anti-aggregation and disaggregation properties. In addition, molecular dynamics simulation studies proved that the interacting residue between Aβ peptide and ABFP was found to be involved in Leu34 and Ile31. Furthermore, the compound was able to protect the Neuro2 a cells against Aβ_25-35 peptide induced toxicity. Overall, the present study evidently proved ABFP as a neuroprotective agent, which might act as a multi-target compound for the treatment of Alzheimer’s disease.     

The intrinsic myenteric innervation of the hind-gut and accessory muscles of defaecation in the cat

Summary The anatomy and intrinsic innervation of the colon, rectum, internal anal sphincter, ano-coccygeus and recto-coccygeus have been studied in the cat with cholinesterase and catecholamine-fluorescence histochemical techniques. A variable pattern of intrinsic innervation by acetylcholinesterase-positive and adrenergic nerves along the length of the large bowel is described and is related to segmental variations in motor activity. A variation in the distribution of non-specific cholinesterase within the muscle layers is also described. Adrenergic nerves in proximal colon are arranged in the usual peri-ganglionic manner but there is also a rich direct adrenergic innervation of the longitudinal muscle in distal colon and rectum, and of circular muscle in lower rectum and internal anal sphincter. This distribution has not been reported in other species. Direct adrenergic innervation of muscle cells has been confirmed at ultrastructural level after treatment with 5-hydroxydopamine. Adrenergic neurones have not been detected in cat bowel. The ano- and recto-coccygeus muscles and internal anal sphincter possess a dense innervation of adrenergic and cholinesterase-positive nerves. It is suggested that the variation in intrinsic innervation along the large bowel should be considered in the interpretation of pharmacological and physiological experiments on this part of the gut.This work was supported by a grant from the King's College Hospital Voluntary Research Trust. We wish to thank Dr. J. P. Tranzer and F. Hoffman-La Roche & Co. Ltd., Basle, for the gift of 5-hydroxydopamine.We also thank Miss M. K. Egan and Mr. K. J. Davies for their technical assistance.     

对肝炎患者进行胆碱酯酶活性监测的临床意义分析

目的:血清胆碱酯酶活性(CHE)是反应肝细胞损害的灵敏指标,对于肝炎疾病的临床应用具有重大的价值,评估血清胆碱酯酶的活性变化是本文的主要目的.方法:对各种类型肝炎患者的CHE活性采用医院引进的国外先进的全自动生化分析仪进行检测,并对患病肝炎组与正常组进行胆碱酯酶活性的对照(P＜0.01).结果:三组肝炎患者在接触时间、基础疾病、血清肌酸激酶(CK)、昏迷时间等有差异有显著性(P＜0.01),在年龄、性别、中毒原因方面没有显著性差异(P＞0.05).迟发性脑病组和无迟发性脑病组在年龄、基础疾病、并发症、接触时间、昏迷时间、CK方面差异有显著性(P＜0.01);而在性别、中毒原因方面差异无显著性(P＞0.05).结论:最终结果表明,CHE活性检测对于判定肝炎患者的预后具有重大的价值和作用,应得到充分的重视,而广泛、有效的应用于临床.     

Efficient synthesis of novel dialkyl-3-cyanopropylphosphate derivatives and evaluation of their anticholinesterase activity

Based on the broad spectrum of biological activities associated with organophosphates, a novel type of this class of compounds was synthesized, bearing a nitrile group, from the sodium alkoxide-catalyzed reaction of dialkylphosphites with γ-ketonitriles at 80 °C under solvent-free conditions. A reaction mechanism involving a phospha-Brook type rearrangement is proposed. Eight title compounds were investigated for their in vitro inhibitory potency and selectivity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using Ellman’s spectrophotometric method. The synthesized derivatives exhibited mostly a moderate activity against both cholinesterases. The IC₅₀ values for BChE were in a smaller concentration range (5.96–23.35 µM) compared to those for AChE inhibition (9.61–53.74 µM). The diethyl-3-cyano-1-p-tolylpropylphosphate which displayed the higher dual inhibitory potency towards both cholinesterases could be considered as a potential candidate for developing new drugs to treat Alzheimer’s disease.     

Design,synthesis, biological evaluation,and molecular modeling studies of chalcone-rivastigmine hybrids as cholinesterase inhibitors

A series of novel chalcone-rivastigmine hybrids were designed, synthesized, and tested in vitro for their ability to inhibit human acetylcholinesterase and butyrylcholinesterase. Most of the target compounds showed hBChE selective activity in the micro- and submicromolar ranges. The most potent compound 3 exhibited comparable IC₅₀ to the commercially available drug (rivastigmine). To better understand their structure activity relationships (SAR) and mechanisms of enzyme-inhibitor interactions, kinetic and molecular modeling studies including molecular docking and molecular dynamics (MD) simulations were carried out. Furthermore, compound 3 blocks the formation of reactive oxygen species (ROS) in SH-SY5Y cells and shows the required druggability and low cytotoxicity, suggesting this hybrid is a promising multifunctional drug candidate for Alzheimer’s disease (AD) treatment.     

Increased heart rate variability in mice overexpressing the Cu/Zn superoxide dismutase

Cu/Zn superoxide dismutase (SOD1) is implicated in various pathological conditions including Down's syndrome, neurodegenerative diseases, and afflictions of the autonomic nervous system (ANS). To assess the SOD1 contribution to ANS dysfunction, especially its influence on cardiac regulation, we studied the heart rate variability (HRV) and cardiac arrhythmias in conscious 12-month-old male and female transgenic mice for the human SOD1 gene (TghSOD1). TghSOD1 mice presented heart rate reduction as compared with control FVB/N individuals. All HRV parameters reflecting parasympathetic activity were increased in TghSOD1. Pharmacological studies confirmed that the parasympathetic tone was exacerbated and the sympathetic pathway was functional in TghSOD1 mice. A high frequency of atrioventricular block and premature ventricular contractions was observed in TghSOD1. By biochemical assays we found that SOD1 activities were multiplied by 9 and 4 respectively in the heart and brainstem of transgenic mice. A twofold decrease in cholinesterase activity was observed in the heart but not in the brainstem. We demonstrate that SOD1 overexpression induces an ANS dysfunction by an exacerbated vagal tone that may be related to impaired cardiac activity of the cholinesterases and may explain the high occurrence of arrhythmias.     

Molar absorption coefficients for the reduced Ellman reagent: reassessment

The Ellman method for assaying thiols is based on the reaction of thiols with the chromogenic DTNB (5,5'-dithiobis-2-nitrobenzoate) whereby formation of the yellow dianion of 5-thio-2-nitrobenzoic acid (TNB) is measured. The TNB molar absorption coefficient, 13.6 x 10(3)M(-1)cm(-1), as published by Ellman in 1959 has been almost universally used until now. Over the years, however, slightly different values have been published, and it has further been shown that TNB reveals thermochromic properties. This should be taken into account when the Ellman method is used for determination of enzyme activities, such as in cholinesterase assays. Our data show that the absorbance spectra of TNB are shifted to longer wavelengths when temperature increases, while absorbance maxima decrease. Our recommended molar absorption coefficients at 412 nm are 14.15 x 10(3)M(-1)cm(-1) at 25 degrees C and 13.8 x 10(3)M(-1)cm(-1) at 37 degrees C (0.1M phosphate buffer, pH 7.4). Molar absorption coefficients for other temperatures and wavelengths are included in the paper.