Inhibition Of Cholinesterase Activity Research Articles

The property differences of essential oils extracted by two methods from Dolichos lablab flowers: chemical composition, anti-microorganism and cholinesterase inhibition activities

In this study, the essential oils of Dolichos lablab (syn. Lablab purpureus) flowers (EOFs) were extracted by enzymatic pretreatment plus microwave extraction (EP-ME) method, and the key factors affecting yield of essential oils were investigated. The kinetic curves of essential oils extracted by EP-ME method were fitted, and the results showed that the first-order kinetic model was more appropriate for essential oils extracted by EP-ME method. Under the optimal extraction conditions, EP-ME method not only had high extraction yield, but also had low consumption time. The yield of essential oil extracted by EP-ME method (0.41 ± 0.021% g/g) was 51.9% higher than that by traditional hydro-distillation (HD) method (0.27 ± 0.013% g/g), and the time and energy consumption were 53.33% and 18.62% of the HD method, respectively. The results of GC-MS showed that the contents of main substances in the essential oils by EP-ME method were remarkably increased, including hexadecanoic acid methyl ester (+11.05%), 9Z,12Z,15Z-octadecatrienoic acid methyl ester (+5.26%), (Z)-9-octadecenoic acid methyl ester (+3.85%), methyl hexadic-9-enoate (+3.11%), methyl linoleate (+2.68%), linalool (+1.83%), and methyl stearate (+1.18%). In vitro activity results revealed that EOFs extracted using EP-ME method not only had certain anti-microorganism activity, but also possessed good cholinesterase inhibition activity, and its semi-inhibition concentrations (IC50) against acetyl-cholinesterase and butyrylcholinesterase were 2.48 and 2.31 mg/mL, respectively. Therefore, the EP-ME method was a kind of green and effective method for extracting high-quality essential oils from Dolichos lablab flowers.

Usnic Acid Derivatives as Multi-Target Anti-Alzheimer's Disease Agents: Design, Synthesis, X-Ray Single Crystal Structure of Zn(II) Complex and Biological Activities.

Alzheimer's disease (AD) is multifactorial, which makes the design of multi-target-directed ligands an attractive strategy for the development of anti-AD drugs. In order to enhance the anti-AD effects and reduce the toxicity, two usnic acid (UA) derivatives (1-2) were designed, synthesized and fully characterized by introducing dimethylamine Schiff base moiety into the toxic "triketone" portion. Ellman's method and molecular docking were used to test the cholinesterase inhibitory activities. Antioxidant activities were studied with Fenton reaction, cyclic voltammetry and C. elegans. The results showed that compared with UA, 1-2 had stronger anti-cholinesterase activities and similar antioxidant activities. Notably, solvent evaporation of 2 and ZnCl2 formed a single crystal, which was revealed to be a Zn(II) complex with UA and tertiary amine as mixed ligands by X-ray diffraction. The hydrolysis of 2 was thus furtherly studied by HPLC. Furthermore, the crystal structure supported the replacement of toxic "triketone" moiety in the chelation process, playing a detoxifying role and at the same time regulating metal homeostasis. In silico prediction also showed low hepatotoxicity and acceptable drug-likeness of 1-2. Overall, this work provided useful insights into multi-target anti-AD candidates with the natural product UA as the lead compound.

Evaluation of Anti-Alzheimer's Potential of Azo-Stilbene-Thioflavin-T derived Multifunctional Molecules: Synthesis, Metal and Aβ Species Binding and Cholinesterase Activity.

Inhibition of amyloid β (Aβ) aggregation and cholinesterase activity are two major therapeutic targets for Alzheimer's disease (AD). Multifunctional Molecules (MFMs) specifically designed to address other contributing factors, such as metal ion induced abnormalities, oxidative stress, toxic Ab aggregates etc. are very much required. Several multifunctional molecules have been developed using different molecular scaffolds. Reported herein is a new series of four MFMs based on ThT, Azo-stilbene and metal ion chelating pockets. The synthesis, characterization, and metal chelation ability for [Cu(II) and Zn(II)] are presented herein. Furthermore, we explored their multifunctionality w.r.t. to their (i) recognition of Aβ aggregates and monomeric form, (ii) utility in modulating the aggregation pathways of both metal-free and metal-bound amyloid-β, (iii) ex-vivo staining of amyloid plaques in 5xFAD mice brain sections, (iv) ability to scavenge free radicals and (v) ability to inhibit cholinesterase activity. Molecular docking studies were also performed with Aβ peptides and acetylcholinesterase enzyme to understand the observed inhibitory effect on activity. Overall, the studies presented here establish the multifunctional nature of these molecules and qualify them as promising candidates for furthermore investigation in the quest for finding Alzheimer's disease treatment.

LC-HRMS Profiling of Phytochemicals with Assessment of Antioxidant, Anticholinesterase, and Antimicrobial Potentials of Astragalus brachystachys DC.

This study provides the first comprehensive report on the chemical constituents and biological activities of an important medicinal plant, Astragalus brachystachys DC. The aerial part samples were collected from Adana, Türkiye, and an ethanol extract was prepared with these parts. The secondary metabolites of the extract were determined by an LC-HRMS analysis. The LC-HRMS analysis showed the presence of 39 different constituents, hyperoside (303.419±10.50 μg/g extract), p-coumaric acid (256.975±8.51 μg/g extract), and rutin (72.684±2.23 μg/g extract) were determined as major compounds in the aerial parts ethanol extract. Attributed to its high total phenolic (58.53±1.30 μg PEs/mg extract) and total flavonoid content (29.98±0.83 μg QEs/mg extract), the extract demonstrated strong antioxidant activity according to three different assays namely DPPH free (IC50: 33.08±0.61 mg/mL), and ABTS cation radical scavenging (IC50: 15.39±0.72 mg/mL) and CUPRAC activity (A0.5: 36.25±0.28 mg/mL) methods. In vitro assays showed that cholinesterase inhibitory activity results were found to be exceptional with 85.95±0.52 % inhibition on acetylcholinesterase and 66.32±1.33 % inhibition on butyrylcholinesterase at 200 mg/mL. Regarding antimicrobial properties, Astragalus brachystachys DC extract was found to be effective against Enterococcus faecalis with a MIC value of 39.06 μg/mL.

Biomarker responses in fish caged in a rice field during a bifenthrin application

The use of pesticides in integrated rice-fish farming could have an impact on fish health. The present study aimed to evaluate, for the first time, the biological effects of the insecticide bifenthrin on fish (Piaractus mesopotamicus and Hoplosternum littorale) using a caging experiment. Fish were divided into two sites: control (C) and bifenthrin exposure (BF). Two cages (n = 8 fish/cage) per species were placed separately at each site. The BF application (Seizer ®) was carried out with a coastal sprayer according to the BF recommended dose for rice cultivation (0.1 L/ha). After 72 hours, fish were collected, and gills, liver, brain, and muscle were dissected for the analysis of biomarkers of accumulation, oxidative stress, and neurotoxicity. In P. mesopotamicus, the main changes were observed in the muscle, where BF accumulated and induced neurotoxicity (inhibition of cholinesterase activity) and oxidative stress (activation of antioxidant enzymes, decreased glutathione levels, increased lipid peroxidation). The gills and liver also showed changes in some markers of the antioxidant system. In H. littorale, BF exposure induced changes in oxidative stress biomarkers in liver (activation of antioxidant enzymes and lipid peroxidation) and gill tissues (alteration in antioxidant markers). These results show that the use of bifenthrin in rice fields poses a risk to fish farming under current pesticide management practices. Furthermore, its use could affect other species in these agroecosystems, highlighting the need for further studies to assess the ecological and productive consequences in a context of increasing pyrethroid use worldwide.

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

Design, Synthesis, and Invitro Pharmacological Evaluation of Novel Resveratrol Surrogate Molecules against Alzheimer's Disease.

A series of resveratrol surrogate molecules were designed, synthesized and biologically evaluated for inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) along with anti-oxidant activity as potential novel multifunctional agents against Alzheimer's disease (AD). Six novel compounds were synthesized by reacting (E)-4-(3,5-Dimethoxystyryl) aniline with benzaldehyde and some selected derivatives of benzaldehyde in the presence of ethanol and a few drops of glacial acetic acid which followed the general scheme involved in the formation of Schiff bases. The spectral analysis data including FT-IR, 1H-NMR, 13C-NMR, and Mass spectroscopy results were found to be in good agreement with the newly synthesized compounds (Resveratrol Surrogate Molecules 1-6). The synthesized compounds were evaluated for their dual cholinesterase inhibitory activities, cytotoxic effect, and anti-oxidant potential. The results showed that compound RSM5 showed potent inhibitory activity against AChE and BChE. In, addition the cytotoxicity of the compound RSM5 is less and found to be within the desirable limit indicating the potential safety of RSM5. Also, it possesses substantial anti-oxidant activity which qualifies RSM5 as an anti-AD agent. Taken together, these findings demonstrate that the molecule RSM5 had the most multifunctional properties and could be a promising lead molecule for the future development of drugs for Alzheimer's treatments.

Chemical Composition, Cholinesterase Inhibitory Effect and Cytotoxic Activity Study of Essential Oils Extracted from Different Parts of Satureja isophylla Rech.f

Background: Based on available literature, no study has yet considered the phytochemical profile and pharmacological activities of essential oils extracted from different parts of Satureja isophylla. Objectives: This study aimed to investigate the chemical composition, cholinesterase (ChE) inhibitory effects, and cytotoxic activities of essential oils extracted from different parts of Satureja isophylla. Methods: Essential oils extracted from the flowers, leaves, stems, and roots of Satureja isophylla, which is endemic to Iran, were separately analyzed using GC-MS. The ChE inhibitory activities of these extracts were tested on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The growth-inhibitory effects of the extracts were assessed against four cancer cell lines: MCF-7, ACHN, AsPC-1, and PC-12. Results: GC-MS analysis identified a total of 51 compounds from different parts of the plant, with α-eudesmol, camphor, elemol, and γ-eudesmol being the main components. The ChE inhibitory activity results indicated significant inhibition of BChE compared to AChE. The essential oils exhibited greater toxicity against AsPC-1 cells compared to other cancer cell lines in the MTT assay. Conclusions: This study is the first to examine the chemical composition and therapeutic effects of essential oils extracted from various parts of Satureja isophylla. Further research is needed to explore additional pharmacological activities and to provide a more comprehensive phytochemical profile of this plant.

Cholinesterase Inhibitory Activity and Molecular Docking Studies of Isocryptolepine-Triazole Adducts.

Due to the rising prevalence of Alzheimer's disease (AD), there is a pressing need for more effective drugs to treat or manage AD's symptoms. Studies have shown that cholinesterase inhibition can improve cognitive and behavioral symptoms associated with AD, by addressing the cholinergic deficit. Based on the recent development of cholinesterase inhibitors with indoloquinoline and triazole moiety, we rationalized that compounds with an isocryptolepine-triazole scaffold may also have the same biological targets. In this study, eighteen previously synthesized isocryptolepine-triazole compounds were assessed for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholine esterase (BChE). The majority of these compounds demonstrated potent selective AChE inhibition. Furthermore, our molecular docking and molecular dynamic simulation studies reveal that the isocryptolepine and triazole moieties are important for the binding of the compounds with the periphery of the AChE's binding pocket. While reductions in molecular weights and lipophilicities may be necessary to improve their pharmacokinetic properties, this work provides valuable insights for designing future AChE inhibitors, based on the novel isocryptolepine-triazole scaffold.

Design, synthesis and anti-Alzheimer's disease activity evaluation of C-3 arylated huperzine A derivatives

A series of C-3 arylated huperzine A (HPA) derivatives (1−30) were designed and synthesized in good yields via palladium-catalyzed Suzuki cross-coupling reaction. Cholinesterase inhibitory and neuroprotective activities of all 30 derivatives were evaluated. Cholinesterase inhibition results revealed that derivatives 2 and 15 exhibited dual inhibitory activity against both acetylcholinesterase (AChE inhibition: 2, IC50 = 1.205 ± 0.395 μM; 15, IC50 = 0.225 ± 0.062 μM) and butyrylcholinesterase (BChE inhibition: 2, IC50 = 8.598 ± 3.605 μM; 15, IC50 = 4.013 ± 0.068 μM), a feature not observed in huperzine A. Molecular docking results indicated that the introduction of aryl groups enhanced the affinity of the derivatives for the acyl-binding pocket of BChE, thereby limiting the hydrolysis of acetyl choline. However, these derivatives exhibited poor performance in cytotoxicity and neuroprotection assays.

Chiral thioureas containing naphthalene moiety as selective butyrylcholinesterase inhibitors: Design, synthesis, cholinesterase inhibition activity and molecular docking studies

Butyrylcholinesterase (BChE), which plays a role in the regulation of acetylcholine (ACh) as well as cholinergic type neurotransmission, also has non-cholinergic functions such as differentiation, proliferation and apoptosis. The strategy of increasing ACh levels without the typical undesirable effects of AChE inhibitors used in treatment with selective inhibition of BChE may be an effective approach to delay the progression of Alzheimer's disease (AD). Based on this approach, twenty derivatives of chiral thioureas containing the naphthalene moiety (1a-10a and 1b-10b) in both enantiomeric forms were designed, synthesized with good yields (up to 90 %), in this study. Also, their AChE and BChE inhibition activities and antioxidant profiles were tested. All chiral thioureas except compound 5b showed excellent inhibitory activity against BChE but lower inhibitory activity against AChE compared to galantamine. The activity results on BChE revealed that compound 1b (S-enantiomer) had the strongest inhibitory effect on BChE (IC50 = 10.18 ± 1.02 μM) with a selectivity index of 7.27 among all compounds. In terms of antioxidant activity, compound 7a (R-isomer) exhibited the overall highest antioxidant profile in the series of chiral thioureas. Molecular docking studies were used to reveal the interactions of the most active compounds with target enzymes. Besides, an estimation of the drug-likeness and pharmacokinetic properties of all chiral thioureas was performed.

Study of multifunctional anti-AD ligands: design, synthesis, X-ray crystal structure and biological evaluation of diosmetin derivatives.

The development of anti-AD drugs has attracted much attention as the number of AD patients is increasing year by year. Five diosmetin derivatives (1-5) were designed and synthesized by introducing carbamate groups. The crystal structure of 1 was analyzed by X-ray diffraction, which showed a large conjugated coplanar structure and might be favorable for the insertion into the Aβ folding. Meanwhile, in vitro experiments were carried out to investigate the anticholinesterase activity, metal chelating property, antioxidant activity, and anti-Aβ aggregation ability of 1-5. The results showed that 1-5 had good cholinesterase inhibitory activities. Compound 4 showed the highest inhibitory activities against butyrylcholinesterase (IC50 = 0.0760μM). Further kinetic experiments and molecular docking studies showed that 4 could bind well to butyrylcholinesterase. The molecular dynamics simulations also signified that compared with diosmetin, 4 could reduce the flexibility of the butyrylcholinesterase protein skeleton to a greater extent, and thus had a better inhibitory effect. In addition, 1-5 could selectively chelate copper ions and all of them had good antioxidant activity as well as anti-Aβ aggregation ability. Among them, 4 had the strongest activity to inhibit Cu2+-induced Aβ aggregation (51.09%) and had low cytotoxicity. In addition, in vivo ROS activity assay (Caenorhabditis elegans) showed that 4 had the ability to scavenge ROS. Besides, the in vivo Aβ aggregation assay showed that 4 could reduce Aβ aggregation. In conclusion, 4 has the potential to be developed into a multifunctional anti-AD drug.

Neuroprotective and Mental Health Benefits of Salt-Tolerant Plants: A Comprehensive Review of Traditional Uses and Biological Properties

This study undertakes a thorough review of the ethnomedicinal properties of salt-tolerant plants and their potential to treat neurological disorders and enhance mental health. Aimed at bridging the gap between historical knowledge and contemporary scientific validation, our research meticulously evaluates both the traditional uses and the existing scientific evidence supporting the neuroprotective effects of these plants, leveraging in vitro and in vivo experimental findings. Through a comprehensive search of articles from 2001 to December 2023 across scientific databases, we identified sixteen species across nine plant families with demonstrated in vitro neuroprotective properties. Among these, the Chenopodiaceae and Juncaceae families emerged as the most represented, including plants such as Salicornia sp., Juncus sp., and Limonium sp., primarily recognized for their cholinesterase inhibitory activity. However, a notable disparity exists between traditional applications and scientific examination, with only six species undergoing in vivo testing. This discrepancy underscores the imperative for future research to delve deeper into validating traditional uses and elucidating the mechanisms underlying neuroprotection. Our findings highlight the need for research on salt-tolerant plants traditionally used for neurological benefits. Key steps include systematic screening, identification of active compounds through bioassay-guided fractionation, and in vivo testing. Integrating traditional knowledge with modern pharmacology, while emphasizing sustainable and ethical approaches, is essential for advancing neuroprotective drug discovery.

Design, synthesis and biological evaluation of 1-aryldonepezil analogues as anti-Alzheimer's disease agents.

Aim: To design and synthesize a novel series of 1-aryldonepezil analogues. Materials & methods: The 1-aryldonepezil analogues were synthesized through palladium/PCy3-catalyzed Suzuki reaction and were evaluated for cholinesterase inhibitory activities and neuroprotective effects. In silico docking of the most effective compound was conducted. Results: The 4-tert-butylphenyl analogue exhibited good inhibitory potency against acetylcholinesterase and butyrylcholinesterase and had a favorable neuroprotective effect on H2O2-induced SH-SY5Y cell injury. Conclusion: The 4-tert-butylphenyl derivative is a promising lead compound for anti-Alzheimer's disease drug development.

Fatty Acid Composition, Antioxidant, and Enzyme Inhibition Activities of Cachrys Crassiloba (Boiss.) Meikle Fruit and Leaf Extracts

The genus Cachrys L. (Apiaceae) is distributed in the Mediterranean region and contains 11 species. C. crassiloba (Boiss.) Meikle is a species that grows in Southwest and Western Anatolia. Considering the literature studies, there were not enough studies on C. crassiloba. In this study, fatty acid composition, total phenol/flavonoid contents, antioxidant and acetyl-butrylcholinesterase, tyrosinase, and α-glucosidase enzyme inhibition activities of n-hexane and ethanol extracts prepared from C. crassiloba fruits and leaves were investigated by spectrophotometric methods at different concentrations. When the results were evaluated, it was found that the hexane extract of C. crassiloba leaf (123.92 ± 4.62 GA mg/g extract) had the highest total phenol content, while the ethanol extract of C. crassiloba fruit (134.38 ± 0.98 QE mg/g extract) had the highest flavonoid content. C. crassiloba hexane and ethanol leaf extracts (IC50= 8.04 ± 1.31 µg/mL; 10.30 ± 3.15 µg/mL) showed good antioxidant activity com-pared to the ascorbic acid (IC50= 14.59 ± 1.96 µg/mL) in DPPH assay. C. crassiloba leaf ethanol extract (IC50= 17.38 ± 5.02 µg/mL) has the highest ABTS scavenging activity. C. crassiloba extracts have mod-erate cholinesterase inhibitory activity. C. crassiloba leaf ethanol extract (IC50= 196.65 ± 1.94 µg/mL) has good tyrosinase enzyme inhibition activity. C. crassiloba leaf hexane extract (36.35% ± 1.13) was found to have significant inhibitory activity against α-glucosidase. In conclusion, besides its antioxidant activity, C. crassiloba may be effective against neurodegenerative diseases and skin disorders such as hyperpigmentation and diabetes mellitus, but further phytochemical analysis studies are required.

New tetrahydro-isoquinoline derivatives as cholinesterase and α-glycosidase inhibitors: Synthesis, characterization, molecular docking & dynamics, ADME prediction, in vitro cytotoxicity and enzyme inhibition studies

In the presented work, it was reported about the synthesis procedure of new isoquinoline derivatives starting from chalcones and acetoacetanilide, a multi-step synthesis pathway yielded four isoquinoline derivatives (5a-d). At the first stage of our research, corresponding cyclohexanone derivatives are synthesized from the Michael addition reaction of chalcones with acetoacetanilide. After that, on the based cyclohexanone derivative was obtained novel isoquinoline derivatives. According to the structures, a plausible reaction mechanism was suggested. The structure of the synthesized compounds was confirmed by NMR spectroscopy method and X-Ray analysis. Additionally, to determine cholinesterase and α-glycosidase inhibition activity compounds 5(a-d) were tested against AChE, BChE and α-Gly as in vitro. In this work, the novel isoquinoline derivatives 5(a-d) demonstrated encouraging inhibitory action against α-glucosidase, as seen by their IC50 values ranging from 9.95 to 19.25 nM. This indicates that they were approximately 1–3 times more active than acarbose (IC50 = 23.07 nM). Also, the molecular docking IFD XP Gscores, dynamics simulations and MM-GBSA ΔG binding free energies of the isoquinoline derivatives on hAChE, hBChE and α-Gly are determined. The molecular dynamics (MD) simulations conducted in this study provided valuable insights into the dynamic behaviors, stabilities, and interaction profiles of ligand–protein complexes involving the R and S isomers of compounds 5c-hAChE, 5c-hBChE, and 5a-αGly. The MD simulations were crucial for understanding the complex stabilities and dynamic mechanisms of the ligand–protein interactions, shedding light on the potential inhibitory roles of these compounds..

In vitro Cholinesterase Inhibitory Activities of Piper betle Stem and their Correlation with In silico Docking Studies of its Phytoconstituents

Background: Worldwide, millions of people are affected by neurodegenerative diseases. Even though treatment may help to reduce some of the mental or physical symptoms connected with neurodegenerative diseases, there is at present no way to slow disease development and no recognized cure. Objective: The current study was carried out to explore the cholinesterase (ChE) inhibitory properties of the stem of Piper betle and correlate them with in silico docking results of its phytoconstituents. Methods: The dried Piper betle stem was used to be extracted with purified water by using the maceration technique. The resultant was assessed for ChE inhibitory activity using Ellman’s method. The inhibitory profile of the aqueous extract of Piper betle (AEPB) stem was compared with rivastigmine, which is a standard cholinesterase inhibitor. The phytoconstituents of AEPB were procured from various literature studies. In silico docking studies were carried out with the help of AutoDock 4.2 software. Results: AEPB considerably inhibited AChE and BuChE with the inhibition constant values of 0.437 ± 0.62 μg/ml and 0.371 ± 0.62 μg/ml, respectively, in a dose-dependent manner. In computational evaluation, the selected phytoconstituents exhibited excellent binding interactions prevailing with cholinesterase targets than the standard rivastigmine. Conclusion: Based on the in vitro and in silico evaluations, Piperol A showed notable concentrationdependent inhibition of AChE and BuChE. These in vitro analyses and molecular docking studies will be helpful for the development of potent ChE inhibitors for the management of Alzheimer’s disease.

Lycopodium alkaloids from Huperzia serrata and their cholinesterase inhibitory activities

Huperzia serrata, belonging to the Lycopodiaceae family, has been traditionally utilized for the management of treating rheumatic numbness, arthritic pain, dysmenorrhea, and contusions. This plant is a rich source of lycopodium alkaloids, some of which have demonstrated notable cholinesterase inhibitory activity. The objective of this study was to identify lycopodium alkaloids with cholinesterase inhibitory properties from H. serrata. The structures of these alkaloids were elucidated by HRESIMS, NMR (including a 1H–15N HMBC experiment), ECD methods and single-crystal X-ray diffraction. The inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were assessed using a modified Ellman's method. Consequently, sixteen lycopodium alkaloids (1–16), including ten previously undescribed ones named huperradines A–G and huperradines I–K (1–7 and 9–11), along with one previously undescribed naturally occurring compound, huperradine H (8), were isolated from H. serrata. Among these, compounds 7 and 1 exhibited potent and moderate AChE inhibition, with IC50 values of 0.876 ± 0.039 μM and 13.125 ± 0.521 μM, respectively. Our results suggest that huperradine G (7) may be a promising lead compound for the development of new AChE inhibitors for Alzheimer's disease.

Development of novel 9H-carbazole-4H-chromene hybrids as dual cholinesterase inhibitors for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disease affecting mental ability and neurocognitive functions. Cholinesterase enzymes affect concentration of acetylcholine in the brain, leading to dementia. Thus, there is an urgent need to develop novel dual cholinesterase inhibitors as possible anti-AD drugs. Herein, we have designed and synthesized a novel series of 9H-carbazole-4H-chromenes 4(a-l) through a one-pot three-component reaction of salicylaldehydes (1), hydroxycarbazole (2) and N-methyl-1-(methylthio)-2-nitroethenamine (3) using triethylamine as a catalyst in ethanol. Synthetic transformation involves the formation of two C-C bonds and one C-O bond in a single step to obtain desired analogs. The rapid one-pot reaction does not require chromatographic purification, proceeds under mild conditions, and exhibits good tolerance toward various functional groups with high synthetic yields. Synthesized compounds were screened for cytotoxicity using MTT assay in BV-2 microglial cells. These compounds were then in-vitro screened against acetylcholinesterase (AChE) and butyrylcholinestrase (BuChE) enzymes. Most of these ligands have shown dual cholinesterase inhibitory activity compared to the standard drug. In-vitro results showed that the compounds 4a and 4d have promising anticholinesterase response against both cholinesterase enzymes (4a, AChE IC50: 5.76µM, BuChE IC50: 48.98µM; 4d, AChE IC50: 3.58µM, BuChE IC50: 42.73µM). In-vitro results were validated by molecular docking and dynamic simulation at 100ns. Molecular docking and molecular dynamics simulation study strongly supported structural features present in these analogs. Together, these analogs could be exploited to develop dual anti-cholinesterase candidates to treat AD in combination with other drugs.

Lathyrane and premyrsinane Euphorbia diterpenes against Alzheimer's disease: Bioinspired synthesis, anti-cholinesterase and neuroprotection bioactivity

The first systematic acylated diversification of naturally scarce premyrsinane diterpenes, together with their biosynthetic precursors lathyrane diterpene were carried out. Two new series of premyrsinane derivates (1a-32a) and lathyrane derivates (1–32) were synthesized from the naturally abundant lathyrane diterpene Euphorbia factor L3 through a bioinspired approach. The cholinesterase inhibitory and neuroprotective activities of these diterpenes were investigated to explore potential anti-Alzheimer's disease (AD) bioactive lead compounds. In general, the lathyrane diterpenes showed the better acetylcholinesterase (AChE) inhibitory activity than that of premyrsinanes. The lathyrane derivative 17 bearing a 3-dimethylaminobenzoyl moiety showed the best AChE inhibition effect with the IC50 value of 7.1 μM. Molecular docking demonstrated that 17 could bond with AChE well (−8 kal/mol). On the other hand, premyrsinanes showed a better neuroprotection profile against H2O2-induced injury in SH-SY5Y cells. Among them, the premyrsinane diterpene 16a had significant neuroprotective effect with the cell viability rate of 113.5 % at 12.5 μM (the model group with 51.2 %). The immunofluorescence, western blot and reactive oxygen species (ROS) analysis were conducted to demonstrate the mechanism of 16a. Furthermore, a preliminary SAR analysis of the two categories of diterpenes was performed to provide the insights for anti-AD drug development.