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.

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

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

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.

Protective effect of bromelain on some metabolic enzyme activities in tyloxapol-induced hyperlipidemic rats.

Elevation of one or more plasma lipids, such as phospholipids, cholesterol esters, cholesterol, and triglycerides, is known as hyperlipidemia. In humans and experimental animals, bromelain, the primary active ingredient isolated from pineapple stems, has several positive effects, including anti-tumor growth, anticoagulation, and anti-inflammation. Hence, the purpose of this study was to determine the possible protective impact of bromelain on some metabolic enzymes (paraoxonase-1, glutathione S-transferase, glutathione reductase, sorbitol dehydrogenase [SDH], aldose reductase [AR], butyrylcholinesterase [BChE], and acetylcholinesterase [AChE]), activity in the heart, kidney, and liver of rats with tyloxapol-induced hyperlipidemia. Rats were divided into three groups: control group, HL-control group (tyloxapol 400 mg/kg, i.p. administered group), and HL+bromelain (group receiving bromelain 250 mg/kg/o.d. prior to administration of tyloxapol 400 mg/kg, i.p.). BChE, SDH, and AR enzyme activities were significantly increased in all tissues in HL-control compared to the control, whereas the activity of other studied enzymes was significantly decreased. Bromelain had a regulatory effect on all tissues and enzyme activities. In conclusion, these results prove that bromelain is a new mediator that decreases hyperlipidemia.

Design, synthesis, and biological evaluation of novel capsaicin-tacrine hybrids as multi-target agents for the treatment of Alzheimer's disease.

A series of novel hybrid compounds were designed, synthesized, and utilized as multi-target drugs to treat Alzheimer's disease (AD) by connecting capsaicin and tacrine moieties. The biological assays indicated that most of these compounds demonstrated strong inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities with IC50 values in the nanomolar, as well as good blood-brain barrier permeability. Among the synthesized hybrids, compound 5s displayed the most balanced inhibitory effect on hAChE (IC50 = 69.8 nM) and hBuChE (IC50 = 68.0 nM), and exhibited promising inhibitory activity against ß-secretase-1 (BACE-1) (IC50 = 3.6 µM). Combining inhibition kinetics and molecular model analysis, compound 5s was shown to be a mixed inhibitor affecting both the catalytic active site (CAS) and peripheral anionic site (PAS) of hAChE. Additionally, compound 5s showed low toxicity in PC12 and BV2 cell assays. Moreover, compound 5s demonstrated good tolerance at the dose of up to 2500 mg/kg and exhibited no hepatotoxicity at the dose of 3 mg/kg in mice, and it could effectively improve memory ability in mice. Taken together, these findings suggest that compound 5s is a promising and effective multi-target agent for the potential treatment of AD.

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.

N-Methyl Costaricine and Costaricine, Two Potent Butyrylcholinesterase Inhibitors from Alseodaphne pendulifolia Gamb.

Studies have been conducted over the last decade to identify secondary metabolites from plants, in particular those from the class of alkaloids, for the development of new anti-Alzheimer's disease (AD) drugs. The genus Alseodaphne, comprising a wide range of alkaloids, is a promising source for the discovery of new cholinesterase inhibitors, the first-line treatment for AD. With regard to this, a phytochemical investigation of the dichloromethane extract of the bark of A. pendulifolia Gamb. was conducted. Repeated column chromatography and preparative thin-layer chromatography led to the isolation of a new bisbenzylisoquinoline alkaloid, N-methyl costaricine (1), together with costaricine (2), hernagine (3), N-methyl hernagine (4), corydine (5), and oxohernagine (6). Their structures were elucidated by the 1D- and 2D-NMR techniques and LCMS-IT-TOF analysis. Compounds 1 and 2 were more-potent BChE inhibitors than galantamine with IC50 values of 3.51 ± 0.80 µM and 2.90 ± 0.56 µM, respectively. The Lineweaver-Burk plots of compounds 1 and 2 indicated they were mixed-mode inhibitors. Compounds 1 and 2 have the potential to be employed as lead compounds for the development of new drugs or medicinal supplements to treat AD.

In Vitro and In Silico Evaluation of Anticholinesterase and Antidiabetic Effects of Furanolabdanes and Other Constituents from Graptophyllum pictum (Linn.) Griffith.

Graptophyllum pictum is a tropical plant noticeable for its variegated leaves and exploited for various medicinal purposes. In this study, seven compounds, including three furanolabdane diterpenoids, i.e., Hypopurin E, Hypopurin A and Hypopurin B, as well as with Lupeol, ß-sitosterol 3-O-ß-d-glucopyranoside, stigmasterol 3-O-ß-d-glucopyranoside and a mixture of ß-sitosterol and stigmasterol, were isolated from G. pictum, and their structures were deduced from ESI-TOF-MS, HR-ESI-TOF-MS, 1D and 2D NMR experiments. The compounds were evaluated for their anticholinesterase activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BchE), as well as their antidiabetic potential through inhibition of α-glucosidase and α-amylase. For AChE inhibition, no sample had IC50 within tested concentrations, though the most potent was Hypopurin A, which had a percentage inhibition of 40.18 ± 0.75%, compared to 85.91 ± 0.58% for galantamine, at 100 µg/mL. BChE was more susceptible to the leaves extract (IC50 = 58.21 ± 0.65 µg/mL), stem extract (IC50 = 67.05 ± 0.82 µg/mL), Hypopurin A (IC50 = 58.00 ± 0.90 µg/mL), Hypopurin B (IC50 = 67.05 ± 0.92 µg/mL) and Hypopurin E (IC50 = 86.90 ± 0.76 µg/mL). In the antidiabetic assay, the furanolabdane diterpenoids, lupeol and the extracts had moderate to good activities. Against α-glucosidase, lupeol, Hypopurin E, Hypopurin A and Hypopurin B had appreciable activities but the leaves (IC50 = 48.90 ± 0.17 µg/mL) and stem (IC50 = 45.61 ± 0.56 µg/mL) extracts were more active than the pure compounds. In the α-amylase assay, stem extract (IC50 = 64.47 ± 0.78 µg/mL), Hypopurin A (IC50 = 60.68 ± 0.55 µg/mL) and Hypopurin B (IC50 = 69.51 ± 1.30 µg/mL) had moderate activities compared to the standard acarbose (IC50 = 32.25 ± 0.36 µg/mL). Molecular docking was performed to determine the binding modes and free binding energies of Hypopurin E, Hypopurin A and Hypopurin B in relation to the enzymes and decipher the structure-activity relationship. The results indicated that G. pictum and its compounds could, in general, be used in the development of therapies for Alzheimer's disease and diabetes.

B-esterase measurements and other blood related biomarkers in loggerhead sea turtles (Caretta caretta) as indicators of health status.

The loggerhead sea turtle (Caretta caretta) has been selected as sentinel species by the Marine Strategy Framework Directive (MSFD) descriptor 10 in relation to marine litter. In this, and other protected species, there is a need to develop conservative pollution biomarkers equally informative of chemical exposures to those traditionally carried out in metabolic organs, such as the liver. With this aim, plasma from turtles undergoing rehabilitation at the Fundació Oceanogràfic rescue centre (Arca del Mar) were selected and tested for B-esterase measurements. Hydrolysis rates of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterases (CEs) using four commercial substrates were undertaken on 191 plasma samples. Results indicated that acetylthiocholine was the most adequate substrate of cholinesterases and butyrate esters for CE measures. The correlation of these parameters with well-established blood biochemistry measurements was analysed. B-esterase measures in wild specimens were discussed in relation to age group, pathology on admission to the rescue centre and season; moreover, contrasts with long-term resident turtles were also made. Although this study provides baseline data on B-esterase measures in a large sample size for this species, more complementary information is still needed in terms of population genetics, chemical exposures, and in relation to other biochemical parameters before they can be confidently applied in wild specimens within the regulatory MSFD.

Design, Synthesis, and Pharmacological Evaluation of Embelin-Aryl/alkyl Amine Hybrids as Orally Bioavailable Blood-Brain Barrier Permeable Multitargeted Agents with Therapeutic Potential in Alzheimer's Disease: Discovery of SB-1448.

The complex and multifaceted nature of Alzheimer's disease has brought about a pressing demand to develop ligands targeting multiple pathways to combat its outrageous prevalence. Embelin is a major secondary metabolite of Embelia ribes Burm f., one of the oldest herbs in Indian traditional medicine. It is a micromolar inhibitor of cholinesterases (ChEs) and ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1) with poor absorption, distribution, metabolism, and excretion (ADME) properties. Herein, we synthesize a series of embelin-aryl/alkyl amine hybrids to improve its physicochemical properties and therapeutic potency against targeted enzymes. The most active derivative, 9j (SB-1448), inhibits human acetylcholinesterase (hAChE), human butyrylcholinesterase (hBChE), and human BACE-1 (hBACE-1) with IC50 values of 0.15, 1.6, and 0.6 µM, respectively. It inhibits both ChEs noncompetitively with ki values of 0.21 and 1.3 µM, respectively. It is orally bioavailable, crosses blood-brain barrier (BBB), inhibits Aß self-aggregation, possesses good ADME properties, and protects neuronal cells from scopolamine-induced cell death. The oral administration of 9j at 30 mg/kg attenuates the scopolamine-induced cognitive impairments in C57BL/6J mice.

In vitro anticancer, antioxidant and enzyme inhibitory potentials of endemic Cephalaria elazigensis var. purpurea with in silico studies.

In this study, the therapeutic potential and phytochemical composition of ethanolic extract of Cephalaria elazigensis var. purpurea (CE), an endemic species, were investigated. For this purpose, the antiproliferative effect of CE on the MCF-7 human breast cancer cell line was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and its effectiveness on colony formation and cell migration was analyzed with clonogenic assay and wound healing assay, respectively. In addition, the cell death detection ELISA (CDDE) assay was conducted to determine the pro-apoptotic capacity of CE. The IC50 value of the CE was determined as 324.2 ± 14.7 µg/mL. Furthermore, upon 1000 µg/mL CE treatment, there was 4.96-fold increase in the population of cells undergoing apoptosis compared to the untreated control cells. The antioxidant activity tests were performed by DPPH free radical, ABTS cation radical, ferric-ion reducing power (FRAP) and ferrous-ion chelating power (FCAP) assays. Antioxidant activity values for the DPPH, ABTS and FRAP assays were found to be 125.6 ± 6.3, 34.09 ± 0.1 and 123.4 ± 4.2 µmol TE/mg DE, respectively. We further determined the effect of CE ethanolic extract against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. CE plays an effective inhibitory role in AChE and BuChE (AChE: IC50: 10.54 µg/mL, BuChE: IC50: 6.84 µg/mL) respectively. Further, molecular docking stuy was conducted to understand the nature of the all compound against AChE an BChE. It is revealed that α-Linolenic acid shows lowest binding energy (-7.90 kcal/mol) towards AChE, on the other side, Linoleic acid shows good binding affinity (-7.40 kcal/mol) for BChE.Communicated by Ramaswamy H. Sarma.

Attenuation of hyperglycemia-associated dyslipidemic, oxidative, cognitive, and inflammatory crises via modulation of neuronal ChEs/NF-κB/COX-2/NOx, and hepatorenal functional deficits by the Tridax procumbens extract.

Tridax procumbens (cotton buttons) is a flowering plant with a medicinal reputation for treating infections, wounds, diabetes, and liver and kidney diseases. The present research was conducted to evaluate the possible protective effects of the T. procumbens methanolic extract (TPME) on an experimentally induced type 2 diabetes rat model. Wistar rats with streptozotocin (STZ)-induced diabetes were randomly allocated into five groups of five animals each, viz., a normal glycemic group (I), diabetic rats receiving distilled water group (II), diabetic rats with 150 (III) and 300 mg/kg of TPME (IV) groups, and diabetic rats with 100 mg/kg metformin group (V). All treatments were administered for 21 consecutive days through oral gavage. Results: Administration of the T. procumbens extract to diabetic rats significantly restored alterations in levels of fasting blood glucose (FBG), body weight loss, serum and pancreatic insulin levels, and pancreatic histology. Furthermore, T. procumbens significantly attenuated the dyslipidemia (increased cholesterol, low-density lipoprotein-cholesterol (LDL-C), triglycerides, and high-density lipoprotein (HDL) in diabetic rats), serum biochemical alterations (alanine transaminase (ALT), aspartate transaminase (AST), alanine phosphatase (ALP), blood urea nitrogen (BUN), creatinine, uric acid, and urea) and full blood count distortion in rats with STZ-induced diabetes. The TPME also improved the antioxidant status as evidenced by increased superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and decreased malondialdehyde (MDA); and decreased levels of cholinesterases (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)), and proinflammatory mediators including nuclear factor (NF)-κB, cyclooxygenase (COX)- 2, and nitrogen oxide (NOx) in the brain of rats with STZ-induced diabetes compared to rats with STZ-induced diabetes that received distilled water. However, TPME treatment failed to attenuate the elevated monoamine oxidases and decreased dopamine levels in the brain of rats with STZ-induced diabetes. Extract characterization by liquid chromatography mass spectrometry (LC-MS) identified isorhamnetin (retention time (RT)= 3.69 min, 8.8%), bixin (RT: 25.06 min, 4.72%), and lupeol (RT: 25.25 min, 2.88%) as the three most abundant bioactive compounds that could be responsible for the bioactivity of the plant. In conclusion, the TPME can be considered a promising alternative therapeutic option for managing diabetic complications owing to its antidiabetic, antihyperlipidemic, antioxidant, and anti-inflammatory effects in rats with STZ-prompted diabetes.

Jatamansinol from Nardostachys jatamansi: a multi-targeted neuroprotective agent for Alzheimer's disease.

Alzheimer's disease (AD) is a multifactorial progressive and irreversible neurodegenerative disorder characterized by severe memory impairment and cognitive disability in the middle and old-aged human population. There are no proven drugs for AD treatment and prevention. In Ayurveda, medhya plants are used to prepare Rasayana, and its consumption improves memory and cognition. Nardostachys jatamansi (D.Don) DC is a medhya plant used in traditional medicine to treat neurological disorders, and its unique pyranocoumarins can be a potential drug candidate for AD. Given its traditional claims, this study aims to find the multi-target potential efficacy of the ligands (drug molecules) against the AD from N. jatamansi pyranocoumarins using computational drug discovery techniques. Drug likeliness analysis confirms that pyranocoumarins of N. jatamansi, such as seselin, jatamansinol, jatamansine, jatamansinone, and dihydrojatamansin are probable drug candidates for AD. Molecular docking, molecular dynamic simulations, and Molecular Mechanics/Generalized Born Surface Area (MM-GBSA) analysis confirm that dihydrojatamansin inhibits acetylcholinesterase (AChE), and jatamansinol inhibits butyrylcholinesterase (BuChE), glycogen synthase kinase 3ß (GSK3ß), and kelch-like ECH-associating protein 1 (Keap1) AD therapeutic targets. Therefore, this study provides potential multi-target inhibitors that would further validate experimental studies, leading to new treatments for AD.Communicated by Ramaswamy H. Sarma.

Isolation, Characterization, and In Silico Interaction Studies of Bioactive Compounds from Caesalpinia bonducella with Target Proteins Involved in Alzheimer's Disease.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder characterized by memory loss, cognitive deterioration, and neuropsychiatric symptoms. Various drug targets implicated in AD are amyloid beta peptides, cholinesterase enzymes, and anti-amylogenic protein. Medicinal plants derived phytochemical constituents provide a vast pool of diverse compounds as a source of novel drugs. In view of this, the Caesalpinia bonducella seed extract and its active phytoconstituents were used to study the disease-modifying effects in Alzheimer's disease. The present study successfully demonstrated the therapeutic potential of various phytochemicals as it binds to multiple drug targets, resulting in inhibition of acetylcholinesterase (AChE) enzyme, butyrylcholinesterase (BuChE), BACE-1 enzyme, and anti-amylogenic protein as indicated by docking analysis. In conclusion, phytochemicals identified can be used as a suitable lead to developing a molecule that might have multi-targeted directed ligand (MTDL) potential and disease amelioration effects in Alzheimer's disease.

Chemical Constituents, Antioxidant, and Enzyme Inhibitory Activities Supported by In-Silico Study of n-Hexane Extract and Essential Oil of Guava Leaves.

Psidium guajava (Guava tree) is one of the most widely known species in the family Myrtaceae. The Guava tree has been reported for its potential antioxidant, anti-inflammatory, antimicrobial, and cytotoxic activities. In the current study, the chemical compositions of the n-hexane extract and the essential oil of P. guajava were investigated using the GC/MS analysis, along with an evaluation of their antioxidant potential, and an investigation into the enzyme inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BchE), tyrosinase, α-amylase, and α-glucosidase. Moreover, molecular docking of the major identified active sites of the target enzymes were investigated. The chemical characterization of the n-hexane extract and essential oil revealed that squalene (9.76%), α-tocopherol (8.53%), and γ-sitosterol (3.90%) are the major compounds in the n-hexane extract. In contrast, the major constituents of the essential oil are D-limonene (36.68%) and viridiflorol (9.68%). The n-hexane extract showed more antioxidant potential in the cupric reducing antioxidant capacity (CUPRAC), the ferric reducing power (FRAP), and the metal chelating ability (MCA) assays, equivalent to 70.80 ± 1.46 mg TE/g, 26.01 ± 0.97 mg TE/g, and 24.83 ± 0.35 mg EDTAE/g, respectively. In the phosphomolybdenum (PM) assay, the essential oil showed more antioxidant activity equivalent to 2.58 ± 0.14 mmol TE/g. The essential oil demonstrated a potent BChE and tyrosinase inhibitory ability at 6.85 ± 0.03 mg GALAE/g and 61.70 ± 3.21 mg KAE/g, respectively. The α-amylase, and α-glucosidase inhibitory activity of the n-hexane extract and the essential oil varied from 0.52 to 1.49 mmol ACAE/g. Additionally, the molecular docking study revealed that the major compounds achieved acceptable binding scores upon docking with the tested enzymes. Consequently, the P. guajava n-hexane extract and oil can be used as a promising candidate for the development of novel treatment strategies for oxidative stress, neurodegeneration, and diabetes mellitus diseases.

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.

Kinetic and structural studies on the inhibition of acetylcholinesterase and butyrylcholinesterase by a series of multitarget-directed galantamine-peptide derivatives.

Complex neurological disorders, including Alzheimer's disease, are one of the major therapeutic areas to which multitarget drug discovery strategies have been applied in the last twenty years. Due to the complex multifactorial etiopathogenesis of Alzheimer's disease, it has been proposed that to be successful the pharmaceutical agents should act on multiple targets in order to restore the complex disease network and to provide disease modifying effects. Here we report on the synthesis and the anticholinergic activity profiles of seven multitarget anti-Alzheimer compounds designed by combining galantamine, a well-known acetylcholinesterase inhibitor, with different peptide fragments endowed with inhibitory activity against BACE-1. A complementary approach based on molecular docking simulations of the galantamine-peptide derivatives in the active sites of acetylcholinesterase and of the related butyrylcholinesterase, as well as on inhibition kinetics, by global fitting of the reaction progress curves, allowed to gain insights into the enzyme-inhibitor mechanism of interaction. The resulting structure-activity relationships pave the way towards the design of more effective pharmacodynamic/pharmacokinetic multitarget inhibitors.

Synthesis, in Vitro Cholinesterase Inhibition, Molecular Docking, DFT, and ADME Studies of Novel 1,3,4-Oxadiazole-2-Thiol Derivatives.

A series of 1,3,4-oxadiazole-2-thiol derivatives bearing various alkyl or aryl moieties were designed, synthesized, and characterized using modern spectroscopic methods to yield 17 compounds (6a-6q) that were screened for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in the search for 'lead' compounds for Alzheimer's disease treatment (AD). The compounds 6q, 6p, 6k, 6o, and 6l showed inhibitory capability against AChE and BChE, with IC50 values ranging from 11.73±0.49 to 27.36±0.29 µM for AChE and 21.83±0.39 to 39.43±0.44 µM for BChE, inhibiting both enzymes within a limited range. The SAR ascertained that the substitution of the aromatic moiety had a profound effect on the AChE and BChE inhibitory potential as compared to the aliphatic substitutions which were supported by the molecular docking studies. The drug-likeness of the most synthesized compounds was confirmed by in silico ADME investigations. These results were additionally supplemented by the molecular orbital analysis (HOMO-LUMO) and electrostatic potential maps got from DFT calculations. ESP maps expose that on all structures, there are two potential binding sites conquered by the most positive and most negative districts.

Harpephyllum caffrum fruit (wild plum) facilitates glucose uptake and modulates metabolic activities linked to neurodegeneration in isolated rat brain: An in vitro and in silico approach.

Alteration in brain glucose metabolism due to glucose uptake reduction has been described in the onset of certain neurodegenerative disorders. This study determined Harpephyllum caffrum fruit's potential ability to improve glucose uptake and its modulatory effects on intrinsic antioxidant, glucogenic, cholinergic, and nucleotide-hydrolyzing enzyme activities in isolated rat brain. Consequently, the bioactive compounds of the fruits were identified with LC-MS. The fruit significantly improved brain glucose uptake following coincubation with glucose and brain tissue. The fruit extract also elevated GSH level, SOD, catalase, glycogen phosphorylase, and ENTPDase activities while simultaneously suppressing NO and malonaldehyde levels and fructose-1,6-bisphosphatase, ATPase, acetylcholinesterase and butyrylcholinesterase activities. LC-MS analysis revealed S-methylcysteine sulfoxide, dihydroquercetin, 3,4-dimethyl-2,5-bis(3,4,5-trimethoxyphenyl) tetrahydrofuran (MTHF), nobiletin, puerarin, quercetin 3-rutinoside, 8-D-glucosyl-4',5,7-trihydroxyflavone, asperulosidic acid, 1,2,4,6-tetragalloylglucose, and phellamurin. This study suggests the neuroprotective effects of H. caffrum fruit due to its ability to enhance glucose uptake, attenuate glucose-induced oxidative stress while modulating glucogenic, cholinergic, and nucleotide-hydrolyzing enzyme activities in normal brain tissues. PRACTICAL APPLICATIONS: Available scientific evidence describes oxidative stress as one of the physiological processes contributing to aging-associated neurodegeneration in humans. In this regard, commonly consumed natural products from plants have attracted much interest due to their ability to mitigate redox imbalance-related pathologies that affect various organs in the body such as the brain. Harpephyllum caffrum or bush mango is an evergreen plant native to the South African vegetation. The fruit from the plant is consumed locally as food or specifically for improving the nutritional quality of meals as deserts or condiments. While previous findings described the high antioxidant properties of the fruits, this study reported possible mechanisms via which the plant may exhibit ameliorative effects against oxidative stress-related neurological disorders in the brain. Hence, findings from the current work present another justification for the significance of fruits as a safer nutraceutical alternative for therapy in neurological disease management.

Polyphenol Composition, Anticholinesterase and Antioxidant Potential of the Extracts of Clinopodium vulgare L.

Clinopidium vulgare L. (wild basil, Lamiaceae) is a well-known medicinal plant used in the traditional medicine in many countries. Medicinal plants present potential sources of bioactive compounds. Many of them are rich in polyphenol compounds that show biological potential in terms of protecting biological molecules from oxidation and in inhibition of cholinesterase enzymes, which may be significant in the treatment of diseases related to oxidative stress. In this work, we examined the chemical composition of Clinopodium vulgare L. hot water and methanol extract using spectroscopic and HPLC/DAD techniques. Using DPPH and FRAP methods the antioxidant activity was analyzed. The ability to protect proteins and lipids from oxidation was also determined as well as the ability of extracts to inhibit cholinesterase enzymes using Ellman's method. Analyzed extracts were rich in polyphenol compounds. Among 16 identified and quantified phenolic compounds dominant were: rosmarinic (26.63 and 34.21 mg/g) and ellagic acid (23.11 and 29.31 mg/g) of hot water and methanol extract, respectively. They show good antioxidant activity and good potential in protecting lipids from oxidation. The ability of extracts to inhibit enzyme acetylcholinesterase was weak, while inhibition of the butyrylcholinesterase was missing. Extracts show prooxidant activity in terms of protecting proteins from oxidation.