Symptomatic Treatment Of Alzheimer's Disease Research Articles

Recent Studies on Heterocyclic Cholinesterase Inhibitors Against Alzheimer's Disease.

Alzheimer's disease is a progressive and neurodegenerative disease characterized by impairment in emotion, language, memory, and cognitive judgment. There are many factors related to Alzheimer's disease, such as amyloid beta plaques (Aβ) due to impaired metabolism of amyloid precursor protein (APP), tau hyperphosphorylation, and accumulation of neurofibrillary tangles, and disruption of the cholinergic system. Disruption of the cholinergic system responsible for cognitive function and memory processes is one of the important causes of Alzheimer's disease. Therefore, cholinesterase (acetylcholinesterase and butyrylcholinesterase) inhibitors that maintain choline (acetylcholine and butyrylcholine) levels in the synaptic gap play an important role in the symptomatic treatment of Alzheimer's disease. Numerous studies have been carried out against Alzheimer's disease involving acetylcholinesterase and butyrylcholinesterase inhibitors. However, there are very few drugs (tacrine, rivastigmine, galantamine, and donepezil) approved as cholinesterase inhibitors. Therefore, cholinesterase inhibitors are needed against Alzheimer's disease. This review is focused on using heterocyclic rings that show remarkable cholinesterase inhibitory activity for Alzheimer's disease. In this review, chemical structures and structure-activity relationships of recently reported cholinesterase inhibitors are emphasized. This review will give important ideas to medicinal chemists in the discovery and development of potent cholinesterase inhibitors in their future studies.

Design, Synthesis and Cholinesterase Inhibitory Activity of Novel 1,3,4-Thiadiazole Derivatives

Inhibition of the cholinesterases (AChE and BChE) plays a pivotal role in the symptomatic treatment of Alzheimer’s disease. The present study reports the synthesis and anticholinesterase activity of five novel thiadiazole analogs in search of anti-Alzheimer agents. The structures of the newly synthesized compounds were characterized using 1H NMR, 13C NMR and HRMS. Tested compounds inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes with IC50 values in the range of 8.250-20.382 μM and 14.143-0.986 μM, respectively. N-(4-Chlorophenyl)-2-[(5-(allylamino)-1,3,4-thiadiazol-2-yl)thio]-N-(3-nitrobenzyl)acetamide (6e) was determined as the most potent inhibitor against both tested enzymes when compared with standard drug tacrine. Molecular docking study was carried out to reveal the binding interactions between compound 6e and the active site of AChE

Flustramine Q, a Novel Marine Origin Acetylcholinesterase Inhibitor from Flustra foliacea

The bryozoan Flustra foliacea produces a range of indole alkaloids, and some have shown weak antibiotic, muscle-relaxant and cytotoxic properties; however, most of them have not been tested for bioactivity. Many of these alkaloids possess a physostigmine scaffold, and physostigmine is a well-known acetylcholinesterase (AChE) inhibitor. AChE inhibitors are of interest as drug leads in neurodegenerative diseases and are currently used in symptomatic treatment of Alzheimer’s disease (AD). In this study, the AChE inhibitory activity of Flustra alkaloids was studied in vitro using the colorimetric method of Ellman and AChE from Electrophorus electricus. Twenty-five compounds isolated from the Icelandic bryozoan F. foliacea were screened at a 100 µM concentration. Two of them, flustramine E and flustramine I, showed inhibition of 48%, and flustramine Q showed 82% inhibition. For flustramine Q, the IC50 was 9.6 µM. Molecular modelling and docking studies indicated that simple in silico designed derivatives of flustramine Q could have potential for increased potency. Marine natural products including brominated indole alkaloids from Flustra foliacea are an interesting new source of AChE inhibitors with potential towards central nervous system disorders, e.g., Alzheimer’s disease.

4-Aminoquinoline-Based Adamantanes as Potential Anticholinesterase Agents in Symptomatic Treatment of Alzheimer's Disease.

Considering that acetylcholinesterase (AChE) inhibition is the most important mode of action expected of a potential drug used for the treatment of symptoms of Alzheimer’s disease (AD), our previous pilot study of 4-aminoquinolines as potential human cholinesterase inhibitors was extended to twenty-two new structurally distinct 4-aminoquinolines bearing an adamantane moiety. Inhibition studies revealed that all of the compounds were very potent inhibitors of AChE and butyrylcholinesterase (BChE), with inhibition constants (Ki) ranging between 0.075 and 25 µM. The tested compounds exhibited a modest selectivity between the two cholinesterases; the most selective for BChE was compound 14, which displayed a 10 times higher preference, while compound 19 was a 5.8 times more potent inhibitor of AChE. Most of the compounds were estimated to be able to cross the blood–brain barrier (BBB) by passive transport. Evaluation of druglikeness singled out fourteen compounds with possible oral route of administration. The tested compounds displayed modest but generally higher antioxidant activity than the structurally similar AD drug tacrine. Compound 19 showed the highest reducing power, comparable to those of standard antioxidants. Considering their simple structure, high inhibition of AChE and BChE, and ability to cross the BBB, 4-aminoquinoline-based adamantanes show promise as structural scaffolds for further design of novel central nervous system drugs. Among them, two compounds stand out: compound 5 as the most potent inhibitor of both cholinesterases with a Ki constant in low nano molar range and the potential to cross the BBB, and compound 8, which met all our requirements, including high cholinesterase inhibition, good oral bioavailability, and antioxidative effect. The QSAR model revealed that AChE and BChE inhibition was mainly influenced by the ring and topological descriptors MCD, Nnum, RP, and RSIpw3, which defined the shape, conformational flexibility, and surface properties of the molecules.

Cholinesterase inhibitory activities of neuroprotective fraction derived from red alga Gracilaria manilaensis

Anti-cholinesterase (ChE)s are commonly prescribed as the symptomatic treatment of Alzheimer’s disease. They are applied to prevent the breakdown of neurotransmitter acetylcholine (ACh) that bind to muscarinic and nicotinic receptors in the synaptic cleft. Seaweeds are one of the richest sources of bioactive compounds for both nutraceuticals and pharmacognosy applications. This study aimed to determine the anti-ChEs activity of Gracilaria manilaensis, one of the red seaweeds notables for its economic importance as food and raw materials for agar production. Methanol extracts (GMM) of G. manilaensis were prepared through maceration, and further purified with column chromatography into a semi-pure fraction. Ellman assay was carried out to determine the anti-acetylcholinesterase (AChE) and anti-butyrylcholinesterase (BuChE) activities of extracts and fractions. Lineweaver-Burk plot analysis was carried out to determine the inhibition kinetic of potent extract and fraction. Major compound(s) from the most potent fraction was determined by liquid chromatography-mass spectrometry (LCMS). GMM and fraction G (GMMG) showed significant inhibitory activity AChE with EC50 of 2.6 mg/mL and 2.3 mg/mL respectively. GMM and GMMG exhibit mixed-inhibition and uncompetitive inhibition respectively against AChE. GMMG possesses neuroprotective compounds such as cynerine A, graveolinine, militarinone A, eplerenone and curumenol. These findings showed a promising insight of G. manilaensis to be served as a nutraceutical for neuronal health care in the future.

2',6'-dihydroxy-4'-methoxy Dihydrochalcone Improves the Cognitive Impairment of Alzheimer's Disease: A Structure-activity Relationship Study.

Chalcones and dihydrochalcones present potent inhibition of acetylcholinesterase, currently considered the most efficient approach for symptomatic treatment of Alzheimer's disease. The present study aimed to explore the potential benefits of 2',6'-dihydroxy-4'-methoxy dihydrochalcone on the cognitive deficits of animals submitted to the streptozotocin-induced Alzheimer's model, as well as evaluating the possible mechanisms of action. Learning and memory functions of different groups of animals were submitted to the streptozotocin-induced Alzheimer's model (STZ 2.5 mg/mL, i.c.v.) and subsequently treated with 2',6'-dihydroxy-4'-methoxy dihydrochalcone (DHMDC) administered at doses of 5, 15, and 30 mg/kg (p.o.), respectively. Rivastigmine (0,6 mg/kg, i.p.) and vehicle were evaluated in aversive memory test (inhibitory avoidance test) and spatial memory test (object recognition test). Molecular docking simulations were performed to predict the binding mode of DHMDC at the peripheral site of AChE, to analyze noncovalent enzyme-ligand interactions. DFT calculations were carried out to study well-known acetylcholinesterase inhibitors and DHMDC. DHMDC markedly increased the learning and memory of mice. STZ caused a significant decline of spatial and aversive memories in mice, attenuated by DHMDC (15 and 30 mg/kg). Furthermore, STZ conspicuously increased lipid peroxidation and compromised the antioxidant levels in mice brains. DHMDC pretreatment significantly increased GSH activity and other oxidative stress markers and decreased TBARS level in the brain of STZ administered mice. AChE activity was significantly decreased by DHMDC in the brain of mice. The results together point out that DHMDC may be a useful drug in the management of dementia.

Biphenylalkoxyamine Derivatives-Histamine H3 Receptor Ligands with Butyrylcholinesterase Inhibitory Activity.

Neurodegenerative diseases, e.g., Alzheimer’s disease (AD), are a key health problem in the aging population. The lack of effective therapy and diagnostics does not help to improve this situation. It is thought that ligands influencing multiple but interconnected targets can contribute to a desired pharmacological effect in these complex illnesses. Histamine H3 receptors (H3Rs) play an important role in the brain, influencing the release of important neurotransmitters, such as acetylcholine. Compounds blocking their activity can increase the level of these neurotransmitters. Cholinesterases (acetyl- and butyrylcholinesterase) are responsible for the hydrolysis of acetylcholine and inactivation of the neurotransmitter. Increased activity of these enzymes, especially butyrylcholinesterase (BuChE), is observed in neurodegenerative diseases. Currently, cholinesterase inhibitors: donepezil, rivastigmine and galantamine are used in the symptomatic treatment of AD. Thus, compounds simultaneously blocking H3R and inhibiting cholinesterases could be a promising treatment for AD. Herein, we describe the BuChE inhibitory activity of H3R ligands. Most of these compounds show high affinity for human H3R (Ki < 150 nM) and submicromolar inhibition of BuChE (IC50 < 1 µM). Among all the tested compounds, 19 (E153, 1-(5-([1,1′-biphenyl]-4-yloxy)pentyl)azepane) exhibited the most promising in vitro affinity for human H3R, with a Ki value of 33.9 nM, and for equine serum BuChE, with an IC50 of 590 nM. Moreover, 19 (E153) showed inhibitory activity towards human MAO B with an IC50 of 243 nM. Furthermore, in vivo studies using the Passive Avoidance Task showed that compound 19 (E153) effectively alleviated memory deficits caused by scopolamine. Taken together, these findings suggest that compound 19 can be a lead structure for developing new anti-AD agents.

Real-world effectiveness, its predictors and onset of action of cholinesterase inhibitors and memantine in dementia: retrospective health record study.

The efficacy of acetylcholinesterase inhibitors and memantine in the symptomatic treatment of Alzheimer's disease is well-established. Randomised trials have shown them to be associated with a reduction in the rate of cognitive decline. To investigate the real-world effectiveness of acetylcholinesterase inhibitors and memantine for dementia-causing diseases in the largest UK observational secondary care service data-set to date. We extracted mentions of relevant medications and cognitive testing (Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores) from de-identified patient records from two National Health Service (NHS) trusts. The 10-year changes in cognitive performance were modelled using a combination of generalised additive and linear mixed-effects modelling. The initial decline in MMSE and MoCA scores occurs approximately 2 years before medication is initiated. Medication prescription stabilises cognitive performance for the ensuing 2-5 months. The effect is boosted in more cognitively impaired cases at the point of medication prescription and attenuated in those taking antipsychotics. Importantly, patients who are switched between agents at least once do not experience any beneficial cognitive effect from pharmacological treatment. This study presents one of the largest real-world examination of the efficacy of acetylcholinesterase inhibitors and memantine for symptomatic treatment of dementia. We found evidence that 68% of individuals respond to treatment with a period of cognitive stabilisation before continuing their decline at the pre-treatment rate.

Anticholinesterase and antioxidant activities of foliar extract from a tropical species: Psidium guajava L. (Myrtaceae) grown in Algeria

Abstract Guava (Psidium guajava L.) is a fruit tree largely used in folk medicine in tropical and subtropical areas. This exotic species was introduced in a botanical garden in the northeast of Algeria in the 1950’s. The aim of this study is to estimate, for the first time, the antioxidant and anticholinesterase activities of chloroform, ethyl acetate and n-butanol extracts of P. guajava growing in Algeria. Six antioxidant assays were tested, results showed very important efficiency in free radical scavenging, reducing power and β-carotene bleaching of tested extracts. Values of IC50 or A0.5 of some samples were lower than those of standards. With regard to anticholinesterase activity, the inhibitory of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) was investigated. The extracts exhibited interesting capacity to inhibit these enzymes with low values of IC50 and even less than that of galanthamine. These activities were correlated with total phenolic content which was more important compared to the one found in extracts from trees growing in tropical and subtropical region. This could be due to resistance and adaptation of P. guajava grown in Algeria. The data obtained suggest the use of bioactive compounds from P. guajava leaves as antioxidant and drugs for symptomatic treatment of Alzheimer disease.

The Binding Mechanisms and Inhibitory Effect of Intravenous Anesthetics on AChE In Vitro and In Vivo: Kinetic Analysis and Molecular Docking.

Inhibitors of acetylcholinesterase (AChE), which have an important role in the prevention of excessive AChE activity and β-amyloid (Aβ) formation are widely used in the symptomatic treatment of Alzheimer's disease (AD). The inhibitory effect of anesthetic agents on AChE was determined by several approaches, including binding mechanisms, molecular docking and kinetic analysis. Inhibitory effect of intravenous anesthetics on AChE as in vitro and in vivo have been discovered. The midazolam, propofol and thiopental have shown competitive inhibition type (midazolam > propofol > thiopental) and Ki values were found to be 3.96.0 ± 0.1, 5.75 ± 0.12 and 29.65 ± 2.04µM, respectively. The thiopental and midazolam showed inhibition effect on AChE in vitro, whereas they showed activation effect in vivo when they are combined together. The order of binding of the drugs to the active site of the 4M0E receptor was found to be midazolam > propofol > thiopental. This study on anesthetic agents that are now widely used in surgical applications, have provided a molecular basis for investigating the drug-enzyme interactions mechanism. In addition, the study is important in understanding the molecular mechanism of inhibitors that are effective in the treatment of AD.

Nutritional Properties, Antioxidant and Anti-Acetylcholinesterase Activities of &lt;i&gt;Pleurotus ostreatus&lt;/i&gt;

Pleurotus ostreatus, the worldwide edible mushroom, has a potent economic values and medicinal properties. In this study, nutritional properties, antioxidant, and anti-acetylcholinesterase activities of P. ostreatus were investigated. The extracts were prepared by maceration and soxhlet extraction with ethanol and decoction with distilled water. Nutritional analysis showed that P. ostreatus has high content of fibers (45.5%), proteins (20.8%) and carbohydrates (68.4%) with low content of lipids (0.56%). HPLC analysis revealed that P. ostreatus has high content of the potential health promoting of β-glucan (42.8%). Acetylcholinesterase (AChE) is a key enzyme in nervous system. Inhibition of this enzyme is used for the symptomatic treatment of Alzheimer’s disease (AD), the most common disease in aging population. Ellman colorimetric method was used to determine Acetylcholinesterase inhibitory (AChEI) activity. All extracts found containing high AChEI activity (IC50 = 1.75-5.91 mg/ml). Oxidative stress plays a major role in the pathogenesis of AD, thus antioxidant activity was also performed in this study. DPPH assay exhibited all P. ostreatus extracts had high antioxidant activity (IC50 = 0.59-5.47 mg/ml). The results suggested that P. ostreatus should be beneficial for AD treatment and the most efficient nutraceutical and functional foods.

Synthesis and AChE-Inhibitory Activity of New Benzimidazole Derivatives.

Alzheimer’s disease (AD), one of the main causes of aged dementia, is a progressive and degenerative neurological disorder characterized by loss of cognition and memory. Although the symptomatic treatment of AD, particularly acetylcholinesterase inhibitors (AChEIs) based on the ‘cholinergic hypothesis’, has been successful in clinic, at present there is no cure for this disease. In this study, we designed compounds carrying benzimidazole and triazole rings on the same chemical skeleton so as to investigate their potential acetylcholinesterase and butyrylcholinesterase activity. Furthermore, molecular modeling study was performed to determine the binding mode of the best inhibitor to the AChE. Among them, compounds 3d and 3h, which featured 3,4-dihydroxy substitution at the phenyl ring and 5(6)-chloro substitution at the benzimidazole ring were found to be potent inhibitors of AChE. The inhibition kinetics of the two most active derivatives 3d and 3h were further studied. The kinetic displayed increasing slope and increasing intercept, which is consistent with a mixed inhibition. The IC50 and Ki values of 3d are 31.9 ± 0.1 nM and 26.2 nM, respectively. Compound 3h exhibited IC50 of 29.5 ± 1.2 nM and Ki of 24.8 nM. The above data compared favorably with data for donepezil (21.8 ± 0.9 nM) the reference compound in our study.

Drug prescription patterns in patients with Alzheimer's disease in an urban neuro-specialty clinic in Western India

Background: Alzheimer’s disease (AD) is one of the most common forms of dementia worldwide with only symptomatic therapies available. In India, there seems to be a scarcity of data regarding drugs prescribed for symptomatic treatment of AD. Aims and Objectives: The objective of this study was to find out drug prescription patterns in AD patients in an urban neuro-speciality clinic in Western India. Materials and Methods: Retrospective data were collected from 100 case files of patients diagnosed with AD visiting a private neuro-speciality clinic. Descriptive statistics were used to analyze the data. Results: The mean age of patients suffering from AD was 74.9 ± 0.9 years. About 90% of patients were >65 years old, with a female preponderance of 56%. About 60% of patients belonged to rural areas and 40% belonged to urban areas. Mini-mental state examination scores revealed a mean score of 14.84 ± 1.20. Regarding drug utilization pattern, 73% of patients were prescribed Donepezil, 15% were on donepezil and memantine, 7% on rivastigmine, and 5% on Galantamine. Donepezil, memantine, donamem, and galantamine were prescribed in tablet form while rivastigmine in capsule form. Only in 15% prescriptions brand name and fixed-dose combinations were used. Conclusion: Despite decades of study of basic etiology and pathogenesis of AD and significant pharmaceutical industrial efforts to develop therapies, till date, there is no effective therapy available to cure AD. AD needs to be understood and analyzed in terms of its prescribing. Patients suffering from dementia and AD should be screened and treated at an early stage. Anticholinesterase drugs and N-methyl-D-aspartate receptor blockers were the most common drugs used for symptomatic treatment of AD.

Influence of Enantiomeric Inhibitors on the Dynamics of Acetylcholinesterase Measured by Elastic Incoherent Neutron Scattering.

The enzyme acetylcholinesterase (AChE) is essential in humans and animals because it catalyzes the breakdown of the nerve-signaling substance acetylcholine. Small molecules that inhibit the function of AChE are important for their use as drugs in the, for example, symptomatic treatment of Alzheimer's disease. New and improved inhibitors are warranted, mainly because of severe side effects of current drugs. In the present study, we have investigated if and how two enantiomeric inhibitors of AChE influence the overall dynamics of noncovalent complexes, using elastic incoherent neutron scattering. A fruitful combination of univariate models, including a newly developed non-Gaussian model for atomic fluctuations, and multivariate methods (principal component analysis and discriminant analysis) was crucial to analyze the fine details of the data. The study revealed a small but clear increase in the dynamics of the inhibited enzyme compared to that of the noninhibited enzyme and contributed to the fundamental knowledge of the mechanisms of AChE-inhibitor binding valuable for the future development of inhibitors.

Alzheimer's disease - State of the art, and emerging diagnostics and therapeutics

Alzheimer's disease - State of the art, and emerging diagnostics and therapeutics Abstract. Alzheimer's disease (AD) constitutes the most prevalent neurodegenerative disorder, and the most frequent cause of dementia. Current diagnostics include a clinical examination, brain imaging, as well as laboratory testing in order to exclude other treatable disorders. Depending on the findings constellation a lumbar puncture with determination of amyloid-β-, tau- and phospho-tau-proteins, PET imaging and if necessary further investigations are performed. Acetylcholineesteraseinhibitors as well as the NMDA-antagonist mematine allow symptomatic treatment of AD. The development of novel curative drugs is now showing considerable progress. After initially frustrating results, immunotherapies addressing amyloid-β pathology are now showing first positive effects when administered early in the disease course. First immunotherapies targeting tau pathology are furthermore reaching phase 2 and 3 trials, after hints of positive clinical effects in phase 1 trials. An additional set of more than 70 trials investigates non-immune mediated treatment strategies. Diagnostic advances include the development of amyloid-PET imaging, where after the amyloid-β-PET, tau-PET imaging is now reaching clinical implementation. In parallel to the technical advances in cerebrospinal fluid diagnostics, first blood-based biomarkers for AD are being developed.

Donepezil-Based Central Acetylcholinesterase Inhibitors by Means of a "Bio-Oxidizable" Prodrug Strategy: Design, Synthesis, and in Vitro Biological Evaluation.

With the aim of reducing side effects of acetylcholinesterase inhibitors (AChEIs) during symptomatic treatment of Alzheimer's disease, we report herein a new class of donepezil-based "bio-oxidizable" prodrugs 1 designed to be converted into dual binding site AChEIs 2. While most of indanone-derived N-benzylpyridinium salts 2 revealed to be highly potent dual binding site hAChEIs (IC50 up to 3 nM), outperforming the standard drug donepezil (IC50 = 11 nM), most of the corresponding 1,4-dihydropyridines 1 were found to be inactive. Promisingly, whereas the selected prodrug 1r showed good permeability in the PAMPA-BBB model and high in vitro antioxidant activity, its conversion to AChEI 2r could be easily achieved under mild conditions when incubated in various oxidizing media. Lastly, both compounds 1r and 2r did not show genotoxicity in vitro and displayed high LD50 values in mice, making this prodrug 1r/drug 2r couple a good candidate for further in vivo biological experiments.

Management of Depression in Patients with Dementia: Is Pharmacological Treatment Justified?

Depression in the context of dementia is common and contributes to poorer outcomes in individuals and those who care for them. Non-pharmacological treatments are the preferred initial approach to managing these symptoms but data in support of these are scarce. There are a number of pharmacological treatment options available to clinicians but efficacy is uncertain and concern about potential side effects in an aging and vulnerable population needs to be taken into consideration. This review aims to provide a concise overview of pharmacological treatments for depression in dementia. Antidepressants are the mainstay of pharmacological treatment for clinically significant depression in the general population but evidence to support their use in dementia is mixed. Trials of antidepressants should generally be reserved for individuals with depression where the symptoms are distressing and surpass the threshold for major depression. Acetylcholinesterase inhibitors and memantine are effective in the symptomatic treatment of Alzheimer's disease but current evidence does not support their use to treat depressive symptoms in dementia. Similarly, antipsychotics and mood stabilizers have no proven efficacy for depression and the risk of adverse effects seems to outweigh any potential benefit. Pain can be a frequent problem in dementia and may have significant effects on behavior and mood. Preliminary evidence supports a role of adequate analgesia in improving mood in people with dementia.

Quantitative EEG After Brain Stimulation and Cognitive Training in Alzheimer Disease.

Medications are the currently accepted symptomatic treatment of Alzheimer disease (AD), but their impact on delaying the progression of cognitive deficits and functional impairment is limited. The authors aimed to explore long-term electrophysiological effects of repetitive transcranial magnetic stimulation interlaced with cognitive training on quantitative electroencephalography (EEG) in patients with AD. Quantitative EEG was assessed on non-repetitive transcranial magnetic stimulation interlaced with cognitive training treatment days before treatment and after each treatment phase in seven patients with mild AD. After 4.5 months (54 sessions) of treatment, a significant increase of delta activity over the temporal region was found compared with pretreatment values. Nonsignificant increases of the log EEG power were found for alpha band over the frontal and temporal regions, beta band over the frontal region, theta band over the frontal, temporal, and parieto-occipital regions, and delta band over the frontal and parieto-occipital regions. Nonsignificant decreases were found for alpha over the parieto-occipital region, and for beta over the temporal and parieto-occipital regions. A positive correlation was found between log alpha power over the frontal and temporal regions at 6 weeks and Mini-Mental State Examination (MMSE) scores at 6 weeks and 4.5 months, and between log alpha power over the parieto-occipital regions and MMSE scores at 6 weeks. A negative correlation was found between log alpha power over the frontal and temporal regions at 6 weeks and baseline Alzheimer's Disease Assessment Scale-cognitive subscale scores. Repetitive transcranial magnetic stimulation interlaced with cognitive training has long-term effects on quantitative EEG in patients with mild AD. Further research on the quantitative EEG long-term effects of transcranial magnetic stimulation interlaced with cognitive training is required to confirm the authors' data.

Pharmacokinetic Modeling to Simulate the Concentration-Time Profiles After Dermal Application of Rivastigmine Patch

Rivastigmine is an inhibitor of acetylcholinesterases and butyrylcholinesterases for symptomatic treatment of Alzheimer disease and is available as oral and transdermal patch formulations. A dermal absorption pharmacokinetic (PK) model was developed to simulate the plasma concentration-time profile of rivastigmine to answer questions relative to the efficacy and safety risks after misuse of the patch (e.g., longer application than 24 h, multiple patches applied at the same time, and so forth). The model comprised 2 compartments which was a combination of mechanistic dermal absorption model and a basic 1-compartment model. The initial values for the model were determined based on the physicochemical characteristics of rivastigmine and PK parameters after intravenous administration. The model was fitted to the clinical PK profiles after single application of rivastigmine patch to obtain model parameters. The final model was validated by confirming that the simulated concentration-time curves and PK parameters (Cmax and area under the drug plasma concentration-time curve) conformed to the observed values and then was used to simulate the PK profiles of rivastigmine. This work demonstrated that the mechanistic dermal PK model fitted the clinical data well and was able to simulate the PK profile after patch misuse.

Chemical characterization and anticholinesterase effects of essential oils derived from Salvia species

Inhibitory effect of Salvia species herbal preparations on acetylcholinesterase (AChE) and butylcholinesterase (BuChE) activitiy may contribute to regulation of cognitive performance and impaired cholinergic functions in patients with Alzheimer’s disease. This functional role of Salvia species and their components makes the investigations on Salvia valuable in medicine-related plant research. Within this work it was aimed to investigate the in vitro anti-cholinesterase effect of essential oils derived from ten Salvia species, which grow in Turkey. The chemical composition of essential oils were characterized by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), respectively. Results showed that all of the essential oils exhibited AChE inhibitory activity. S. pseudeuphratica, S. hydrangea and S. divaricata essential oils demonstrated the most potent AChE inhibitory effect [50% inhibition concentration (IC50) = 26.00 ± 2.00 μg/mL, 40.0 ± 4.00, 64.68 ± 4.16, respectively]. The essential oil of S. pseudeuphratica demonstrated the highest inhibitory activity against AChE and BuChE among the tested Salvia essential oils. Evidences from the our study augment the importance of essential oils obtained from Salvia species and may support utilization of Salvia species for symptomatic treatment of Alzheimer disease.