Synthesis and investigation of the cholinesterase inhibitory and antioxidant capacities of some novel N'-(quinolin-4-ylmethylene)propanehydrazides against Alzheimer's disease.

One of the worst long-term health issues of the past few decades is Alzheimer's disease (AD). Unfortunately, there are currently insufficient choices for treating and caring for AD, which makes it a popular subject for drug development research. Studies on the development of drugs for AD have primarily concentrated on the use of multitarget directed ligands. Following this strategy, we designed new ChE inhibitors with additional antioxidant and metal chelator effects. In this research, eight novel N'-(quinolin-4-ylmethylene)propanehydrazide derivatives were synthesized and characterized. We then evaluated the inhibition potency of all the final compounds for cholinesterase enzymes. Among them, 4e (IC50 acetylcholinesterase [AChE] = 0.69 µM and butyrylcholinesterase [BChE]= 26.00 µM) and 4h (IC50's AChE= 7.04 µM and BChE= 16.06 µM) were found to be the most potent AChE and BChE inhibitors, respectively.

Neuroprotection of Cholinergic Neurons with a Tau Aggregation Inhibitor and Rivastigmine in an Alzheimer's-like Tauopathy Mouse Model.

Basal forebrain cholinergic dysfunction, most likely linked with tau protein aggregation, is a characteristic feature of Alzheimer's disease (AD). Recent evidence suggests that tau protein is a putative target for the treatment of dementia, and the tau aggregation inhibitor, hydromethylthionine mesylate (HMTM), has emerged as a potential disease-modifying treatment. However, its efficacy was diminished in patients already receiving approved acetylcholinesterase inhibitors. In this study, we ask whether this negative interaction can also be mimicked in experimental tau models of AD and whether the underlying mechanism can be understood. From a previous age profiling study, 6-month-old line 1 (L1) tau transgenic mice were characterized by a severe reduction in several cholinergic markers. We therefore assessed whether long-term pre-exposure with the acetylcholinesterase inhibitor rivastigmine alone and in conjunction with the tau aggregation inhibitor HMTM can reverse cholinergic deficits in L1. Rivastigmine and HMTM, and combinations of the two compounds were administered orally for 11 weeks to both L1 and wild-type mice. The brains were sectioned with a focus on the basal forebrain, motor cortex and hippocampus. Immunohistochemical staining and quantification of choline acetyltransferase (ChAT), tyrosine kinase A (TrkA)-positive neurons and relative optical intensity (ROI) for vesicular acetylcholine transporter (VAChT), and acetylcholinesterase (AChE) reactivity confirmed reversal of the diminished cholinergic phenotype of interneurons (nucleus accumbens, striatum) and projection neurons (medial septum, nucleus basalis magnocellularis) by HMTM, to a greater extent than by rivastigmine alone in L1 mice. Combined administration did not yield additivity but, in most proxies, led to antagonistic effects in which rivastigmine decreased the benefits shown with HMTM alone. Local markers (VAChT and AChE) in target structures of the basal forebrain, motor cortex and hippocampal CA3 seemed to be normalized by HMTM, but not by rivastigmine or the combination of both drugs. HMTM, which was developed as a tau aggregation inhibitor, strongly decreased the tau load in L1 mice, however, not in combination with rivastigmine. Taken together, these data confirm a cholinergic phenotype in L1 tau transgenic mice that resembles the deficits observed in AD patients. This phenotype is reversible by HMTM, but at the same time appears to be subject to a homeostatic regulation induced by chronic pre-treatment with an acetylcholinesterase inhibitor, which interferes with the efficacy of HMTM. The strongest phenotypic reversal coincided with a normalization of the tau load in the cortex and hippocampus of L1, suggesting that tau accumulation underpins the loss of cholinergic markers in the basal forebrain and its projection targets.

Potential acetylcholinesterase inhibitors to treat Alzheimer's disease.

OBJECTIVE: Alzheimer's disease (AD) is identified by neuropathological symptoms, and there is now no effective treatment for the condition. A lack of the brain neurotransmitter acetylcholine has been related to the etiology of Alzheimer's disease. Acetylcholinesterase is an enzyme that breaks down acetylcholine to an inactive form and causes the death of cholinergic neurons. Conventional treatments were used but had less effectiveness. Therefore, there is a crucial need to identify alternative compounds with potential anti-cholinesterase agents and minimal undesirable effects. MATERIALS AND METHODS: Fluoroquinolones and benzimidazole-benzothiazole derivatives offer antimicrobial, anti-inflammatory, anti-oxidant, anti-diabetic, and anti-Alzheimer activities. To enhance the chemical portfolio of cholinesterase inhibitors, a variety of fluoroquinolones and benzimidazole-benzothiazole compounds were evaluated against acetylcholinesterase (AChE) butyrylcholinesterase (BChE) enzymes. For this purpose, molecular docking and adsorption, distribution, metabolism, excretion, and toxicology ADMET models were used for in-silico studies for both AChE and BChE enzymes to investigate possible binding mechanisms and drug-likeness of the compounds. The inhibitory effect of docked heterocyclic compounds was also verified in vitro against AChE and BChE enzymes. Fluoroquinolones (Z, Z3, Z4, Z6, Z8, Z12, Z15, and Z9) and benzimidazole-benzothiazole compounds (TBIS-16, TBAF-1 to 9) passed through the AChE inhibition assay and their IC50 values were calculated. RESULTS: The compound 1-ethyl-6-fluoro-7-(4-(2-(4-nitrophenylamino)-2-oxoethyl)piperazin-1-yl) -4-oxo-1,4 di-hydroquinoline-3-carboxylic acid and 2-((1H-benzo[d]imidazol-2-yl)methyl)-N'-(3-bromobenzyl)-4-hydroxy-2H-thiochromene-3-carbohydrazide 1,1-dioxide (Z-9 and TBAF-6) showed the lowest IC50 values against AChE/BChE (0.37±0.02/2.93±0.03 µM and 0.638±0.001/1.31±0.01 µM, respectively) than the standard drug, donepezil (3.9±0.01/4.9±0.05 µM). During the in-vivo investigation, behavioral trials were performed to analyze the neuroprotective impact of Z-9 and TBAF-6 compounds on AD mouse models. The groups treated with Z-9 and TBAF-6 compounds had better cognitive behavior than the standard drug. CONCLUSIONS: This study found that Z-9 (Fluoroquinolones) and TBAF-6 (benzimidazole-benzothiazole) compounds improve behavioral and biochemical parameters, thus treating neurodegenerative disorders effectively.

Disentangling the formation, mechanism, and evolvement of the covalent methanesulfonyl fluoride acetylcholinesterase adduct: Insights into an aged-like inactive complex susceptible to reactivation by a combination of nucleophiles.

Chemical warfare nerve agents and pesticides, known as organophosphorus compounds inactivate cholinesterases (ChEs) by phosphorylating the serine hydroxyl group located at the active site of ChEs. Over the course of time, phosphorylation is followed by loss of an organophosphate-leaving group and the bond with ChEs becomes irreversible, a process known as aging. Differently, structurally related irreversible catalytic poisons bearing sulfur instead of phosphorus convert ChEs in its aged form only by covalently binding to the key catalytic serine. Kinetic and crystallographic studies of the interaction between Torpedo californica acetylcholinesterase (TcAChE) and a small organosulfonate, methanesulfonyl fluoride (MSF), indeed revealed irreversibly methylsulfonylated serine 200, to be isosteric with the bound aged sarin/soman analogues. The potent bulky reversible inhibitor 7-bis-tacrine (BTA) adopts, in the active site of the crystal structure of the MSF-enzyme adduct, a location and an orientation that closely resemble the one being found in the crystal structure of the BTA-enzyme complex. Remarkably, the presence of BTA accelerates the rate of methanesulfonylation by a factor of two. This unexpected result can be explained on the basis of two facts: i) the steric hindrance exerted by BTA to MSF in accessing the active site and ii) the acceleration of the MSF-enzyme adduct formation as a consequence of the lowering of the rotational and translational degrees of freedom in the proximity of the catalytic serine. It is well known that pralidoxime (2-Pyridine Aldoxime Methyl chloride, 2-PAM) alone or in the presence of the substrate acetylcholine cannot reactivate the active site serine of the TcAChE-MSF adduct. We show that the simultaneous presence of 2-PAM and the additional neutral oxime, 2-[(hydroxyimino)methyl]-l-methylimidazol (2-HAM), triggers the reactivation process of TcAChE within the hour timescale. Overall, our results pave the way toward the likely use of a cocktail of distinctive oximes as a promising recipe for an effective and fast reactivation of aged cholinesterases.

Eucalyptus globulus leaf-isolated isorhapontin serves as a natural insecticide via acetylcholinesterase inhibition.

Acetylcholinesterase (AChE) inhibitors cause insect death by preventing the hydrolysis of the neurotransmitter acetylcholine, which overstimulates the nervous system. In this study, isorhapontin, isolated from E. globulus leaves, was evaluated as a natural insecticide with AChE inhibition at 12.5 µM. Using kinetic analyses, we found that isorhapontin acted as a competitive inhibitor that binds to the active site of AChE. The inhibition constant (Ki) was 6.1 µM. Furthermore, isorhapontin and resveratrol, which have basic skeletons, were predicted to bind to the active site of AChE via molecular docking. A comparison of the hydrogen bonding between the two stilbenes revealed characteristic differences in their interactions with amino acids. In isorhapontin, Trp83, Gly149, Tyr162, Tyr324, and Tyr370 interacted with the sugar moiety. These results suggest that with further development, isorhapontin can be used as an insecticide alternative.

New Charged Cholinesterase Inhibitors: Design, Synthesis, and Characterization.

Triazoles and triazolium salts are very common subunits in the structures of various drugs. Medicaments with a characteristic 1,2,3-triazole core are also being developed to treat neurodegenerative disorders associated with cholinesterase enzyme activity. Several naphtho- and thienobenzo-triazoles from our previous research emerged as being particularly promising in that sense. For this reason, in this research, new naphtho- and thienobenzo-triazoles 23-34, as well as 1,2,3-triazolium salts 44-51, were synthesized and tested. Triazolium salts 44-46 showed excellent activity while salts 47 and 49 showed very good inhibition toward both butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzymes. In contrast, neutral photoproducts were shown to be selective towards BChE but with very good inhibition potential as molecules 24-27. The representative of newly prepared compounds, 45 and 50, were stable in aqueous solution and revealed intriguing fluorimetric properties, characterized by a strong Stokes shift of >160 nm. Despite their condensed polycyclic structure shaped similarly to well-known DNA-intercalator ethidium bromide, the studied compounds did not show any interaction with ds-DNA, likely due to the unfavorable steric hindrance of substituents. However, the studied dyes bind proteins, particularly showing very diverse inhibition properties toward AChE and BChE. In contrast, neutral photoproducts were shown to be selective towards a certain enzyme but with moderate inhibition potential. The molecular docking of the best-performing candidates to cholinesterases' active sites identified cation-π interactions as the most responsible for the stability of the enzyme-ligand complexes. As genotoxicity studies are crucial when developing new active substances and finished drug forms, in silico studies for all the compounds synthesized have been performed.

In Vitro and In Silico of Cholinesterases Inhibition and In Vitro and In Vivo Anti-Melanoma Activity Investigations of Extracts Obtained from Selected Berberis Species.

Berberis species have a long history of use in traditional Chinese medicine, Ayurvedic medicine, and Western herbal medicine. The aim of this study was the quantification of the main isoquinoline alkaloids in extracts obtained from various Berberis species by HPLC, in vitro and in silico determination of anti-cholinesterase activity, and in vitro and in vivo investigations of the cytotoxic activity of the investigated plant extracts and alkaloid standards. In particular, Berberis species whose activity had not been previously investigated were selected for the study. In the most investigated Berberis extracts, a high content of berberine and palmatine was determined. Alkaloid standards and most of the investigated plant extracts exhibit significant anti-cholinesterase activity. Molecular docking results confirmed that both alkaloids are more favourable for forming complexes with acetylcholinesterase compared to butyrylcholinesterase. The kinetic results obtained by HPLC-DAD indicated that berberine noncompetitively inhibited acetylcholinesterase, while butyrylcholinesterase was inhibited in a mixed mode. In turn, palmatine exhibited a mixed inhibition of acetylcholinesterase. The cytotoxic activity of berberine and palmatine standards and plant extracts were investigated against the human melanoma cell line (A375). The highest cytotoxicity was determined for extract obtained from Berberis pruinosa cortex. The cytotoxic properties of the extract were also determined in the in vivo investigations using the Danio rerio larvae xenograft model. The obtained results confirmed a significant effect of the Berberis pruinosa cortex extract on the number of cancer cells in a living organism. Our results showed that extracts obtained from Berberis species, especially the Berberis pruinosa cortex extract, can be recommended for further in vivo experiments in order to confirm the possibility of their application in the treatment of neurodegenerative diseases and human melanoma.

4-Oxypiperidine Ethers as Multiple Targeting Ligands at Histamine H3 Receptors and Cholinesterases.

This study examines the properties of a novel series of 4-oxypiperidines designed and synthesized as histamine H3R antagonists/inverse agonists based on the structural modification of two lead compounds, viz., ADS003 and ADS009. The products are intended to maintain a high affinity for H3R while simultaneously inhibiting AChE or/and BuChE enzymes. Selected compounds were subjected to hH3R radioligand displacement and gpH3R functional assays. Some of the compounds showed nanomolar affinity. The most promising compound in the naphthalene series was ADS031, which contained a benzyl moiety at position 1 of the piperidine ring and displayed 12.5 nM affinity at the hH3R and the highest inhibitory activity against AChE (IC50 = 1.537 µM). Eight compounds showed over 60% eqBuChE inhibition and hence were qualified for the determination of the IC50 value at eqBuChE; their values ranged from 0.559 to 2.655 µM. Therapy based on a multitarget-directed ligand combining H3R antagonism with additional AChE/BuChE inhibitory properties might improve cognitive functions in multifactorial Alzheimer's disease.

Insight into antioxidant-like activity and computational exploration of identified bioactive compounds in Talinum triangulare (Jacq.) aqueous extract as potential cholinesterase inhibitors.

BACKGROUND: Recent reports have highlighted the significance of plant bioactive components in drug development targeting neurodegenerative disorders such as Alzheimer's disease (AD). Thus, the current study assessed antioxidant activity and enzyme inhibitory activity of the aqueous extract of Talinum triangulare leave (AETt) as well as molecular docking/simulation of the identified phytonutrients against human cholinesterase activities. METHODS: In vitro assays were carried out to assess the 2,2- azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) cation radicals and cholinesterase inhibitory activities of AETt using standard protocols. High performance liquid chromatography coupled with diode-array detection (HPLC-DAD) was employed to identify compounds in AETt. Also, for computational analysis, identified bioactive compounds from AETt were docked using Schrodinger's GLIDE against human cholinesterase obtained from the protein data bank ( https://www.rcsb.org/ ). RESULTS: The results revealed that AETt exhibited a significant concentration-dependent inhibition against ABTS cation radicals (IC50 = 308.26 ± 4.36 µg/ml) with butylated hydroxytoluene (BHT) as the reference. Similarly, AETt demonstrated a significant inhibition against acetylcholinesterase (AChE, IC50 = 326.49 ± 2.01 µg/ml) and butyrylcholinesterase (BChE, IC50 = 219.86 ± 4.13 µg/ml) activities with galanthamine as the control. Molecular docking and simulation analyses revealed rutin and quercetin as potential hits from AETt, having showed strong binding energies for both the AChE and BChE. In addition, these findings were substantiated by analyses, including radius of gyration, root mean square fluctuation, root mean square deviation, as well as mode similarity and principal component analyses. CONCLUSION: Overall, this study offers valuable insights into the interactions and dynamics of protein-ligand complexes, offering a basis for further drug development targeting these proteins in AD.

Synthesis and molecular docking studies of 5-trifluoromethoxy-2-indolinones as cholinesterase dual inhibitors.

Background: In Alzheimer's disease, butyrylcholinesterase (BuChE) activity gradually increases, while acetylcholinesterase (AChE) activity decreases or remains unchanged. Dual inhibitors have important roles in regulation of synaptic acetylcholine levels and progression of Alzheimer's disease. Methods: 1-(Thiomorpholin-4-ylmethyl)/benzyl-5-trifluoromethoxy-2-indolinones (6-7) were synthesized. AChE and BuChE inhibitory effects were investigated with Ellman's method. Molecular docking studies were performed for analyzing the possible binding interactions at active sites. Results: Compound 6g was the strongest inhibitor against both AChE (Ki = 0.35 µM) and BuChE (Ki = 0.53 µM). It showed higher inhibitory effects than both donepezil and galantamine. Moreover, compound 7m had a higher inhibitory effect than galantamine and the effect was comparable to that of donepezil against both AChE (Ki = 0.69 µM) and BuChE (Ki = 0.95 µM). Conclusion: The benzyl substitution compared with 1-(thiomorpholin-4-ylmethyl) group significantly increased both AChE and BuChE inhibitory effects.

Quantitative T2 mapping-based longitudinal assessment of brain injury and therapeutic rescue in the rat following acute organophosphate intoxication.

Acute intoxication with organophosphate (OP) cholinesterase inhibitors poses a significant public health risk. While currently approved medical countermeasures can improve survival rates, they often fail to prevent chronic neurological damage. Therefore, there is need to develop effective therapies and quantitative metrics for assessing OP-induced brain injury and its rescue by these therapies. In this study we used a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP), to test the hypothesis that T2 measures obtained from brain magnetic resonance imaging (MRI) scans provide quantitative metrics of brain injury and therapeutic efficacy. Adult male Sprague Dawley rats were imaged on a 7T MRI scanner at 3, 7 and 28 days post-exposure to DFP or vehicle (VEH) with or without treatment with the standard of care antiseizure drug, midazolam (MDZ); a novel antiseizure medication, allopregnanolone (ALLO); or combination therapy with MDZ and ALLO (DUO). Our results show that mean T2 values in DFP-exposed animals were: (1) higher than VEH in all volumes of interest (VOIs) at day 3; (2) decreased with time; and (3) decreased in the thalamus at day 28. Treatment with ALLO or DUO, but not MDZ alone, significantly decreased mean T2 values relative to untreated DFP animals in the piriform cortex at day 3. On day 28, the DUO group showed the most favorable T2 characteristics. This study supports the utility of T2 mapping for longitudinally monitoring brain injury and highlights the therapeutic potential of ALLO as an adjunct therapy to mitigate chronic morbidity associated with acute OP intoxication.

Diethoxyphosphoryloxy-oleanolic acid is a nanomolar-inhibitor of butyrylcholinesterase.

A series of new betulin, lupeol, erythrodiol, and oleanolic acid phosphoryloxy- and furoyloxy-derivatives has been synthesized and their structure was confirmed by NMR spectroscopy. Synthesized compounds were subjected to Ellman's assays to determine their ability to inhibit the enzymes AChE and BChE. Among them, diethoxyphosphoryloxy-oleanolic acid inhibited BChE with a value of 99%, thereby acting as a mixed-type inhibitor holding very low Ki values of Ki = 6.59 nM and Ki ' = 1.97 nM, respectively.

Morphing cholinesterase inhibitor amiridine into multipotent drugs for the treatment of Alzheimer's disease.

The search for novel drugs to address the medical needs of Alzheimer's disease (AD) is an ongoing process relying on the discovery of disease-modifying agents. Given the complexity of the disease, such an aim can be pursued by developing so-called multi-target directed ligands (MTDLs) that will impact the disease pathophysiology more comprehensively. Herewith, we contemplated the therapeutic efficacy of an amiridine drug acting as a cholinesterase inhibitor by converting it into a novel class of novel MTDLs. Applying the linking approach, we have paired amiridine as a core building block with memantine/adamantylamine, trolox, and substituted benzothiazole moieties to generate novel MTDLs endowed with additional properties like N-methyl-d-aspartate (NMDA) receptor affinity, antioxidant capacity, and anti-amyloid properties, respectively. The top-ranked amiridine-based compound 5d was also inspected by in silico to reveal the butyrylcholinesterase binding differences with its close structural analogue 5b. Our study provides insight into the discovery of novel amiridine-based drugs by broadening their target-engaged profile from cholinesterase inhibitors towards MTDLs with potential implications in AD therapy.

Changes in cardiovascular autonomic control induced by chronic inhibition of acetylcholinesterase during pyridostigmine or donepezil treatment of spontaneously hypertensive rats.

Chronic treatment with acetylcholinesterase inhibitors may be a promising therapeutic strategy for treatment of cardiovascular diseases. The aim of our study was to analyze the changes in blood pressure (BP) and heart rate (HR) during 14 days of treatment with two different acetylcholinesterase inhibitors - pyridostigmine (PYR) having only peripheral effects or donepezil (DON) with both peripheral and central effects. In addition, we studied their effects on the cardiovascular response to restraint stress and on sympathovagal control of HR in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). SHR were characterized by elevated BP and increased low-frequency component of systolic BP variability (LF-SBPV), but their cardiac vagal tone and HR variability (HRV) were reduced compared with WKY. Chronic treatment with either acetylcholinesterase inhibitor decreased HR and increased HRV in both strains. PYR treatment slightly decreased BP and LF-SBPV in the dark phase of the day. Neither drug significantly altered BP response to stress, but PYR attenuated HR increase during restraint stress. Regarding sympathovagal balance, acute methylatropine administration caused a greater increase of HR in WKY than in SHR. Chronic PYR or DON treatment enhanced HRV and HR response to methylatropine (vagal tone) in WKY, whereas PYR but not DON treatment potentiated HRV and vagal tone in SHR. In conclusion, vagal tone was lower in SHR compared with WKY, but was enhanced by chronic PYR treatment in both strains. Thus, chronic peripheral, but not central, acetylcholinesterase inhibition has major effects on HR and its variability in both normotensive and hypertensive rats.

Protective Effects of Red Ginseng Against Tacrine-Induced Hepatotoxicity: An Integrated Approach with Network Pharmacology and Experimental Validation.

Introduction: Tacrine, an FDA-approved acetylcholinesterase inhibitor, has shown efficacy in treating Alzheimer's disease, but its clinical use is limited by hepatotoxicity. This study investigates the protective effects of red ginseng against tacrine-induced hepatotoxicity, focusing on oxidative stress. Methods: A network depicting the interaction between compounds and targets was constructed for RG. Effect of RG was determined by MTT and FACS analysis with cells stained by rhodamine 123. Proteins were extracted and subjected to immunoblotting for apoptosis-related proteins. Results: The outcomes of the network analysis revealed a significant association, with 20 out of 82 identified primary RG targets aligning with those involved in oxidative liver damage including notable interactions within the AMPK pathway. in vitro experiments showed that RG, particularly at 1000µg/mL, mitigated tacrine-induced apoptosis and mitochondrial damage, while activating the LKB1-mediated AMPK pathway and Hippo-Yap signaling. In mice, RG also protected the liver injury induced by tacrine, as similar protective effects to silymarin, a well-known drug for liver toxicity protection. Discussion: Our study reveals the potential of RG in mitigating tacrine-induced hepatotoxicity, suggesting the administration of natural products like RG to reduce toxicity in Alzheimer's disease treatment.

Variability of Isoquinoline Alkaloid Profiles and Anticholinesterase Activities with Binding-Mode Predictions of Glaucium flavum Population.

In this study, phytochemical and biological activity studies supported by docking were carried out on a species of the genus Glaucium, a repository of isoquinoline alkaloids. The GC-MS (Gas Chromatography-Mass Spectrometry) method is used to characterize the isoquinoline alkaloids of Glaucium flavum Crantz. (Papaveraceae). G. flavum was collected from seven different regions of Türkiye (Antalya, Urla-Izmir, Mordogan-Izmir, Mugla, Assos-Canakkale, Karabiga-Canakkale, Giresun) and totally 17 compounds were detected by GC-MS. Glaucine was found to be the major constituent in the sample collected from Mugla, whereas isocorydine was recorded to be the principal alkaloid in other samples. Further fractionation studies on G. flavum collected from Antalya province in Southwestern Türkiye, yielded five major alkaloids (isocorydine 1, dihydrosanguinarine 2, glaucine 3, dehydroglaucine 4, protopine 5) which were characterized by spectroscopic methods. Anticholinesterase activities of the extracts and isolated alkaloids were also tested by in vitro Ellman method. The isolated compounds were also analyzed by a molecular docking technique to determine the binding orientations in the gorge of the active site of acetylcholinesterase (AChE) and a homology model of butyrylcholinesterase (BuChE). This is the first comparative investigation of the phytochemical composition and biodiversity of Glaucium flavum species growing in Türkiye.

Lycopodium Alkaloids from Huperzia goebelii.

One new fawcettimine-type Lycopodium alkaloid, hupertimine F (1), together with five known (2-6) Lycopodium alkaloids were isolated from Huperzia goebelii. The structure of 1 was elucidated by 1D and 2D NMR spectra, HRESIMS, and X-ray diffraction. Structurally, 1 represents the fourth example of Lycopodium alkaloids characterized by a 5/5/5/5/6 pentacyclic ring system with a 1-aza-7-oxabicyclo[2.2.1]heptane moiety. These known compounds 2, 3, 5, and 6 were isolated from H. goebelii for the first time. Compounds 1-6 were evaluated for acetylcholinesterase, butyrylcholinesterase and monoamine oxidase B inhibitory activities in vitro.

Restoration of nerve agent impaired neuromuscular transmission in rat diaphragm by bispyridinium non-oximes - Structure-activity relationships.

Organophosphate (OP) poisoning is currently treated with atropine, oximes and benzodiazepines. The nicotinic signs, i.e., respiratory impairment, can only be targeted indirectly via the use of oximes as reactivators of OP-inhibited acetylcholinesterase. Hence, compounds selectively targeting nicotinic acetylcholine receptors (nAChRs) might fundamentally improve current treatment options. The bispyridinium compound MB327 has previously shown some therapeutic effect against nerve agents in vitro and in vivo. Nevertheless, compound optimization was deemed necessary, due to limitations (e.g., toxicity and efficacy). The current study investigated a series of 4-tert-butyl bispyridinium compounds and of corresponding bispyridinium compounds without substituents in a rat diaphragm model using an indirect field stimulation technique. The length of the respective linker influenced the ability of the bispyridinium compounds to restore muscle function in rat hemidiaphragms. The current data show structure-activity relationships for a series of bispyridinium compounds and provide insight for future structure-based molecular modeling.

Multi-target potential of newly designed tacrine-derived cholinesterase inhibitors: Synthesis, computational and pharmacological study.

Simple and scalable synthetic approach was used for the preparation of thirteen novel tacrine derivatives consisting of tacrine and N-aryl-piperidine-4-carboxamide moiety connected by a five-methylene group linker. An anti-Alzheimer disease (AD) potential of newly designed tacrine derivatives was evaluated against two important AD targets, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In vitro pharmacological evaluation showed strong ChE inhibitory activity of all compounds, with IC50 values ranging from 117.5 to 455 nM for AChE and 34 to 324 nM for BuChE. As a representative of the series with the best cytotoxicity / ChE inhibitory activity ratio, expressed as the selectivity index (SI), 2-chlorobenzoyl derivative demonstrated mixed-type inhibition on AChE and BuChE, suggesting binding to both CAS and PAS of the enzymes. It also exhibited antioxidant capacity and neuroprotective potential against amyloid-ß (Aß) toxicity in the culture of neuron-like cells. In-depth computational analysis corroborated well with in vitro ChE inhibition, illuminating that all compounds exhibit significant potential in targeting both enzymes. Molecular dynamics (MD) simulations revealed that 2-chlorobenzoyl derivative, created complexes with AChE and BuChE that demonstrated sufficient stability throughout the observed MD simulation. Computationally predicted ADME properties indicated that these compounds should have good blood-brain barrier (BBB) permeability, an important factor for CNS-targeting drugs. Overall, all tested compounds showed promising pharmacological behavior, highlighting the multi-target potential of 2-chlorobenzoyl derivative which should be further investigated as a new lead in the drug development process.

Design, synthesis and biological evaluation of bakuchiol derivatives as multi-target agents for the treatment of Alzheimer's disease.

The concept of multi-target-directed ligands offers fresh perspectives for the creation of brand-new Alzheimer's disease medications. To explore their potential as multi-targeted anti-Alzheimer's drugs, eighteen new bakuchiol derivatives were designed, synthesized, and evaluated. The structures of the new compounds were elucidated by IR, NMR, and HRMS. Eighteen compounds were assayed for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in vitro using Ellman's method. It was shown that most of the compounds inhibited AChE and BuChE to varying degrees, but the inhibitory effect on AChE was relatively strong, with fourteen compounds showing inhibition of >50% at the concentration of 200 µM. Among them, compound 3g (IC50 = 32.07 ± 2.00 µM) and compound 3n (IC50 = 34.78 ± 0.34 µM) showed potent AChE inhibitory activities. Molecular docking studies and molecular dynamics simulation showed that compound 3g interacts with key amino acids at the catalytically active site (CAS) and peripheral anionic site (PAS) of acetylcholinesterase and binds stably to acetylcholinesterase. On the other hand, compounds 3n and 3q significantly reduced the pro-inflammatory cytokines TNF-α and IL-6 released from LPS-induced RAW 264.7 macrophages. Compound 3n possessed both anti-acetylcholinesterase activity and anti-inflammatory properties. Therefore, an in-depth study of compound 3n is expected to be a multi-targeted anti-AD drug.