Galantamine--a novel cholinergic drug with a unique dual mode of action for the treatment of patients with Alzheimer's disease

Benzyloxychalcone Hybrids as Prospective Acetylcholinesterase Inhibitors against Alzheimer's Disease: Rational Design, Synthesis, In Silico ADMET Prediction, QSAR, Molecular Docking, DFT, and Molecular Dynamic Simulation Studies

Acetylcholinesterase inhibitors (AChEIs) are crucial therapeutic targets for both the early and severe stages of Alzheimer's disease (AD). Chalcones and their chromone-based derivatives are well-known building blocks with anti-Alzheimer properties. This study synthesized 4-benzyloxychalcone derivatives and characterized their structures using IR, 1H NMR, 13C NMR, and HRMS. Additionally, the synthesized 4-benzyloxychalcone derivatives were tested for anti-acetylcholinesterase (AChE) activity. The synthesized compounds outperformed galantamine, which is used as a positive control against acetylcholinesterase. Utilizing an acetylcholinesterase (AChE) receptor (PDB ID: 4EY7)-chalcone derivative (12a-c), a molecular docking investigation was performed on the synthesized compounds. The goal was to predict the binding sites and energies of the derivatives with respect to the receptor amino acids. The dynamic behavior of the ligand-receptor complex resulting from the interaction of the best docking compounds 12a and 12c with the acetylcholinesterase receptor was used to analyze the stability via MD simulation. MM/GBSA and MM/PBSA were used to calculate free binding energies using snapshots from system trajectories. Advanced computational approaches incorporating long-range corrections were utilized to calculate the molecular characteristics of chalcone derivatives 12a-c at the DFT/wB97XD/6-311++G(d,p) level. We used the molecular electrostatic surface potential (MESP) with high-quality data and visualization to find the most active site in these molecules. Reactivity descriptors, including the condensed Fukui function, chemical hardness (η), dual descriptors, chemical potential (μ), and electrophilicity (ω), were calculated for the chalcone derivatives.

Recent advances in the total synthesis of galantamine, a natural medicine for Alzheimer's disease

Covering: 2006 to 2023(-)-Galantamine is a natural product with distinctive structural features and potent inhibitory activity against acetylcholine esterase (AChE). It is clinically approved for the treatment of Alzheimer's disease. The clinical significance and scarcity of this natural product have prompted extensive and ongoing efforts towards the chemical synthesis of this challenging tetracyclic structure. The objective of this review is to summarize and discuss recent progress in the total synthesis of galantamine from 2006 to 2023. The contents are organized according to the synthetic strategies for the construction of the quaternary center. Key features of each synthesis have been highlighted, followed by a summary and outlook at the end.

Targeting calciumopathy for neuroprotection: focus on calcium channels Cav1, Orai1 and P2X7

As the uncontrolled entry of calcium ions (Ca2+) through plasmalemmal calcium channels is a cell death trigger, the conjecture is here raised that mitigating such an excess of Ca2+ entry should rescue from death the vulnerable neurons in neurodegenerative diseases (NDDs). However, this supposition has failed in some clinical trials (CTs). Thus, a recent CT tested whether isradipine, a blocker of the Cav1 subtype of voltage-operated calcium channels (VOCCs), exerted a benefit in patients with Parkinson's disease (PD); however, outcomes were negative. This is one more of the hundreds of CTs done under the principle of one-drug-one-target, that have failed in Alzheimer's disease (AD) and other NDDs during the last three decades. As there are myriad calcium channels to let Ca2+ ions gain the cell cytosol, it seems reasonable to predict that blockade of Ca2+ entry through a single channel may not be capable of preventing the Ca2+ flood of cells by the uncontrolled Ca2+ entry. Furthermore, as Ca2+ signaling is involved in the regulation of myriad functions in different cell types, it seems also reasonable to guess that a therapy should be more efficient by targeting different cells with various drugs. Here, we propose to mitigate Ca2+ entry by the simultaneous partial blockade of three quite different subtypes of plasmalemmal calcium channels that is, the Cav1 subtype of VOCCs, the Orai1 store-operated calcium channel (SOCC), and the purinergic P2X7 calcium channel. All three channels are expressed in both microglia and neurons. Thus, by targeting the three channels with a combination of three drug blockers we expect favorable changes in some of the pathogenic features of NDDs, namely (i) to mitigate Ca2+ entry into microglia; (ii) to decrease the Ca2+-dependent microglia activation; (iii) to decrease the sustained neuroinflammation; (iv) to decrease the uncontrolled Ca2+ entry into neurons; (v) to rescue vulnerable neurons from death; and (vi) to delay disease progression. In this review we discuss the arguments underlying our triad hypothesis in the sense that the combination of three repositioned medicines targeting Cav1, Orai1, and P2X7 calcium channels could boost neuroprotection and delay the progression of AD and other NDDs.

Alkaloids as drug leads in Alzheimer's treatment: Mechanistic and therapeutic insights

Alzheimer's disease (AD) has few effective treatment options and continues to be a major global health concern. AD is a neurodegenerative disease that typically affects elderly people. Alkaloids have potential sources for novel drug discovery due to their diverse chemical structures and pharmacological activities. Alkaloids, natural products with heterocyclic nitrogen-containing structures, are considered potential treatments for AD. This review explores the neuroprotective properties of alkaloids in AD, focusing on their ability to regulate pathways such as amyloid-beta aggregation, oxidative stress, synaptic dysfunction, tau hyperphosphorylation, and neuroinflammation. The FDA has approved alkaloids such as acetylcholinesterase inhibitors like galantamine and rivastigmine. This article explores AD's origins, current market medications, and clinical applications of alkaloids in AD therapy. This review explores the development of alkaloid-based drugs for AD, focusing on pharmacokinetics, blood-brain barrier penetration, and potential adverse effects. Future research should focus on the clinical evaluation of promising alkaloids, developing recently discovered alkaloids, and the ongoing search for novel alkaloids for medical treatment. A pharmaceutical option containing an alkaloid may potentially slow down the progression of AD while enhancing its symptoms. This review highlights the potential of alkaloids as valuable drug leads in treating AD, providing a comprehensive understanding of their mechanisms of action and therapeutic implications.

Review of Pharmacotherapeutic Targets in Alzheimer's Disease and Its Management Using Traditional Medicinal Plants

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired daily functioning. While there is currently no cure for AD, several pharmacotherapeutic targets and management strategies have been explored. Additionally, traditional medicinal plants have gained attention for their potential role in AD management. Pharmacotherapeutic targets in AD include amyloid-beta (Aβ) aggregation, tau protein hyperphosphorylation, neuroinflammation, oxidative stress, and cholinergic dysfunction. Traditional medicinal plants, such as Ginkgo biloba, Huperzia serrata, Curcuma longa (turmeric), and Panax ginseng, have demonstrated the ability to modulate these targets through their bioactive compounds. Ginkgo biloba, for instance, contains flavonoids and terpenoids that exhibit neuroprotective effects by reducing Aβ deposition and enhancing cerebral blood flow. Huperzia serrata, a natural source of huperzine A, has acetylcholinesterase-inhibiting properties, thus improving cholinergic function. Curcuma longa, enriched with curcumin, exhibits anti-inflammatory and antioxidant effects, potentially mitigating neuroinflammation and oxidative stress. Panax ginseng's ginsenosides have shown neuroprotective and anti-amyloidogenic properties. The investigation of traditional medicinal plants as a complementary approach to AD management offers several advantages, including a lower risk of adverse effects and potential multi-target interactions. Furthermore, the cultural knowledge and utilization of these plants provide a rich source of information for the development of new therapies. However, further research is necessary to elucidate the precise mechanisms of action, standardize preparations, and assess the safety and efficacy of these natural remedies. Integrating traditional medicinal-plant-based therapies with modern pharmacotherapies may hold the key to a more comprehensive and effective approach to AD treatment. This review aims to explore the pharmacotherapeutic targets in AD and assess the potential of traditional medicinal plants in its management.

Multifunctional Nanocarriers for Alzheimer's Disease: Befriending the Barriers

Neurodegenerative diseases (NDDs) have been increasing in incidence in recent years and are now widespread worldwide. Neuronal death is defined as the progressive loss of neuronal structure or function which is closely associated with NDDs and represents the intrinsic features of such disorders. Amyotrophic lateral sclerosis, frontotemporal dementia, Alzheimer's, Parkinson's, and Huntington's diseases (AD, PD, and HD, respectively) are considered neurodegenerative diseases that affect a large number of people worldwide. Despite the testing of various drugs, there is currently no available therapy that can remedy or effectively slow the progression of these diseases. Nanomedicine has the potential to revolutionize drug delivery for the management of NDDs. The use of nanoparticles (NPs) has recently been developed to improve drug delivery efficiency and is currently subjected to extensive studies. Nanoengineered particles, known as nanodrugs, can cross the blood-brain barrier while also being less invasive compared to the most treatment strategies in use. Polymeric, magnetic, carbonic, and inorganic NPs are examples of NPs that have been developed to improve drug delivery efficiency. Primary research studies using NPs to cure AD are promising, but thorough research is needed to introduce these approaches to clinical use. In the present review, we discussed the role of metal-based NPs, polymeric nanogels, nanocarrier systems such as liposomes, solid lipid NPs, polymeric NPs, exosomes, quantum dots, dendrimers, polymersomes, carbon nanotubes, and nanofibers and surfactant-based systems for the therapy of neurodegenerative diseases. In addition, we highlighted nanoformulations such as N-butyl cyanoacrylate, poly(butyl cyanoacrylate), D-penicillamine, citrate-coated peptide, magnetic iron oxide, chitosan (CS), lipoprotein, ceria, silica, metallic nanoparticles, cholinesterase inhibitors, an acetylcholinesterase inhibitors, metal chelators, anti-amyloid, protein, and peptide-loaded NPs for the treatment of AD.

The Effect of Galantamine on Lipopolysaccharide-induced Acute Lung Injury During Neutropenia Recovery in Mice

BACKGROUND/AIM

Acute lung injury (ALI) is associated with a high mortality rate and cancer patients who receive chemotherapy are at high risk of ALI during neutropenia recovery. Galantamine is a cholinesterase inhibitor used for Alzheimer's disease treatment. Previous studies have shown that galantamine reduced inflammatory response in lipopolysaccharide (LPS)-induced ALI in rats. Mer protein was negatively associated with inflammatory response. The aim of the study was to investigate whether galantamine is effective in LPS-induced ALI during neutropenia recovery and its effect on Mer tyrosine kinase (MerTK) expression in mice.

MATERIALS AND METHODS

Intraperitoneal cyclophosphamide was given to mice to induce neutropenia. After 7 days, LPS was administered by intratracheal instillation. Intraperitoneal galantamine was given once before LPS administration and in another group, galantamine was given twice before LPS administration.

RESULTS

Galantamine attenuated LPS-induced ALI in histopathological analysis. The neutrophil percentage was lower in the group where galantamine was injected once, compared to the LPS group (p=0.007). MerTK expression was also higher in the group where galantamine was injected once but did not reach statistical significance (p=0.101).

CONCLUSION

Galantamine attenuated inflammation in LPS-induced ALI during neutropenia recovery.

Alzheimer's disease current therapies, novel drug delivery systems and future directions for better disease management

Alzheimer's disease (AD), is a neurodegenerative disorder that escalates with time, exerting a significant impact on physical and mental health and leading to death. The prevalence of AD is progressively rising along with its associated economic burden and necessitates effective therapeutic approaches in the near future. This review paper aims to offer an insightful overview of disease pathogenesis, current FDA-approved drugs, and drugs in different clinical phases. It also explores innovative formulations and drug delivery strategies, focusing on nanocarriers and long-acting medications (LAMs) to enhance treatment efficacy and patient adherence. The review also emphasizes preclinical evidence related to nanocarriers and their potential to improve drug bioavailability, pharmacokinetics, and pharmacodynamics parameters, while also highlighting their ability to minimize systemic side effects. By providing a comprehensive analysis, this review furnishes valuable insights into different pathophysiological mechanisms for future drug development. It aims to inform the development of treatment strategies and innovative formulation approaches for delivering existing molecules in Alzheimer's disease, ultimately striving to improve patient compliance.

Pharmacological Treatment of Cognitive Impairment Associated With Schizophrenia: State of the Art and Future Perspectives

Cognitive Impairment Associated with Schizophrenia (CIAS) represents one of the core dimensions of Schizophrenia Spectrum Disorders (SSD), with an important negative impact on real-world functional outcomes of people living with SSD. Treatment of CIAS represents a therapeutic goal of considerable importance, and while cognition-oriented evidence-based psychosocial interventions are available, effective pharmacological treatment could represent a game-changer in the lives of people with SSD. The present critical review reports and discusses the evidence regarding the effects of several pharmacological agents that are available in clinical practice or are under study, commenting on both current and future perspectives of CIAS treatment. In particular, the effects on CIAS of antipsychotic medications, anticholinergic medications, benzodiazepines, which are currently commonly used in the treatment of SSD, and of iclepertin, d-serine, luvadaxistat, xanomeline-trospium, ulotaront, anti-inflammatory molecules, and oxytocin, which are undergoing regulatory trials or can be considered as experimental agents, will be reported and discussed. Currently, available pharmacological agents do not appear to provide substantial benefits on CIAS, but accurate management of antipsychotic medications and avoiding treatments that can further exacerbate CIAS represent important strategies. Some molecules that are currently being investigated in Phase 2 and Phase 3 trials have provided very promising preliminary results, but more information is currently required to assess their effectiveness in real-world contexts and to provide clear recommendations regarding their use in clinical practice. The results of ongoing and future studies will reveal whether any of these molecules represents the awaited pharmacological game-changer in the treatment of CIAS.

Acetylcholine and metacognition during sleep

Acetylcholine is a neurotransmitter and neuromodulator involved in a variety of cognitive functions. Additionally, acetylcholine is involved in the regulation of REM sleep: cholinergic neurons in the brainstem and basal forebrain project to and innervate wide areas of the cerebral cortex, and reciprocally interact with other neuromodulatory systems, to produce the sleep-wake cycle and different sleep stages. Consciousness and cognition vary considerably across and within sleep stages, with metacognitive capacity being strikingly reduced even during aesthetically and emotionally rich dream experiences. A notable exception is the phenomenon of lucid dreaming-a rare state whereby waking levels of metacognitive awareness are restored during sleep-resulting in individuals becoming aware of the fact that they are dreaming. The role of neurotransmitters in these fluctuations of consciousness and cognition during sleep is still poorly understood. While recent studies using acetylcholinesterase inhibitors suggest a potential role of acetylcholine in the occurrence of lucid dreaming, the underlying mechanisms by which this effect is produced remains un-modelled and unknown; with the causal link between cholinergic mechanisms and upstream psychological states being complex and elusive. Several theories and approaches targeting the association between acetylcholine and metacognition during wakefulness and sleep are highlighted in this review, moving through microscopic, mesoscopic and macroscopic levels of analysis to detail this phenomenon at several organisational scales. Several exploratory hypotheses will be developed to guide future research towards fully articulating how metacognition is affected by activity at the acetylcholine receptor.

Protective effects of L-arginine on Alzheimer's disease: Modulating hippocampal nitric oxide levels and memory deficits in aluminum chloride-induced rat model

There is evidence that high daily intake of aluminum (Al) is associated with an increased risk of dementia or cognitive decline. We injected L-arginine into the dorsal hippocampus (DH) of an AlCl3-induced Alzheimer's model and studied memory deficit, β-amyloid (βA) accumulation, neurodegeneration, and molecular changes. Male Wistar rats were cannulated unilaterally in the DH under a stereotaxic apparatus and a dose of AlCl3 (1-200 μg/rat) was injected into the CA1. After recovery, L-arginine and L-NAME (0.05-25 μg/rat) were injected into CA1 and animals were tested in novelty seeking task. One group received βA (2 μg/rat, intra CA1) as a reference group. Control groups received saline (1 μL/rat, intra-CA1) and galantamine (25 μg/rat, intra-CA1), respectively. Finally, rats were anesthetized and hippocampal tissues were isolated on ice. Levels of neuronal NO synthase (nNOS), β-secretase and soluble guanylyl cyclase (sGC) were measured by western blotting. βA formation and the number of CA1 neurons were assessed by Congo red and Nissl staining. NOS activation by NADPH-diaphorase (NADPH-d) was investigated. All data were analyzed using analysis of variance (ANOVA) at α = 0.05 level. Like βA, AlCl3 (25 μg/rat) caused accumulation of βA in the DH and increased stopping of the animal on the novel side (indicating a recall deficit). CA1 neurons decreased, and nNOS and β-secretase, but not sGC, showed a change consistent with Alzheimer's. However, prophylactic intervention of L-arginine at 3-9 μg/rat was protective, probably by nNOS stimulation in DH, as shown by NADPH-d assay. L-arginine may protect against Alzheimer's by increasing hippocampal NO levels.

Antioxidant and anti-Alzheimer activities of Clivia miniata (Lindl) roots, bulbs, and aerial parts: In-vitro and in-silico studies

Clivia miniata (Lindl) is a member of the family Amaryllidaceae known for its chemically diverse alkaloids with a wide range of biological activities. Many reports revealed a direct role of oxidative stress in the early stage of Alzheimer's disease (AD). Meanwhile, β-site amyloid precursor protein cleavage enzyme 1 (BACE-1) is a molecular target for the treatment of AD. We aimed to investigate C. miniata root, bulb, and aerial part chemical profiling, antioxidant, BACE-1, and AChE enzyme inhibitory activities. Results showed that the total root had the most potent radical scavenging activity as compared to the total bulb and aerial part, respectively. Ethanol root extract had the most potent BACE-1 inhibitory activity (IC50 = 0.02 ± 0.001 µg/mL) as compared to the bulb and aerial part (IC50 = 0.93 ± 0.13, 1.80 ± 0.24 µg/mL), respectively. Moreover, the total root extract mitigated AChE enzyme activity more than total bulb and aerial fractions with IC50 values of (0.06 ± 0.02, 0.58 ± 0.3, and 1.89 ± 0.42 µg/mL, respectively. Bioassay-guided acid-base fractionation confirmed superior BACE-1 inhibitory activity of the root fractions particularly, methylene chloride and ethyl acetate fractions with (IC50 values of 0.21 ± 0.60 and 0.01 ± 0.001 µg/mL), respectively. UPLC-MS analysis of ethyl acetate and methylene chloride fractions of C. miniata root led to the identification of eight phenolics and thirteen alkaloids, respectively. Molecular docking studies against BACE-1 protein revealed that lycorine di-hexoside, miniatine, and cliviaaline were the most promising hits. Further investigation of anti-AD potential of the aforementioned small molecules is required.

Guidelines for pharmacotherapy in Alzheimer's disease - A primer on FDA-approved drugs

The growing prevalence of dementia makes it important for us to better understand its pathophysiology and treatment modalities, to improve the quality of life of patients and caregivers. Alzheimer's disease (AD), a neurodegenerative disease, is the most common form of amnestic dementia in the geriatric population. Pathophysiology of AD is widely attributed to aggregation of amyloid-beta (Aβ) plaques and hyperphosphorylation of tau proteins. Initial treatment modalities aimed to increase brain perfusion in a non-specific manner. Subsequent therapy focused on rectifying neurotransmitter imbalance in the brain. Newer drugs modify the progression of the disease by acting against aggregated Aβ plaques. However, not all drugs used in therapy of AD have been granted approval by the United States Food and Drug Administration (FDA). This review categorizes and summarizes the FDA-approved drugs in the treatment of AD in a manner that would make it a convenient reference for researchers and practicing physicians alike. Drugs that mitigate symptoms of dementia may be categorized into mitigators of Behavioral and Psychological Symptoms of Dementia (BPSD), and mitigators of cognitive decline. BPSD mitigators include brexpiprazole, an atypical antipsychotic with a once-daily dosage suited to treat agitation in dementia patients, and suvorexant, an orexin receptor antagonist used to treat sleep disturbances. Cognitive decline mitigators include cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine and glutamate inhibitors such as memantine. Donepezil is the most commonly prescribed drug. It is cheap, well-tolerated, and may be prescribed orally once daily, or as a transdermal patch once weekly. It increases ACh levels, enhances oligodendrocyte differentiation and also protects against Aβ toxicity. However, regular cardiac monitoring is required due to reports of cardiac conduction side effects. Rivastigmine requires a twice-daily oral dosage or once-daily replacement of transdermal patch. It has fewer cardiac side effects than donepezil, but local application-site reactions have been noted. Galantamine, in addition to improving cognitive symptoms in a short span of time, also delays the development of BPSDs and has minimal drug-drug interactions by virtue of having multiple metabolic pathways. However, cardiac conduction disturbances must be closely monitored for. Memantine, a glutamate regulator, acts as an anti-Parkinsonian agent and an antidepressant, in addition to improving cognition and neuroprotection, and requires a once-daily dosage in the form of immediate-release or sustained-release oral tablets. Disease-modifying drugs such as aducanumab and lecanemab reduce the Aβ burden. Both act by binding with fibrillary conformations of Aβ plaques in the brain. These drugs have a risk of causing amyloid-related imaging abnormalities, especially in persons with ApoE4 gene. Aducanumab is administered once every 4 weeks and lecanemab once every 2 weeks. The decision on the choice of the drug must be made after considering the availability of drug, compliance of patient (once-daily vs. multiple doses daily), cost, specific comorbidities, and the risk-benefit ratio for the particular patient. Other non-pharmacological treatment modalities must also be adopted to have a holistic approach toward the treatment of AD.

A combination of metformin and galantamine exhibits synergistic benefits in the treatment of sarcopenia

Age-associated sarcopenia, characterized by a progressive loss in muscle mass and strength, is the largest cause of frailty and disability in the elderly worldwide. Current treatments involve nonpharmacological guidelines that few subjects can abide by, highlighting the need for effective drugs. Preclinical models were employed to test the benefits of RJx-01, a combination drug composed of metformin and galantamine, on sarcopenia. In worms, RJx-01 treatment improved lifespan, locomotion, pharyngeal pumping, and muscle fiber organization. The synergistic effects of RJx-01 were recapitulated in a transgenic mouse model that displays an exacerbated aging phenotype (Opa1-/-). In these mice, RJx-01 ameliorated physical performance, muscle mass and force, neuromuscular junction stability, and systemic inflammation. RJx-01 also improved physical performance and muscle strength in 22-month-old WT mice and also improved skeletal muscle ultrastructure, mitochondrial morphology, autophagy, lysosomal function, and satellite cell content. Denervation and myofiber damage were decreased in RJx-01-treated animals compared with controls. RJx-01 improved muscle quality rather than quantity, indicating that the improvement in quality underlies the beneficial effects of the combination drug. The studies herein indicate synergistic beneficial effects of RJx-01 in the treatment of sarcopenia and support the pursuit of RJx-01 in a human clinical trial as a therapeutic intervention for sarcopenia.

Protective Effect of Galantamine against Doxorubicin-Induced Neurotoxicity

BACKGROUND AND AIMS

Doxorubicin (DOX) causes cognitive impairment (chemobrain) in patients with cancer. While DOX damages the cholinergic system, few studies have focused on the protective effects of cholinergic function on chemobrain. The acetylcholinesterase inhibitor galantamine (GAL) demonstrates neuroprotective properties. We investigated the mechanisms associated with DOX-induced cognitive impairments and the potential protective role of GAL in preventing chemobrain.

MAIN METHODS

Female Wistar rats were divided into control, DOX, GAL, and DOX + GAL groups. The rats in the DOX group were administered DOX (5 mg/kg intraperitoneally twice weekly for two weeks), while those in the GAL group were orally administered GAL (2.5 mg/kg) via oral gavage once daily for 15 days. The combination group (DOX + GAL) received GAL (once daily) and DOX (two times per week) concurrently. The body weights and survival rates were monitored daily. The animals were subjected to behavioral tests to assess the memory function followed by the biochemical estimation of inflammatory markers, including tumor necrosis factor-α (TNF-α), interleukine-1β (IL-1β), and interleukine-6 (IL-6) in rat brain tissue and RT-qPCR.

KEY FINDINGS

DOX caused a reduction in the body weight and survival rate, which was alleviated by GAL concomitant treatment with DOX (DOX + GAL). These groups had reduced body weights and survival rates. DOX-treated animals exhibited an impairment of short-term spatial working memory, manifested as a behavioral alteration in the Y-maze test, the novel object recognition (NOR) test, and the elevated plus-maze (EPM) test. Concurrent treatment with GAL (DOX + GAL) showed improved memory function, as evidenced by an increase in the number of entries and time spent in the novel arm, the time spent exploring the novel object, and the transfer latency in the Y-maze, NOR test, and EPM test, respectively. These findings were also supported by biochemical observations showing the reversal of DOX-induced changes in IL-1β, IL-6, and TNF-α, as well as their relative expression of mRNA in brain tissue following concurrent GAL treatment.

CONCLUSION

GAL appeared to be a neuroprotective agent against neuroinflammation caused by DOX by reducing inflammatory markers in the brain.

Therapeutic and medicinal effects of snowdrop (Galanthus spp.) in Alzheimer's disease: A review

Genus Galanthus (Amaryllidaceae) is an early spring flowering bulbous plant. Galanthus species contain alkaloids that have shown pharmacological activity. Galanthamine is an alkaloid that was extracted from Galanthus and other Amaryllidaceae. Owing to its acetylcholinesterase (AChE) inhibitory activity, galanthamine is used and marketed to treat Alzheimer's disease (AD). The aim of the present study, while introducing the botanical and pharmacological characteristics and various aspects of the medicinal plant Galanthus, is to emphasize the effect of this plant in the treatment of AD. In this web-based study in 2021, articles indexed in scientific databases in English language, including ISI Web of Knowledge, PubMed, Scopus, MedLib, Medknow, SID, ISC, and also articles and e-books published in Springer, Elsevier, John Wiley and Sons, and Taylor and Francis were evaluated from 1990 to 2021, using the following keywords: "Galanthus" "galanthamine," "Alzheimer's disease." Amaryllidaceae-type alkaloids possess an anticholinesterase activity. The most studied Galanthus alkaloid, galanthamine, is a long-acting, selective, reversible, competitive inhibitor of AChE and an allosteric modulator of the neuronal nicotinic receptor for acetylcholine (ACh). Owing to its AChE inhibitory activity, galanthamine is used to treat certain stages of AD. Galantamine can act as a parasympathomimetic agent, especially as a reversible cholinesterase inhibitor. Galantamine is not structurally associated with other AChE inhibitors. Hence, its proposed mechanism of action involves the reversible inhibition of AChE, preventing hydrolysis of ACh that results in an increased concentration of ACh at cholinergic synapses.

Nose-to-brain delivery of galantamine loaded nanospray dried polyacrylic acid/taurodeoxycholate mixed matrix as a protective therapy in lipopolysaccharide-induced Alzheimer's in mice model

One of the promising drug delivery approaches is performed by nanosizing the administered drug product using the nanospray drying technique. In this study, a combination of several formulation factors was integrated and exploited to augment the bioavailability of galantamine hydrobromide (GAL) via the intranasal route. Nanosized polymeric particles were fabricated using the mucoadhesive polymer, polyacrylic acid (PAA), and the permeability booster, sodium taurodeoxycholate (TDC). First, a preliminary study was conducted to adjust the nanospray drying conditions. Then, formulations were prepared on the basis of a mixed factorial experimental design and further analyzed using Design Expert® software. Different responses were investigated: particle size, polydispersity index, spray rate, drying efficiency, and percent yield. The optimized formulation was further assessed for physical morphology using the scanning electron microscope, flowability, in vitro drug release, and in vivo brain cell uptake using confocal laser scanning microscopy. The promising formulation (F6), composed of equal ratio of PAA and TDC and 20 mg GAL, exhibited a particle size of 185.55 ± 4.3 nm, polydispersity index of 0.413 ± 0.02, and yield-value of 69.58 ± 5.82 %. It also displayed good flowability, complete drug release within 2 h, and enhanced in vivo fluorescent dye uptake and penetration in brain cells. The efficacy of the optimized formulation was examined using lipopolysaccharide-induced Alzheimer's in mice. Results revealed the advantageous influence of the optimized formulation (F6) through downregulation of NF-κβ, IL-1β and GFAP as well as upregulating TGF-1β in adult mice.

Neurotoxicity evoked by organophosphates and available countermeasures

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABA_AR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.

Advances in anticancer alkaloid-derived metallo-chemotherapeutic agents in the last decade: Mechanism of action and future prospects

Metal-based complexes have occupied a pioneering niche in the treatment of many chronic diseases, including various types of cancers. Despite the phenomenal success of cisplatin for the treatment of many solid malignancies, a limited number of metallo-drugs are in clinical use against cancer chemotherapy till date. While many other prominent platinum and non‑platinum- based metallo-drugs (e.g. NAMI-A, KP1019, carboplatin, oxaliplatin, titanocene dichloride, casiopeinas® etc) have entered clinical trials, many have failed at later stages of R&D due to deleterious toxic effects, intrinsic resistance and poor pharmacokinetic response and low therapeutic efficacy. Nonetheless, research in the area of medicinal inorganic chemistry has been increasing exponentially over the years, employing novel target based drug design strategies aimed at improving pharmacological outcomes and at the same time mitigating the side-effects of these drug entities. Over the last few decades, natural products became one of the key structural motifs in the anticancer drug development. Many eminent researchers in the area of medicinal chemistry are devoted to develop new 3d-transition metal-based anticancer drugs/repurpose the existing bioactive compounds derived from myriad pharmacophores such as coumarins, flavonoids, chromones, alkaloids etc. Metal complexes of natural alkaloids and their analogs such as luotonin A, jatrorrhizine, berberine, oxoaporphine, 8-oxychinoline etc. have gained prominence in the anticancer drug development process as the naturally occurring alkaloids can be anti-proliferative, induce apoptosis and exhibit inhibition of angiogenesis with better healing effect. While some of them are inhibitors of ERK signal-regulated kinases, others show activity based on cyclooxygenases-2 (COX-2) and telomerase inhibition. However, the targets of these alkaloid complexes are still unclear, though it is well-established that they demonstrate anticancer potency by interfering with multiple pathways of tumorigenesis and tumor progression both in vitro and in vivo. Over the last decade, many significant advances have been made towards the development of natural alkaloid-based metallo-drug therapeutics for intervention in cancer chemotherapy that have been summarized below and reviewed in this article.

Galantamine attenuates autoinflammation in a mouse model of familial mediterranean fever

BACKGROUND

Autoinflammatory diseases, a diverse group of inherited conditions characterized by excessive innate immune activation, have limited therapeutic options. Neuroimmune circuits of the inflammatory reflex control innate immune overactivation and can be stimulated to treat disease using the acetylcholinesterase inhibitor galantamine.

METHODS

We tested the efficacy of galantamine in a rodent model of the prototypical autoinflammatory disease familial Mediterranean fever (FMF). Multiple chronic disease markers were evaluated in animals that received long-term galantamine treatment compared to vehicle.

RESULTS

Long-term treatment with galantamine attenuated the associated splenomegaly and anemia which are characteristic features of this disease. Further, treatment reduced inflammatory cell infiltration into affected organs and a subcutaneous air pouch.

CONCLUSIONS

These findings suggest that galantamine attenuates chronic inflammation in this mouse model of FMF. Further research is warranted to explore the therapeutic potential of galantamine in FMF and other autoinflammatory diseases.

Discovery of pyrrole derivatives as acetylcholinesterase-sparing butyrylcholinesterase inhibitor

Inspired by the crucial roles of (hetero)aryl rings in cholinesterase inhibitors and the pyrrole ring in new drug discovery, we synthesized 19 pyrrole derivatives and investigated their cholinesterase inhibitory activity. As a result, compounds 3o, 3p, and 3s with a 1,3-diaryl-pyrrole skeleton showed high selectivity toward BChE over AChE with a best IC₅₀ value of 1.71 ± 0.087 µM, which were comparable to donepezil. The pharmaceutical potential of these structures was further predicted and compounds 3o and 3p were proved to meet well with the Lipinsky's five rules. In combination of the inhibition kinetic studies with the results of molecular docking, we concluded that compound 3p inhibited BChE in a mixed competitive mode. This research has proved the potential of the 1,3-diaryl-pyrrole skeleton as a kind of selective BChE inhibitor.

LC-MS/MS assay of fluoropezil and its two major metabolites in human plasma: an application to pharmacokinetic studies

Background: LC-MS/MS methods were developed for pharmacokinetic analysis and verified to measure fluoropezil, a new AchE inhibitor for Alzheimer's disease treatment, and its two primary metabolites (N-debenzyl fluoride fluoropezil [M1] and N-oxidized fluoropezil [M11]) in human plasma. Methods & results: Analytes were extracted from 50 μl plasma using protein precipitation and separated by HPLC using a bridged ethyl hybrid column and gradient elution procedure. Analytical detection was performed with a triple quadrupole mass spectrometer and electrospray ionization source in multiple reaction monitoring mode. The LC-MS/MS method was fully validated. The quantification linear ranges were 0.100-50.0 ng/ml (fluoropezil), 0.0500-25.0 ng/ml (M1) and 0.0500-25.0 ng/ml (M11). Conclusion: A sensitive, reliable LC-MS/MS method was established and used successfully to explore the pharmacokinetics of fluoropezil.

Risk of Serious Adverse Events Associated With Individual Cholinesterase Inhibitors Use in Older Adults With Dementia: A Population-Based Cohort Study

BACKGROUND AND OBJECTIVE

Cholinesterase inhibitors (ChEIs) are used as first-line pharmacotherapy to manage dementia. However, there are limited data regarding their relative safety. This study evaluated the risk of serious adverse events (SAEs) associated with individual ChEIs in older adults with dementia and also examined sex-based and dose-based effects on this risk.

METHODS

This was a retrospective cohort study using 2013-2015 US Medicare claims data involving Parts A, B, and D. Patients aged ≥ 65 years with a dementia diagnosis and incident use of the ChEIs, namely donepezil, galantamine, or rivastigmine, were included. The primary outcome of interest was SAEs defined as emergency department visits, inpatient hospitalizations, or death within 6 months of ChEI initiation. Multivariable Cox proportional hazards regression with propensity score (PS) as a covariate and inverse probability of treatment weighting generated using generalized boosted models was used to assess the risk of SAEs across individual ChEIs.

RESULTS

The study included 767,684 older adults with dementia who were incident new users of ChEIs (donepezil 79.42%, rivastigmine 17.67%, galantamine 2.91%). SAEs were observed in 15.5% of the cohort within 6 months of ChEI prescription. Cox regression model with PS as covariate found that patients prescribed rivastigmine (adjusted hazard ratio [aHR] 1.12; 95% CI 1.03-1.33) and galantamine (aHR 1.51; 95% CI 1.24-1.84) were at increased risk of SAEs compared with patients on donepezil. Stratified analyses revealed that rivastigmine was associated with an 18% increased risk for SAEs in females (aHR 1.18; 95% CI 1.06-1.31), and galantamine was associated with a 71% increased risk in males (aHR 1.71; 95% CI 1.17-2.51) compared with donepezil. High and recommended index doses of rivastigmine and galantamine were associated with an increased risk of SAEs compared with donepezil. The findings were consistent in sensitivity analyses.

CONCLUSION

The study found that the risk of SAEs varied across individual ChEIs, with sex and dose moderating these effects. Therefore, these moderating effects should be carefully considered in personalizing dementia care.

Asymmetric Total Syntheses of (-)-Lycoramine, (-)-Lycoraminone, (-)-Narwedine, and (-)-Galanthamine

A concise asymmetric total synthesis of naturally occurring Amaryllidaceae alkaloids sharing dihydrobenzofuran scaffolds, (-)-galanthamine (1a), (-)-lycoramine (1b), (-)-narwedine (2a), and (-)-lycoraminone (2b), is reported. Orthoester Johnson-Claisen rearrangement of allyl alcohol (+)-9 (98% ee) in diisopropylethylamine furnished enantioenriched cyclohexene (+)-8 (97.4% ee) with a quaternary stereogenic center.

Natural Products from Plants and Algae for Treatment of Alzheimer’s Disease: A Review

Neurodegenerative disorders including Parkinson’s disease (PD), Huntington’s disease (HD) and the most frequent, Alzheimer’s disease (AD), represent one of the most urgent medical needs worldwide. Despite a significantly developed understanding of disease development and pathology, treatments that stop AD progression are not yet available. The recent approval of sodium oligomannate (GV-971) for AD treatment in China emphasized the potential value of natural products for the treatment of neurodegenerative disorders. Many current clinical studies include the administration of a natural compound as a single and combination treatment. The most prominent mechanisms of action are anti-inflammatory and anti-oxidative activities, thus preserving cellular survival. Here, we review current natural products that are either approved or are in testing for a treatment of neurodegeneration in AD. In addition to the most important compounds of plant origin, we also put special emphasis on compounds from algae, given their neuroprotective activity and their underlying mechanisms of neuroprotection.

Cholinergic and Neuroimmune Signaling Interact to Impact Adult Hippocampal Neurogenesis and Alcohol Pathology Across Development

Alcohol (ethanol) use and misuse is a costly societal issue that can affect an individual across the lifespan. Alcohol use and misuse typically initiates during adolescence and generally continues into adulthood. Not only is alcohol the most widely abused drug by adolescents, but it is also one of the most widely abused drugs in the world. In fact, high rates of maternal drinking make developmental ethanol exposure the most preventable cause of neurological deficits in the Western world. Preclinical studies have determined that one of the most consistent effects of ethanol is its disruption of hippocampal neurogenesis. However, the severity, persistence, and reversibility of ethanol’s effects on hippocampal neurogenesis are dependent on developmental stage of exposure and age at assessment. Complicating the neurodevelopmental effects of ethanol is the concurrent development and maturation of neuromodulatory systems which regulate neurogenesis, particularly the cholinergic system. Cholinergic signaling in the hippocampus directly regulates hippocampal neurogenesis through muscarinic and nicotinic receptor actions and indirectly regulates neurogenesis by providing anti-inflammatory regulatory control over the hippocampal environmental milieu. Therefore, this review aims to evaluate how shifting maturational patterns of the cholinergic system and its regulation of neuroimmune signaling impact ethanol’s effects on adult neurogenesis. For example, perinatal ethanol exposure decreases basal forebrain cholinergic neuron populations, resulting in long-term developmental disruptions to the hippocampus that persist into adulthood. Exaggerated neuroimmune responses and disruptions in adult hippocampal neurogenesis are evident after environmental, developmental, and pharmacological challenges, suggesting that perinatal ethanol exposure induces neurogenic deficits in adulthood that can be unmasked under conditions that strain neural and immune function. Similarly, adolescent ethanol exposure persistently decreases basal forebrain cholinergic neuron populations, increases hippocampal neuroimmune gene expression, and decreases hippocampal neurogenesis in adulthood. The effects of neither perinatal nor adolescent ethanol are mitigated by abstinence whereas adult ethanol exposure-induced reductions in hippocampal neurogenesis are restored following abstinence, suggesting that ethanol-induced alterations in neurogenesis and reversibility are dependent upon the developmental period. Thus, the focus of this review is an examination of how ethanol exposure across critical developmental periods disrupts maturation of cholinergic and neuroinflammatory systems to differentially affect hippocampal neurogenesis in adulthood.

Cognition and serotonin in Parkinson's disease

Cognitive impairment affects up to 80% of patients with Parkinson's disease (PD) and is associated with poor quality of life. PD cognitive dysfunction includes poor working memory, impairments in executive function and difficulty in set-shifting. The pathophysiology underlying cognitive impairment in PD is still poorly understood, but there is evidence to support involvements of the cholinergic, dopaminergic, and noradrenergic systems. Only rivastigmine, an acetyl- and butyrylcholinesterase inhibitor, is efficacious for the treatment of PD dementia, which limits management of cognitive impairment in PD. Whereas the role of the serotonergic system in PD cognition is less understood, through its interactions with other neurotransmitters systems, namely, the cholinergic system, it may be implicated in cognitive processes. In this chapter, we provide an overview of the pharmacological, clinical and pathological evidence that implicates the serotonergic system in mediating cognition in PD.

Nanonization of Magnoflorine-Encapsulated Novel Chitosan-Collagen Nanocapsules for Neurodegenerative Diseases: In Vitro Evaluation

Neurodegeneration is one of the most common diseases in the aged population, characterized by the loss in the function of neuronal cells and their ultimate death. One of the common features in the progression of this type of diseases is the oxidative stress. Drugs which are currently being used have been found to show lateral side effects, which is partly due to their inefficiency to cross blood-brain barrier. Nanoencapsulation of bioactive compounds is a profound approach in this direction and has become a method of choice nowadays. This study involved the evaluation of the anti-oxidative properties of magnoflorine (MF), which is an aporphine quaternary alkaloid, and synthesis of MF-loaded chitosan-collagen nanocapsules (MF-CCNc) for its better efficacy as a potent anti-oxidant. Physiochemical characterization of the synthesized nanocapsules was done by using dynamic light scattering and transmission electron microscopy. It revealed that the synthesized nanocapsules are of small size range, as small as 12 ± 2 nm, and are more or less of spherical shape. Sustained release was shown by MF in the in vitro drug release studies. Both MF and MF-CCNc were found to have good anti-oxidant potential with IC50 < 25 μg/mL. No major cytotoxicity was shown by the synthesized nanocapsules on SH-SY5Y cells. In silico anti-acetylcholinesterase (AChE) studies were also done, and they revealed that MF can be a potent inhibitor of AChE.

Morphological classification and changes in dementia (Review)

The progressive functional decline that involves both cognitive and neuropsychiatric symptoms characteristic to dementia is one of the leading research topics. The risk for dementia is an intertwined mix between aging, genetic risk factors, and environmental influences. APOEε4, which is one of the apolipoprotein E (APOE) alleles, is the major genetic risk factor for late-onset of the most common form of dementia, Alzheimer's. Advances in machine learning have led to the development of artificial intelligence (AI) algorithms to help diagnose dementia by magnetic resonance imaging (MRI) in order to detect it in the preclinical stage. The basis of the determinations starts from the morphometry of cerebral atrophies. The present review focused on MRI techniques which are a leading tool in identifying cortical atrophy, white matter dysfunctionalities, cerebral vessel quality (as a factor for cognitive impairment) and metabolic asymmetries. In addition, a brief overview of Alzheimer's disease was presented and recent neuroimaging in the field of dementia with an emphasis on structural MR imaging and more powerful methods such as diffusion tensor imaging, quantitative susceptibility mapping, and magnetic transfer imaging were explored in order to propose a simple systematic approach for the diagnosis and treatment of dementia.

Risk of overactive bladder associated with cholinesterase inhibitors in dementia

BACKGROUND

Although cholinesterase inhibitors (ChEIs) are the primary treatment for dementia, they are associated with overactive bladder (OAB), necessitating antimuscarinic use. Limited data exist regarding the risk of OAB across individual ChEIs in dementia. This study evaluated the risk of OAB associated with individual ChEIs in older adults with dementia.

METHODS

This was a new user retrospective cohort study using Medicare claims data involving Parts A, B, and D claims dataset from 2013 to 2015. The study included older adults (aged 65 and older) with a diagnosis of dementia using donepezil, galantamine, or rivastigmine. New ChEI claims were identified with a 6-month baseline washout period. Patients with OAB diagnosis or any antimuscarinic or mirabegron use in the baseline period were excluded. The primary outcome of interest was OAB diagnosis or prescription of antimuscarinics or mirabegron within 6 months of ChEI initiation. Multivariable cox proportional hazards regression with propensity scores (PS) as covariates and inverse probability of treatment weighting generated using generalized boosted models was used to assess the risk of OAB among donepezil, galantamine, and rivastigmine users.

RESULTS

The study included 524,975 older adults with dementia who were incident users of ChEIs (donepezil 80.72%, rivastigmine 16.41%, galantamine 2.87%). Overall, OAB diagnosis/antimuscarinic/mirabegron prescription was observed in 5.07% of the cohort within 6 months of ChEIs prescription. The Cox regression model with PS as covariate approach found that donepezil use increased the risk of OAB compared to rivastigmine (aHR, 1.13; 95% CI, 1.08-1.28; p < 0.0001). However, there was no differential risk of OAB between galantamine and rivastigmine. The findings were consistent with the generalized boosted models.

CONCLUSIONS

The study found that the risk of OAB varies across individual ChEIs with an increased risk of OAB with donepezil compared to rivastigmine. The study findings suggest the need to understand and manage medication-related morbidity in older adults with dementia.

Assessment and Validation of Globodera pallida as a Novel In Vivo Model for Studying Alzheimer's Disease

BACKGROUND

Whole transgenic or non-transgenic organism model systems allow the screening of pharmacological compounds for protective actions in Alzheimer's disease (AD).

AIM

In this study, a plant parasitic nematode, Globodera pallida, which assimilates intact peptides from the external environment, was investigated as a new potential non-transgenic model system of AD. Methods: Fresh second-stage juveniles of G. pallida were used to measure their chemosensory, perform immunocytochemistry on their neurological structures, evaluate their survival rate, measure reactive oxygen species, and determine total oxidized glutathione to reduced glutathione ratio (GSSG/GSH) levels, before and after treatment with 100 µM of various amyloid beta (Aβ) peptides (1-40, 1-42, 17-42, 17-40, 1-28, or 1-16). Wild-type N2 C. elegans (strain N2) was cultured on Nematode Growth Medium and directly used, as control, for chemosensory assays.

RESULTS

We demonstrated that: (i) G. pallida (unlike Caenorhabditis elegans) assimilates amyloid-β (Aβ) peptides which co-localise with its neurological structures; (ii) pre-treatment with various Aβ isoforms (1-40, 1-42, 17-42, 17-40, 1-28, or 1-16) impairs G. pallida's chemotaxis to differing extents; (iii) Aβ peptides reduced survival, increased the production of ROS, and increased GSSG/GSH levels in this model; (iv) this unique model can distinguish differences between different treatment concentrations, durations, and modalities, displaying good sensitivity; (v) clinically approved neuroprotective agents were effective in protecting G. pallida from Aβ (1-42) exposure. Taken together, the data indicate that G. pallida is an interesting in vivo model with strong potential for discovery of novel bioactive compounds with anti-AD activity.

Pharmacological Influencing of The Cholinergic Anti-inflammatory Pathway in Infectious Diseases and Inflammatory Pathologies

The cholinergic anti-inflammatory pathway is a part of the parasympathetic nervous system and it can also be entitled as an anti-inflammatory reflex. It consists of terminations of the vagal nerve into blood, acetylcholine released from the terminations, macrophages and other cells having α7 nicotinic acetylcholine receptor (α7 nAChR), calcium ions crossing through the receptor and interacting with nuclear factors, and erythrocytes with acetylcholinesterase (AChE) terminating the neurotransmission. Stopping of inflammatory cytokines production is the major task for the cholinergic antiinflammatory pathway. The cholinergic anti-inflammatory pathway can be stimulated or suppressed by agonizing or antagonizing α7 nAChR or by inhibition of AChE. This review is focused on cholinergic anti-inflammatory pathway regulation by drugs. Compounds that inhibit cholinesterases (for instance, huperzine, rivastigmine, galantamine), and their impact on the cholinergic anti-inflammatory pathway are discussed here and a survey of actual literature is provided.

α7-Acetylcholine Receptor Signaling Reduces Neuroinflammation After Subarachnoid Hemorrhage in Mice

Aneurysmal subarachnoid hemorrhage (aSAH) causes a robust inflammatory response which leads worse brain injury and poor outcomes. We investigated if stimulation of nicotinic acetylcholine α7 receptors (α7-AChR) (receptors shown to have anti-inflammatory effects) would reduce inflammation and improve outcomes. To investigate the level of peripheral inflammation after aSAH, inflammatory markers were measured in plasma samples collected in a cohort of aSAH patients. To study the effect of α7-AChR stimulation, SAH was induced in adult mice which were then treated with a α7-AChR agonist, galantamine, or vehicle. A battery of motor and cognitive tests were performed 24 h after subarachnoid hemorrhage. Mice were euthanized and tissue collected for analysis of markers of inflammation or activation of α7-AChR-mediated transduction cascades. A separate cohort of mice was allowed to survive for 28 days to assess long-term neurological deficits and histological outcome. Microglia cell culture subjected to hemoglobin toxicity was used to assess the effects of α7-AChR agonism. Analysis of eighty-two patient plasma samples confirmed enhanced systemic inflammation after aSAH. α7-AChR agonism reduced neuroinflammation at 24 h after SAH in male and female mice, which was associated with improved outcomes. This coincided with JAK2/STAT3 and IRAK-M activity modulations and a robust improvement in neurological/cognitive status that was effectively reversed by interfering with various components of these signaling pathways. Pharmacologic inhibition partially reversed the α7-AChR agonist's benefits, supporting α7-AChR as a target of the agonist's therapeutic effect. The cell culture experiment showed that α7-AChR agonism is directly beneficial to microglia. Our results demonstrate that activation of α7-AChR represents an attractive target for treatment of SAH. Our findings suggest that α7-AChR agonists, and specifically galantamine, might provide therapeutic benefit to aSAH patients.

Dextran Sodium Sulphate-Induced Gastrointestinal Injury Further Aggravates the Impact of Galantamine on the Gastric Myoelectric Activity in Experimental Pigs

Galantamine has been used as a treatment for Alzheimer disease. It has a unique, dual mode of action (inhibitor of acetylcholinesterase and allosteric modulator of nicotinic acetylcholine receptors). Nausea (in about 20%), vomiting (10%) and diarrhoea (5–7%) are the most common side effects. The aim of this study was to assess the effect of galantamine on porcine gastric myoelectric activity without (Group A) and with (Group B) dextran sodium sulphate (DSS)-induced gastrointestinal injury. Galantamine hydrobromide was administrated to twelve pigs as a single intragastric dose (24 mg). Gastric myoelectric activity was investigated by electrogastrography (EGG). Basal (15 min before galantamine administration) and study recordings after galantamine administration (300 min) were evaluated using a running spectral analysis. Results were expressed as dominant frequency of gastric slow waves and power analysis (areas of amplitudes). Altogether, 3780 one-minute EGG recordings were evaluated. In Group A, power was steady from basal values for 180 min, then gradually decreased till 270 min (p = 0.007). In Group B, there was a rapid gradual fall from basal values to those after 120 min (p = 0.007) till 300 min (p ˂ 0.001). In conclusion, galantamine alone revealed an unfavourable effect on porcine myoelectric activity assessed by gastric power. It can be a plausible explanation of galantamine-associated dyspepsia in humans. DSS caused further profound decrease of EGG power. That may indicate that underlying inflammatory, ischaemic or NSAIDs-induced condition of the intestine in humans can have aggravated the effect of galantamine on gastric myoelectric activity.

Bridging Cyanobacteria to Neurodegenerative Diseases: A New Potential Source of Bioactive Compounds against Alzheimer's Disease

Neurodegenerative diseases (NDs) represent a drawback in society given the ageing population. Dementias are the most prevalent NDs, with Alzheimer’s disease (AD) representing around 70% of all cases. The current pharmaceuticals for AD are symptomatic and with no effects on the progression of the disease. Thus, research on molecules with therapeutic relevance has become a major focus for the scientific community. Cyanobacteria are a group of photosynthetic prokaryotes rich in biomolecules with confirmed activity in pathologies such as cancer, and with feasible potential in NDs such as AD. In this review, we aimed to compile the research works focused in the anti-AD potential of cyanobacteria, namely regarding the inhibition of the enzyme β-secretase (BACE1) as a fundamental enzyme in the generation of β-amyloid (Aβ), the inhibition of the enzyme acetylcholinesterase (AChE) lead to an increase in the availability of the neurotransmitter acetylcholine in the synaptic cleft and the antioxidant and anti-inflammatory effects, as phenomena associated with neurodegeneration mechanisms.

Evaluation of the Therapeutic Effect of Lycoramine on Alzheimer's Disease in Mouse Model

BACKGROUND

Alzheimer's disease is one of the leading health problems characterized by the accumulation of Aβ and hyperphosphorylated tau that account for the senile plaque formations causing extensive cognitive decline. Many of the clinical diagnoses of Alzheimer's disease are made in the late stages, when the pathological changes have already progressed.

OBJECTIVE

The objective of this study is to evaluate the promising therapeutic effects of a natural compound, lycoramine, which has been shown to have therapeutic potential in several studies and to understand its mechanism of action on the molecular level via differential protein expression analyses.

METHODS

Lycoramine and galantamine, an FDA approved drug used in the treatment of mild to moderate AD, were administered to 12 month-old 5xFAD mice. Effects of the compounds were investigated by Morris water maze, immunohistochemistry and label- free differential protein expression analyses.

RESULTS

Here we demonstrated the reversal of cognitive decline via behavioral testing and the clearance of Aβ plaques. Proteomics analysis provided in-depth information on the statistically significant protein perturbations in the cortex, hippocampus and cerebellum sections to hypothesize the possible clearance mechanisms of the plaque formation and the molecular mechanism of the reversal of cognitive decline in a transgenic mouse model. Bioinformatics analyses showed altered molecular pathways that can be linked with the reversal of cognitive decline observed after lycoramine administration but not with galantamine.

CONCLUSION

Lycoramine shows therapeutic potential to halt and reverse cognitive decline at the late stages of disease progression, and holds great promise for the treatment of Alzheimer's disease.

Microsequential injection analysis/lab-on-valve system for the automatic evaluation of acetylcholinesterase inhibitors

A miniaturized microsequential injection/lab-on-valve (µSIA-LOV) system was developed and shown to be a useful alternative to perform inhibitory studies on acetylcholinesterase. These studies are essential for the evaluation of the potential therapeutic effect of drugs commonly used in the treatment of Alzheimer's disease. Donepezil, galantamine, and rivastigmine were tested, in addition to compounds based on the xanthone scaffold. Four of these xanthone derivatives were identified as having EC₅₀ values between 676 and 4466 µmol/l, showing a potential inhibitory effect higher than the clinical agent rivastigmine. The developed automatic system added advantages of reduction of reagents and sample consumption (around 55 µl per analysis), lower cost per analysis, and the generation of less waste (around 1.2 ml per analysis). The µSIA-LOV system is also a robust, rapid, reliable, and simple system to use. Docking studies suggested a possible mode of interaction with the target acetylcholinesterase protein.

Identification of 1,2,4-Triazolylthioethanone Scaffold for the Design of New Acetylcholinesterase Inhibitors

Acetylcholinesterase (AChE) inhibitors are the most effective drugs for Alzheimer's disease treatment. However, considering the potential and failure rates of AChE inhibitors, chemical scaffolds targeting cholinesterase specifically are still very limited. Herein, we report a new class of AChE inhibitors identified by employing a virtual screening approach that combines shape similarity with molecular docking calculations. Virtual screening followed by the evaluation of AChE inhibitory activity allowed us to identify 1,2,4-triazolylthioethanones as a novel class of AChE inhibitors. Thirteen compounds with 1,2,4-triazolylthiothanone core and IC₅₀ values in the range of 0.15±0.07 to 3.32±0.92 μM have been reported here. Our findings shed light into a class of AChE inhibitors that could be useful starting point for the development of novel therapeutics to tackle Alzheimer's disease.

Antimuscarinic Cascade Across Individual Cholinesterase Inhibitors in Older Adults with Dementia

BACKGROUND

Acetylcholinesterase inhibitors (AChEIs) have been associated with an increased risk of starting antimuscarinic treatment to treat overactive bladder (OAB)-an example of a prescribing cascade. Limited comparative data exist regarding the prescribing cascade of antimuscarinics across individual AChEIs in older adults with dementia.

OBJECTIVE

This study examined the association between individual AChEI use and antimuscarinic cascade in older adults with dementia.

METHODS

We conducted a new user retrospective cohort study from January 2005 to December 2018 using data from the TriNetX electronic medical record database, a federated electronic medical records network in the US. The cohort included patients 65 years or older with a diagnosis of dementia using AChEIs (donepezil, galantamine, or rivastigmine). Individual AChEIs were identified with index dates from 1 January 2006 to 31 June 2018, with a 1-year washout period. The study excluded patients with any antimuscarinic use and OAB diagnosis 1 year before the AChEI index date. The primary outcome of interest was the prescription of antimuscarinics within 6 months of the AChEI index date. A Cox proportional hazard model was used to assess the association between individual incident AChEI use and antimuscarinic prescribing cascade after controlling for several covariates.

RESULTS

The study included 47,059 older adults with dementia who were incident users of AChEIs. Most of these patients were initiated with donepezil (83.1%), followed by rivastigmine (12.3%) and galantamine (4.6%). Overall, 8.16% of the study cohort had incident OAB diagnosis or antimuscarinic prescription. Antimuscarinics were initiated by 1725 (3.7%) older adults with dementia within 6 months of AChEI prescription, and cascade varied widely across individual agents-donepezil (3.9%), rivastigmine (2.6%), and galantamine (2.9%). Cox proportional hazard analyses revealed that donepezil users had an increased risk of receiving antimuscarinics (adjusted hazard ratio 1.55, 95% confidence interval 1.31-1.83) compared with rivastigmine. The findings were consistent in sensitivity analyses.

CONCLUSION

This study found that donepezil use is more likely to lead to antimuscarinic cascade than rivastigmine. Future studies are needed to determine the potential consequences of this cascade in dementia.

Inhibitors of Cholinesterases in Pharmacology: the Current Trends

Inhibitors of cholinesterases are a wide group of low molecular weight compounds with a significant role in the current pharmacology. Besides the pharmacological importance, they are also known as toxic compounds like military nerve agents. In the pharmacology, drugs for Alzheimer disease, myasthenia gravis and prophylaxis of poisoning by nerve agents can be mentioned as the relevant applications. Besides this, anti-inflammation and antiphrastic drugs are other pharmacological applications of these inhibitors. This review is focused on a survey of cholinesterase inhibitors with known or expected pharmacological impact and indications of their use. Recent literature with comments is provided here as well.

Anticholinesterase Activities of Different Solvent Extracts of Brewer's Spent Grain

Cholinesterases, involved in acetylcholine catabolism in the central and peripheral nervous system, have been strongly linked with neurodegenerative diseases. Current therapeutic approaches using synthetic drugs present several side effects. Hence, there is an increasing research interest in naturally-occurring dietary polyphenols, which are also considered efficacious. Food processing by-products such as brewer’s spent grain (BSG) would be a potential bio-source of polyphenols. In this study, polyphenol-rich BSG extracts using 60% acetone and 0.75% NaOH solutions were generated, which were further subjected to liquid–liquid partitioning using various organic solvents. The water-partitioned fractions of the saponified extracts had the highest total polyphenol content (6.2 ± 2.8 mgGAE/g dw) as determined by Folin–Ciocalteu reagent, while the LC-MS/MS showed ethyl acetate fraction with the highest phenolics (2.9 ± 0.3 mg/g BSG dw). The best inhibitions of acetyl- (37.9 ± 2.9%) and butyryl- (53.6 ± 7.7%) cholinesterases were shown by the diethyl ether fraction of the saponified extract. This fraction contained the highest sum of quantified phenolics (99 ± 21.2 µg/mg of extract), and with significant (p < 0.01) inhibitory contribution of decarboxylated-diferulic acid. Amongst the standards, caffeic acid presented the highest inhibition for both cholinesterases, 25.5 ± 0.2% for acetyl- and 52.3 ± 0.8% for butyryl-cholinesterase, respectively, whilst the blends insignificantly inhibited both cholinesterases. The results showed that polyphenol-rich BSG fractions have potentials as natural anti-cholinesterase agents.

QbD-steered development of mixed nanomicelles of galantamine: Demonstration of enhanced brain uptake, prolonged systemic retention and improved biopharmaceutical attributes

PURPOSE

Numerous oral treatment options have been reported for neurological disorders, especially Alzheimer's disease (AD). Galantamine (GAL) is one of such drugs duly approved for management of AD. However, it exhibits poor brain penetration, low intestinal permeation and requires frequent dosing in AD treatment. The present studies, accordingly, were undertaken to develop DSPE-PEG 2000-based micelles loaded with GAL for efficient brain uptake, improved and extended pharmacokinetics, along with reduced dosing regimen.

METHODS

Mixed nanomicelles (MNMs) were systematically formulated using QbD approach, and characterized for morphology, entrapment efficiency andin vitrodrug release.

RESULTS

Studies on CaCo-2 and neuronal U-87 cell lines exhibited substantial enhancement in the cellular permeability and uptake of the developed MNMs. Pharmacokinetic studies performed on rats showed significantly improved values of plasma AUC (i.e., 2.28-fold, p < 0.001), ostensibly due to bypassing of hepatic first-pass metabolism and improved intestinal permeability, together with significant rise in MRT (2.08-fold, p < 0.001) and t_max (4.80-fold; p < 0.001) values, indicating immense potential for prolonged drug residence in body.Besides, substantial elevation in brain drug levels, distinctly improved levels of biochemical parameters in brain homogenates and cognitive improvement in β-amyloid-treated rats, testify the superiority in MNMs in therapeutic management of AD.

CONCLUSIONS

The preclinical findings of the developed nanocarrier systems successfully demonstrate the notable potential of enhanced drug efficacy, extended duration of action and improved patient compliance.

Loss of Basal Forebrain Cholinergic Neurons Following Adolescent Binge Ethanol Exposure: Recovery With the Cholinesterase Inhibitor Galantamine

Binge drinking and alcohol abuse are common during adolescence and cause both cognitive deficits and lasting cholinergic pathology in the adult basal forebrain. Acetylcholine is anti-inflammatory and studies using the preclinical adolescent intermittent ethanol (AIE; 5.0 g/kg, i.g., 2 day on/2 day off from postnatal day [P]25 to P54) model of human adolescent binge drinking report decreased basal forebrain cholinergic neurons (BFCNs) and induction of proinflammatory genes that persist long into adulthood. Recent studies link AIE-induced neuroimmune activation to cholinergic pathology, but the underlying mechanisms contributing to the persistent loss of BFCNs are unknown. We report that treatment with the cholinesterase inhibitor galantamine (4.0 mg/kg, i.p.) administered during AIE (i.e., P25-P54) or following the conclusion of AIE (i.e., P57-P72) recovered the persistent loss of cholinergic neuron phenotype markers (i.e., ChAT, TrkA, and p75NTR) and somal shrinkage of residual ChAT + neurons known to persist in AIE-exposed adults. Galantamine treatment also recovered the AIE-increased expression of the proinflammatory receptors TLR4 and RAGE, the endogenous TLR4/RAGE agonist HMGB1, and the transcription activation marker pNF-κB p65. Interestingly, we find BFCNs express TLR4 and RAGE, and that AIE treatment increased pNF-κB p65 expression in adult ChAT + IR neurons, consistent with intracellular HMGB1-TLR4/RAGE signaling within BFCNs. AIE increased epigenetic transcription silencing markers (i.e., H3K9me2 and H3K9me3) in the adult basal forebrain and H3K9me2 occupancy at cholinergic phenotype gene promoters (i.e., ChAT and TrkA). The finding of no AIE-induced changes in total basal forebrain NeuN + neurons with galantamine reversal of AIE-induced ChAT + neuron loss, TLR4/RAGE-pNF-κB p65 signals, and epigenetic transcription silencing markers suggests that AIE does not cause cell death, but rather the loss of the cholinergic phenotype. Together, these data suggest that AIE induces HMGB1-TLR4/RAGE-pNF-κB p65 signals, causing the loss of cholinergic phenotype (i.e., ChAT, TrkA, and p75NTR) through epigenetic histone transcription silencing that result in the loss of the BFCN phenotype that can be prevented and restored by galantamine.

Cholinesterase inhibitors for vascular dementia and other vascular cognitive impairments: a network meta-analysis

BACKGROUND

Vascular cognitive impairment (VCI) describes a broad spectrum of cognitive impairments caused by cerebrovascular disease, ranging from mild cognitive impairment to dementia. There are currently no pharmacological treatments recommended for improving either cognition or function in people with VCI. Three cholinesterase inhibitors (donepezil, galantamine, and rivastigmine) are licenced for the treatment of dementia due to Alzheimer's disease. They are thought to work by compensating for reduced cholinergic neurotransmission, which is also a feature of VCI. Through pairwise comparisons with placebo and a network meta-analysis, we sought to determine whether these medications are effective in VCI and whether there are differences between them with regard to efficacy or adverse events.

OBJECTIVES

(1) To assess the efficacy and safety of cholinesterase inhibitors in the treatment of adults with vascular dementia and other VCI. (2) To compare the effects of different cholinesterase inhibitors on cognition and adverse events, using network meta-analysis.

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's register, MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost), Web of Science Core Collection (ISI Web of Science), LILACS (BIREME), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform on 19 August 2020.

SELECTION CRITERIA

We included randomised controlled trials in which donepezil, galantamine, or rivastigmine was compared with placebo or in which the drugs were compared with each other in adults with vascular dementia or other VCI (excluding cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)). We included all drug doses and routes of administration.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified eligible trials, extracted data, assessed risk of bias, and applied the GRADE approach to assess the certainty of the evidence. The primary outcomes were cognition, clinical global impression, function (performance of activities of daily living), and adverse events. Secondary outcomes were serious adverse events, incidence of development of new dementia, behavioural disturbance, carer burden, institutionalisation, quality of life and death. For the pairwise analyses, we pooled outcome data at similar time points using random-effects methods. We also performed a network meta-analysis using Bayesian methods.

MAIN RESULTS

We included eight trials (4373 participants) in the review. Three trials studied donepezil 5 mg or 10 mg daily (n= 2193); three trials studied rivastigmine at a maximum daily dose of 3 to 12 mg (n= 800); and two trials studied galantamine at a maximum daily dose of 16 to 24 mg (n= 1380). The trials included participants with possible or probable vascular dementia or cognitive impairment following stroke. Mean ages were between 72.2 and 73.9 years. All of the trials were at low or unclear risk of bias in all domains, and the evidence ranged from very low to high level of certainty. For cognition, the results showed that donepezil 5 mg improves cognition slightly, although the size of the effect is unlikely to be clinically important (mean difference (MD) -0.92 Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) points (range 0 to 70), 95% confidence interval (CI) -1.44 to -0.40; high-certainty evidence). Donepezil 10 mg (MD -2.21 ADAS-Cog points, 95% CI -3.07 to -1.35; moderate-certainty evidence) and galantamine 16 to 24 mg (MD -2.01 ADAS-Cog point, 95%CI -3.18 to -0.85; moderate-certainty evidence) probably also improve cognition, although the larger effect estimates still may not be clinically important. With low certainty, there may be little to no effect of rivastigmine 3 to 12 mg daily on cognition (MD 0.03 ADAS-Cog points, 95% CI -3.04 to 3.10; low-certainty evidence). Adverse events reported in the studies included nausea and/or vomiting, diarrhoea, dizziness, headache, and hypertension. The results showed that there was probably little to no difference between donepezil 5 mg and placebo in the number of adverse events (odds ratio (OR) 1.22, 95% CI 0.94 to 1.58; moderate-certainty evidence), but there were slightly more adverse events with donepezil 10 mg than with placebo (OR 1.95, 95% CI 1.20 to 3.15; high-certainty evidence). The effect of rivastigmine 3 to 12 mg on adverse events was very uncertain (OR 3.21, 95% CI 0.36 to 28.88; very low-certainty evidence). Galantamine 16 to 24 mg is probably associated with a slight excess of adverse events over placebo (OR 1.57, 95% CI 1.02 to 2.43; moderate-certainty evidence). In the network meta-analysis (NMA), we included cognition to represent benefit, and adverse events to represent harm. All drugs ranked above placebo for cognition and below placebo for adverse events. We found donepezil 10 mg to rank first in terms of benefit, but third in terms of harms, when considering the network estimates and quality of evidence. Galantamine was ranked second in terms of both benefit and harm. Rivastigmine had the lowest ranking of the cholinesterase inhibitors in both benefit and harm NMA estimates, but this may reflect possibly inadequate doses received by some trial participants and small trial sample sizes.

AUTHORS' CONCLUSIONS

We found moderate- to high-certainty evidence that donepezil 5 mg, donepezil 10 mg, and galantamine have a slight beneficial effect on cognition in people with VCI, although the size of the change is unlikely to be clinically important. Donepezil 10 mg and galantamine 16 to 24 mg are probably associated with more adverse events than placebo. The evidence for rivastigmine was less certain. The data suggest that donepezil 10 mg has the greatest effect on cognition, but at the cost of adverse effects. The effect is modest, but in the absence of any other treatments, people living with VCI may still wish to consider the use of these agents. Further research into rivastigmine is needed, including the use of transdermal patches.

Treating disorders across the lifespan by modulating cholinergic signaling with galantamine

Advances in understanding the regulatory functions of the nervous system have revealed neural cholinergic signaling as a key regulator of cytokine responses and inflammation. Cholinergic drugs, including the centrally acting acetylcholinesterase inhibitor, galantamine, which are in clinical use for the treatment of Alzheimer's disease and other neurodegenerative and neuropsychiatric disorders, have been rediscovered as anti-inflammatory agents. Here, we provide a timely update on this active research and clinical developments. We summarize the involvement of cholinergic mechanisms and inflammation in the pathobiology of Alzheimer's disease, Parkinson's disease, and schizophrenia, and the effectiveness of galantamine treatment. We also highlight recent findings demonstrating the effects of galantamine in preclinical and clinical settings of numerous conditions and diseases across the lifespan that are characterized by immunological, neurological, and metabolic dysfunction.

Cholinesterase Inhibitory Potential of Quercetin towards Alzheimer's Disease - A Promising Natural Molecule or Fashion of the Day? - A Narrowed Review

Natural substances are known to have strong protective effects against neurodegenerative diseases. Among them, phenolic compounds, especially flavonoids, come to the fore with their neuroprotective effects. Since quercetin, which is found in many medicinal plants and foods, is also taken through diet, its physiological effects on humans are imperative. Many studies have been published up to date on the neuroprotective properties of quercetin, a flavanol derivative. However, there is no review published so far summarizing the effect of quercetin on the cholinesterase (ChE) enzymes related to the cholinergic hypothesis, which is one of the pathological mechanisms of Alzheimer's Disease (AD). However, ChE inhibitors, regardless of natural or synthetic, play a vital role in the treatment of AD. Although the number of studies on the ChE inhibitory effect of quercetin is limited, it deserves to be discussed in a review article. With this sensitivity, the neuroprotective effect of quercetin against AD through ChE inhibition was scrutinized in the current review study. In addition, studies on the bioavailability of quercetin and its capacity to cross the blood-brain barrier and how this capacity and bioavailability can be increased were given. Generally, studies containing data published in recent years were obtained from search engines such as PubMed, Scopus, and Medline and included herein. Consequently, quercetin should not be considered as a fashionable natural compound and should be identified as a promising compound, especially with increased bioavailability, for the treatment of AD.