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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]

• Design and synthesis of N -benzylpyrrolidine analogs. • Compounds 4k and 4o exhibited balanced inhibition of AChE, BChE, and BACE-1. • Propidium iodide displacement and inhibition of Aβ aggregation by 4k and 4o. • Ex vivo study of rat hippocampal homogenates suggested antioxidant potential. • Amelioration of scopolamine- and Aβ-induced cognitive impairment in AD rat models. Multitarget molecular hybrids of N -benzyl pyrrolidine derivatives were designed, synthesized, and biologically evaluated for the treatment of Alzheimer's disease (AD). Among the synthesized compounds, 4k and 4o showed balanced enzyme inhibitions against cholinesterases (AChE and BChE) and BACE-1. Both leads showed considerable PAS-AChE binding capability, excellent brain permeation, potential disassembly of Aβ aggregates, and neuroprotective activity against Aβ-induced stress. Compounds 4k and 4o also ameliorated cognitive dysfunction against the scopolamine-induced amnesia model in the Y-maze test. The ex vivo study signified attenuated brain AChE activity and antioxidant potential of compounds 4k and 4o. Furthermore, compound 4o also showed improvement in Aβ-induced cognitive dysfunction by the Morris water maze test with excellent oral absorption characteristics ascertained by the pharmacokinetic study. In silico molecular docking and dynamics simulation studies of leads suggested their consensual binding affinity toward PAS-AChE in addition to aspartate dyad of 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]

• Machine learning models were built from a potential in house database. • Multistep virtual screening method were used to identify a novel dual acetylcholinesterase and butyrylcholinesterase inhibitor from the Maybridge database. • In silico drug likeliness properties were evaluated for top hit compounds. • CD05692 was proposed as a potential novel dual acetylcholinesterase and butyrylcholinesterase inhibitors. • Synthesis and in vitro ChE (hAChE and hBChE) inhibition estimation of top hit CD05692. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are crucial targets that catalyse the breakdown of acetylcholine (ACh) and are implicated in the pathogenesis of Alzheimer's disease (AD). Thus, the development of cholinesterase (AChE and BChE) inhibitors with a novel scaffold is an effective way to intervene in the pathogenesis of AD. This study used a multistep virtual screening method combined with machine learning (ML) models and structural bioinformatics to identify a novel dual acetylcholinesterase and butyrylcholinesterase inhibitor from the Maybridge database. Finally, five common hits (AW00462, AW00794, MWP01235, SCR00709, CD05692) were found after a consensus analysis of classification models and multistep screening protocol which showed their potential against AChE and BChE enzymes. Further, MM/GBSA free energy calculation and MD simulation studies predicted CD05692 as a potential inhibitor, which formed stable interactions with the active site residues compared with the other compounds. The docking score of CD05692 was found maximum negative (AChE= -15.03 Kcal/mole; BChE= -7.07 Kcal/mole) compared with the other identified hits. The MM/GBSA binding free energy ∆G (AChE= -76.34 Kcal/mole; BChE= -74.72 Kcal/mole) and the HOMO orbital energy (-0.352,410 eV) was also predicted to be in favour of CD05692. The in silico pharmacokinetic investigations also ascertained its drug likeliness properties. Finally, compound CD05692 was synthesised, characterized and evaluated in vitro for ChE (hAChE and hBChE) inhibitory potential. The IC 50 value of the lead CD05692 has shown good hAChE inhibition (IC 50 = 0.927 ± 0.019 µM) and moderate hBChE inhibition (IC 50 = 6.377 ± 0.038 µM). Thus, based on this study, we proposed that CD05692 could further be optimized as a lead to design potential cholinesterase inhibitors to combat AD. [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]