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1.
Behav Brain Res ; 286: 97-103, 2015 Jun 01.
Article in English | MEDLINE | ID: mdl-25732954

ABSTRACT

The present work describes, for the first time, the in vivo effects of the multitarget compound AVCRI104P3, a new anticholinesterasic drug with potent inhibitory effects on human AChE, human BuChE and BACE-1 activities as well as on the AChE-induced and self-induced Aß aggregation. We characterized the behavioral effects of chronic treatment with AVCRI104P3 (0.6 µmol kg(-1), i.p., 21 days) in a sample of middle aged (12-month-old) male 129/Sv×C57BL/6 mice with poor cognitive performance, as shown by the slow acquisition curves of saline-treated animals. Besides, a comparative assessment of cognitive and non-cognitive actions was done using its in vitro equipotent doses of huprine X (0.12 µmol kg(-1)), a huperzine A-tacrine hybrid. The screening assessed locomotor activity, anxiety-like behaviors, cognitive function and side effects. The results on the 'acquisition' of spatial learning and memory show that AVCRI104P3 exerted pro-cognitive effects improving both short- and long-term processes, resulting in a fast and efficient acquisition of the place task in the Morris water maze. On the other hand, a removal test and a perceptual visual learning task indicated that both AChEIs improved short-term 'memory' as compared to saline treated mice. Both drugs elicited the same response in the corner test, but only AVCRI104P3 exhibited anxiolytic-like actions in the dark/light box test. These cognitive-enhancement and anxiolytic-like effects demostrated herein using a sample of middle-aged animals and the lack of adverse effects, strongly encourage further studies on AVCRI104P3 as a promising multitarget therapeutic agent for the treatment of cholinergic dysfunction underlying natural aging and/or dementias.


Subject(s)
Aging/drug effects , Aging/psychology , Anti-Anxiety Agents/pharmacology , Cognition Disorders/drug therapy , Heterocyclic Compounds, 4 or More Rings/pharmacology , Nootropic Agents/pharmacology , Aminoquinolines/pharmacology , Animals , Anxiety/drug therapy , Cholinesterase Inhibitors/pharmacology , Cognition/drug effects , Learning/drug effects , Male , Memory, Long-Term/drug effects , Memory, Short-Term/drug effects , Mice, 129 Strain , Mice, Inbred C57BL , Motor Activity/drug effects , Random Allocation , Visual Perception/drug effects
2.
Curr Med Chem ; 21(9): 1152-9, 2014.
Article in English | MEDLINE | ID: mdl-24059241

ABSTRACT

Amyloid aggregation is linked to a large number of human disorders, from neurodegenerative diseases as Alzheimer's disease (AD) or spongiform encephalopathies to non-neuropathic localized diseases as type II diabetes and cataracts. Because the formation of insoluble inclusion bodies (IBs) during recombinant protein production in bacteria has been recently shown to share mechanistic features with amyloid self-assembly, bacteria have emerged as a tool to study amyloid aggregation. Herein we present a fast, simple, inexpensive and quantitative method for the screening of potential anti-aggregating drugs. This method is based on monitoring the changes in the binding of thioflavin-S to intracellular IBs in intact Eschericchia coli cells in the presence of small chemical compounds. This in vivo technique fairly recapitulates previous in vitro data. Here we mainly use the Alzheimer's related ß-amyloid peptide as a model system, but the technique can be easily implemented for screening inhibitors relevant for other conformational diseases simply by changing the recombinant amyloid protein target. Indeed, we show that this methodology can be also applied to the evaluation of inhibitors of the aggregation of tau protein, another amyloidogenic protein with a key role in AD.


Subject(s)
Amyloid beta-Peptides/analysis , Inclusion Bodies/chemistry , Thiazoles/chemistry , Amyloid beta-Peptides/metabolism , Benzothiazoles , Escherichia coli/chemistry , Escherichia coli/metabolism , Humans , Inclusion Bodies/metabolism , Time Factors
3.
Curr Med Chem ; 20(13): 1623-34, 2013.
Article in English | MEDLINE | ID: mdl-23410162

ABSTRACT

In the past decades drug discovery practice has escaped from the complexity of the formerly used phenotypic screening in animals to focus on assessing drug effects on isolated protein targets in the search for drugs that exclusively and potently hit one selected target, thought to be critical for a given disease, while not affecting at all any other target to avoid the occurrence of side-effects. However, reality does not conform to these expectations, and, conversely, this approach has been concurrent with increased attrition figures in late-stage clinical trials, precisely due to lack of efficacy and safety. In this context, a network biology perspective of human disease and treatment has burst into the drug discovery scenario to bring it back to the consideration of the complexity of living organisms and particularly of the (patho)physiological environment where protein targets are (mal)functioning and where drugs have to exert their restoring action. Under this perspective, it has been found that usually there is not one but several disease-causing genes and, therefore, not one but several relevant protein targets to be hit, which do not work on isolation but in a highly interconnected manner, and that most known drugs are inherently promiscuous. In this light, the rationale behind the currently prevailing single-target-based drug discovery approach might even seem a Utopia, while, conversely, the notion that the complexity of human disease must be tackled with complex polypharmacological therapeutic interventions constitutes a difficult-to-refuse argument that is spurring the development of multitarget therapies.


Subject(s)
Drug Discovery/methods , Molecular Targeted Therapy/methods , Protein Interaction Maps/drug effects , Animals , Humans , Pharmaceutical Preparations/chemistry , Pharmacology/methods
4.
Neurodegener Dis ; 11(3): 129-40, 2013.
Article in English | MEDLINE | ID: mdl-22626981

ABSTRACT

BACKGROUND: Different studies have established that cholinergic neurodegeneration could be a major pathological feature of Alzheimer's disease (AD). Thus, enhancement of the central cholinergic neurotransmission has been regarded as one of the most promising strategies for the symptomatic treatment of AD, mainly by means of reversible acetylcholinesterase inhibitors (AChEIs). The cognitive-enhancing properties of both huprine X, a new AChEI, and the structurally related huperzine A, as well as their effects on the regulation of several neurochemical processes related to AD have been studied in triple transgenic mice (3xTg-AD). METHODS: Seven-month-old homozygous 3xTg-AD male mice, which received chronic intraperitoneal treatment with either saline, huprine X (0.12 µmol·kg(-1)) or huperzine A (0.8 µmol·kg(-1)) were subjected to a battery of behavioural tests after 3 weeks of treatment and thereafter the brains were dissected to study the neurochemical effects induced by the two AChEIs. RESULTS: Treatments with huprine X and huperzine A improved learning and memory in the Morris water maze and some indicators of emotionality without inducing important adverse effects. Moreover, huprine X and huperzine A activate protein kinase C/mitogen-activated protein kinase pathway signalling, α-secretases (ADAM 10 and TACE) and increase the fraction of phospho-glycogen synthase kinase 3-ß. CONCLUSION: Results obtained herein using a sample of 3xTg-AD animals strongly suggest that the treatment with the two AChEIs not only improves the cognitive performance of the animals but also induces some neurochemical changes that could contribute to the beneficial effects observed.


Subject(s)
Alkaloids/therapeutic use , Alzheimer Disease/drug therapy , Aminoquinolines/therapeutic use , Brain Chemistry/drug effects , Brain Chemistry/genetics , Cognition Disorders/drug therapy , Heterocyclic Compounds, 4 or More Rings/therapeutic use , Sesquiterpenes/therapeutic use , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Animals , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Cognition Disorders/genetics , Cognition Disorders/metabolism , Hippocampus/drug effects , Hippocampus/metabolism , Humans , Male , Maze Learning/drug effects , Maze Learning/physiology , Mice , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Transgenic , Neuroprotective Agents/therapeutic use
5.
Pharmacol Biochem Behav ; 95(4): 485-93, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20363245

ABSTRACT

The behavioural effects of huprine X, a new anticholinesterasic inhibitor, as well as its effects on the regulation of protein kinase C (PKC), mitogen activated protein kinase (MAPK) and alpha-secretase (ADAM10 and TACE/ADAM17) related to amyloid precursor protein (APP) processing remain to be established. In the present work, 12 month old 126/SvxC57b/6 male mice which received chronic i.p. treatment with either saline, huprine X (0.04 micromol kg(-1) or huprine X (0.12 micromol kg(-1), were submitted to a battery of behavioural tests and thereafter the brains were dissected to study the neurochemical effects induced by huprine X. The results show that, in a dose dependent manner, huprine X facilitates learning and memory in the Morris water maze and improves some indicators of emotionality without inducing adverse effects, affecting motor activity nor anxiety-like behaviours, as measured in the open-field and corner tests. Moreover activation of downstream PKC/MAPK signaling pathways may underly these behavioural effects as well as the stimulation of the non-amyloidogenic processing of APP. Results obtained herein using a sample of aged animals strongly suggest that huprine X constitutes a promising therapeutic agent for the treatment of cholinergic dysfunction underlying aging and/or dementias.


Subject(s)
Aminoquinolines/pharmacology , Behavior, Animal/drug effects , Cholinesterase Inhibitors/pharmacology , Heterocyclic Compounds, 4 or More Rings/pharmacology , Mitogen-Activated Protein Kinases/metabolism , Protein Kinase C-alpha/metabolism , ADAM Proteins/metabolism , ADAM10 Protein , ADAM17 Protein , Aging , Aminoquinolines/administration & dosage , Aminoquinolines/adverse effects , Aminoquinolines/therapeutic use , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Protein Precursor/metabolism , Animals , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Cholinesterase Inhibitors/administration & dosage , Cholinesterase Inhibitors/adverse effects , Cholinesterase Inhibitors/therapeutic use , Dose-Response Relationship, Drug , Heterocyclic Compounds, 4 or More Rings/administration & dosage , Heterocyclic Compounds, 4 or More Rings/adverse effects , Heterocyclic Compounds, 4 or More Rings/therapeutic use , Hippocampus/drug effects , Hippocampus/metabolism , Learning/drug effects , Male , Membrane Proteins/metabolism , Mice , Mice, Inbred C57BL , Motor Activity/drug effects , Protein Transport/drug effects , Random Allocation , Signal Transduction/drug effects , Time Factors
6.
Curr Med Chem ; 15(24): 2433-55, 2008.
Article in English | MEDLINE | ID: mdl-18855672

ABSTRACT

The therapeutic arsenal for the treatment of Alzheimer's disease (AD) remains confined to a group of four inhibitors of AChE and one NMDA receptor antagonist, which are used to provide a relief of the very late symptoms of the dementia, i.e. the cognitive and functional decline. In line with the growing body of evidence of the pivotal role of the beta-amyloid peptide (Abeta) in the pathogenesis of AD, alternative classes of drugs targeting mainly the formation or the aggregation of Abeta are actively pursued by the pharmaceutical industry, as they could positively modify the course of AD, stopping or slowing down disease progression. While the first amyloid-directed disease-modifying drugs go ahead with their clinical development and could reach the market as soon as 2009, mounting preclinical and clinical evidences is pointing towards a disease-modifying role also for currently marketed anti-Alzheimer AChE inhibitors (AChEIs), particularly for donepezil. In this review, the neuroprotective effects exhibited by currently commercialized AChEIs will be briefly discussed, together with the secondary mechanisms through which they could exert such effects. This review will focus also on particular classes of AChEIs, namely dual binding site AChEIs, which are being purposely designed to target Abeta aggregation and / or other biological targets that contribute to AD pathogenesis, thus constituting very promising disease-modifying anti-Alzheimer drug candidates.


Subject(s)
Acetylcholinesterase/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/enzymology , Cholinesterase Inhibitors/therapeutic use , Amyloid beta-Peptides/metabolism , Animals , Binding Sites , Cholinesterase Inhibitors/chemistry , Clinical Trials as Topic , Humans , Protein Binding
7.
J Mol Neurosci ; 30(1-2): 89-90, 2006.
Article in English | MEDLINE | ID: mdl-17192641

ABSTRACT

Transmissible spongiform encephalopaties are caused by an extracellular surface protein, the scrapie prion protein (PrPsc), which is an aberrant form of normal and functional cellular PrP (PrPc). The pathological hallmarks of these diseases are the accumulation and deposition of PrPsc in the form of amyloid fibrils in the central nervous system (Tateishi et al., 1988), similar to amyloid-beta (Abeta) protein in Alzheimer's disease (AD). In some patients, Abeta and prion pathology can coexist (Hainfellner et al., 1998), and a common spatial pattern of protein deposition has been described (Armstrong et al., 2001). In addition, it is well-known that acetylcholinesterase (AChE) colocalizes with Abeta deposits of brains in AD patients and accelerates assembly of Abeta peptides through the peripheral site of the enzyme (Inestrosa et al., 1996). The aim of the present study was to analyze time course and concentration dependence of the AChE proaggregating effect on synthetic peptide-spanning residues 106-126 of human PrP (PrP106-126) and the reversion of this effect by different AChE inhibitors (AChEIs).


Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Inhibitors/pharmacology , Peptide Fragments/metabolism , Prions/metabolism , Alkaloids , Kinetics , Peptide Fragments/drug effects , Prions/drug effects , Scrapie , Sesquiterpenes/pharmacology
8.
Biochem Biophys Res Commun ; 346(1): 89-94, 2006 Jul 21.
Article in English | MEDLINE | ID: mdl-16750169

ABSTRACT

Acetylcholinesterase (AChE), a senile plaque component, promotes amyloid-beta-protein (Abeta) fibril formation in vitro. The presence of prion protein (PrP) in Alzheimer's disease (AD) senile plaques prompted us to assess if AChE could trigger the PrP peptides aggregation as well. Consequently, the efficacy of AChE on the PrP peptide spanning-residues 106-126 aggregation containing a coumarin fluorescence probe (coumarin-PrP 106-126) was studied. Kinetics of coumarin-PrP 106-126 aggregation showed a significant increase of maximum size of aggregates (MSA), which was dependent on AChE concentration. AChE-PrP 106-126 aggregates showed the tinctorial and optical amyloid properties as determined by polarized light and electronic microscopy analysis. A remarkable inhibition of MSA was obtained with propidium iodide, suggesting that AChE triggers PrP 106-126 and Abeta aggregation through a similar mechanism. Huprines (AChE inhibitors) also significantly decreased MSA induced by AChE as well, unveiling the potential interest for some AChE inhibitors as a novel class of potential anti-prion drugs.


Subject(s)
Acetylcholinesterase/metabolism , Peptide Fragments/chemistry , Prions/chemistry , Alkaloids , Aminoquinolines/pharmacology , Animals , Cattle , Cholinesterase Inhibitors/pharmacology , Coumarins , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Microscopy, Fluorescence , Peptide Fragments/metabolism , Prions/metabolism , Propidium/pharmacology , Protein Structure, Secondary/drug effects , Sesquiterpenes/pharmacology
9.
Curr Med Chem ; 13(4): 399-422, 2006.
Article in English | MEDLINE | ID: mdl-16475930

ABSTRACT

In the last decade much attention has been paid to the development of metabolically non-reversible dimeric or hybrid compounds, which combine two structural units of one or two lead compounds of interest for the treatment of Alzheimer's disease. As a consequence of their capability to simultaneously interact with two binding sites of the same biological target (the enzyme acetylcholinesterase in most cases), to expand their interaction in the main binding site of the target molecule, or to interact with two different biological targets of interest in the pathogenesis of the disease, these dimeric or hybrid compounds exhibit an improved pharmacological profile including high affinity interactions, additional non conventional actions or complementary actions, what makes them potential drug candidates for the treatment of Alzheimer's disease. Herein, we review from a structural point of view the main classes of dimeric or hybrid compounds developed for the treatment of Alzheimer's disease, along with the pharmacological profile of the most active compounds.


Subject(s)
Alzheimer Disease/drug therapy , Cholinesterase Inhibitors/therapeutic use , Aminoquinolines/chemistry , Animals , Binding Sites/drug effects , Cognition Disorders/drug therapy , Heterocyclic Compounds, 4 or More Rings/chemistry , Humans , Monoamine Oxidase Inhibitors/chemistry , Monoamine Oxidase Inhibitors/therapeutic use , Piperidines/therapeutic use , Structure-Activity Relationship , Tacrine/analogs & derivatives , Tacrine/chemistry
10.
Brain Res ; 1061(2): 73-9, 2005 Nov 09.
Article in English | MEDLINE | ID: mdl-16248990

ABSTRACT

The main goal of the present study was to analyse the effects of (+/-)-huprine X ((+/-)-HX) and galantamine (GAL), with potentiating action on nicotinic receptors, and huperzine A (HPA), devoid of nicotinic activity, on [3H]-acetylcholine ([3H]-ACh) release in striatal slices of rat brain. All compounds are non-covalent and reversible inhibitors of AChE. Addition of (+/-)-HX (0.01 microM), GAL (10 microM) and HPA (0.1 microM) to the superfusion medium decreased the release of the ACh neurotransmitter to a similar extent: 36%, 30% and 34%, respectively (P<0.01). This effect was reverted in the presence of atropine (ATR; 0.1 microM), which blocks the pre-synaptic muscarinic M2 receptor. After that, a wide range of concentrations of drugs, concomitantly with ATR (0.1 microM), was studied in the presence of haloperidol (HAL; 0.01 microM), a dopamine D2 antagonist. In these conditions, a dose-dependent increase of [3H]-ACh release was observed in the presence of (+/-)-HX, GAL and HPA. To test the role of nicotinic receptors in the drugs' effects on [3H]-ACh release, mecamylamine (MEC) 100 microM was used to block such receptors. MEC alone significantly decreased neurotransmitter release by 18% (P<0.05), but no change was obtained in the presence of both ATR and MEC. Under these conditions, (+/-)-HX, GAL and HPA increased the release of [3H]-ACh by 37%, 25% and 38%, respectively (P<0.01). Taking into account all of these data, the present results suggest that the effects induced by (+/-)-HX and GAL nicotinic-receptor potentiators seem to be mainly due to their ability in inhibiting acetylcholinesterase activity, but not by interaction on the nicotinic receptors.


Subject(s)
Acetylcholine/metabolism , Aminoquinolines/pharmacology , Cholinesterase Inhibitors , Galantamine/pharmacology , Heterocyclic Compounds, 4 or More Rings/pharmacology , Nicotinic Agonists/pharmacology , Receptors, Nicotinic/drug effects , Alkaloids , Animals , Atropine/pharmacology , Dopamine Antagonists/pharmacology , Dose-Response Relationship, Drug , Haloperidol/pharmacology , In Vitro Techniques , Mecamylamine/pharmacology , Nicotinic Antagonists/pharmacology , Parasympatholytics/pharmacology , Perfusion , Rats , Rats, Sprague-Dawley , Sesquiterpenes/pharmacology
11.
Neurosci Lett ; 379(2): 106-9, 2005 May 06.
Article in English | MEDLINE | ID: mdl-15823425

ABSTRACT

The cholinergic profile of (+/-)-huprine Y and (+/-)-huprine Z on muscarinic receptors has been determined. Displacement of [3H]-pirenzepine and [3H]-QNB plus pirenzepine was performed in rat hippocampus. Both compounds showed a higher degree of affinity to M1 muscarinic receptors (P < 0.01) than to M2 muscarinic receptors. To determine the M1 agonist or antagonist role of the two huprines, studies of inositol phosphates (IP) production were performed. Both huprines significantly stimulated IP accumulation in a concentration-dependent manner. The reversion of this effect by different antagonists showed that M1 muscarinic receptors were activated by (+/-)-huprine Y and (+/-)-huprine Z, but some other mechanisms, such as alpha1-adrenoceptors or nicotinic receptors, were involved.


Subject(s)
Aminoquinolines/pharmacology , Cholinergic Antagonists/pharmacology , Heterocyclic Compounds, 4 or More Rings/pharmacology , Hippocampus/drug effects , Receptors, Muscarinic/drug effects , Aminoquinolines/analysis , Animals , Binding, Competitive/drug effects , Cerebral Cortex/drug effects , Dose-Response Relationship, Drug , Drug Interactions , Heterocyclic Compounds, 4 or More Rings/analysis , Hippocampus/cytology , In Vitro Techniques , Male , Pirenzepine/pharmacology , Rats , Rats, Sprague-Dawley , Tritium
12.
J Alzheimers Dis ; 6(6): 577-83; discussion 673-81, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15665397

ABSTRACT

Acetylcholinesterase inhibitors (AChEI) are among the drugs most widely used in the treatment of Alzheimer's disease. They increase the levels of acetylcholine and thus improve the cognitive symptoms that are impaired. We tested whether specific AChEI show additional neuroprotective properties against colchicine-induced apoptosis in cerebellar granule neurons (CGNs), a well established apoptotic model mediated by neuronal cytoskeleton alteration. Colchicine-induced apoptosis is due to an increase in the activity of GSK-3beta and CDK5, two enzymes involved in cytoskeletal alteration. Furthermore, the intrinsic apoptotic pathway is activated by colchicines, as revealed by cytochrome c release and Bax translocation. Tacrine, (-)-huperzine A and (+/-)-huprine Y, the AChEI tested in the study, did not reverse the loss of neuronal viability induced by colchicine. Moreover, the increase in apoptotic features induced by colchicine treatment, as measured by flow cytometry and nuclear chromatin condensation, was not prevented by these AChEI. Although some of these drugs are of interest to treat Alzheimer's disease, their lack of efficacy in the prevention of colchicine-induced apoptosis in CGNs suggests that they cannot prevent neuronal loss due to cytoskeleton alteration.


Subject(s)
Aminoquinolines/pharmacology , Apoptosis/drug effects , Cholinesterase Inhibitors/pharmacology , Cytoskeleton/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Neuroprotective Agents/pharmacology , Sesquiterpenes/pharmacology , Tacrine/pharmacology , Alkaloids , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Aminoquinolines/administration & dosage , Animals , Animals, Newborn , Cerebellum/drug effects , Cerebellum/metabolism , Cerebellum/pathology , Cholinesterase Inhibitors/administration & dosage , Colchicine/adverse effects , Colchicine/antagonists & inhibitors , Cytoskeleton/pathology , Disease Models, Animal , Flow Cytometry , Glycogen Synthase Kinase 3/drug effects , Glycogen Synthase Kinase 3/metabolism , Heterocyclic Compounds, 4 or More Rings/administration & dosage , Neurons/drug effects , Neurons/metabolism , Neurons/pathology , Neuroprotective Agents/administration & dosage , Rats , Rats, Sprague-Dawley , Sesquiterpenes/administration & dosage , Tacrine/administration & dosage
13.
Mini Rev Med Chem ; 2(1): 11-25, 2002 Feb.
Article in English | MEDLINE | ID: mdl-12369954

ABSTRACT

The cholinergic hypothesis of Alzheimer's disease has spurred the development of numerous structural classes of compounds with different pharmacological profiles aimed at increasing central cholinergic neurotransmission, thus providing a symptomatic treatment for this disease. Indeed, the only drugs currently approved for the treatment of Alzheimer's disease are cholinomimetics with the pharmacological profile of acetylcholinesterase inhibitors. Recent evidence of a potential disease modifying role of acetylcholinesterase inhibitors and M(1) muscarinic agonists have led to a revival of this approach, which might be considered as more than a symptomatic treatment.


Subject(s)
Alzheimer Disease/drug therapy , Cholinergic Agents/therapeutic use , Aged , Alzheimer Disease/pathology , Animals , Cholinesterase Inhibitors/therapeutic use , Humans , Receptors, Presynaptic/drug effects
14.
Biochemistry ; 41(9): 2970-81, 2002 Mar 05.
Article in English | MEDLINE | ID: mdl-11863435

ABSTRACT

Huprine X is a novel acetylcholinesterase (AChE) inhibitor, with one of the highest affinities reported for a reversible inhibitor. It is a synthetic hybrid that contains the 4-aminoquinoline substructure of one anti-Alzheimer drug, tacrine, and a carbobicyclic moiety resembling that of another AChE inhibitor, (-)-huperzine A. Cocrystallization of huprine X with Torpedo californica AChE yielded crystals whose 3D structure was determined to 2.1 A resolution. The inhibitor binds to the anionic site and also hinders access to the esteratic site. Its aromatic portion occupies the same binding site as tacrine, stacking between the aromatic rings of Trp84 and Phe330, whereas the carbobicyclic unit occupies the same binding pocket as (-)-huperzine A. Its chlorine substituent was found to lie in a hydrophobic pocket interacting with rings of the aromatic residues Trp432 and Phe330 and with the methyl groups of Met436 and Ile439. Steady-state inhibition data show that huprine X binds to human AChE and Torpedo AChE 28- and 54-fold, respectively, more tightly than tacrine. This difference stems from the fact that the aminoquinoline moiety of huprine X makes interactions similar to those made by tacrine, but additional bonds to the enzyme are made by the huperzine-like substructure and the chlorine atom. Furthermore, both tacrine and huprine X bind more tightly to Torpedo than to human AChE, suggesting that their quinoline substructures interact better with Phe330 than with Tyr337, the corresponding residue in the human AChE structure. Both (-)-huperzine A and huprine X display slow binding properties, but only binding of the former causes a peptide flip of Gly117.


Subject(s)
Acetylcholinesterase/chemistry , Aminoquinolines/chemistry , Cholinesterase Inhibitors/chemistry , Heterocyclic Compounds, 4 or More Rings/chemistry , Torpedo/metabolism , Alkaloids , Aminoquinolines/pharmacology , Animals , Binding Sites , Chlorine/chemistry , Cholinesterase Inhibitors/pharmacology , Computer Simulation , Crystallization , Crystallography, X-Ray , Heterocyclic Compounds, 4 or More Rings/pharmacology , Kinetics , Ligands , Models, Molecular , Protein Conformation , Sesquiterpenes/chemistry , Species Specificity , Tacrine/chemistry
15.
J Med Chem ; 44(26): 4733-6, 2001 Dec 20.
Article in English | MEDLINE | ID: mdl-11741490

ABSTRACT

Two 12-amino-6,7,8,11-tetrahydro-7,11-methanocycloocta[b]quinoline derivatives [9-Me(Et)] (syn-huprines) have been obtained by condensation of known 7-alkylbicyclo[3.3.1]non-6-en-3-ones with 2-(trifluoromethyl)aniline, followed by basic cyclization of the resulting imine, and chromatographic separation of the regioisomeric mixture of products, thus obtained. The new (+/-)-syn-huprines were shown to be slightly less active bovine or human acetylcholinesterase inhibitors than the corresponding anti-derivatives. Molecular modeling simulations allow us to explain the differences in inhibitory activity of these compounds on the basis of an inverse solvation effect.


Subject(s)
Acetylcholinesterase/metabolism , Aminoquinolines/chemical synthesis , Cholinesterase Inhibitors/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Aminoquinolines/chemistry , Animals , Cattle , Cholinesterase Inhibitors/chemistry , Heterocyclic Compounds, 4 or More Rings/chemistry , Humans , Models, Molecular , Stereoisomerism , Structure-Activity Relationship
16.
Eur J Pharmacol ; 421(2): 77-84, 2001 Jun 08.
Article in English | MEDLINE | ID: mdl-11399262

ABSTRACT

The effects of the tacrine-huperzine A hybrid acetylcholinesterase inhibitors, (+/-)-12-amino-3-chloro-9-methyl-6,7,10,11-tetrahydro-7,11-methanocycloocta[b]quinoline hydrochloride ((+/-)-huprine Y) and (+/-)-12-amino-3-chloro-9-ethyl-6,7,10,11-tetrahydro-7,11-methanocycloocta[b]quinoline hydrochloride ((+/-)-huprine X), were tested on spontaneous synaptic activity by measuring the amplitude, the rise time, the rate of rise, the half-width and the area or the electrical charge of the miniature endplate potentials (m.e.p.ps) recorded extracellularly on Torpedo electric organ fragments. (+/-)-Huprine Y and (+/-)-huprine X at a concentration of 500 nM increased all the m.e.p.p. variables analyzed. The effect of (+/-)-huprine Y was smaller than that of (+/-)-huprine X for all the variables except for the rate of rise where there was no significant difference. The effects of these drugs were also tested on nicotinic receptors by analyzing the currents elicited by acetylcholine (100 microM) in Xenopus laevis oocytes, transplanted with membranes from Torpedo electric organ. Both drugs inhibited the currents in a reversible manner, (+/-)-huprine Y (IC(50)=452 nM) being more effective than (+/-)-huprine X (IC(50)=4865 nM). The Hill coefficient was 0.5 for both drugs. The inhibition of the nicotinic receptor was voltage-dependent and decreased at depolarizing potentials, and there was no significant difference in the effects between (+/-)-huprine Y and (+/-)-huprine X at concentrations near to their IC(50) values. At depolarizing potentials between -20 and +15 mV, these drugs did not have any detectable effect on the blockade of the nicotinic receptor. Both huprines increased the desensitization of the nicotinic receptors since the current closed quickly in the presence of the drugs, and there was no significant difference in this effect between (+/-)-huprine Y (500 nM) and (+/-)-huprine X (5 microM). We conclude that (+/-)-huprine Y and (+/-)-huprine X increase the level of acetylcholine in the synaptic cleft more effectively than tacrine. The interaction of (+/-)-huprine X with nicotinic receptors is weaker than that of (+/-)-huprine Y, suggesting that (+/-)-huprine X would be more specific to maintain the extracellular acetylcholine concentration.


Subject(s)
Aminoquinolines/pharmacology , Cholinesterase Inhibitors/pharmacology , Electric Organ/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Acetylcholine/pharmacology , Aminoquinolines/chemistry , Animals , Dose-Response Relationship, Drug , Electric Organ/physiology , Female , Heterocyclic Compounds, 4 or More Rings/chemistry , Membrane Potentials/drug effects , Oocytes/drug effects , Oocytes/physiology , Stereoisomerism , Synapses/drug effects , Torpedo , Xenopus
17.
Mini Rev Med Chem ; 1(2): 163-74, 2001 Jul.
Article in English | MEDLINE | ID: mdl-12369981

ABSTRACT

Tacrine-huperzine A hybrids (huprines) are a new class of very potent and selective acetylcholinesterase (AChE) inhibitors. Huprines were designed from tacrine and (-)-huperzine A through a conjunctive approach. They combine the 4-aminoquinoline substructure of tacrine with the carbobicyclic substructure of (-)-huperzine A. Structural variations on several parts of a lead structure have allowed to complete a structure-activity relationship exploration of this new structural family and have led to several huprines more active than other known AChE inhibitors.


Subject(s)
Alzheimer Disease/drug therapy , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/therapeutic use , Sesquiterpenes/therapeutic use , Tacrine/analogs & derivatives , Tacrine/therapeutic use , Alkaloids , Cholinesterase Inhibitors/chemistry , Drug Design , Humans , Models, Molecular , Molecular Conformation , Sesquiterpenes/chemical synthesis , Structure-Activity Relationship , Tacrine/chemical synthesis
18.
J Med Chem ; 43(24): 4657-66, 2000 Nov 30.
Article in English | MEDLINE | ID: mdl-11101357

ABSTRACT

Several new 12-amino-6,7,10,11-tetrahydro-7, 11-methanocycloocta[b]quinoline derivatives (tacrine-huperzine A hybrids, huprines) have been synthesized and tested as acetylcholinesterase (AChE) inhibitors. All of the new compounds contain either a methyl or ethyl group at position 9 and one or two (chloro, fluoro, or methyl) substituents at positions 1, 2, or 3. Among the monosubstituted derivatives, the more active are those substituted at position 3, their activity following the order 3-chloro > 3-fluoro > 3-methyl > 3-hydrogen. For the 1,3-difluoro and 1,3-dimethyl derivatives, the effect of the substituents is roughly additive. No significant differences were observed for the inhibitory activity of 9-methyl vs 9-ethyl derivatives mono- or disubstituted at positions 1 and/or 3. The levorotatory enantiomers of these hybrid compounds are much more active (eutomers) than the dextrorotatory forms (distomers) as AChE inhibitors. Compounds rac-20, (-)-20, rac-26, (-)-26, rac-30, (-)-30, and rac-31 showed human AChE inhibitory activities up to 28.5-fold higher than for the corresponding bovine enzyme. Also, rac-19, (-)-20, (-)-30, and rac-31 were very selective for human AChE vs butyrylcholinesterase (BChE), the AChE inhibitory activities being 438-871-fold higher than for BChE. Several hybrid compounds, specially (-)-20 and (-)-30, exhibited tight-binding character, showing higher activity after incubation of the enzyme with the inhibitor than without incubation, though the reversible nature of the enzyme-inhibitor interaction was demonstrated by dialysis. The results of the ex vivo experiments also supported the tight-binding character of compounds (-)-20 and (-)-30 and showed their ability to cross the blood-brain barrier. Molecular modeling simulations of the AChE-inhibitor complex provided a basis to explain the differences in inhibitory activity of these compounds.


Subject(s)
Acetylcholinesterase/metabolism , Bridged Bicyclo Compounds/chemical synthesis , Cholinesterase Inhibitors/chemical synthesis , Neuroprotective Agents/chemical synthesis , Quinolines/chemical synthesis , Sesquiterpenes/chemistry , Tacrine/chemistry , Alkaloids , Alzheimer Disease/drug therapy , Animals , Bridged Bicyclo Compounds/chemistry , Bridged Bicyclo Compounds/pharmacology , Butyrylcholinesterase/metabolism , Cattle , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/pharmacology , Humans , In Vitro Techniques , Male , Mice , Models, Molecular , Neuromuscular Junction/drug effects , Neuromuscular Junction/physiology , Neuromuscular Nondepolarizing Agents/pharmacology , Neuroprotective Agents/chemistry , Neuroprotective Agents/pharmacology , Quinolines/chemistry , Quinolines/pharmacology , Rats , Rats, Sprague-Dawley , Stereoisomerism , Structure-Activity Relationship , Tubocurarine/pharmacology
19.
Mol Pharmacol ; 57(2): 409-17, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10648652

ABSTRACT

Inhibitors of the enzyme acetylcholinesterase (AChE) slow and sometimes reverse the cognitive decline experienced by individuals with Alzheimer's disease. Huperzine A, a natural product used in traditional Chinese herbal medicine, and tacrine (Cognex) are among the potent AChE inhibitors used in this treatment, but the search for more selective inhibitors continues. We report herein the synthesis and characterization of (-)-12-amino-3-chloro-9-ethyl-6,7, 10,11-tetrahydro-7,11-methanocycloocta[b]quinoline hydrochloride (huprine X), a hybrid that combines the carbobicyclic substructure of huperzine A with the 4-aminoquinoline substructure of tacrine. Huprine X inhibited human AChE with an inhibition constant K(I) of 26 pM, indicating that it binds to this enzyme with one of the highest affinities yet reported. Under equivalent assay conditions, this affinity was 180 times that of huperzine A, 1200 times that of tacrine, and 40 times that of E2020 (donepezil, Aricept), the most selective AChE inhibitor currently approved for therapeutic use. The association and dissociation rate constants for huprine X with AChE were determined, and the location of its binding site on the enzyme was probed in competition studies with the peripheral site inhibitor propidium and the acylation site inhibitor edrophonium. Huprine X showed no detectable affinity for the edrophonium-AChE complex. In contrast, huprine X did form a ternary complex with propidium and AChE, although its affinity for the free enzyme was found to be 17 times its affinity for the propidium-AChE complex. These data indicated that huprine X binds to the enzyme acylation site in the active site gorge but interferes slightly with the binding of peripheral site ligands.


Subject(s)
Acetylcholinesterase/metabolism , Alzheimer Disease/drug therapy , Aminoquinolines/pharmacology , Cholinesterase Inhibitors/pharmacology , Heterocyclic Compounds, 4 or More Rings/pharmacology , Acetylcholinesterase/drug effects , Acylation , Aminoquinolines/chemical synthesis , Aminoquinolines/therapeutic use , Binding, Competitive , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/therapeutic use , Erythrocytes/enzymology , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/therapeutic use , Humans , Intercalating Agents/pharmacology , Kinetics , Propidium/pharmacology
20.
J Med Chem ; 42(17): 3227-42, 1999 Aug 26.
Article in English | MEDLINE | ID: mdl-10464010

ABSTRACT

Eleven new 12-amino-6,7,10,11-tetrahydro-7, 11-methanocycloocta[b]quinoline derivatives [tacrine (THA)-huperzine A hybrids, rac-21-31] have been synthesized as racemic mixtures and tested as acetylcholinesterase (AChE) inhibitors. For derivatives unsubstituted at the benzene ring, the highest activity was obtained for the 9-ethyl derivative rac-20, previously prepared by our group. More bulky substituents at position 9 led to less active compounds, although some of them [9-isopropyl (rac-22), 9-allyl (rac-23), and 9-phenyl (rac-26)] show activities similar to that of THA. Substitution at position 1 or 3 with methyl or fluorine atoms always led to more active compounds. Among them, the highest activity was observed for the 3-fluoro-9-methyl derivative rac-28 [about 15-fold more active than THA and about 9-fold more active than (-)-huperzine A]. The activity of some THA-huperzine A hybrids (rac-19, rac-20, rac-28, and rac-30), which were separated into their enantiomers by chiral medium-pressure liquid chromatography (chiral MPLC), using microcrystalline cellulose triacetate as the chiral stationary phase, showed the eutomer to be always the levorotatory enantiomer, their activity being roughly double that of the corresponding racemic mixture, the distomer being much less active. Also, the activity of some of these compounds inhibiting butyrylcholinesterase (BChE) was tested. Most of them [rac-27-31, (-)-28, and (-)-30], which are more active than (-)-huperzine A as AChE inhibitors, turned out to be quite selective for AChE, although not so selective as (-)-huperzine A. Most of the tested compounds 19-31 proved to be much more active than THA in reversing the neuromuscular blockade induced by d-tubocurarine. Molecular modeling of the interaction of these compounds with AChE from Torpedo californica showed them to interact as truly THA-huperzine A hybrids: the 4-aminoquinoline subunit of (-)-19 occupies the same position of the corresponding subunit in THA, while its bicyclo[3.3.1]nonadiene substructure roughly occupies the same position of the corresponding substructure in (-)-huperzine A, in agreement with the absolute configurations of (-)-19 and (-)-huperzine A.


Subject(s)
Cholinesterase Inhibitors/chemical synthesis , Neuroprotective Agents/chemical synthesis , Quinolines/chemical synthesis , Sesquiterpenes/chemical synthesis , Tacrine/analogs & derivatives , Tacrine/chemical synthesis , Acetylcholinesterase/chemistry , Alkaloids , Animals , Binding Sites , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/pharmacology , Diaphragm/drug effects , Diaphragm/innervation , Diaphragm/physiology , In Vitro Techniques , Male , Models, Molecular , Muscle Contraction/drug effects , Neuromuscular Junction/drug effects , Neuromuscular Junction/physiology , Neuroprotective Agents/chemistry , Neuroprotective Agents/pharmacology , Phrenic Nerve/drug effects , Phrenic Nerve/physiology , Quinolines/chemistry , Quinolines/pharmacology , Rats , Rats, Sprague-Dawley , Sesquiterpenes/chemistry , Sesquiterpenes/pharmacology , Stereoisomerism , Structure-Activity Relationship , Tacrine/chemistry , Tacrine/pharmacology , Torpedo
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