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• Isoquinoline alkaloids were tested against cholinesterases in vitro and in silico. • N -norgalanthamine is the most active one inhibiting both cholinesterases. • 8-Hydroxy-9-methoxycrinine was a strong inhibitor of AChE. • (+)-9- O -demethylhomolycorine displayed a moderate BChE inhibition. • This is the first report on ChE inhibition by three off the tested alkaloids. All cholinesterase (ChE) inhibitory drugs in clinical use are nitrogenous compounds and among them, galanthamine as the latest anticholinesterase drug, contains a tetrahydroisoquinoline structure. For this reason, isoquinoline alkaloids seem to be attractive in search for novel drug candidates towards Alzheimer's disease (AD). Therefore, in the current work, we investigated inhibitory capacity of several alkaloids representing expanding group of biogenetically-related isoquinoline alkaloids from the Amaryllidaceae including lycorine, (+)-9- O -demethylhomolycorine, 6-hydroxybuphanisine, 9- O -demethoxymontanine, 3- epi- hydroxy-bulbispermine, tazettine, haemanthamine, (+)-haemanthidine, (-)-crinine, 8-hydroxy-9-methoxycrinine, and N -norgalanthamine against ChEs by microtiter enzyme inhibition assays. Our findings indicated that N -norgalanthamine is the most active one inhibiting both acetylcholinesterase (AChE, IC 50 = 2.42 ± 0.16 µg/mL) and butyrylcholinesterase (BChE, IC 50 = 20.87 ± 1.01 µg/mL) at 100 μg/mL, whereas IC 50 values of galanthamine used as the reference were 1.33 ± 0.11 µg/mL and 37.69 ± 2.93 µg/mL for AChE and BChE, respectively. Beside this, 8-hydroxy-9-methoxycrinine was a strong inhibitor of AChE (IC 50 = 6.92 ± 0.51 µg/mL), while (+)-9- O -demethylhomolycorine displayed a moderate BChE inhibition (IC 50 = 83.57 ± 1.36 µg/mL). Relevantly, 8-hydroxy-9-methoxycrinine and N -norgalanthamine were docked into active gorges of hAChE (PDB: 4EY6) and hBChE (PDB: 4TPK), which pointed out the detail that N -norgalanthamine displayed a very similar binding mode of to that of galanthamine. Moreover, both AChE-inhibiting alkaloids were found to stably bind to hAChE active site occupying the middle of the gorge between the catalytic site and the peripheral anionic site. 8-Hydroxy-9-methoxycrinine was also docked into the active site of BChE. We can conclude that among the tested alkaloids, N -norgalanthamine with dual ChE inhibitory effect seems to be the most promising anti-Alzheimer candidate molecule for future experiments. [ABSTRACT FROM AUTHOR]

Berberine is an alkaloid with a wide range of reported beneficial health effects. The current work provides an extensive literature analysis on berberine. Bibliometric data were identified by means of the search string TOPIC=(“berberin*” OR “umbellatine*”), which yielded 5,547 publications indexed in the Web of Science Core Collection electronic database. The VOSviewer software generated bubble maps to visualize semantic terms with citation results. The ratio of original articles to reviews was 13.6:1. The literature has been growing more quickly since the 2010s. Major contributing countries were China, the United States, India, Japan, and South Korea. Most of the publications appeared in journals specialized in pharmacology pharmacy, biochemistry molecular biology, chemistry, and plant science. Some of the frequently mentioned chemicals/chemical classes were alkaloid, palmatine, jatrorrhizine, coptisine, isoquinoline, and sanguinarine. The prevalent medical conditions under investigation included Alzheimer’s disease, cancer, diabetes, and obesity. [ABSTRACT FROM AUTHOR]

Pteryxin is a dihydropyranocoumarin derivative found in Apiaceae family. In this study, pteryxin, which was previously isolated from the fruits of Mutellina purpurea , was investigated for its inhibitory potential against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), which are the key enzymes in the pathology of Alzheimer's disease (AD). The compound was tested in vitro using ELISA microplate reader at 100 μg/ml and found to cause 9.30 ± 1.86% and 91.62 ± 1.53% inhibition against AChE and BChE, respectively. According to our results, pteryxin (IC 50 = 12.96 ± 0.70 μg/ml) was found to be a more active inhibitor of BChE than galanthamine (IC 50 = 22.16 ± 0.91 μg/ml; 81.93± 2.52% of inhibition at 100 μg/ml). Further study on pteryxin using molecular docking experiments revealed different possible binding modes with both polar and hydrophobic interactions inside the binding pocket of BChE. Top docking solution points out to the formation of two hydrogen bonds with the catalytic residues S198 and H438 of BChE as well as a strong π - π stacking with W231. Therefore, pteryxin as a natural coumarin seems to be a strong BChE inhibitor, which could be considered as a lead compound to develop novel BChE inhibitors for AD treatment. [ABSTRACT FROM AUTHOR]

Ethnopharmacology has been an important starting point in medical and pharmaceutical sciences for discovering drug candidates from natural sources. In this regard, the genus Salvia L., commonly known as sage, is one of the best-known medicinal and aromatic plants of the Lamiaceae family; it has been recorded as being used for memory enhancement in European folk medicine. Despite the various uses of sage in folk medicines, the records that have pointed out sage's memory-enhancing properties have paved the way for the aforementioned effect to be proven on scientific grounds. There are many preclinical studies and excellent reviews referring to the favorable effect of different species of sage against the cognitive dysfunction that is related to Alzheimer's disease (AD). Hence, the current review discusses clinical studies that provide evidence for the effect of Salvia species on cognitive dysfunction. Clinical studies have shown that some Salvia species, i.e., hydroalcoholic extracts and essential oils of S. officinalis L. and S. lavandulaefolia leaves in particular, have been the most prominently effective species in patients with mild to moderate AD, and these species have shown positive effects on the memory of young and healthy people. However, the numbers of subjects in the studies were small, and standardized extracts were not used for the most part. Our review points out to the need for longer-term clinical studies with higher numbers of subjects being administered standardized sage preparations. [ABSTRACT FROM AUTHOR]

Abstract: In this study, cholinesterase inhibitory potential relevant to Alzheimer''s disease and antioxidant activities of the dichloromethane, ethyl acetate, and ethanol extracts from the aerial parts and/or roots of fourteen Salvia (sage) species (S. argentea, S. bracteata, S. caespitosa, S. cryptantha, S. glutinosa, S. indica, S. microstegia, S. multicaulis, S. pinnata, S. quezelii, S. syriaca, S. tobeyi, S. verticillata subsp. amasiaca, and S. viscosa) were investigated. Cholinesterase inhibition was determined by Ellman method at 25, 50, and 100μgml−1. Their antioxidant activity was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, metal-chelation capacity, and ferric-reducing antioxidant power (FRAP) assays. Total phenol and flavonoid contents of the extracts were also determined. The dichloromethane and ethanol extracts of the aerial parts of S. cryptantha were the most active ones against AChE (56.22±1.07%) and BChE (33.80±4.18%), respectively. The ethanol extracts exhibited better scavenging activity and FRAP. Anticholinesterase activity of 9 Salvia species (S. argentea, S. bracteata, S. caespitosa, S. indica, S. pinnata, S. quezelii, S. syriaca, S. tobeyi, and S. viscosa) is reported for the first time in the current study. [Copyright &y& Elsevier]

Several extracts of the leaves and fruits of Juglans regia L. were assessed for their neuroprotective effects through antioxidant and anti-cholinesterase methods. Anticholinesterase activity was determined against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the enzymes vital for Alzheimer's disease, at 50, 100 and 200 μg ml− 1. Antioxidant activity was tested using radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), N, N-dimethyl- p-phenylenediamine (DMPD), superoxide (SO), nitric oxide (NO) and hydrogen peroxide (H2O2) radicals, as well as ferric ion-chelating capacity, ferric- and phosphomolybdenum-reducing antioxidant power at 500, 1000 and 2000 μg ml− 1. Total phenol and flavonoid quantification of the extracts was calculated. The extracts scavenged DPPH radical in varying degrees; however, they did not scavenge DPMD and H2O2. Only the dichloromethane and water extracts were able to quench SO (10.09 ± 1.38%) and NO (24.09 ± 2.19%) radicals, respectively, at low level. The extracts showed either low or no BChE inhibition and no AChE inhibition. [ABSTRACT FROM AUTHOR]

Abstract: In vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory and antioxidant activities of the aqueous and ethanol extracts of the leaves, ripe fruits, and unripe fruits of Juniperus communis ssp. nana, Juniperus oxycedrus ssp. oxycedrus, Juniperus sabina, Juniperus foetidissima, and Juniperus excelsa were investigated in the present study. Cholinesterase inhibition of the extracts was screened using ELISA microplate reader. Antioxidant activity of the extracts was tested by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging, ferrous ion-chelating, and ferric-reducing antioxidant power (FRAP) assays. Total phenol and flavonoid contents of the extracts were determined spectrophotometrically. The extracts had low or no inhibition towards AChE, whereas the leaf aqueous extract of J. foetidissima showed the highest BChE inhibition (93.94±0.01%). The leaf extracts usually exerted higher antioxidant activity. We herein describe the first study on anticholinesterase and antioxidant activity by the methods of ferrous ion-chelating, superoxide radical scavenging, and ferric-reducing antioxidant power (FRAP) assays of the mentioned Juniperus species. [Copyright &y& Elsevier]

Abstract: Dichloromethane, ethyl acetate, acetone, methanol, and water extracts prepared from the fruits and leaves of Laurocerasus officinalis Roem. (LO) (Rosaceae) were screened for their cholinesterase inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in pathogenesis of Alzheimer''s disease (AD), using ELISA microplate reader at 50, 100, and 200μgmL−1. As AD is associated with oxidative stress, the antioxidant activity of the extracts was also tested by radical-forming methods against 2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), and superoxide radicals as well as iron-related methods; iron-chelating capacity and ferric-reducing antioxidant power (FRAP) assays. Total phenol and flavonoid quantification was achieved using Folin–Ciocalteau and AlCl3 reagents, respectively. The highest AChE (44.01±1.75%) and BChE (19.91±0.37%) inhibition was caused by the LO-leaf-methanol extract 200μgmL−1, while it showed the best radical-scavenging activity against DPPH at 2000μgmL−1. Only, the dichloromethane and water extracts of the fruits and the leaf water extract had an iron-chelating capacity, while the leaf methanol extract displayed the highest FRAP. The leaf methanol extract (113.45±0.71mgg−1 extract) was found to be the richest in total phenols, while the leaf acetone extract (139.90±4.64mgg−1 extract) had the most abundant amount of total flavonoids. [Copyright &y& Elsevier]

Based on our continuous effort to investigate chemistry and biology of the plant secondary metabolites, we were able to isolate a glycosidal flavonoid 1 from the Wild Egyptian Artichoke. The activity of dihydromyricetin 3-O-rhamnoside (sin. dihydromyricitrin, ampelopsin 3-O-rhamnoside) (1) against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE); its absolute configuration using X-ray crystallography were determined for the first time. Inhibitory activity of 1 against AChE and BChE enzymes were determined using a slightly modified version of Ellman's method. Compound 1 was revealed to have a potent inhibition against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC50 values of 0.070 ± 0.008 and 0.071 ± 0.004 mM, respectively, where IC50 values of the reference drug (galanthamine) were 0.023 ± 0.15 and 0.047 ± 0.91 mM. Compound 1 could be a promising molecule against Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Cholinesterase (ChE) inhibition is an important treatment strategy for Alzheimer's disease (AD) as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are involved in the pathology of AD. In the current work, ChE inhibitory potential of twenty-four natural products from different chemical classes (i.e., diosgenin, hecogenin, rockogenin, smilagenin, tigogenin, astrasieversianins II and X, astragalosides I, IV, and VI, cyclocanthosides E and G, macrophyllosaponins A-D, kokusaginin, lamiide, forsythoside B, verbascoside, alyssonoside, ipolamide, methyl rosmarinate, and luteolin-7-O-glucuronide) was examined using ELISA microtiter assay. Among them, only smilagenin and kokusaginine displayed inhibitory action against AChE (IC50 = 43.29 ± 1.38 and 70.24 ± 2.87 µg/mL, respectively). BChE was inhibited by only methyl rosmarinate and kokusaginine (IC50 = 41.46 ± 2.83 and 61.40 ± 3.67 µg/mL, respectively). IC50 values for galantamine as the reference drug were 1.33 ± 0.11 µg/mL for AChE and 52.31 ± 3.04 µg/mL for BChE. Molecular docking experiments showed that the orientation of smilagenin and kokusaginine was mainly driven by the interactions with the peripheral anionic site (PAS) comprising residues of hAChE, while kokusaginine and methyl rosmarinate were able to access deeper into the active gorge in hBChE. Our data indicate that similagenin, kokusaginine, and methyl rosmarinate could be hit compounds for designing novel anti-Alzheimer agents. [ABSTRACT FROM AUTHOR]

Phosphodiesterases (PDEs) consisted of 11 subtypes (PDE1 to PDE11) and over 40 isoforms that regulate levels of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP), the second messengers in cell functions. PDE inhibitors (PDEIs) have been attractive therapeutic targets due to their involvement in diverse medical conditions, e.g. cardiovascular diseases, autoimmune diseases, Alzheimer's disease (AD), etc. Among them; AD with a complex pathology is a progressive neurodegenerative disorder which affect mostly senile people in the world and only symptomatic treatment particularly using cholinesterase inhibitors in clinic is available at the moment for AD. Consequently, novel treatment strategies towards AD are still searched extensively. Since PDEs are broadly expressed in the brain, PDEIs are considered to modulate neurodegenerative conditions through regulating cAMP and cGMP in the brain. In this sense, several synthetic or natural molecules inhibiting various PDE subtypes such as rolipram and roflumilast (PDE4 inhibitors), vinpocetine (PDE1 inhibitor), cilostazol and milrinone (PDE3 inhibitors), sildenafil and tadalafil (PDE5 inhibitors), etc have been reported showing encouraging results for the treatment of AD. In this review, PDE superfamily will be scrutinized from the view point of structural features, isoforms, functions and pharmacology particularly attributed to PDEs as target for AD therapy. Image 1 • Phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP as well as cGMP controlling many physiological processes. • AD is one of the most prevalent age-related neurodegenerative diseases typically associated with neuroinflammation. • Pharmacological targets which are involved in blocking PDEs can be considered as new medicinal approaches in cognitive disorders and dementia. • Several neuropsychopharmacological mechanisms are involved in therapeutic effect of PDEs inhibitors in AD. • Numerous cellular signaling pathways are involved in beneficial effects of PDEs in AD such as PKA/PKG and cAMP/CREB/BDNF. [ABSTRACT FROM AUTHOR]

• Novel [3-substitue-6-oxopyridazin-1(6 H)-yl]methyl carbamate derivatives were synthesized. • Compounds 7c , 14c , and 16c showed significant inhibitory activity against eqBuChE. • Compound 7c displayed a competitive inhibition while 14c and 16c showed a mixed-type inhibition. • Molecular docking study was performed for the selected compounds. In the current study, forty-four new [3-(2/3/4-methoxyphenyl)-6-oxopyridazin-1(6 H)-yl]methyl carbamate derivatives were synthesized and evaluated for their ability to inhibit electric eel acetylcholinesterase (Ee AChE) and equine butyrylcholinesterase (eqBuChE) enzymes. According to the inhibitory activity results, [3-(2-methoxyphenyl)-6-oxopyridazin-1(6 H)-yl]methyl heptylcarbamate (16c , eqBuChE, IC 50 = 12.8 μM; Ee AChE, no inhibition at 100 μM) was the most potent eqBuChE inhibitor among the synthesized compounds and was found to be a moderate inhibitor compared to donepezil (eqBuChE, IC 50 = 3.25 μM; Ee AChE, IC 50 = 0.11 μM). Kinetic and molecular docking studies indicated that compounds 16c and 14c (hexylcarbamate derivative, eqBuChE, IC 50 = 35 μM; Ee AChE, no inhibition at 100 μM) were mixed-type inhibitors which accommodated within the catalytic active site (CAS) and peripheral anionic site (PAS) of hBuChE through stable hydrogen bonding and π-π stacking. Furthermore, it was determined that [3-(2-methoxyphenyl)-6-oxopyridazin-1(6 H)-yl]methyl (4-methylphenyl)carbamate 7c (eqBuChE, IC 50 = 34.5 μM; Ee AChE, 38.9% inhibition at 100 μM) was the most active derivative against Ee AChE and a competitive inhibitor binding to the CAS of hBuChE. As a result, 6-(2-methoxyphenyl)pyridazin-3(2 H)-one scaffold is important for the inhibitory activity and compounds 7c , 14c and 16c might be considered as promising lead candidates for the design and development of selective BuChE inhibitors for Alzheimer's disease treatment. [ABSTRACT FROM AUTHOR]