Chemical constituents of the trunk bark of Pyrularia edulis (Cervantesiaceae) and their acetylcholinesterase inhibitory activity assessed through in vitro and in silico approaches

Carbamate derivatives of N-propargylaminoindans (Series I) and N-propargylphenethylamines (Series II) were synthesized via multistep procedures from the corresponding hydroxy precursors. The respective rasagiline- and selegiline-related series were designed to combine inhibitory activities of both acetylcholine esterase (AChE) and monoamine oxidase (MAO) by virtue of their carbamoyl and propargylamine pharmacophores. Each compound was tested for these activities in vitro in order to find molecules with similar potencies against each enzyme. Compounds with such dual AChE and MAO inhibitory activities are expected to have potential for the treatment of Alzheimer's disease. The observed SAR also offers insight into the requirements of the active sites on these enzymes. A carbamate moiety was found to be essential for AChE inhibition, which was absent in the corresponding hydroxy precursors. The propargyl group caused 2-70-fold decrease in AChE inhibitory activity (depending on the position of the carbamoyl group) of Series I, but had little or no effect in Series II. Thus, the 6- and 7-carbamyloxyphenyls in Series I were either equipotent to, or slightly (2- to 5-fold) less active as AChE inhibitors than, the corresponding compounds in Series II, while the 4-carbamyloxyphenyls were more potent. The presence of the carbamate moiety in 6- and 7-carbamyloxyphenyls of Series I, considerably decreased MAO-A and -B inhibitory activity, compared to that of the parent hydroxy analogues, while the opposite was true for Series II. Thus, the 6- and 7-carbamyloxyphenyls in Series I were 2-3 orders of magnitude weaker MAO inhibitors while the 4- carbamyloxyphenyls were equipotent with the corresponding compounds in Series II. In both series, N-methylation of the propargylamine enhanced the MAO (A and B equally) inhibitory activities and decreased the AChE inhibitory activity. Two candidates belonging to the indan and tetralin ring systems (24c, 27b) and one phenethylamine (53d) were identified as possible leads for further development based on the following criteria: (a) comparable AChE and MAO-B inhibitory activities, (b) good to moderate AChE inhibitory activity, and (c) lack of strong MAO-A selectivity. However, it is likely that these compounds will be metabolized to the corresponding phenols, with inhibitory activities against AChE and/or MAO-A or -B, different from those of the parent carbamates. Thus, the apparent enzyme inhibition will be a result of the combined inhibition of all of these individual metabolites. The results of our ongoing in vivo screening programs will be published elsewhere.

The phytochemicals in the leaves of Cotoneaster mongolica Pojark, as well as their antioxidant and acetylcholinesterase (AChE) inhibitory activity were studied. The methanol extract of the leaves showed acetylcholinesterase inhibitory activity (IC50, 32.61 ± 0.51 μg/mL). The n-butanol fraction of this extract exhibited DPPH radical scavenging (IC50, 55.70 ± 0.15 μg/mL) and AChE inhibitory activity (IC50, 72.50 ± 0.60 μg/mL). From the n-butanol fraction quercetin (1), hyperoside (2), kaempferol-5-O-β-D-glucopyranoside (3), sissotrin (4), ursolic acid (5), corosolic acid (6), euscaphic acid (7), prunasin (8), (2R)-mandeloyl-β-D-glucopyranose (9), (Z)-3-hexenyl-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside (10), benzyl-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside (11) and arbutin (12) have been isolated and identified. Hyperoside, one of the major constituents among the isolated compounds, was active in both tested assays. Flavonol derivatives could provide the activity of this plant species.

ABSTRACT: Alzheimer’s disease is a progressive neurodegenerative disorder of the central nervous system. Acetylcholinesterase inhibition is one of the proposed mechanisms for treatment of Alzheimer’s disease. Currently, acetylcholinesterase inhibitors such as tacrine, donepezil, rivastigmine and galantamine are applied in different stages of Alzheimer’s disease teratment. In recent years, various heterocyclic systems have been used as a skeleton to discover new acetylcholinesterase inhibitors. On the other hand, it is known that the benzoxazolone heterocyclic structure exhibited a wide range of biological activities. In this study, a series N-substituted-5-chloro-2(3H)-benzoxazolone derivatives were synthesized and evaluated their acetylcholinesterase inhibitory activity. These compounds were synthesized by Mannich reaction of 5-chloro-2(3H)-benzoxazolone with the appropriated amines. The acetylcholinesterase inhibitory activity of the title compounds was determined by colorimetric Ellman’s method. The preliminary screening results indicated that 5-chloro-2-(3H)- benzoxazolone scaffold demonstrated different inhibition range against acetylcholinesterase enzyme depending on the structural differences. KEY WORDS: acetylcholinesterase Inhibitory activity, 2(3H)-benzoxazolone, mannich reaction, Ellman’s method, synthesis.

Lycopodium clavatum is used in traditional medicine to treat conditions such as rheumatism, digestive disorders, and skin diseases. As part of our ongoing research on bioactive compounds from Vietnamese medicinal plants, phytochemical investigations of whole plants led to the isolation of five compounds (1–5). Using advanced analytical techniques, including electrospray ionization mass spectrometry (ESI-MS) and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy, the structures of these compounds were successfully elucidated as 21-epi-serratenediol (1), serratenediol (2), tohogenol (3), methyl ferulate (4), and methyl p-coumarate (5). The in vitro acetylcholinesterase (AChE) inhibitory activities of these compounds were evaluated, revealing that compound 3 exhibited an IC50 value of 8.3 ± 0.6 μM, which is comparable to that of the positive control, tacrine (IC50 = 2.5 ± 0.2 μM). Additionally, compounds 4 and 5 exhibited potent antioxidant activity in the DPPH assay, comparable to those of L-ascorbic acid (vitamin C). The results suggest that triterpenoids from L. clavatum are responsible for the AChE inhibitory activities, while caffeic acid derivatives contribute to the antioxidant activity. This study represents the first investigation into the chemical constituents, antioxidant properties, and AChE inhibitory effects of L. clavatum collected in Vietnam.

In this study, the fermentation of Artemisia capillaris by probiotic Leuconostoc mesenteroides MKJW (MKJW) was optimized to increase the acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory and antioxidant activities using the response surface method (RSM). The independent variables were the contents of A. capillaris, Gryllus bimaculatus, and yeast extract, while the dependent variables were AChE inhibitory activity, BuChE inhibitory activity, and antioxidant activities such as FRAP, reducing power, and DPPH radical scavenging ability. Seventeen experimental runs were designed with RSM and analyzed after fermentation with MKJW. Quadratic models were used to analyze the inhibition of AChE and BuChE, and a linear model was used to analyze the FRAP. The three models were significantly appropriate (p < 0.0001). The highest optimal condition of the AChE inhibitory activity was derived by a multiple regression equation. When the optimum fermentation conditions were A. capillaris 6.75%, G. bimaculatus 0.18%, and yeast extract 1.27%, 91.1% was reached for AChE inhibitory, 74.0% for BuChE inhibitory, and 34.1 mM FeSO4 for FRAP. The predicted dependent variables were not significantly different from the experimental values (p > 0.05). In conclusion, the A. capillaris fermented by MKJW might be used as a natural antidementia improving agent with AChE inhibitory, BuChE inhibitory, and antioxidant activities.

The aim of this study was to investigate chemical constituents of the leaves of Acanthopanax henryi, and their antioxidant, acetyl cholinesterase inhibitory activities. Caffeoyl quinic acid derivates and flavonoids were obtained from A. henry, through column chromatography technologies, and the content of major constituents was determined by the HPLC-UV method. Anti-oxidant activity of the isolated metabolites was evaluated by free radical scavenging (DPPH, ABTS radicals) and superoxide anion scavenging. The results showed that di-caffeoyl quinic acid derivates had stronger antioxidant activity than positive controls (ascorbic acid, trolox and allopurinol). Acetyl cholinesterase inhibitory activity was estimated on the constituents, among which, quercetin, 4-caffeoyl-quinic acid and 4,5-caffeoyl quinic acid were found to have strong acetyl cholinesterase inhibitory activity with IC50 values ranging from 62.6 to 121.9 μM. The present study showed that some of the tested constituents from the leaves of A. henryi exhibit strong antioxidant and acetyl cholinesterase inhibitory effects. This suggest that the leaves of A. henryi can be used as a new natural complementary source of acetyl cholinesterase inhibitors and anti-oxidant agents, thus being a promising potential complementary source against Alzheimer's disease.

Commercially available essential oils extracted from Artemisia dracunculus L., Inula graveolens L., Lavandula officinalis Chaix, and Ocimum sanctum L. and the components of these oils were screened by the microplate assay method for determining their acetylcholinesterase (AChE) inhibitory activity. The composition profiles of the oils were characterized by gas chromatography-mass spectrometry (GC-MS) analysis, and the relationships between the oil components and the AChE inhibitory activity of the oils were outlined. The results showed that all of the oils, except that of A. dracunculus from Hungary, exhibited AChE inhibitory activity, and the A. dracunculus oil from France showed the most potent inhibitory activity [50% inhibition concentration (IC(50)) = 0.058 mg/mL]. The AChE inhibitory activity of I. graveolens oil has not been reported to date, and this study is the first to reveal this activity in the oil. Among the essential oil components, five components, namely, 1,8-cineole, α-pinene, eugenol, α-terpineol, and terpinen-4-ol, showed AChE inhibitory activity, with IC(50) values of 0.015, 0.022, 0.48, 1.3, and 3.2 mg/mL, respectively. Eugenol, in particular, was found to be a potent AChE inhibitor along with determination of the IC(50) value, a finding that has been reported for the first time in this study. However, the ratio of the contribution of the active components, including a novel AChE inhibitor, to the observed AChE inhibitory activity of the essential oils was not very high. The results of this study raise concerns about the AChE inhibitory activity of widely produced and readily accessible commercial essential oils.

Alzheimer’s disease (AD) is a neurodegenerative disease and the most cause of dementia in elderly adults. Acetylcholinesterase (AChE) is an important beneficial target for AD to control cholinergic signaling deficit. Centella asiatica (CA) has proven to be rich with active ingredients for memory enhancement. In the present study, the chemical profiling of three accession extracts of CA namely SECA-K017, SECA-K018, and, SECA-K019 were performed using high-performance liquid chromatography (HPLC). Four biomarker triterpene compounds were detected in all CA accessions. Quantitative analysis reveals that madecassoside was the highest triterpene in all the CA accessions. The biomarker compounds and the ethanolic extracts of three accessions were investigated for their acetylcholinesterase (AChE) inhibitory activity using Ellman’s spectrophotometer method. The inhibitory activity of the triterpenes and accession extracts was compared with the standard AChE inhibitor eserine. The results from the in vitro study showed that the triterpene compounds exhibited an AChE inhibitory activity with the half-maximal inhibitory concentration (IC50) values between 15.05 ± 0.05 and 59.13 ± 0.18 µg/mL. Asiatic acid was found to possess strong AChE inhibitory activity followed by madecassic acid. Among the CA accession extracts, SECA-K017 and SECA-K018 demonstrated a moderate AChE inhibitory activity with an IC50 value of 481.5 ± 0.13 and 763.5 ± 0.16 µg/mL, respectively from the in silico docking studies, it is observed that asiatic acid and madecassic acid showed very good interactions with the active sites and fulfilled docking parameters against AChE. The present study suggested that asiatic acid and madecassic acid in the CA accessions could be responsible for the AChE inhibitory action and could be used as markers to guide further studies on CA as potential natural products for the treatment of AD.

Homalomena aromatica Schott is a valuable medicinal aromatic plant having wide range of applications in ethnobotany, pharmacology, perfumery and flavor industry. Traditionally, various part of H. aromatica such as leaves and rhizomes were applied to treat joint pain, skin diseases, colds, asthma, diarrhea, and jaundice. Whole herbs extracts are used to address muscle weakness, rheumatism, and allergies, purify the blood, treat deafness, and promote wound healing, especially in postpartum women. The present study is subjected to assess anti-inflammatory, anti-diabetic, tyrosinase inhibitory, acetylcholinesterase (AChE), antimicrobial, and genotoxic efficacies of H. aromatica rhizome essential oil (HAEO). To validate the findings of biological assays, in silico methods including Prediction of Activity Spectra for Substances (PASS) tool, target prediction, and molecular docking were employed. Using Clevenger apparatus dry rhizome of HAEO was extracted. The chemical profiling was performed using gas chromatography/mass spectrometry (GC/MS) where HAEO yield was 1.09%±0.641% (v/w) with 12 compounds where linalool was identified as major compound (76.29%). Anti-inflammatory activity showed IC50 value for protease inhibitory assay 19.59µL/mL and albumin denaturation assay 32.16µL/mL. The IC50 value for α-amylase inhibitory activity showed 29.84µL/mL, whereas tyrosinase inhibitory activity showed 73.62µL/mL. Acetylcholinesterase inhibitory (AChEase) activity revealed an IC50 value of 38.13µL/mL. Antimicrobial activity showed minimal inhibitory concentration (MIC) values of 10±0.47 and 45±0.47µg/mL against Staphylococcus aureus and Candida albicans. Genotoxicity analysis showed HAEO has moderate toxic effect. In silico results identified six potential targets via Swiss target prediction: (AChE, CYP51, peroxisome proliferator-activated receptor [PPAR], cyclooxygenase-2 [COX-2], and tyrosinase-related protein 1 [TYRP1]). Additionally, molecular docking studies revealed Linalool -7.4kcal/mol, Spathulenol -8.5kcal/mol, aromadendrene oxide-(2) -8.3kcal/mol better docking scores. For the first time, this study reports on anti-diabetic, anti-tyrosinase, acetylcholinesterase inhibitory activities and genotoxicity of HAEO. In silico investigation supports these activities by evaluating binding affinities and interactions between compounds and their respective targets through molecular docking. From the current reports, HAEO can be used for development of natural drugs in near future.

BackgroundThe evaluation of the correlations between antioxidant and anti-acetylcholinesterase activities of methanol leaf extracts of three Nigerian endemic plants, Spondias mombin, Carica papaya and Kalanchoe crenata, was carried out. Their constituent phytochemicals were identified by HPLC–DAD fingerprinting. The antioxidant activity as typified by 2,2-diphenyl-1-picrylhydrazyl (DPPH·), 2,2′-azino-bis-(3-ethylbenthiazoline-6-sulfonic acid (ABTS·+) and nitric oxide (NO) scavenging activities were evaluated. The acetylcholinesterase (AChE) inhibitory activity of the extracts was also determined.ResultsThe extracts contained appreciable amounts of the flavonoids, quercetin and kaempferol. The extracts of Spondias mombin, Carica papaya and Kalanchoe crenata showed concentration-dependent inhibitory activities against DPPH· and ABTS·+ with IC50 of 43.29 ± 0.443 µg/mL, 59.27 ± 0.644 µg/mL and 80.20 ± 0.414 µg/mL; 25.43 ± 0.325 (µg/mL), 39.84 ± 0.163 µg/mL and 59.02 ± 0.376 (µg/mL), respectively. The IC50 for the NO scavenging activities of the Spondias mombin, Carica papaya and Kalanchoe crenata extracts were 41.99 ± 0.217 µg/mL, 50.44 ± 0.281 µg/mL and 60.12 ± 0.512 µg/mL, respectively. The IC50 for the inhibitory effects on AChE was 53.24 ± 0.327 µg/mL, 60.95 ± 0.290 µg/m and 70.5 ± 0.426 µg/mL, respectively. The effectiveness of the plant in all the experimental tests was in the following order: S. mombin > C. papaya > K. crenata. The total flavonoid and total phenolic contents have extremely significant positive correlations with the antioxidant activities and AChE inhibitory activity. The correlation coefficients (r2) of DPPH scavenging activity and NO scavenging activity with the AChE inhibitory activity were 0.8295 µg/mL and 0.7337 µg/mL, respectively (P < 0.0001). The molecular docking and pharmacokinetic analyses on some constituent phytochemicals showed that quercetin, kaempferol, ferulic acid, leucocyanidin, gallic acid and isorhamnetin fulfilled the requirements for an anti-Alzheimer drug.ConclusionsThe results suggest that the plant species provide a significant source of secondary metabolites that can act as natural antioxidants and acetylcholinesterase inhibitors, which will be helpful in the treatment of Alzheimer’s disease.

The aim of this investigation was to see if the crude extract of Sarcococca saligna (Ss.Cr) contains chemicals with gut function inhibitory activity by using in vitro and in vivo assays. Ss.Cr caused a dose-dependent (0.03 - 3 mg/mL) inhibitory effect on K+-induced contractions in rat stomach fundus, guinea-pig ileum and rabbit jejunum preparations. The calcium channel blocking(CCB) activity was confirmed when Ss.Cr caused a rightward shift in the Ca++ dose-response curves. It also potentiated, at lower do-ses (0.001 - 0.03 mg/mL), the contractile effect of a fixed dose of acetylcholine (ACh), similar to physostigmine, and suppressed the effect of ACh at higher doses (0.3 - 1.0 mg/mL). Both Ss.Cr and physostigmine inhibited acetylcholinesterase (AChE), in the in vitro assay, confirming the AChE inhibitory activity. In the in vivo studies, Ss.Cr exhibited antidiarrheal and antisecretory activities against castor oil-induced diarrhea and intestinal fluid accumulation in mice. Characteristic steroidal compounds of the plant (saracocine, saracodine, saracorine and alkaloid-C), exhibited a similar combination of AChE inhibitory and CCB activities. Thus this study provides a sound mechanistic base for some of the traditional uses of the plant in hyperactive gut states, in addition to providing the first evidence for verapamil to possess additional AChE inhibitory activity. Furthermore, these characteristic compounds with dual activity may be good candidates for further studies on their usefulness in Alzheimer's disease.

Nanoparticles are widely used in the biotechnology and biomedicalfield. Green synthetic methods of nanoparticles are a simple and environmentallybenign process that declines the demerits of conventional chemical andphysical methods. The synthesis of semiconductor and metal nanoparticles is a risingdo research part, due to the possible applications in the progress of new technologies.The present research information the synthesis and characterization of zinc oxide nanoparticles (ZnO NPs) using C. Sinensis leaf extract. The findings of these studies show the green synthesized ZnO NPs are effective, safe, and eco-friendly as they arestable and have abundant flower shapes with maximum particles in size ranging from 100 nm indiameter. The synthesized ZnO NPs have been tested against the pathogenic microorganismsand showed an excellent zone of inhibition. DPPH radical scavenging activity of synthesized ZnO NPs expressed DPPH free radicals as a percentage of inhibition andIC50value of 70.37%. Acetylcholine esterase (AChE) inhibitory activity possesses the maximum amount of the synthesized ZnO NPs. Since the results ofthe current work, it was concluded that the synthesized ZnO NPs exhibited significant antibacterial and acetylcholine esterase inhibitory activities. Hence it can beused as a drug with multifunction in treating Alzheimer’s disease (AD).

α-Mangostin has been reported to possess a broad range of pharmacological effects including potent cholinesterase inhibition, but the development of α-mangostin as a potential lead compound is impeded by its toxicity. The present study investigated the impact of simple structural modification of α-mangostin on its cholinesterase inhibitory activities and toxicity toward neuroblastoma and liver cancer cells. The dialkylated derivatives retained good acetylcholinesterase (AChE) inhibitory activities with IC50 values between 4.15 and 6.73 µM, but not butyrylcholinesterase (BChE) inhibitory activities, compared with α-mangostin, a dual inhibitor (IC50 : AChE, 2.48 µM; BChE, 5.87 µM). Dialkylation of α-mangostin produced AChE selective inhibitors that formed hydrophobic interactions at the active site of AChE. Interestingly, all four dialkylated derivatives of α-mangostin showed much lower cytotoxicity, being 6.4- to 9.0-fold and 3.8- to 5.5-fold less toxic than their parent compound on neuroblastoma and liver cancer cells, respectively. Likewise, their selectivity index was higher by 1.9- to 4.4-fold; in particular, A2 and A4 showed improved selectivity index compared with α-mangostin. Taken together, modification of the hydroxyl groups of α-mangostin at positions C-3 and C-6 greatly influenced its BChE inhibitory and cytotoxic but not its AChE inhibitory activities. These dialkylated derivatives are viable candidates for further structural modification and refinement, worthy in the search of new AChE inhibitors with higher safety margins.

Morus alba L. (white mulberry) has been commonly used as a functional food and for medicinal purposes. Hence, the aim of the study was to compare the phenolic profile of white mulberry commercial samples in relation to their antioxidant potential and acetylcholinesterase (AChE) inhibitory activity. It is of interest to determine whether herbal products originating from different commercial sources differ in their phenolic profiles. For this purpose, a simple and rapid high-performance liquid chromatography (HPLC) method was used for the separation and determination of ten major phenolic compounds. Total phenolic (TPC), total flavonoid (TFC), and total phenolic acid contents (TPAC), as well as l(+)-ascorbic acid (ASA) contents, were determined. The antioxidant potential was assessed by DPPH (2,2-diphenyl-1-picrylhydrazyl radical) scavenging activity and ferric-reducing/antioxidant power (FRAP) assay, while the AChE inhibitory activity was determined by the Ellman assay for water extracts. The study revealed that excluding two herbal products containing fruits and a sample containing leaves of white mulberry, yerba mate and lemon, the remaining samples were generally consistent in terms of phenolic composition as well as antioxidant potential and AChE inhibitory activity. This reflects the health-promoting properties of the samples under study. Moreover, the results showed that the water extracts of white mulberry were richer in phenolic compounds and presented higher antioxidant activity than the hydromethanolic extracts. However, the water extracts showed low inhibitory activity against AChE. Moreover, the correlation analysis indicated a high positive relationship between phenolic composition and antioxidant activity in extracts of white mulberry. Overall, the obtained results may be useful in the evaluation of new dietary supplements and food products. The water extracts of white mulberry could be used for antioxidant purposes, while the hydromethanolic extracts could be incorporated in antioxidant formulations.

Two new phenylpropanoids, named (2'R*,3'R*)-2',3'-dihydroxy-4'-methoxy-caffeoyl butyrate (1), 9-acetoxy syringin (2), and a new dihydrostilbene, named (8'R)-4',5-dihydroxy-4,8'-dimethoxy-2-hydroxyethyl diphenylethane (3), together with five analogues (4–8), were isolated from the flower buds of Magnolia biondii Pamp. Their structures were elucidated by extensive spectroscopic analyses and comparison with literature data. The absolute configurations were deduced by comparison of experimental and calculated gauge-independent atomic orbital (GIAO) 1 D NMR data. Moreover, the isolated compounds (1–8) were evaluated in vitro for their acetylcholinesterase (AChE) inhibitory activities.