小檗碱衍生物抗胆碱酯酶和抗炎活性的研究

目的： 研究小檗碱衍生物的抗胆碱酯酶和抗炎双重抗阿尔茨海默病的活性。方法： 以Ellman、酶联免疫 (ELISA) 和抗氧化能力指数 (ORAC) 的方法分别进行体外胆碱酯酶 (乙酰胆碱酯酶和丁酰胆碱酯酶)、环氧合酶 (环氧合酶-1和环氧合酶-2) 抑制活性以及氧自由基清除能力的测定。同时,通过二甲苯所致耳肿胀实验评价其体内抗炎活性,以MTT法进一步了解化合物对SH-SY5Y细胞生存能力的影响。结果： 体外胆碱酯酶抑制活性筛选表明,所有化合物的乙酰胆碱酯酶抑制活性达到纳摩尔水平,其中化合物4d和4f对AChE的半数抑制浓度分别为72.00 ± 12.31 nmol&;#8226;L-1和133.9 ± 17.95 nmol&;#8226;L-1。在此基础上,进一步评价4d和4f在10 µmol&;#8226;L-1浓度下的环氧合酶抑制活性。其中4d对环氧合酶没有抑制活性,而4f对环氧合酶1(COX-1)和2(COX-2)的抑制率分别为3.1%和100%,其ORAC值为0.27 ± 0.013,优于阳性对照tacrine。10 mg&;#8226;kg-1剂量的4f对二甲苯致小鼠耳片肿胀度的抑制达到39.5% （P < 0.001）,与celecoxib相当。其对SH-SY5Y细胞存活能力影响不大,10 µmol&;#8226;L-1浓度下细胞存活率达85%。结论： 小檗碱衍生物4f具有较好的抗胆碱酯酶活性和抗炎活性,是具有潜力的抗阿尔茨海默病化合物。     

In vitro and ex vivo anticholinesterase activities of Erythrina velutina leaf extracts

Context: Erythrina velutina (EV) Willd (Fabaceae–Faboideae) is a medicinal tree that is commonly used in Brazil for the treatment of several central nervous system disorders.

Objective: The anticholinesterase activity of EV is described in this work.

Methods: Concentration-response curves (0–1.6?mg/mL) for EV leaf aqueous extract (AE) and alkaloid-rich extracts (AKEs) were performed in vitro. Cholinesterase inhibition was examined in mouse brains, as the cholinesterase source, and in pure acetylcholinesterase (AChE) or butyrylcholinesterase (BuChE). Mice were treated with AE or AKE (100, 200, and 400?mg/kg, p.o.) and their brains were used for the measurement of cholinesterase activity (CA) ex vivo.

Results: CA was inhibited by AE (IC₅₀?=?0.57 [0.43–0.75] mg/mL) and AKE (IC₅₀?=?0.52 [0.39–0.70] mg/mL) in brain homogenates in a concentration-dependent manner. The ex vivo experiments indicated that AE (400?mg/kg, p?<?0.05, 32.2?±?3.9% of inhibition) and AKE (all doses: p?<?0.05–p?<?0.001, 29.6?±?3.2% as the maximum inhibition) significantly inhibited CA in the central nervous system after oral administration. AE and AKE inhibited AChE and BuChE activities in a concentration-dependent manner (AE: IC_50AChE?=?0.56 [0.38–0.81] mg/mL, IC_50BuChE?=?2.95 [1.51–5.76] mg/mL, AKE: IC_50AChE?=?0.87 [0.60–12.5] mg/mL, IC_50BuChE?=?2.67 [0.87–8.11] mg/mL).

Discussion and conclusions: These data indicated that AE and AKE crossed the blood-brain barrier to inhibit CA in the brain. AE and AKE also exhibited a dual inhibitory action on acetyl- and BuChE.     

Phenolic composition,antioxidant and anti-acetylcholinesterase activities of the Tunisian Scabiosa arenaria

Abstract

Context: There is a need for the discovery of novel natural antioxidants and acetylcholinesterase inhibitors (AChEIs) that are safe and effective at a global level. This is the first study on antioxidant and anti-acethylcholinesterase activity of Scabiosa arenaria Forssk (Dipsacaceae).

Objective: The antioxidant potential and anti-acetylcholinesterase (AChE) activity of S. arenaria were investigated.

Material and methods: The crude, ethyl acetate (EtOAc), butanol (n-BuOH) and water extracts prepared from flowers, fruits and stems and leaves of S. arenaria were tested to determine their total polyphenol content (TPC), total flavonoid content (TFC), total condensed tannin content (CTC) and their antioxidant activity by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), reducing power and β-carotene bleaching inhibition activity. Anti-AChE activity was also determined.

Results: EtOAc and n-BuOH fractions of fruits had both the highest (TPC) (269.09?mg gallic acid equivalents/g dry weight). The crude extract of stems and leaves had the highest TFC (10.9?mg quercetin equivalent/g dry weight). The n-BuOH fraction of stems and leaves had the highest CTC (489.75?mg catechin equivalents/g dry weight). The EtOAc fraction of flowers exhibit a higher activity in each antioxidant system with a special attention for DPPH assay (IC₅₀?=?0.017?mg/mL) and reducing power (EC₅₀?=?0.02?mg/mL). The EtOAc and n-BuOH fractions of stems and leaves showed strong inhibition of AChE (IC₅₀?=?0.016 and 0.029?mg/mL, respectively).

Discussion and conclusions: These results suggest the potential of S. arenaria as a possible source of novel compounds and as an alternative antioxidant and AChEIs.     

Muscarinic M1 agonists in the treatment of Alzheimer’s disease

The treatment of Alzheimer’s disease attempts to correct cholinergic deficiency in the brain. In addition to the established, but restricted, efficacy of acetylcholinesterase inhibitors, attempts are being made to develop agents which will stimulate muscarinic receptors directly. This approach is logical and was found efficacious in several animal models of the disease; however none of these agents succeeded in clinical studies. Several reasons might account for this failure, which are discussed, as well as the prospects for the future.     

Efficacy of rivastigmine tartrate,transdermal system,in Alzheimer’s disease

Introduction: As the most common major neurocognitive disorder, Alzheimer’s disease (AD) will play an increasingly important role both socially and financially as the population ages. Approved treatments for AD are symptomatic in nature and show modest improvements in cognition and global functioning among patients with AD.

Areas Covered: This article focuses on the pharmacokinetics, pharmacodynamics, efficacy, and safety of the transdermal patch form of the cholinesterase inhibitor rivastigmine. The rivastigmine transdermal system is approved for the treatment of patients with mild, moderate, and severe AD. Three randomized trials have shown the rivastigmine patch to be efficacious and tolerable across all stages of AD.

Expert Opinion: The rivastigmine patch offers several advantages over the capsule form, including decreased peak to trough plasma fluctuations, reduced rates of nausea and vomiting, better treatment adherence, higher probability of reaching the target dose, ease of administration, and greater satisfaction among caregivers. These factors may be especially important in patients with severe AD, in which patients are more vulnerable to adverse side effects from higher doses. While the patch is more expensive than generic therapies, patient populations that may benefit from the patch include those that are particularly sensitive to GI side effects, have chronic gastrointestinal problems, have difficulty swallowing medications, or have failed to respond with high doses of other generic options.     

An update on the utility and safety of cholinesterase inhibitors for the treatment of Alzheimer’s disease

ABSTRACT

Introduction: Alzheimer’s disease (AD) is the most common cause of major neurocognitive disorders with a prevalence in the US of about 5.7 million in 2018. With the disease burden projected to increase dramatically in the coming years, it is imperative to review the current available treatment regimens for their safety and utility. The cholinesterase inhibitors (ChEIs) have continued to play a pivotal role in managing the symptoms and possibly slowing the rate of progression of AD since 1993. Owing to their being a mainstay in the treatment of AD, the safety and efficacy of prescribing these drugs needs to be reviewed often, especially with the approval of new formulations and doses.

Areas covered: The three ChEIs currently approved by the FDA are donepezil, rivastigmine and galantamine. This article will review the safety and tolerability of these ChEIs and analyze the potential disease modifying properties of these drugs. The authors have reviewed all recent literature including review articles, meta-analyzes, clinical trials and more.

Expert opinion: These ChEIs differ subtly in their mechanisms of action, in their tolerability and safety and FDA-approved indications. All are considered first-line, symptomatic treatments of the various phases of AD and may even have potentially disease-modifying effects.     

Pharmacotherapeutic strategies in the treatment of severe Alzheimer’s disease

Introduction: Alzheimer’s disease (AD) is a slowly progressive neurodegenerative disease. Patients with severe AD often require assistance with daily functioning and have a substantially higher probability of admission to nursing homes compared to the general population.

Areas covered: Medications approved by the US Food and Drug Administration for the treatment of severe AD include the cholinesterase inhibitors (ChEIs), donepezil (10 and 23 mg/day) and rivastigmine (transdermal patch, 13.3 mg/24 hours), and the N-methyl-D-aspartate receptor antagonist memantine (immediate- and extended-release formulations). This article will review the efficacy, safety, and tolerability data of these agents in the treatment of severe AD. Issues related to combination therapy, neuropsychiatric symptoms, and treatment discontinuation are also discussed.

Expert opinion: AD therapeutics provide benefits on measures of cognition, functioning, behavior, and global status even in the severe stages of AD. Combination therapy with memantine and ChEIs may provide additive benefits compared with ChEI monotherapy. Decisions regarding discontinuation of these medications should be made on a case-by-case basis, with some evidence suggesting that discontinuation may worsen cognition and functional impairment. It is recommended that patients entering the terminal stages of AD discontinue all medications not necessary for comfort.     

Synthesis,in vitro and in vivo characterization of glycosyl derivatives of ibuprofen as novel prodrugs for brain drug delivery

New glycosyl derivatives of ibuprofen (I, II, III, and IV) were synthesized in order to overcome the ineffective delivery of ibuprofen across the blood–brain barrier owing to its low permeability, using d-glucose as a drug targeting agent. Ibuprofen was linked directly to the C-2, C-3, C-4, and C-6 positions of glucose via ester bonds. Furthermore, in vitro stabilities of the four ester derivatives were evaluated to determine both their stability in aqueous medium and their feasibility to undergo enzymatic cleavage by esterase in biological samples to regenerate the original drug. From the obtained results, compounds I–IV appeared to be moderately stable in pH 7.43 buffer solution, rat plasma, and brain tissue extracts. In vivo experiments showed that the AUC_0–t of ibuprofen in plasma after the injection of prodrugs is several times higher than that of AUC_0–t after the injection of ibuprofen. In addition, the maximal concentration of ibuprofen in brain after the administration of ester IV was three fold higher than that of the control group. Also, the concentration of ibuprofen was kept stable in brain for about 4?h for four esters, which was beneficial for the treatment of Alzheimer’s disease and highlighted the possibility of brain drug delivery of ibuprofen using prodrug strategies.     

Synthesis,in vitro and structural aspects of benzothiazole analogs as anti-oxidants and potential neuroprotective agents

Catalase, an important antioxidant enzyme, is known to have a neuroprotective role against neurodegenerative disorder. Earlier study has focussed on benzothiazole-triazole hybrid molecules that are larger in size and molecular weight and inhibit the amyloid β (Aβ)-catalase interaction thus aid in neuroprotection. Here we have synthesized the novel benzothiazole molecules with low molecular weight using One-pot methodology and assayed the neuroprotective effects of the synthesized compounds in the U87 MG cell line under H₂O₂ induced stressed condition and compared with other cell lines such as breast cancer (MCF-7) and macrophage (RAW-264.7) using cell viability assay. These analogs were found to enhance the neuronal cell viability and protect neuronal cells from the ROS mediated neuronal damage induced by H₂O₂. Furthermore, compounds 6a, 6b, 6c, 6d, and 7a modulate catalase and enhanced the catalase activity up to 90 % during the H₂O₂ exposure in the U87MG cell line. These analogs (6a, 6b, 6c and 6d) have exhibited strong binding energies of -7.39, -7.52, -6.5 and -7.1 as observed by molecular modeling studies using AutoDockTool-1.5.6. Lig Plot + program using potent analogs 6b and 6c and catalase enzyme indicated the presence of hydrophobic interactions in the catalytic site of catalase enzyme. Furthermore, a simulation study was conducted between ligand and catalase protein by DESMOND software that further strengthens these ligand and enzyme interactions. In silico ADMET study was conducted by the Swiss ADME program revealed the drug-likeliness of these analogs. The present study has identified benzothiazole analogs such as 6b, 6c and 6d have potential catalase modulating activity and is comparable with that of known drug Valproic acid, thus help in neuroprotection. This study can be further taken up for the in vivo animal model study for the possible therapy.     

P-糖蛋白在神经退行性疾病中的作用

神经退行性疾病( neurodegenerative disease)是一种以神经元退行性病变为基础的慢性进行性神经系统疾病,发病机制尚不明了,但一些内源性和外源性物质在脑部的异常聚集和沉积与其病因密切相关,且其往往是P糖蛋白的底物.近年来研究表明血脑屏障的p-糖蛋白在一些神经退行性疾病发展过程中表达会减少,这可能导致致病性内外源性物质的进一步聚集和沉积,恶化病情.本文对近年来有关P-糖蛋白在神经退行性疾病的发病和病情进展中的作用作一综述.     

Molecular interactions of 4-acetoxy-plakinamine B with peripheral anionic and other catalytic subsites of the aromatic gorge of acetylcholinesterase: Computational and structural insights

Abstract

Context: A steroidal alkaloid, 4-acetoxy-plakinamine B (4APB), is a recently discovered marine natural product with inhibitory effect against acetylcholinesterase (AChE), but its mechanism of interaction with the enzyme remains to be elucidated.

Objective: The main objective was to study molecular binding mode of the compound, its interactions with catalytic subsites and molecular mechanism behind its significant inhibitory effect.

Materials and methods: All possible interactions of ligands in the binding sites were analyzed using FRED 2.1 and the OMEGA pre-generated multi-conformer library.

Results: Dipole–dipole interactions were observed between the secondary amino group of 4APB and Ser200 at a distance of 3.91?Å and also with Gly117 and Gly118. A further dipole–dipole interaction was between Arg289 and the heterocyclic nitrogen. Hydrogen bonding interactions were observed between Tyr130 and secondary amino and C-4 acetyl groups as well as between heterocyclic nitrogen and Phe288 at a distance of 3.04?Å. Hydrophobic interactions were evident between rings C/D of 4APB and with Phe288, Phe330 and Phe331. The computational studies revealed 4APB’s critical molecular interaction with amino acids of peripheral active (PAS) and anionic (AS) subsites.

Discussion: Our data provided molecular evidence for the mixed competitive inhibitory effect of 4APB. For lead optimization, structural insights revealed the N-methyl group of 4APB could be replaced by NH₂ moiety to generate a more favorable hydrogen bonding with Glu199. A polar group insertion such as NH₂ or OH at certain sites of the 4APB skeleton is also recommended.

Conclusion: These computational insights explained the mixed-competitive enzyme kinetic behavior of 4APB. This study outlines a strategy for designing novel derivatives of 4APB with potentially better AChE inhibitory activities through interaction at the PAS and AS sites.     

Inhibition of IKKβ by celastrol and its analogues – an in silico and in vitro approach

Context: Alzheimer’s disease (AD) is the most common form of dementia affecting the aged population and neuroinflammation is one of the most observed AD pathologies. NF-κB is the central regulator of inflammation and inhibitor κB kinase (IKK) is the converging point in NF-κB activation. Celastrol is a natural triterpene used as a treatment for inflammatory conditions.

Objective: This study determines the neuroprotective and inhibitory effect of celastrol on amyloid beta_1-42 (Aβ_1-42) induced cytotoxicity and IKKβ activity, respectively.

Materials and methods: Retinoic acid differentiated IMR-32 cells were treated with celastrol (1?μM) before treatment with Aβ_1-42 (IC₃₀ 10?μM) for 24?h. The cytotoxicity and IKK phosphorylation were measured by MTT and western blotting analysis, respectively. We screened 36 celastrol analogues for the IKKβ inhibition by molecular docking and evaluated their drug like properties to delineate the neuroprotective effects.

Results: Celastrol (1?μM) inhibited Aβ_1-42 (10?μM) induced IκBα phosphorylation and protected IMR-32 cells from cell death. Celastrol and 25 analogues showed strong binding affinity with IKKβ as evidenced by strong hydrogen-bonding interactions with critical active site residues. All the 25 analogues displayed strong anti-inflammatory properties but only 11 analogues showed drug-likeness. Collectively, molecule 15 has highest binding affinity, CNS activity and more drug likeness than parent compound celastrol.

Discussion and conclusion: The decreased expression of pIκBα in celastrol pretreated cells affirms the functional representation of inhibited IKKβ activity in these cells. The neuroprotective potentials of celastrol and its analogues may be related to IKK inhibition.     

Neuronal apoptosis as a therapeutic target in neurodegenerative disease

Apoptosis is a form of physiological or programmed cell death. It has been speculated that this process might account for the death of selective neuronal populations in certain progressive neurodegenerative disorders, including Alzheimer’s disease (AD) and Parkinson’s disease (PD) and some circumstantial evidence to support this view has been forthcoming. Increased understanding of the molecular pathophysiology of neuronal apoptosis may therefore present significant new therapeutic targets, to slow or halt neurodegeneration. This article reviews patents from the last five years which claim the use of apoptotic modulators in neurodegenerative disease. Although there are a significant number of claims, very few are buttressed with strong experimental evidence; this is usually from cell culture studies, rather than animal models of neurodegenerative disease; only a single human clinical study was identified. Thus, although treatment of neurodegenerative disease by means of manipulating apoptosis is an area of much activity and holds promise for the future, clinical application of current patents is unlikely in the near future. Extant medications may conceivably exert some of their action through effects on apoptosis.     

In vitro antioxidant and anti-inflammatory activities of Angelica decursiva

Mounting evidences continue to support the involvement of oxidative/nitrosative stress and inflammation in the pathogenesis of many diseases. Plant constituents having antioxidant activities together with anti-inflammatory activities may provide better opportunities to develop anti-inflammatory agents. In view of this, we evaluated the antioxidant and antiinflammatory activities of methanolic extract of whole plants of Angelica decursiva, and its solvent soluble fractions via in vitro activities against lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 cells, as well as in vitro scavenging activities against 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, NO, and peroxynitrite. Among the tested fractions, the ethyl acetate fraction was found as the most active antioxidant fraction together with significant anti-inflammatory effect. From the active ethyl acetate fraction, four coumarin derivatives consisting of nodakenin, nodakenetin, umbelliferone, and umbelliferone-6-carboxylic acid, along with a phenolic compound, vanillic acid, were isolated. Among them, umbelliferone 6-carboxylic acid and vanillic acid were isolated for the first time from this plant. In all antioxidant assays, vanillic acid showed the highest antioxidant potential followed by umbelliferone 6-carboxylic acid among the isolated compounds. In the anti-inflammatory assay, umbelliferone 6-carboxylic acid exhibited the highest inhibitory activity against lipopolysaccharide-induced NO production in RAW 264.7 cells with an IC₅₀ value of 72.98 μg/mL. Therefore, the present study reveals the potential antioxidant and antiinflammatory activities of whole plants of A. decursiva and its constituents, mainly umbelliferone 6-carboxylic acid, which could be used in the development of therapeutic and preventive agents for oxidative stress-related inflammatory diseases.     

Insulin deprivation decreases insulin degrading enzyme levels in primary cultured cortical neurons and in the cerebral cortex of rats with streptozotocin-induced diabetes

Background

Many studies have indicated a relationship between diabetes and Alzheimer’s disease (AD). However, the molecular mechanism underlying this association has not been clarified. Among several factors, insulin degrading enzyme (IDE), which plays roles in the degradation of both insulin and amyloid β (Aβ), has gained interest as a potential target in efforts to solve this puzzle. This study sought to examine the effects of varying insulin and/or glucose concentrations on IDE expression.

In vitro antioxidant and antitumor activities of six selected plants used in the Traditional Arabic Palestinian herbal medicine

Context: Despite several pharmacological applications of the medicinal plants in the Traditional Arabic Palestinian Herbal Medicine in Palestine (TAPHM), studies on their antioxidant properties are still scarce.

Objective: This work evaluates the antioxidant and antitumor activities of the ethanol extracts from different parts of six plants: [Arum palaestinum Boiss (Araceae), Urtica pilulifera L. (Urticaceae), Coridothymus capitatus (L.) Reichb (Lamiaceae), Majorana syriaca (L.) Rafin. (Lamiaceae), Teucrium creticum L. (Lamiaceae), and Teucrium capitatum L. (Lamiaceae)] used in the TAPHM.

Materials and methods: The antioxidant activity was evaluated for the ethanol extracts by DPPH and β-carotene–linoleic acid assays together with total contents of phenols and flavonoids. For the anti-carcinogenic evaluation, the extracts were tested for the ability to inhibit the proliferation of breast cancer cells (MCF-7) using the MTT reduction assay.

Results: Among the extracts, the U. pilulifera had the highest amount of total phenolics, possessing the second highest total flavonoids. It also showed a maximum cytotoxic activity (IC₅₀?=?63?µg/ml), followed by C. capitatus, and A. palaestinum. Otherwise, the extract of T. creticum was demonstrated to be an efficient scavenger of O₂ (IC₅₀?=?83?µg/ml), followed by M. syriaca, C. capitatus, T. capitatum, A. palaestinum, and U. pilulifera.

Discussion and conclusion: The results suggest that the investigated plants have shown varied antioxidant capacities which were strongly correlated with their contents of phenolics. Accordingly, this study proposes that the therapeutic benefit of these plants can be, at least in part, attributed to its potential inhibition of oxidative processes.     

Combating psychosis in Parkinson’s disease patients: the use of antipsychotic drugs

Parkinson’s disease (PD) patients commonly experience psychotic symptoms, with the most frequent manifestation being visual hallucinations. In PD, psychosis is predominantly drug induced and an important issue for clinicians to address as it increases the risk of nursing home placement as well as mortality. This review summarises the current knowledge regarding the clinical manifestations, pathophysiology and risk factors for drug-induced psychosis in patients with PD and focuses on treatment, especially with regard to the atypical antipsychotics.     

Metrifonate alters antioxidant levels and caspase activity in cerebral cortex of Wistar rats

Metrifonate (trichlorfon) is an inhibitor of acetylcholinesterase (AChE). It was used as an Alzheimer’s disease (AD) drug; however, the application was withdrawn due to adverse effects. Implication of metrifonate for the antioxidant status and regulation of apoptotic processes was evaluated in the present study. Wistar rats (six per group) were exposed subcutaneously to either 60 or 120?mg/kg of body weight of metrifonate and compared with the controls treated with saline only. Cerebral cortex and liver tissues were collected from animals 40?min after exposure. Activities of AChE, glutathione reductase, glutathione-S-transferase, caspase 3, total protein level, thiobarbituric acid reactive substances, reduced glutathione level and ferric reducing antioxidant power (FRAP) were assayed in the tissue samples. Metrifonate had only lower impact on oxidative stress in the liver. Cerebral cortex tissues had decreased AChE and increased caspase 3 activities as well as the FRAP level. Owing to the novel findings, suitability of metrifonate for AD therapy is discussed.     

Review of the acetylcholinesterase inhibitor galanthamine

Galanthamine (or galantamine, Reminyl^®) is a tertiary alkaloid acetylcholinesterase inhibitor (AChEI) which has been approved in several countries for the symptomatic treatment of senile dementia of the Alzheimer’s type. Derived from bulbs of the common snowdrop and several Amaryllidaceae plants, (-)-galanthamine (GAL) has long been used in anaesthetics to reverse neuromuscular paralysis induced by turbocurarine-like muscle relaxants and more recently, has been shown to attenuate drug- and lesion-induced cognitive deficits in animal models of learning and memory. GAL directly inhibits acetylcholinesterase activity, while demonstrating much weaker activity on butyrylcholinesterase (BuChE). GAL also stimulates pre- and postsynaptic nicotinic receptors, although the clinical significance of this finding is yet unclear. Numerous variants and analogues of GAL have also been developed, with varying potency in inhibiting AChE activity. GAL is readily absorbed after oral administration, with a t_maxof 52 min and a plasma elimination t_½ of 5.7 h. The efficacy of GAL administered to Alzheimer’s disease (AD) patients has been well demonstrated by large-scale clinical trials. Typical of AChEIs, the most common adverse events associated with GAL are nausea and vomiting. In conclusion, evidence to date suggests galanthamine to be similar to other AChEIs in improving cognitive function in AD patients.