BACKGROUND: Rivastigmine is a pseudo-irreversible cholinesterase inhibitor used for therapy of Alzheimer's disease and non-Alzheimer dementia syndromes. In humans, rivastigmine can cause significant gastrointestinal side effects that can limit its clinical use. The aim of this study was to assess the impact of rivastigmine on gastric motor function by means of electrogastrography (EGG) in experimental pigs. METHODS: Six experimental adult female pigs (Sus scrofa f. domestica, hybrids of Czech White and Landrace breeds; 3-month-old; mean weight 30.7 ± 1.2 kg) were enrolled into the study twice and created two experimental groups. In group A, a single intragastric dose of 6 mg rivastigmine hydrogen tartate was administered in the morning to fasting pigs before EGG recording. In group B, rivastigmine was administered to overnight fasting animals in a dietary bolus in the morning for 7 days (6 mg per day). On day 8, an intragastric dose of 12 mg rivastigmine was given in the morning to fasting pigs before EGG. EGG recording was accomplished by means of an EGG standalone system. Recordings from both groups were evaluated in dominant frequency and EGG power (areas of amplitudes). RESULTS: In total, 1,980 one-minute EGG intervals were evaluated. In group A, basal EGG power (median 1290.5; interquartile range 736.5-2330 μV2) was significantly higher in comparison with the power of intervals T6 (882; 577-1375; p = 0.001) and T10 (992.5; 385-2859; p = 0.032). In group B, the dominant frequency increased significantly from basal values (1.97 ± 1.57 cycles per minute) to intervals T9 (3.26 ± 2.16; p < 0.001) and T10 (2.14 ± 1.16; p = 0.012), respectively. In group B, basal EGG power (median 1030.5; interquartile range 549-5093) was significantly higher in comparison with the power of intervals T7 (692.5; 434-1476; p = 0.002) and T8 (799; 435-1463 μV2; p = 0.004). CONCLUSIONS: Both single as well as repeated intragastric administration of rivastigmine hydrogen tartrate caused a significant decrease of EGG power (areas of amplitudes) in experimental pigs. EGG power may serve as an indirect indicator of gastric motor competence. These findings might provide a possible explanation of rivastigmine-associated dyspepsia in humans.

• MeSH
• Alzheimer Disease * MeSH
• Cholinesterase Inhibitors pharmacology   MeSH
• Electromyography MeSH
• Phenylcarbamates pharmacology   MeSH
• Gastrointestinal Tract MeSH
• Infant MeSH
• Humans MeSH
• Rivastigmine pharmacology   MeSH
• Stomach * MeSH
• Animals MeSH
• Check Tag
• Infant MeSH
• Humans MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cholinesterase Inhibitors MeSH
• Phenylcarbamates MeSH
• Rivastigmine MeSH

Alzheimer's disease (AD) is the most common cause of dementia in elderly people; currently, there is no efficient treatment. Considering the increase in life expectancy worldwide AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. A great amount of experimental and clinical evidence indicated that AD is a complex disorder characterized by widespread neurodegeneration of the CNS, with major involvement of the cholinergic system, causing progressive cognitive decline and dementia. The current treatment, based on the cholinergic hypothesis, is only symptomatic and mainly involves the restoration of acetylcholine (ACh) levels through the inhibition of acetylcholinesterase (AChE). Since the introduction of the Amaryllidaceae alkaloid galanthamine as an antidementia drug in 2001, alkaloids have been one of the most attractive groups for searching for new AD drugs. The present review aims to comprehensively summarize alkaloids of various origins as multi-target compounds for AD. From this point of view, the most promising compounds seem to be the β-carboline alkaloid harmine and several isoquinoline alkaloids since they can simultaneously inhibit several key enzymes of AD's pathophysiology. However, this topic remains open for further research on detailed mechanisms of action and the synthesis of potentially better semi-synthetic analogues.

• Keywords
• Alzheimer’s disease, marine alkaloids, multi-target compounds, plant alkaloids,
• MeSH
• Acetylcholinesterase MeSH
• Alkaloids * pharmacology   MeSH
• Alzheimer Disease * drug therapy   MeSH
• Cholinesterase Inhibitors pharmacology   MeSH
• Galantamine therapeutic use   MeSH
• Humans MeSH
• Aged MeSH
• Check Tag
• Humans MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Alkaloids * MeSH
• Cholinesterase Inhibitors MeSH
• Galantamine MeSH

Twenty-four novel compounds bearing tetrahydroacridine and N-propargyl moieties have been designed, synthesised, and evaluated in vitro for their anti-cholinesterase and anti-monoamine oxidase activities. Propargyltacrine 23 (IC50 = 21 nM) was the most potent acetylcholinesterase (AChE) inhibitor, compound 20 (IC50 = 78 nM) showed the best inhibitory human butyrylcholinesterase (hBChE) profile, and ligand 21 afforded equipotent and significant values on both ChEs (human AChE [hAChE]: IC50 = 0.095 ± 0.001 µM; hBChE: IC50 = 0.093 ± 0.003 µM). Regarding MAO inhibition, compounds 7, 15, and 25 demonstrated the highest inhibitory potential towards hMAO-B (IC50 = 163, 40, and 170 nM, respectively). In all, compounds 7, 15, 20, 21, 23, and 25 exhibiting the most balanced pharmacological profile, were submitted to permeability and cell viability tests. As a result, 7-phenoxy-N-(prop-2-yn-1-yl)-1,2,3,4-tetrahydroacridin-9-amine hydrochloride (15) has been identified as a permeable agent that shows a balanced pharmacological profile [IC50 (hAChE) = 1.472 ± 0.024 µM; IC50 (hBChE) = 0.659 ± 0.077 µM; IC50 (hMAO-B) = 40.39 ± 5.98 nM], and consequently, as a new hit-ligand that deserves further investigation, in particular in vivo analyses, as the preliminary cell viability test results reported here suggest that this is a relatively safe therapeutic agent.

• Keywords
• Alzheimer’s disease, Cholinesterase inhibitor, monoamine oxidase inhibitor, propargyl amines, tacrine,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• Alzheimer Disease * drug therapy   MeSH
• Amines MeSH
• Butyrylcholinesterase * metabolism   MeSH
• Cholinesterase Inhibitors pharmacology   therapeutic use   MeSH
• Monoamine Oxidase Inhibitors pharmacology   MeSH
• Humans MeSH
• Ligands MeSH
• Monoamine Oxidase MeSH
• Oxidoreductases MeSH
• Drug Design MeSH
• Tacrine therapeutic use   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Amines MeSH
• Butyrylcholinesterase * MeSH
• Cholinesterase Inhibitors MeSH
• Monoamine Oxidase Inhibitors MeSH
• Ligands MeSH
• Monoamine Oxidase MeSH
• Oxidoreductases MeSH
• Tacrine MeSH

Nerve agents pose a real threat to both the military and civil populations, but the current treatment of the poisoning is unsatisfactory. Thus, we studied the efficacy of prophylactic use of memantine alone or in combination with clinically used reversible acetylcholinesterase inhibitors (pyridostigmine, donepezil, rivastigmine) against soman. In addition, we tested their influence on post-exposure therapy consisting of atropine and asoxime. Pyridostigmine alone failed to decrease the acute toxicity of soman. But all clinically used acetylcholinesterase inhibitors administered alone reduced the acute toxicity, with donepezil showing the best efficacy. The combination of memantine with reversible acetylcholinesterase inhibitors attenuated soman acute toxicity significantly. The pretreatment administered alone or in combinations influenced the efficacy of post-exposure treatment in a similar fashion: (i) pyridostigmine or memantine alone did not affect the antidotal treatment, (ii) centrally acting reversible acetylcholinesterase inhibitors alone increased the antidotal treatment slightly, (iii) combination of memantine with reversible acetylcholinesterase inhibitors increased the antidotal treatment more markedly. In conclusion, memantine alone failed to decrease the acute toxicity of soman or increase post-exposure antidotal treatment efficacy. The combination of memantine with donepezil significantly increased post-exposure effectiveness (together 5.12, pretreatment alone 1.72). Both drugs, when applied together, mitigate soman toxicity and boost post-exposure treatment.

• Keywords
• Donepezil, Memantine, Mice, Pyridostigmine, Rivastigmine, Soman,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• Antiparkinson Agents administration & dosage   MeSH
• Cholinesterase Inhibitors administration & dosage   toxicity   MeSH
• Donepezil administration & dosage   MeSH
• Dopamine Agents administration & dosage   MeSH
• Drug Therapy, Combination MeSH
• Memantine administration & dosage   MeSH
• Mice MeSH
• Pre-Exposure Prophylaxis methods   MeSH
• Soman toxicity   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Antiparkinson Agents MeSH
• Cholinesterase Inhibitors MeSH
• Donepezil MeSH
• Dopamine Agents MeSH
• Memantine MeSH
• Soman MeSH

Alzheimer's disease (AD) is a progressive age-related neurodegenerative disease recognized as the most common form of dementia among elderly people. Due to the fact that the exact pathogenesis of AD still remains to be fully elucidated, the treatment is only symptomatic and available drugs are not able to modify AD progression. Considering the increase in life expectancy worldwide, AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. Due to their complex nitrogen-containing structures, alkaloids are considered to be promising candidates for use in the treatment of AD. Since the introduction of galanthamine as an antidementia drug in 2001, Amaryllidaceae alkaloids (AAs) and further isoquinoline alkaloids (IAs) have been one of the most studied groups of alkaloids. In the last few years, several compounds of new structure types have been isolated and evaluated for their biological activity connected with AD. The present review aims to comprehensively summarize recent progress on AAs and IAs since 2010 up to June 2021 as potential drugs for the treatment of AD.

• Keywords
• Alzheimer’s disease, acetylcholinesterase, butyrylcholinesterase, docking study, isoquinoline alkaloids, monoaminooxidase, neuroprotective activity, prolyl oligopeptidase,
• MeSH
• Amaryllidaceae Alkaloids metabolism   MeSH
• Alzheimer Disease metabolism   MeSH
• Amaryllidaceae chemistry   MeSH
• Neurodegenerative Diseases metabolism   MeSH
• Prolyl Oligopeptidases metabolism   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Amaryllidaceae Alkaloids MeSH
• Prolyl Oligopeptidases MeSH

Alzheimer's disease (AD) is a multifactorial neurodegenerative condition of the central nervous system (CNS) that is currently treated by cholinesterase inhibitors and the N-methyl-d-aspartate receptor antagonist, memantine. Emerging evidence strongly supports the relevance of targeting butyrylcholinesterase (BuChE) in the more advanced stages of AD. Within this study, we have generated a pilot series of compounds (1-20) structurally inspired from belladine-type Amaryllidaceae alkaloids, namely carltonine A and B, and evaluated their acetylcholinesterase (AChE) and BuChE inhibition properties. Some of the compounds exhibited intriguing inhibition activity for human BuChE (hBuChE), with a preference for BuChE over AChE. Seven compounds were found to possess a hBuChE inhibition profile, with IC50 values below 1 µM. The most potent one, compound 6, showed nanomolar range activity with an IC50 value of 72 nM and an excellent selectivity pattern over AChE, reaching a selectivity index of almost 1400. Compound 6 was further studied by enzyme kinetics, along with in-silico techniques, to reveal the mode of inhibition. The prediction of CNS availability estimates that all the compounds in this survey can pass through the blood-brain barrier (BBB), as disclosed by the BBB score.

• Keywords
• Alzheimer’s disease, amaryllidaceae alkaloid, butyrylcholinesterase, docking studies, norbelladine-type,
• MeSH
• Acetylcholinesterase chemistry   MeSH
• Amaryllidaceae Alkaloids chemistry   MeSH
• Butyrylcholinesterase chemistry   MeSH
• Cholinesterase Inhibitors chemistry   pharmacology   MeSH
• Humans MeSH
• Tumor Cells, Cultured MeSH
• Neuroblastoma drug therapy   pathology   MeSH
• Computer Simulation MeSH
• Cell Proliferation MeSH
• Molecular Docking Simulation * MeSH
• Tyramine analogs & derivatives   chemistry   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Amaryllidaceae Alkaloids MeSH
• Butyrylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH
• norbelladine MeSH Browser
• Tyramine MeSH

Alzheimer's disease (AD) is a complex disorder with unknown etiology. Currently, only symptomatic therapy of AD is available, comprising cholinesterase inhibitors and N-methyl-d-aspartate (NMDA) receptor antagonists. Drugs targeting only one pathological condition have generated only limited efficacy. Thus, combining two or more therapeutic interventions into one molecule is believed to provide higher benefit for the treatment of AD. In the presented study, we designed, synthesized, and biologically evaluated 15 novel fluoren-9-amine derivatives. The in silico prediction suggested both the oral availability and permeation through the blood-brain barrier (BBB). An initial assessment of the biological profile included determination of the cholinesterase inhibition and NMDA receptor antagonism at the GluN1/GluN2A and GluN1/GluN2B subunits, along with a low cytotoxicity profile in the CHO-K1 cell line. Interestingly, compounds revealed a selective butyrylcholinesterase (BChE) inhibition pattern with antagonistic activity on the NMDARs. Their interaction with butyrylcholinesterase was elucidated by studying enzyme kinetics for compound 3c in tandem with the in silico docking simulation. The docking study showed the interaction of the tricyclic core of new derivatives with Trp82 within the anionic site of the enzyme in a similar way as the template drug tacrine. From the kinetic analysis, it is apparent that 3c is a competitive inhibitor of BChE.

• Keywords
• Alzheimer’s disease, N-methyl-d-aspartate receptor, acetylcholinesterase, butyrylcholinesterase, fluorene, in silico, in vitro, multi-target directed ligands,
• MeSH
• Alzheimer Disease drug therapy   enzymology   genetics   pathology   MeSH
• Butyrylcholinesterase chemistry   drug effects   genetics   MeSH
• CHO Cells MeSH
• Cholinesterase Inhibitors chemistry   pharmacology   MeSH
• Cricetulus MeSH
• Fluorenes chemistry   pharmacology   MeSH
• Blood-Brain Barrier drug effects   MeSH
• Enzyme Inhibitors pharmacology   MeSH
• Humans MeSH
• Computer Simulation MeSH
• Receptors, N-Methyl-D-Aspartate antagonists & inhibitors   genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Butyrylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH
• fluorene MeSH Browser
• Fluorenes MeSH
• Enzyme Inhibitors MeSH
• N-methyl D-aspartate receptor subtype 2A MeSH Browser
• NR2B NMDA receptor MeSH Browser
• Receptors, N-Methyl-D-Aspartate MeSH

Inhibiting the formation of amyloid fibrils is a crucial step in the prevention of the human neurological disorder, Alzheimer's disease (AD). Ionic liquid (IL) mediated interactions are an expedient approach that exhibits inhibition effects on amyloid fibrils. In view of the beneficial role of ILs, in this work we have explored complexation of anti-Alzheimer's drugs (i.e., tacrine and PC-37) and an amino acid-functionalized IL [AIL (4-PyC8)]. Maintaining standard physiological conditions, the binding mechanism, thermo-dynamical properties and binding parameters were studied by employing UV-vis, fluorescence, FTIR, 1H NMR, COSY and NOESY spectroscopy. The present investigation uncovers the fact that the interaction of anti-Alzheimer's drugs with 4-PyC8 is mediated through H-bonding and van der Waals forces. The Benesi-Hildebrand relation was used to evaluate the binding affinity and PC-37 showed the highest binding when complexed with 4-PyC8. FTIR spectra showed absorption bands at 3527.98 cm-1 and 3527.09 cm-1 for the PC-37 + 4-PyC8 system which is quite promising compared to tacrine. 1H-NMR experiments recorded deshielding for tacrine at relatively higher concentrations than PC-37. COSY investigations suggest that anti-Alzheimer's drugs after complexation with 4-PyC8 show a 1 : 1 ratio. The cross-peaks of the NOESY spectra involve correlations between anti-Alzheimer's drugs and AIL protons, indicating complexation between them. The observed results indicate that these complexes are expected to have a possible therapeutic role in reducing/inhibiting amyloid fibrils when incorporated into drug formulations.

• Publication type
• Journal Article MeSH

Thirteen known (1-12 and 16) and three previously undescribed Amaryllidaceae alkaloids of belladine structural type, named carltonine A-C (13-15), were isolated from bulbs of Narcissus pseudonarcissus cv. Carlton (Amaryllidaceae) by standard chromatographic methods. Compounds isolated in sufficient amounts, and not tested previously, were evaluated for their in vitro acetylcholinesterase (AChE; E.C. 3.1.1.7), butyrylcholinesterase (BuChE; E.C. 3.1.1.8) and prolyl oligopeptidase (POP; E.C. 3.4.21.26) inhibition activities. Significant human BuChE (hBUChE) inhibitory activity was demonstrated by newly described alkaloids carltonine A (13) and carltonine B (14) with IC50 values of 913 ± 20 nM and 31 ± 1 nM, respectively. Both compounds displayed a selective inhibition pattern for hBuChE with an outstanding selectivity profile over AChE inhibition, higher than 100. The in vitro data were further supported by in silico studies of the active alkaloids 13 and 14 in the active site of hBuChE.

• Keywords
• Alzheimer’s disease, Amaryllidaceae, Narcissus pseudonarcissus cv. Carlton, alkaloids, butyrylcholinesterase, carltonine A–C, docking studies,
• MeSH
• Alkaloids chemistry   pharmacology   MeSH
• Butyrylcholinesterase chemistry   metabolism   MeSH
• Cholinesterase Inhibitors chemistry   pharmacology   MeSH
• Humans MeSH
• Narcissus chemistry   MeSH
• Molecular Docking Simulation MeSH
• Protein Binding MeSH
• Binding Sites MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Alkaloids MeSH
• Butyrylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH

Tacrine was the first drug to be approved for Alzheimer's disease (AD) treatment, acting as a cholinesterase inhibitor. The neuropathological hallmarks of AD are amyloid-rich senile plaques, neurofibrillary tangles, and neuronal degeneration. The portfolio of currently approved drugs for AD includes acetylcholinesterase inhibitors (AChEIs) and N-methyl-d-aspartate (NMDA) receptor antagonist. Squaric acid is a versatile structural scaffold capable to be easily transformed into amide-bearing compounds that feature both hydrogen bond donor and acceptor groups with the possibility to create multiple interactions with complementary sites. Considering the relatively simple synthesis approach and other interesting properties (rigidity, aromatic character, H-bond formation) of squaramide motif, we combined this scaffold with different tacrine-based derivatives. In this study, we developed 21 novel dimers amalgamating squaric acid with either tacrine, 6-chlorotacrine or 7-methoxytacrine representing various AChEIs. All new derivatives were evaluated for their anti-cholinesterase activities, cytotoxicity using HepG2 cell line and screened to predict their ability to cross the blood-brain barrier. In this contribution, we also report in silico studies of the most potent AChE and BChE inhibitors in the active site of these enzymes.

• Keywords
• 6-chlorotacrine, 7-methoxytacrine, Alzheimer’s disease, bis(7)-tacrine, cholinesterases, in silico, in vitro, squaramides, tacrine,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• Butyrylcholinesterase metabolism   MeSH
• Quinine analogs & derivatives   chemistry   pharmacology   MeSH
• Cholinesterase Inhibitors chemical synthesis   chemistry   pharmacology   MeSH
• Kinetics MeSH
• Humans MeSH
• Models, Molecular MeSH
• Molecular Structure MeSH
• Tacrine chemistry   pharmacology   MeSH
• Dose-Response Relationship, Drug MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Butyrylcholinesterase MeSH
• Quinine MeSH
• Cholinesterase Inhibitors MeSH
• squaramide MeSH Browser
• Tacrine MeSH