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Novel hybrids N-(4-phenoxybenzyl)aniline were designed, synthesized, and evaluated for their potential AChE inhibitory activity along with antioxidant potential. The inhibitory potential (IC 50) of synthesized analogs was evaluated against human cholinesterases (hAChE and hBChE) using Ellman's method. Among all the tested compounds, 42 with trimethoxybenzene substituent showed maximum hAChE inhibition with the competitive type of enzyme inhibition (IC 50 = 1.32 µM; Ki = 0.879 µM). Further, parallel artificial membrane permeation assay (PAMPA-BBB) showed favorable BBB permeability by most of the synthesized compounds. Meanwhile, compound 42 also inhibited AChE-induced Aβ aggregation (39.5–66.9%) in thioflavin T assay. The in vivo behavioral studies showed dose-dependent improvement in learning and memory by compound 42. The ex vivo studies also affirmed the significant AChE inhibition and antioxidant potential of compound 42 in brain homogenates. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Novel hybrids bearing a 2-aminopyrimidine (2-AP) moiety linked to substituted 1,3,4-oxadiazoles were designed, synthesized and biologically evaluated. Among the developed compounds, 28 noncompetitively inhibited human acetylcholinesterase (hAChE; pIC 50 = 6.52; Ki = 0.17 µM) and showed potential in vitro antioxidant activity (60.0%) when evaluated using the Ellman's and DPPH assays, respectively. Compound 28 competitively displaced propidium iodide (PI) from the peripheral anionic site (PAS) of hAChE (17.6%) and showed high blood-brain barrier (BBB) permeability, as observed in the PAMPA-BBB assay. Additionally, compound 28 inhibited hAChE-induced Aβ aggregation in a concentration-dependent manner according to the thioflavin T assay and was devoid of neurotoxic liability towards SH-SY5Y cell lines, as demonstrated by the MTT assay. The behavioral studies of compound 28 in mice showed a significant reversal of scopolamine-induced amnesia, as observed in Y-maze and passive avoidance tests. Furthermore, compound 28 exhibited significant AChE inhibition in the brain in ex vivo studies. An evaluation of oxidative stress biomarkers revealed the antioxidant potential of 28. Moreover, in silico molecular docking and dynamics simulation studies were used as a computational tool to evaluate the interactions of compound 28 with the active site residues of hAChE. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Biphenyl-3-oxo-1,2,4-triazine linked piperazines were designed and synthesized. • Compound 6g significantly inhibited the AChE and showed good CNS permeability. • In vivo studies showed significant improvement in learning and memory. • Biochemical analysis showed potential antioxidant property by compound 6g. Abstract A series of novel piperazine tethered biphenyl-3-oxo-1,2,4-triazine derivatives were designed, and synthesized. Amongst the synthesized analogs, compound 6g showed significant non-competitive inhibitory potential against acetylcholinesterase (AChE, IC 50 ; 0.2 ± 0.01 μM) compared to standard donepezil (AChE, IC 50 : 0.1 ± 0.002 μM). Compound 6g also exhibited significant displacement of propidium iodide from the peripheral anionic site (PAS) of AChE (22.22 ± 1.11%) and showed good CNS permeability in PAMPA-BBB assay (P e (exp) , 6.93 ± 0.46). The in vivo behavioral studies of compound 6g indicated significant improvement in cognitive dysfunctions against scopolamine-induced amnesia mouse models. Further, ex vivo studies showed a significant AChE inhibition and reversal of the scopolamine-induced oxidative stress by compound 6g. Moreover, molecular docking and dynamics simulations of compound 6g showed a consensual binding affinity and active site interactions with the PAS and active catalytic site (CAS) residues of AChE. [ABSTRACT FROM AUTHOR]

Some promising acetylcholinesterase (AChE) inhibitors with an antioxidant potential were designed, synthesised, and evaluated for their role in treating cognitive dysfunctions. The in silico Gaussian-based quantitative structureactivity relationship (QSAR), virtual screening (VS), QikProp drug-likeliness prediction and docking pose filtration protocols were adapted to design and screen the novel series of diaryl ether derivatives. Further, the selected compounds were investigated for their molecular binding stability using molecular dynamics (MD) simulation analysis and molecular mechanics generalised born surface area (MM-GBSA). The identified hits were synthesised and evaluated for their in vitro AChE inhibition and antioxidant potential. Among all the synthesized compounds, the compound 39 was observed as potent AChE inhibitor (AChE IC50 = 1.30 ± 0.09 μm; Ki = 0.054 ± 0.009 μM), and also the antioxidant potential of compound 39 (52.9%) was observed significantly better than standard donepezil (<10%) and parallel to ascorbic acid (56.6%). Further, compound 39 ameliorated the scopolamine-induced cognitive impairment in the Y-maze and passive avoidance testsin mice models. Ex vivo and biochemical analysis established the brain AChE inhibitory potential and antioxidant properties of compound 39. The results signified compound 39 to be a promising lead for the treatment of cognitive dysfunctions. [ABSTRACT FROM AUTHOR]

Millions of people worldwide are currently afflicted with neurologic conditions like a seizure, depression, stress, Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, the precise etiopathology of these diseases is still unknown. Substantial studies are being conducted to discover more treatments against these disorders because many patients do not experience the therapeutic benefits that would be expected from using existing pharmaceutical strategies. Herbal medicines which have been used in traditional medicine for millennia to treat various neurological problems are also being investigated and scientifically assessed. Punicalagin is a known polyphenol that has significant antioxidant, anti-inflammatory, anti-viral, anti-proliferative, and anti-cancer properties. Around the world, traditional use of herbal drugs is gaining wider acceptance as a part of complementary and alternative medicine. The scientific community should pay attention to these many neuroprotective pharmacodynamic activities of Punicalagin to create effective pharmacotherapeutic plans, as evidenced by mounting data in pre-clinical research investigations. The current review describes the recent studies on the pharmacological effects of Punicalagin in a variety of neurological illnesses and paves the way for further study in this field. [ABSTRACT FROM AUTHOR]

Abstract The multitarget-directed strategy offers an effective and promising paradigm to treat the complex neurodegenerative disorder, such as Alzheimer's disease (AD). Herein, a series of N -benzylpiperidine analogs (17 – 31 and 32 – 46) were designed and synthesized as multi-functional inhibitors of acetylcholinesterase (AChE) and β-secretase-1 (BACE-1) with moderate to excellent inhibitory activities. Among the tested inhibitors, 25, 26, 40, and 41 presented the most significant and balanced inhibition against both the targets. Compounds 40 and 41 exhibited high brain permeability in the PAMPA-BBB assay, significant displacement of propidium iodide from the peripheral anionic site (PAS) of AChE, and were devoid of neurotoxicity towards SH-SY5Y neuroblastoma cell lines up to the maximum tested concentration of 80 μM. Meanwhile, both these compounds inhibited self- and AChE-induced Aβ aggregation in thioflavin T assay, which was also re-affirmed by morphological characterization of Aβ aggregates using atomic force microscopy (AFM). Moreover, 40 and 41 ameliorated the scopolamine-induced cognitive impairment in elevated plus and Y-maze experiments. Ex vivo and biochemical analysis established the brain AChE inhibitory potential and antioxidant properties of these compounds. Further, improvement in Aβ 1-42 -induced cognitive impairment was also observed by compound 41 in the Morris water maze experiment with significant oral absorption characteristics ascertained by the pharmacokinetic studies. Graphical abstract Image 1 Highlights • Design and synthesis of a series of N -benzylpiperidine analogs (17 – 46). • Compounds 25, 26, 40, and 41 exhibited balanced inhibition of AChE and BACE-1. • Propidium iodide displacement and inhibition of Aβ aggregation by 40 and 41. • Biochemical analysis of rat brain homogenates suggested antioxidant potential. • Amelioration of scopolamine- and Aβ-induced cognitive impairment in AD rat models. [ABSTRACT FROM AUTHOR]

The cholinesterases are essential targets implicated in the pathogenesis of Alzheimer's disease (AD). In the present study, virtual screening and molecular docking are performed to identify the potential hits. Docking-post processing (DPP) and pose filtration protocols against AChE and BChE resulted in three hits (AW00308, HTS04089, and JFD03947). Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) and molecular dynamics simulation analysis affirmed the stability and binding pattern of the docked complex JFD03947, which was further synthesized and evaluated for in vitro cholinesterase inhibition (AChE, IC50 = 0.062 µM; BChE, IC50 = 1.482 µM) activity. The enzyme kinetics study of the JFD03947 against hAChE and hBChE suggested a mixed type of inhibition. The results of thioflavin T-assay also elicited anti-Aβ aggregation activity by JFD03947. Further, biological evaluation of identified compound JFD03947 also showed neuroprotective ability against the SH-SY5Y neuroblastoma cell lines. [ABSTRACT FROM AUTHOR]

• 4-AP tethered 1,3,4-oxadiazole derivatives were designed and synthesized. • Compound 9 elicited significant non-competitive type of hAChE inhibition. • Compound 9 showed significant brain permeability in PAMPA-BBB assay. • Compound 9 ameliorated scopolamine- induced cognitive impairment in mice models. • Biochemical analysis using brain homogenates suggested antioxidant activity by 9. The novel hybrids bearing 4-aminopyridine (4-AP) tethered with substituted 1,3,4-oxadiazole nucleus were designed, synthesized, and evaluated for their potential AChE inhibitory property along with significant antioxidant potential. The inhibitory potential (IC 50) of synthesized analogs was evaluated against human cholinesterases (hAChE and hBChE) using Ellman's method. Among all the compounds, 9 with 4-hydroxyl substituent showed maximum hAChE inhibition with the non-competitive type of enzyme inhibition (IC 50 = 1.098 µM; Ki = 0.960 µM). Further, parallel artificial membrane permeation assay (PAMPA-BBB) showed significant BBB permeability in most of the synthesized compounds. Meanwhile, compound 9 also inhibited AChE-induced Aβ aggregation (38.2–65.9%) by thioflavin T assay. The in vivo behavioral studies showed dose-dependent improvement in learning and memory by compound 9. The ex vivo studies also affirmed the significant AChE inhibition and antioxidant potential of compound 9 in brain homogenates. [ABSTRACT FROM AUTHOR]

Highlights • The pathophysiological roles and underlying mechanisms of several hypotheses involved in AD are extensively reviewed. • A detailed investigation of all the conventional and novel therapeutic targets. • The identification of structural and functional motifs with a comprehensive framework of the active sites involved. • To elucidate and simplify the complexity and call for attention on the crucial areas to discover innovative therapeutics. Abstract AD is a progressive neurodegenerative disorder and a leading cause of dementia in an aging population worldwide. The enormous challenge which AD possesses to global healthcare makes it as urgent as ever for the researchers to develop innovative treatment strategies to fight this disease. An in-depth analysis of the extensive available data associated with the AD is needed for a more comprehensive understanding of underlying molecular mechanisms and pathophysiological pathways associated with the onset and progression of the AD. The currently understood pathological and biochemical manifestations include cholinergic, Aβ, tau, excitotoxicity, oxidative stress, ApoE, CREB signaling pathways, insulin resistance, etc. However, these hypotheses have been criticized with several conflicting reports for their involvement in the disease progression. Several issues need to be addressed such as benefits to cost ratio with cholinesterase therapy, the dilemma of AChE selectivity over BChE, BBB permeability of peptidic BACE-1 inhibitors, hurdles related to the implementation of vaccination and immunization therapy, and clinical failure of candidates related to newly available targets. The present review provides an insight to the different molecular mechanisms involved in the development and progression of the AD and potential therapeutic strategies, enlightening perceptions into structural information of conventional and novel targets along with the successful applications of computational approaches for the design of target-specific inhibitors. [ABSTRACT FROM AUTHOR]

Some novel indolizine derivatives were synthesized by bioisosteric modification of imidazo[1,2- a ]pyridine for anti-inflammatory activity. The physicochemical characterization and structure of compounds were elucidated by state of the art spectroscopic technique. Induced fit docking was performed for initial screening to elucidate the interactions with corresponding amino acids of cyclooxygenase (COX-1, COX-2) and lipoxygenase (LOX) enzymes. The target compounds 53 – 60 were then evaluated against in vivo carrageenan and arachidonic acid induced rat paw edema models for anti-inflammatory activity. Amongst all the synthesized derivatives, compound 56 showed the significant anti-inflammatory activity in both rat paw edema models with very less ulcerogenic liability in comparison to standard diclofenac, celecoxib, and zileuton. The compounds 56 was further assessed to observe in vitro enzyme inhibition assay on both cyclooxygenase and lipoxygenase enzyme where it showed a preferential and selective non-competitive enzyme inhibition towards the COX-2 (IC 50 = 14.91 μM, Ki = 0.72 µM) over COX-1 (IC 50 > 50 μM) and a significant non-competitive inhibition of soybean lipoxygenase enzyme (IC 50 = 13.09 μM, Ki = 0.92 µM). Thus, in silico, in vivo , and in vitro findings suggested that the synthesized indolizine compound 56 has a dual COX-2 and LOX inhibition characteristic and parallel in vivo anti-inflammatory activity in comparison to the standard drugs. [ABSTRACT FROM AUTHOR]

Series of some 3,5-dimethoxy- N -methylenebenzenamine and 4-(methyleneamino)benzoic acid derivatives comprising of N -methylenebenzenamine nucleus were designed, synthesized, characterized, and assessed for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE) inhibitory, and antioxidant activity thereby improving learning and memory in rats. The IC 50 values of all the compound along with standard were determined on AChE and BChE enzyme. The free radical scavenging activity was also assessed by in vitro DPPH (2,2-diphenyl-1-picryl-hydrazyl) and hydrogen peroxide radical scavenging assay. The selective inhibitions of all compounds were observed against AChE in comparison with standard donepezil. The enzyme kinetic study of the most active compound 4 indicated uncompetitive AChE inhibition. The docking studies of compound 4 exhibited the worthy interaction on active-site gorge residues Phe330 and Trp279 responsible for its high affinity towards AChE, whereas lacking of the BChE inhibition was observed due to a wider gorge binding site and absence of important aromatic amino acids interactions. The ex vivo study confirmed AChE inhibition abilities of compound 4 at brain site. Further, a considerable decrease in escape latency period of the compound was observed in comparison with standard donepezil through in vivo Spatial Reference Memory (SRM) and Spatial Working Memory (SWM) models which showed the cognition-enhancing potential of compound 4 . The in vivo reduced glutathione (GSH) estimation on rat brain tissue homogenate was also performed to evaluate free radical scavenging activity substantiated the antioxidant activity in learning and memory. [ABSTRACT FROM AUTHOR]

• In-silico based virtual screening of a library (Drug Central Database) containing 4199 FDA approved drugs; MM/GBSA and MD simulation analysis were performed. • Novel structurally modified propamidine derivatives were synthesized, characterized and tested for their anti-AD activity. • Compound 27 was a well-balanced and promising multi-targeting agent. • Compound 27 exhibited good self and AChE-induced Aβ aggregation inhibition in thioflavin T assay. • Compound 27 displayed significant improvement in cognitive dysfunctions against scopolamine-induced amnesia mouse models. The use of multifunctional agents could act as a crucial strategy in the management of neurodegenerative disorders like Alzheimer's disease (AD). In search of multitargeted directed ligands for the treatment of AD, a drug repositioning study has been performed using In silico tools. Virtual screening of a library (Drug Central Database) containing 4199 FDA-approved drugs was utilized for the purpose, and denopamine, guanethidine, and propamidine were identified as hits to target both acetylcholinesterase (AChE) and β-secretase (BACE-1). Further, MM/GBSA and MD simulation analysis was also performed which suggested that propamidine, an antibacterial and antifungal drug , may become a crucial pharmacophore to design multi-target directed ligands for AD therapy. Finally, a series of structurally modified derivatives of propamidine by replacement of terminal amidines with substituted benzamide and acetamide moiety on both ends were synthesized, characterized, and tested for their anti-AD action. Compound 27 of the structurally modified series of propamidine has shown significant in vitro hAChE and hBACE-1 inhibition at submicromolar concentration range (hAChE: IC 50 = 0.832 ± 0.05 µM and hBACE-1: IC 50 = 0.428 ± 0.036 µM). Compounds 27 has also shown significant propidium iodide displacement from the PAS binding region and exhibited good self and AChE-induced Amyloid-β (Aβ) aggregation inhibition in thioflavin T assay. The in-vivo behavioral studies of compound 27 displayed significant improvement in cognitive dysfunctions against scopolamine-induced amnesia mouse models. [Display omitted] [ABSTRACT FROM AUTHOR]

• Novel 4, 5-diphenyl-1 H -imidazole linked piperazine hybrids were rationally designed. • Compound 6f was a well-balanced and promising multi-targeting agent. • Compound 6f showed good propidium iodide displacement. • compound 6f (10 mg/kg) showed a statistically non-significant difference in % spontaneous alterations The multi-targeted organized strategy provides effectual and significant results to cure progressive neurodegenerative diseases like AD. Treatment for this awful disease is in infancy till now. A series of novel 4, 5-diphenyl-1 H -imidazole linked piperazine hybrids (6a-g and 7a-g) were synthesized by utilizing the concept of bio-isosteric replacement and hybrid pharmacophore approaches. The targeted compounds were identified by spectroscopic techniques and assessed for in vitro cholinesterase, BACE-1 inhibition, propidium iodide displacement, and Aβ disaggregation activities. Within the targeted inhibitors, 6f exhibited the most significant and inhibitory capacity against eeAChE (IC 50 = 0.416 ± 0.018 μM), eqBChE (IC 50 = 0.474 ± 0.054 μM), and BACE-1 (IC 50 = 0.392 ± 0.021 μM) targets. Propidium iodide displacement showed that compound 6f could be effectively linked with AChE's PAS (10 μM = 29.09 %, 50 μM = 41.43%). It showed inhibitory potential against both self (21.28 to 30.85%) and AChE-induced (25.70 to 51.07%) Aβ aggregation in thioflavin T assay. Moreover, the most active compound 6f was evaluated by performing in vivo behavioural studies with the help of the scopolamine-induced Y-maze model. The in vitro and in vivo in collaboration with in silico molecular docking and molecular dynamics simulation leads to ascertain the active site interaction of compound 6f with AChE and BACE-1. [ABSTRACT FROM AUTHOR]

The diverse nature of Alzheimer's disease (AD) has prompted researchers to develop multi-functional agents. Herein, we have designed and synthesized molecular hybrids of 2-pyridylpiperazine and 5-phenyl-1,3,4-oxadiazoles. Biological activities of synthesized compounds suggested significant and balanced inhibitory potential against target enzymes. In particular, compound 49 containing 2,4-difluoro substitution at terminal phenyl ring considered as most potential lead with inhibition of acetylcholinesterase (hAChE, IC 50 = 0.054 μM), butyrylcholinesterase (hBChE, IC 50 = 0.787 μM) and beta-secretase-1 (hBACE-1, IC 50 = 0.098 μM). The enzyme kinetics study of 49 against hAChE suggested a mixed type of inhibition (Ki = 0.030 μM). Also, 48 and 49 showed significant displacement of propidium iodide from the peripheral anionic site (PAS) of hAChE, excellent blood-brain barrier (BBB) permeability in parallel artificial membrane permeation assay (PAMPA), and neuroprotective ability against SH-SY5Y neuroblastoma cell lines. Further, 49 also exhibited anti-Aβ aggregation activity in self- and AChE-induced thioflavin T assay, which was ascertained by morphological characterization by atomic force microscopy (AFM). Moreover, in vivo behavioral studies signified learning and memory improvement by compound 49 in scopolamine- and Aβ-induced cognitive dysfunctions performed on Y-maze and Morris water maze. The ex vivo studies suggested decreased AChE activity and antioxidant potential of compound 49 , with good oral absorption characteristics ascertained by pharmacokinetic studies. Image 1 • Design and synthesis of 2-pyridylpiperazine and 5-phenyl-1,3,4-oxadiazoles hybrids. • Compounds 48 and 49 exhibited balanced inhibition of AChE and BACE-1. • Propidium iodide displacement and inhibition of Aβ aggregation by 48 and 49. • Ex vivo study of rat hippocampal homogenates suggested antioxidant potential. • Amelioration of scopolamine- and Aβ-induced cognitive impairment in AD rat models. [ABSTRACT FROM AUTHOR]