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.

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.

Neuroprotective evaluation of diospyrin against drug-induced Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease linked to memory impairment. A current investigation was performed to assess the neuroprotective effect of Diospyrin, a novel therapeutic agent, for the curing of Alzheimer's disease. For this purpose, in-vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory assays and antioxidant studies were conducted, whereas in-vivo studies involved different behavioral animal models tests such as elevated plus maze (EPM), morris water maze (MWM) and paddling Y-maze test. Results of the in-vitro analysis showed IC50 values of 95 µg/mL for AChE and 110 µg/mL for BChE as compared to the standard drug donepezil (IC50: 95 & 85 µg/mL, respectively). DPPH antioxidant assay showed a maximum of 72.85% inhibition (IC50: 139.74 µg/mL) of DPPH-free radicals at the highest concentration of 1000 µg/mL as compared to the ascorbic acid (IC50: 13.72 µg/mL). Moreover, the in-vivo analysis revealed that diospyrin treatment demonstrated gradual betterment in memory and enhanced motor functionality. On the other hand, the computational analysis also showed that the diospyrin had exceptional binding affinities for both AChE and BChE enzymes. In the net shell, it may be deduced that our compound diospyrin could be a valuable drug candidate in managing neurodegenerative disorders like AD.

Chemical and Biological Aspects of Different Species of the Genus Clinanthus Herb. (Amaryllidaceae) from South America.

The genus Clinanthus Herb. is found in the Andes Region (South America), mainly in Peru, Ecuador, and Bolivia. These plants belong to the Amaryllidaceae family, specifically the Amaryllidoideae subfamily, which presents an exclusive group of alkaloids known as Amaryllidaceae alkaloids that show important structural diversity and pharmacological properties. It is possible to find some publications in the literature regarding the botanical aspects of Clinanthus species, although there is little information available about their chemical and biological activities. The aim of this work was to obtain the alkaloid profile and the anti-cholinesterase activity of four different samples of Clinanthus collected in South America: Clinanthus sp., Clinanthus incarnatus, and Clinanthus variegatus. The alkaloid extract of each sample was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and their potential against the enzymes acetyl- and butyrylcholinesterase were evaluated. Thirteen alkaloids have been identified among these species, while six unidentified structures have also been detected in these plants. The alkaloid extract of the C. variegatus samples showed the highest structural diversity as well as the best activity against AChE, which was likely due to the presence of the alkaloid sanguinine. The results suggest this genus as a possible interesting new source of Amaryllidaceae alkaloids, which could contribute to the development of new medicines.

A retrospective screening method for carbamate toxicant exposure based on butyrylcholinesterase adducts in human plasma with ultra-high performance liquid chromatography-tandem mass spectrometry.

Carbamate pesticides are extensively used in agriculture for their inhibition to acetylcholinesterase and damages to the insects' neural systems. Because of their toxicity, human poisoning incidents caused by carbamate pesticide exposure have occurred from time to time. What's more, some lethally toxic carbamate toxicants known as carbamate nerve agents (CMNAs) have been supplemented in Schedule 1 of the Annex on Chemicals in the Chemical Weapons Convention (CWC) by Organisation of the Prohibition of Chemical Weapons (OPCW) from 2020. And some other carbamates, like physostigmine, have been used in clinical treatment as anticholinergic drugs and their misuse may also cause damages to the body. Similar to organophosphorus toxicants, carbamate toxicants would react with butyrylcholinesterase (BChE) in plasma when entering the human body, resulting in the BChE adducts, based on which the exposure of carbamate toxicants could be detected retrospectively. In this study, methylcarbamyl nonapeptide and dimethylcarbamyl nonapeptide from pepsin digestion of BChE adducts were identified with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in product ion scan mode. Carbofuran was chosen as the target to establish the detection method of carbamate toxicant exposure based on methylcarbamyl nonapeptide digested from methylcarbamyl BChE. Procainamide-gel affinity purification, pepsin digestion and UHPLC-MS/MS analysis in multiple reaction monitoring (MRM) mode were applied. Under the optimized conditions of sample preparation and UHPLC-MS/MS MRM analysis, the limits of detection (LODs) reached 10.0 ng/mL of plasma exposed to carbofuran with satisfactory specificity. The quantitation approach was established with d3-carbofuran-exposed plasma as the internal standard (IS) and the linearity range was 30.0-1.00 × 103 nmol/L (R2 >0.998) with the accuracy of 95.6%-107% and precision of ≤9% relative standard deviation (RSD). The applicability was also evaluated by N,N-dimethyl-carbamates with the LODs of 30.0 nmol/L for pirimicarb-exposed plasma based on dimethylcarbamyl nonapeptide. Because most of carbamate toxicants has methylcarbamyl or dimethylcarbamyl groups, this approach could be applied on the retrospective screening of carbamate toxicant exposure including CMNAs, carbamate pesticides or carbamate drugs. This study could provide an effective means in the fields of CWC verification, toxicological mechanism investigation and down-selection of potential treatment options.

Chemical composition, cholinesterase, and α-glucosidase inhibitory activity of the essential oils of some Iranian native Salvia species.

BACKGROUND: The plants from Salvia genus contain widely distributed species which have been used in folk medicine as well as pharmaceutical and food industries. METHODS: The chemical composition of 12 native Iranian Salvia species (14 plants) was identified using gas chromatography-mass spectrometry (GC-MS). Also, the inhibitory activity of all essential oils (EOs) was evaluated toward α-glucosidase and two types of cholinesterase (ChE) using spectrophotometric methods. The in vitro α-glucosidase inhibition assay was performed by the determination of p-nitrophenol (pNP) obtained from the enzymatic dissociation of p-nitrophenol-α-D-glucopyranoside (pNPG) as the substrate. In vitro ChE inhibitory assay was conducted based on the modified Ellman's procedure using the measurement of 5-thio-2-nitrobenzoic acid produced from the hydrolysis of thiocholine derivatives as the substrate, in the presence of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). RESULTS: Totally, 139 compounds were detected and caryophyllene oxide and trans-ß-caryophyllene were the most abundant compounds in all EOs. The yield of EOs extracted from the plants were also calculated in the range of 0.06 to 0.96% w/w. Herein, α-glucosidase inhibitory activity of 8 EOs was reported for the first time and among all, S. spinosa L. was found to be the most potent inhibitor (90.5 inhibition at 500 µg/mL). Also, the ChE inhibitory activity of 8 species was reported for the first time and our results showed that the BChE inhibitory effect of all EOs was more potent than that of AChE. The ChE inhibition assay indicated that S. mirzayanii Rech.f. & Esfand. collected from Shiraz was the most potent inhibitor (72.68% and 40.6% at the concentration of 500 µg/mL, toward AChE and BChE, respectively). CONCLUSIONS: It seems that native Salvia species of Iran could be considered in the development of anti-diabetic and anti-Alzheimer's disease supplements.

LC-HRMS Profiling and Phenolic Content, Cholinesterase, and Antioxidant Activities of Terminalia citrina.

Terminalia citrina (T. citrina) belongs to the Combretaceae family and is included in the class of medicinal plants in tropical countries such as Bangladesh, Myanmar, and India. The antioxidant activities of lyophilized water (WTE) and alcohol extracts (ETE) of T. citrina fruits, their phenolic content by LC-HRMS, and their effects on cholinesterases (ChEs; AChE, acetylcholinesterase, and BChE, butyrylcholinesterase) were investigated. Especially ten different analytical methods were applied to determine the antioxidant capacity. Compared with similar studies for natural products in the literature, it was determined that both WTE and ETE exhibited strong antioxidant capacity. Syringe and ellagic acids were higher than other acids in ETE and WTE. IC50 values for ETE and WTE in DPPH radical and ABTS⋅+ scavenging activities were calculated as 1.69-1.68 µg mL-1 and 6.79-5.78 µg mL-1 , respectively. The results of the biological investigations showed that ETE and WTE had an inhibition effect against ChEs, with IC50 values of 94.87 and 130.90 mg mL-1 for AChE and 262.55 and 279.70 mg mL-1 for BChE, respectively. These findings indicate that with the prominence of herbal treatments, T. citrina plant may guide the literature in treating Alzheimer's Disease, preventing oxidative damage, and mitochondrial dysfunction.

Anti-Alzheimer's Activity of Polyphenolic Stilbene-Rich Acetone Fraction of the Oil-Removed Seeds of Passiflora edulis: in Vivo and in Silico Studies.

The stilbene-rich acetone fraction in high yield (6.6 %, PEAS) of Passiflora edulis Sims was prepared and evaluated for neuroprotective activity in murine Alzheimer's disease model induced by aluminum chloride and D-galactose. The phytochemical and HPLC-DAD-MS analysis of the polyphenolic stilbene-rich acetone fraction showed that it contained different stilbenes including trans-piceatannol, scirpusins A-B and cassigarol E. The total phenolic content (TPC) of PEAS was 413.87±1.71 mg GAE eqv/g. The neuroprotective activity of PEAS is typically presented in the Morris water maze-reference Spatial Memory test, where the Alzheimer's mice treated at 100 mg/kg (Alz-ED1) and 200 mg/kg (Alz-ED2) spent less than 47 % and 66 % of the time, respectively, than the Alzheimer's model mice (Alz). Two simple stilbenes, trans-piceatannol and trans-resveratrol, showed selectively inhibitory activity in silico against acetylcholinesterase (AChE). Two stilbene dimers, cassigarol E and scirpusin A, exhibited low nanomolar inhibitory potential against AChE and butyrylcholinesterase (BChE), significantly lower than those of the positive control, donepezil and tacrine. These findings suggest that the stilbenes from P. edulis seeds, particularly the stilbene dimers, warrant further investigation as potential neuroprotective candidates in the prevention of cognitive deficits associated with Alzheimer's disease.

Isolation, In Vitro and In Silico Anti-Alzheimer and Anti-Inflammatory Studies on Phytosteroids from Aerial Parts of Fragaria × ananassa Duch.

Based on the pharmacological importance of different species of fragaria, this research was carried out for the isolation of bioactive compounds from Fragaria × ananassa. Using the conventional gravity column chromatography followed by small analytical column purification, two major components were isolated from the plant materials. The structures of both compounds (1 and 2) were accurately confirmed with GC-MS analysis by comparison of the fragmentation pattern within the library of the instrument. Further, the NMR analysis was also used to supplement the structural evidence. Compound 1 was observed to be 4,22-cholestadien-3-one, while compound 2 was identified as stigmast-4-en-3-one. Both compounds were evaluated for anticholinesterase, COX/LOX inhibitions and antioxidant assays. Compound 1 exhibited the IC50 values of 20.29, 27.35, 10.70, 80.10 and 7.40 µg/mL against acetylcholinesterase, butyrylcholinesterase, COX-2, COX-1 and 5-LOX, respectively. Similarly, the IC50 values of compound 2 against the same targets were 14.51, 10.65, 8.45, 109.40 and 8.71 µg/mL. Similarly, both compounds were less potent in ABTS and DPPH targets with IC50 values in the range of 185.83-369.86 µg/mL. Despite the low potencies of these compounds in antioxidant targets, they can be considered as supplementary targets in Alzheimer and inflammation. The molecular docking studies for the in vitro anti-Alzheimer and anti-inflammatory targets were also performed, which showed excellent binding interactions with the respective target proteins. In conclusion, the isolated phytosteroids from Fragaria × ananassa were evaluated scientifically for anti-Alzheimer and anti-inflammatory activities using in vitro and molecular docking approaches.

Spiroisoxazoline Inhibitors of Acetylcholinesterase from Pseudoceratina verrucosa. Quantitative Chiroptical Analysis of Configurational Heterogeneity, and Total Synthesis of (±)-Methyl Purpuroceratate C.

Examination of the MeOH extract of the sponge, Pseudoceratina cf. verrucosa, Berquist 1995 collected near Ningaloo Reef, Western Australia for selective acetylcholinesterase (AChE) inhibitors, yielded five new bromotyrosine alkaloids, methyl purpuroceratates A and B (1b and 2b), purpuroceratic acid C (3a), and ningalamides A and B (4 and 5). The structures of 1-4 share the dibromo-spirocyclohexadienyl-isoxazoline (SIO) ring system found in purealidin-R, while ketoxime 5 is analogous to ianthelline and purpurealidin I. The planar structures of all five compounds were obtained from analysis of MS, 1D and 2D NMR data, and the absolute configuration of the spiroisoxazoline (SIO) unit was assigned by electronic circular dichroism (ECD) and comparison with standards prepared by total synthesis of methyl purpuroceratate C, (±)-3b. Compound 4 is the most complex SIO described, to date. The configuration of the homoserine module (C) in 4 was ascertained, after acid hydrolysis, by derivatization of an l-tryptophanamide derivative based on Marfey's reagent. Chiral-phase HPLC, with comparison to synthetic standards, revealed that most SIOs isolated from P. cf. verrucosa were configurationally heterogeneous; some, essentially racemic. Chiral-phase HPLC, with UV-ECD detection, is demonstrated as a superlative method for configurational assignment and quantitation of the enantiomeric composition of SIOs. Two SIOs─aerophobin-1 and aplysinamisine II─emerged as selective inhibitors of AChE over butyrylcholinesterase (BuChE, IC50 ratio >10), while aplysamine-2 moderately inhibited both cholinesterases (ChEs, IC50, (AChE) 0.46 µM; IC50, (BuChE) 1.03 µM). SIO alkaloids represent a potential new structural manifold for lead-discovery of new therapeutics for treatment of Alzheimer's disease.

In Vitro and In Silico Evaluation of Cholinesterase Inhibition by Alkaloids Obtained from Branches of Abuta panurensis Eichler.

Alkaloids are natural products known as ethnobotanicals that have attracted increasing attention due to a wide range of their pharmacological properties. In this study, cholinesterase inhibitors were obtained from branches of Abuta panurensis Eichler (Menispermaceae), an endemic species from the Amazonian rainforest. Five alkaloids were isolated, and their structure was elucidated by a combination of 1D and 2D 1H and 13C NMR spectroscopy, HPLC-MS, and high-resolution MS: Lindoldhamine isomer m/z 569.2674 (1), stepharine m/z 298.1461 (2), palmatine m/z 352.1616 (3), 5-N-methylmaytenine m/z 420.2669 (4) and the N-trans-feruloyltyramine m/z 314.1404 (5). The compounds 1, 3, and 5 were isolated from A. panurensis for the first time. Interaction of the above-mentioned alkaloids with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes was investigated in silico by molecular docking and molecular dynamics. The molecules under investigation were able to bind effectively with the active sites of the AChE and BChE enzymes. The compounds 1-4 demonstrated in vitro an inhibitory effect on acetylcholinesterase with IC50 values in the range of 19.55 µM to 61.24 µM. The data obtained in silico corroborate the results of AChE enzyme inhibition.

Towards the Pharmacological Validation and Phytochemical Profiling of the Decoction and Maceration of Bruguiera gymnorhiza (L.) Lam.-A Traditionally Used Medicinal Halophyte.

Decoctions (leaves and roots) of Bruguiera gymnorhiza (L.) Lam. are traditionally used against diabetes in many countries, including Mauritius. This study endeavoured to evaluate the inhibitory potential of leaves, roots, twigs and fruits extracts (decoction and maceration) of B. gymnorhiza against key enzymes relevant to diabetes. Considering complications related to diabetes, other clinical enzymes, namely, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, elastase and pancreatic lipase, were used. Identification of compounds was carried out using ultra-high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS). Antioxidant capacities were assessed using DPPH, ABTS, FRAP, CUPRAC, phosphomolybdenum, metal chelating. The relationship between mode of extraction, plant parts and biological activities was determined using multivariate analysis. Macerated fruits, rich in phytochemicals (phenolic, flavanol, tannin, and triterpenoid), exhibited substantially high antioxidant capacities related to radical scavenging (DPPH: 547.75 ± 10.99 and ABTS: 439.59 ± 19.13 mg TE/g, respectively) and reducing potential (CUPRAC: 956.04 ± 11.90 and FRAP: 577.26 ± 4.55 mg TE/g, respectively). Additionally, the same extract significantly depressed AChE and BChE (3.75 ± 0.03 and 2.19 ± 0.13 mg GALAE/g, respectively), tyrosinase (147.01 ± 0.78 mg KAE/g), elastase (3.14 ± 0.08 mg OE/g) and amylase (1.22 ± 0.01 mmol ACAE/g) enzymatic activities. Phytochemical results confirmed the presence of 119 compounds in all maceration and 163 compounds in all decoction samples. The screening also revealed important compounds in the extracts, namely, quinic acid, brugierol, bruguierol A, epigallocatechin, chlorogenic acid, to name a few. Multivariate analysis reported that the plant parts of B. gymnorhiza greatly influenced the observed biological activities in contrast to the types of extraction methods employed. Docking calculations have supported the findings of the experimental part through the high binding affinity and strong interactions of some compounds against tyrosinase, AChE, BChE and elastase enzymes. The decocted root and leaf of B. gymnorhiza showed low to moderate antidiabetic activity, thereby partially supporting its traditional uses in the management of diabetes. However, the fruit, the most active organ, can be used as a diet supplement to reduce the risk of diabetes complications after evaluating its cytotoxic effects.

Polyphenol Contents, Potential Antioxidant, Anticholinergic and Antidiabetic Properties of Mountain Mint (Cyclotrichium leucotrichum).

In the present work, antioxidant and antidiabetic potentials of mountain mint [Cyclotrichium leu-cotrichum (Stapf ex Rech. Fil.) Leblebici] was the first time appraised. In this sense, methanol (MECL) and water (WECL) extracts were obtained from aerial parts of mountain mint (Cyclotrichium leucotrichum) and studied for their antioxidant ability by several bioanalytical assays. Also, their inhibition profiles were realized toward several metabolic enzymes connected to some diseases, including butyrylcholinesterase (BChE), α-glycosidase, acetylcholinesterase (AChE), and α-amylase enzymes. Additionally, their phenolic contents were determined by putative chromatographic method of LC/MS/MS. Consequently, nineteen phenolic molecules were identified in MECL and fifteen phenolic molecules were found in WECL. Also, antioxidant effects of both extracts were studied using by the methods of 1,1-diphenyl-2-picryl-hydrazyl (DPPH⋅), 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS.+ ) and N,N-dimethyl-p-phenylenediamine (DMPD.+ ) scavenging activities, ferric (Fe3+ ) and cupric (Cu2+ ) ions and Fe3+ -2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) reducing capacities. MECL and WECL were found as powerful DPPH⋅ (IC50 : 23.74 and 28.85 µg/mL), ABTS.+ (IC50 : 12.53 and 14.05 µg/mL) and DMPD.+ scavenging effects (IC50 : 43.52 and 54.80 µg/mL). Also, both extracts demonstrated the effective inhibition on AChE (IC50 : 69.31 and 115.51 µg/mL), BChE (IC50 : 57.75 and 86.62 µg/mL), α-glycosidase (IC50 : 36.47 and 62.94 µg/mL) and α-amylase (IC50 : 1.01 and 3.43 µg/mL). This study will be useful for future studies to determine the antioxidant properties and enzyme inhibition profile of food, medical and industrially important plants.

Chemical constituents and anticholinesterase activity of the essential oil of Algerian Elaeoselinum thapsioides (Desf.) maire.

Elaeoselinum thapsioides (Desf.) Maire (Apiaceae) is an Algerian medicinal plant used in traditional medicine to treat different diseases. The essential oil obtained by hydrodistillation from the aerial parts of Elaeoselinum thapsioides growing wild in Algeria, was analyzed by GC-MS for the first time. Forty-five compounds were detected, accounting for 93.8% of the total oil, which was characterized by a high content of hydrocarbons derivatives of monoterpenes (75.9%). Myrcene (61.0%) was the principal constituent of the essential oil, followed by germacrene D (10.3%), α-pinene (6.5%) and ß-pinene (2.9%). In vitro anticholinesterase activity of the essential oil was investigated by the Ellman method that evidenced a low acetylcholinesterase and butyrylcholinesterase inhibitory effect.[Formula: see text].

Imino-2H-Chromene Based Derivatives as Potential Anti-Alzheimer's Agents: Design, Synthesis, Biological Evaluation and in Silico Study.

A new series of imino-2H-chromene derivatives were rationally designed and synthesized as novel multifunctional agents against Alzheimer's disease. A set of phenylimino-2H-chromenes as well as the newly synthesized iminochromene derivatives were evaluated as BACE1, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) inhibitors. The results indicated that among the iminochromene set, 10c bearing fluorobenzyl moiety was the most potent BACE1 inhibitor with an IC50 value 6.31 µM. In vitro anti-cholinergic activities demonstrated that compound 10a bearing benzyl pendant was the best inhibitor of AChE (% inhibition at 30 µM=24.4) and BuChE (IC50 =3.3 µM). Kinetic analysis of compound 10a against BuChE was also performed and showed a mixed-type inhibition pattern. The neuroprotective assessment revealed that compound 11b, a phenylimino-2H-chromene derivative with hydroxyethyl moiety, provided 32.3 % protection at 25 µM against Aß-induced PC12 neuronal cell damage. In addition, docking and simulation studies of the most potent compounds against BACE1 and BuChE confirmed the experimental results.

Human carboxylesterase 1A plays a predominant role in the hydrolytic activation of remdesivir in humans.

Remdesivir, an intravenous nucleotide prodrug, has been approved for treating COVID-19 in hospitalized adults and pediatric patients. Upon administration, remdesivir can be readily hydrolyzed to form its active form GS-441524, while the cleavage of the carboxylic ester into GS-704277 is the first step for remdesivir activation. This study aims to assign the key enzymes responsible for remdesivir hydrolysis in humans, as well as to investigate the kinetics of remdesivir hydrolysis in various enzyme sources. The results showed that remdesivir could be hydrolyzed to form GS-704277 in human plasma and the microsomes from human liver (HLMs), lung (HLuMs) and kidney (HKMs), while the hydrolytic rate of remdesivir in HLMs was the fastest. Chemical inhibition and reaction phenotyping assays suggested that human carboxylesterase 1 (hCES1A) played a predominant role in remdesivir hydrolysis, while cathepsin A (CTSA), acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) contributed to a lesser extent. Enzymatic kinetic analyses demonstrated that remdesivir hydrolysis in hCES1A (SHUTCM) and HLMs showed similar kinetic plots and much closed Km values to each other. Meanwhile, GS-704277 formation rates were strongly correlated with the CES1A activities in HLM samples from different individual donors. Further investigation revealed that simvastatin (a therapeutic agent for adjuvant treating COVID-19) strongly inhibited remdesivir hydrolysis in both recombinant hCES1A and HLMs. Collectively, our findings reveal that hCES1A plays a predominant role in remdesivir hydrolysis in humans, which are very helpful for predicting inter-individual variability in response to remdesivir and for guiding the rational use of this anti-COVID-19 agent in clinical settings.

Chemical Composition and Biological Activities of Essential Oils from the Leaves, Stems, and Roots of Kadsura coccinea.

The chemical composition and biological activities of the essential oils from the leaves, stems, and roots of Kadsura coccinea (K. coccinea) were investigated. The essential oils were extracted by hydro distillation and analyzed by gas chromatography mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Antioxidant activities of the essential oils were examined with DPPH radical scavenging assay, ABTS cation radical scavenging assay, and ferric reducing antioxidant power assay. Antimicrobial activities were evaluated by determining minimum inhibitory concentrations (MIC) and minimum microbiocidal concentrations (MMC). Acetylcholinesterase and butyrylcholinesterase inhibitory activity of the essential oils were also tested. A total of 46, 44, and 47 components were identified in the leaf, stem, and root oils, representing 95.66%, 97.35%, and 92.72% of total composition, respectively. The major compounds of three essential oils were α-pinene (16.60-42.02%), ß-pinene (10.03-18.82%), camphene (1.56-10.95%), borneol (0.50-7.71%), δ-cadinene (1.52-7.06%), and ß-elemene (1.86-4.45%). The essential oils were found to have weak antioxidant activities and cholinesterase inhibition activities. The essential oils showed more inhibitory effects against Staphylococcus aureus (S. aureus) than those of other strains. The highest antimicrobial activity was observed in the root oil against S. aureus, with MIC of 0.78 mg/mL. Therefore, K. coccinea essential oils might be considered as a natural antibacterial agent against S. aureus with potential application in food and pharmaceutical industries.

Bio-Guided Fractionation of Stem Bark Extracts from Phyllanthus muellarianus: Identification of Phytocomponents with Anti-Cholinesterase Activity.

A combination of flash chromatography, solid phase extraction, high-performance liquid chromatography, and in vitro bioassays was used to isolate phytocomponents endowed with anticholinesterase activity in extract from Phyllanthus muellarianus. Phytocomponents responsible for the anti-cholinesterase activity of subfractions PMF1 and PMF4 were identified and re-assayed to confirm their activity. Magnoflorine was identified as an active phytocomponent from PMF1 while nitidine was isolated from PMF4. Magnoflorine was shown to be a selective inhibitor of human butyrylcholinesterase-hBChE (IC50 = 131 ± 9 µM and IC50 = 1120 ± 83 µM, for hBuChE and human acetylcholinesterase-hAChE, respectively), while nitidine showed comparable inhibitory potencies against both enzymes (IC50 = 6.68 ± 0.13 µM and IC50 = 5.31 ± 0.50 µM, for hBChE and hAChE, respectively). When compared with the commercial anti-Alzheimer drug galanthamine, nitidine was as potent as galanthamine against hAChE and one order of magnitude more potent against hBuChE. Furthermore, nitidine also showed significant, although weak, antiaggregating activity towards amyloid-ß self-aggregation.

In silico, theoretical biointerface analysis and in vitro kinetic analysis of amine compounds interaction with acetylcholinesterase and butyrylcholinesterase.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are considered important target for drug design against Alzheimer's disease. In the present study in silico analysis; theoretical analysis of biointerface between ligand and interacting amino acid residues of proteins; and in vitro analysis of enzyme inhibition kinetics were carried out to delineate the inhibitory property of amine compounds against AChE/BChE. High throughput virtual screening of amine compounds identified three compounds (2-aminoquinoline, 2-aminobenzimidazole and 2-amino-1-methylbenzimidazole) that best interacted with AChE/BChE. Molecular docking analysis revealed the interaction of these compounds in the active site gorge of AChE/BChE, in particular with amino acid residues present in the peripheral anionic site. Molecular dynamics simulation confirmed the stable binding of these compounds with AChE/BChE. Binding energy calculated through MMGBSA method identified the non-covalent interactions (electrostatic and Van der Waals interactions) have contributed to the stable binding of the amine compounds with the AChE/BChE. Biointerface between amine compounds and AChE/BChE were visualized through Hirshfeld surface analysis. The inter-fragment interaction energies for the possible contacts between amine compounds and amino acid residues were carried out for the first time. All the amine compounds showed mixed-type of inhibition with moderate Ki value in in vitro analysis.

Chemical Composition and Anticholinesterase Activity of the Essential Oil of Leaves and Flowers from the Ecuadorian Plant Lepechinia paniculata (Kunth) Epling.

This work aimed to study the chemical composition, cholinesterase inhibitory activity, and enantiomeric analysis of the essential oil from the aerial parts (leaves and flowers) of the plant Lepechinia paniculata (Kunth) Epling from Ecuador. The essential oil (EO) was obtained through steam distillation. The chemical composition of the oil was evaluated by gas chromatography, coupled to mass spectrometry (GC-MS) and a flame ionization detector (GC-FID). The analyses led to the identification of 69 compounds in total, of which 40 were found in the leaves and 29 were found in the flowers of the plant. The major components found in the oil were 1,8-Cineole, ß-Pinene, δ-3-Carene, α-Pinene, (E)-Caryophyllene, Guaiol, and ß-Phellandrene. Flower essential oil showed interesting selective inhibitory activity against both enzymes AChE (28.2 ± 1.8 2 µg/mL) and BuChE (28.8 ± 1.5 µg/mL). By contrast, the EO of the leaves showed moderate mean inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), with IC50 values of 38.2 ± 2.9 µg/mL and 47.4 ± 2.3 µg/mL, respectively.