Identification of Butyrylcholinesterase and Monoamine Oxidase B Targeted Ligands and their Putative Application in Alzheimer's Treatment: A Computational Strategy

The vascular effects of peppermint (Mentha longifolia. L) on aorta in a mouse model: an ex-vivo and computational study

The present study examined the vascular effects of peppermint or mint (Mentha longifolia L.) using an abdominal aortic rings model. Concentration-response curves for mint oil were generated after precontracting isolated mouse aorta with phenylephrine. The effect of different receptor antagonists and ion channel or enzyme inhibitors on the vasorelaxant potential of mint oil were studied. Molecular docking studies were conducted using computational techniques to investigate the potential interactions between the bioactive constituents of mint oil and key vascular targets. The tension of aortic rings, which had been contracted by phenylephrine, relaxed as a function of the concentration of mint oil (0.0002-2 mg/mL). Pretreatment of the rings with the nitric oxide synthase inhibitor (L-NAME), a nonselective β-blocker (propranolol), and a muscarinic receptor blocker (atropine) didn't show significant resistance to the vasodilatory effects of the mint oil. The vasodilatory effects of mint oil were significantly diminished when the rings were pretreated with glibenclamide, an inhibitor of ATP-sensitive K+ channels. In addition, indomethacin, a cyclooxygenase (COX) inhibitor, did influence mint oil's tension in the preparations precontracted with phenylephrine. The present findings imply that ATP-sensitive K+ channels activation, blocking of Ca2+ channels, and inhibition of COX play a role in mediating the mint oil-induced vasorelaxation. Molecular docking studies of mint oil constituents showed that β-Elemene and Aromadendrene can interact with K+ and Ca2+ channels through various hydrophobic interactions with key amino acid residues. Additional work is needed to confirm the possible beneficial application of mint oil or its constituents in regulating the vascular tone.

Synthesis and Neurobehavioral Evaluation of a Potent Multitargeted Inhibitor for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) poses a significant health challenge worldwide, affecting millions of individuals, and projected to increase further as the global population ages. Current pharmacological interventions primarily target acetylcholine deficiency and amyloid plaque formation, but offer limited efficacy and are often associated with adverse effects. Given the multifactorial nature of AD, there is a critical need for novel therapeutic approaches that simultaneously target multiple pathological pathways. Targeting key enzymes involved in AD pathophysiology, such as acetylcholinesterase, butyrylcholinesterase, beta-site APP cleaving enzyme 1 (BACE1), and gamma-secretase, is a potential strategy to mitigate disease progression. To this end, our research group has conducted comprehensive in silico screening to identify some lead compounds, including IQ6 (SSZ), capable of simultaneously inhibiting the enzymes mentioned above. Building upon this foundation, we synthesized SSZ, a novel multitargeted ligand/inhibitor to address various pathological mechanisms underlying AD. Chemically, SSZ exhibits pharmacological properties conducive to AD treatment, featuring pyrrolopyridine and N-cyclohexyl groups. Preclinical experimental evaluation of SSZ in AD rat model showed promising results, with notable improvements in behavioral and cognitive parameters. Specifically, SSZ treatment enhanced locomotor activity, ameliorated gait abnormalities, and improved cognitive function compared to untreated AD rats. Furthermore, brain morphological analysis demonstrated the neuroprotective effects of SSZ, attenuating Aβ-induced neuronal damage and preserving brain morphology. Combined treatment of SSZ and conventional drugs (DON and MEM) showed synergistic effects, suggesting a potential therapeutic strategy for AD management. Overall, our study highlights the efficacy of multitargeted ligands like SSZ in combating AD by addressing the complex etiology of the disease. Further research is needed to elucidate the full therapeutic potential of SSZ and the exploration of similar compounds in clinical settings, offering hope for an effective AD treatment in the future.

Design of vilazodone-donepezil chimeric derivatives as acetylcholinesterase inhibitors by QSAR, molecular docking and molecular dynamics simulations

Alzheimer's disease (AD) is a disease that affects the cognitive abilities of older adults, and it is one of the biggest global medical challenges of the 21st century. Acetylcholinesterase (AChE) can increase acetylcholine concentrations and improve cognitive function in patients, and is a potential target to develop small molecule inhibitors for the treatment of Alzheimer's disease (AD). In this study, 29 vilazodone-donepezil chimeric derivatives are systematically studied using 3D-QSAR modeling, and a robust and reliable Topomer CoMFA model was obtained with: q2 = 0.720, r2 = 0.991, F = 287.234, N = 6, and SEE = 0.098. Based on the established model and combined with the ZINC20 database, 33 new compounds with ideal inhibitory activity are successfully designed. Molecular docking and ADMET property prediction also show that these newly designed compounds have a good binding ability to the target protein and can meet the medicinal conditions. Subsequently, four new compounds with good comprehensive ability are selected for molecular dynamics simulation, and the simulation results confirm that the newly designed compounds have a certain degree of reliability and stability. This study provides guidance for vilazodone-donepezil chimeric derivatives as a potential AChE inhibitor and has certain theoretical value.

A comprehensive review on the progress and challenges of tetrahydroisoquinoline derivatives as a promising therapeutic agent to treat Alzheimer's disease

Alzheimer's disease (AD) is the most common and irreversible neurodegenerative disorder worldwide. While the precise mechanism behind this rapid progression and multifaceted disease remains unknown, the numerous drawbacks of the available therapies are prevalent, necessitating effective alternative treatment methods. In view of the rising demand for effective AD treatment, numerous reports have shown that tetrahydroisoquinoline (THIQ) is a valuable scaffold in various clinical medicinal molecules and has a promising potential as a therapeutic agent in treating AD due to its significant neuroprotective, anti-inflammatory, and antioxidative properties via several mechanisms that target the altered signaling pathways. Therefore, this review comprehensively outlines the potential application of THIQ derivatives in AD treatment and the challenges in imparting the action of these prospective therapeutic agents. The review emphasizes a number of THIQ derivatives, including Dauricine, jatrorrhizine, 1MeTIQ, and THICAPA, that have been incorporated in AD studies in recent years. Subsequently, a dedicated section of the review briefly discusses the emerging potential benefits of multi-target therapeutics, which lie in their ability to be integrated with alternative therapeutics. Eventually, this review elaborates on the rising challenges and future recommendations for the development of therapeutic drug agents to treat AD effectively. In essence, the valuable research insights of THIQ derivatives presented in this comprehensive review would serve as an integral reference for future studies to develop potent therapeutic drugs for AD research.

New cyclopentaquinoline and 3,5-dichlorobenzoic acid hybrids with neuroprotection against oxidative stress for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative brain disease. Thus, drugs including donepezil, rivastigmine, and galantamine are not entirely effective in the treatment of this multifactorial disease. The present study evaluates eight derivatives (3a-3h) as candidates with stronger anti-AD potential but with less side effects. Reactive oxygen species (ROS) assays were used to assess oxidative stress which involve in the neurodegeneration. The neuroprotective properties of 3e against oxidative stress were done in three experiments using MTT test. The anti-AD potential was determined based on their anticholinesterase inhibition ability, determined using Ellman's method, Aβ aggregation potential according to thioflavin (Th) fluorescence assay, and their antioxidative and anti-inflammatory activities. Compound 3e exhibited moderate cholinesterase inhibition activity (AChE, IC₅₀ = 0.131 µM; BuChE, IC₅₀ = 0.116 µM; SI = 1.13), significant inhibition of Aβ(1-42) aggregation (55.7%, at 5 µM) and acceptable neuroprotective activity. Extensive analysis of in vitro and in vivo assays indicates that new cyclopentaquinoline derivatives offer promise as candidates for new anti-AD drugs.

Association of mTOR Pathway and Conformational Alterations in C-Reactive Protein in Neurodegenerative Diseases and Infections

Inflammatory biomarkers have been very useful in detecting and monitoring inflammatory processes along with providing helpful information to select appropriate therapeutic strategies. C-reactive protein (CRP) is a nonspecific, but quite useful medical acute inflammatory biomarker and is associated with persistent chronic inflammatory processes. Several studies suggest that different levels of CRP are correlated with neurological disorders such as Alzheimer's disease (AD). However, dynamics of CRP levels have also been observed in virus/bacterial-related infections leading to inflammatory responses and this triggers mTOR-mediated pathways for neurodegeneration diseases. The biophysical structural transition from CRP to monomeric CRP (mCRP) and the significance of the ratio of CRP levels on the onset of symptoms associated with inflammatory response have been discussed. In addition, mTOR inhibitors act as immunomodulators by downregulating the expression of viral infection and can be explored as a potential therapy for neurological diseases.

Virtual screening and molecular dynamics simulation study of abyssomicins as potential inhibitors of COVID-19 virus main protease and spike protein

The lack of any effective cure for the infectious COVID-19 disease has created a sense of urgency and motivated the search for effective antiviral drugs. Abyssomicins are actinomyces-derived spirotetronates polyketides antibiotics known for their promising antibacterial, antitumor, and antiviral activities. In this study, computational approaches were used to investigate the binding mechanism and the inhibitory ability of 38 abyssomicins against the main protease (Mpro) and the spike protein receptor-binding domain (RBD) of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The results identified abyssomicins C, J, W, atrop-O-benzyl abyssomicin C, and atrop-O-benzyl desmethyl abyssomicin C as the most potential inhibitors of Mpro and RBD with binding energy ranges between -8.1 and -9.9 kcal mol-1; and between -6.9 and -8.2 kcal mol-1, respectively. Further analyses of physicochemical properties and drug-likeness suggested that all selected active abyssomicins, with the exception of abyssomicin J, obeyed Lipinski's rule of five. The stability of protein-ligand complexes was confirmed by performing molecular dynamics simulation for 100 ns and evaluating parameters such as such as root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), solvent accessible surface area (SASA), total number of contacts, and secondary structure. Prime/MM-GBSA (Molecular Mechanics-General Born Surface Area) and principal component analysis (PCA) analyses also confirmed the stable nature of protein-ligand complexes. Overall, the results showed that the studied abyssomicins have significant interactions with the selected protein targets; therefore, they were deemed viable candidates for further in vitro and in vivo evaluation.Communicated by Ramaswamy H. Sarma.

Biomarker Quantification, Spectroscopic, and Molecular Docking Studies of the Active Compounds Isolated from the Edible Plant Sisymbrium irio L

Phytochemical investigation of the ethanolic extract of the aerial parts of Sisymbrium irio L. led to the isolation of four unsaturated fatty acids (1–4), including a new one (4), and four indole alkaloids (5–8). The structures of the isolated compounds were characterized with the help of spectroscopic techniques such as 1D, 2D NMR, and mass spectroscopy, and by correlation with the known compounds. In terms of their notable structural diversity, a molecular docking approach with the AutoDock 4.2 program was used to analyze the interactions of the identified fatty acids with PPAR-γ and the indole alkaloids with 5-HT1A and 5-HT2A, subtypes of serotonin receptors, respectively. Compared to the antidiabetic drug rivoglitazone, compound 3 acted as a potential PPAR-γ agonist with a binding energy of −7.4 kcal mol−1. Moreover, compound 8 displayed the strongest affinity, with binding energies of −6.9 kcal/mol to 5HT1A and −8.1 kcal/mol to 5HT2A, using serotonin and the antipsychotic drug risperidone as positive controls, respectively. The results of docked conformations represent an interesting target for developing novel antidiabetic and antipsychotic drugs and warrant further evaluation of these ligands in vitro and in vivo. On the other hand, an HPTLC method was developed to quantify α-linolenic acid in the hexane fraction of the ethanol extract of S. irio. The regression equation/correlation coefficient (r2) for linolenic acid was Y = 6.49X + 2310.8/0.9971 in the linearity range of 100–1200 ng/band. The content of α-linolenic acid in S. irio aerial parts was found to be 28.67 μg/mg of dried extract.

Multiple roles of fucoxanthin and astaxanthin against Alzheimer's disease: Their pharmacological potential and therapeutic insights

Alzheimer's disease (AD) is the most devastating neurodegenerative disorder affecting the elderly. The exact pathology of AD is not yet fully understood and several hallmarks such as the deposition of amyloid-β, tau hyperphosphorylation, and neuroinflammation, as well as mitochondrial, metal ions, autophagy, and cholinergic dysfunctions are known as pathologic features of AD. Since no definitive treatment has been proposed to target AD to date, many natural products have shown promising preventive potentials and contributed to slowing down the disease progression. Algae is a promising source of novel bioactive substances known to prevent neurodegenerative disorders including AD. In this context, fucoxanthin and astaxanthin, natural carotenoids abundant in algae, has shown to possess neuroprotective properties through antioxidant, and anti-inflammatory characteristics in modulating the symptoms of AD. Fucoxanthin and astaxanthin exhibit anti-AD activities by inhibition of AChE, BuChE, BACE-1, and MAO, suppression of Aβ accumulation. Also, fucoxanthin and astaxanthin inhibit apoptosis induced by Aβ_1-42 and H₂O₂-induced cytotoxicity, and modulate the antioxidant enzymes (SOD and CAT), through inhibition of the ERK pathway. Moreover, cellular and animal studies on the beneficial effects of fucoxanthin and astaxanthin against AD were also reviewed. The potential role of fucoxanthin and astaxanthin exhibits great efficacy for the management of AD by acting on multiple targets.

Nanomedicine-based immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease caused by the deposition of amyloid β (Aβ) fibrils forming extracellular plaques and the development of neurofibrillary tangles (NFT) of intracellular hyperphosphorylated tau protein. Currently, the AD treatments focus on improving cognitive and behavioral symptoms and have limited success. It is imperative to develop novel treatment approaches that can control/inhibit AD progression, especially in the elderly population. Immunotherapy provides a promising and safe treatment option for AD by boosting the patient's immune system. The minimum immune surveillance in the immune-privileged brain, however, makes immunotherapy for AD a challenging endeavor. Therefore, the success of AD immunotherapy depends mainly on the strategy by which therapeutics is delivered to the brain rather than its efficacy. The blood-brain barrier (BBB) is a major obstacle to therapeutic delivery into the brain microenvironment. Various nano-formulations have been exploited to improve the efficacy of AD immunotherapy. In this review, the applications of different types of nano-formulations in augmenting AD immunotherapy have been discussed.

New compounds from heterocyclic amines scaffold with multitarget inhibitory activity on Aβ aggregation, AChE, and BACE1 in the Alzheimer disease

The preset neurodegenerations in Alzheimer disease (AD) are due to several mechanisms such as amyloidogenic proteolysis, neuroinflammation, mitochondrial dysfunction, neurofibrillary tangles, cholinergic dysfunction, among others. The aim of this work was to develop multitarget molecules for the treatment of AD. Therefore, a family of 64 molecules was designed based on ligand structure pharmacophores able to inhibit the activity of beta secretase (BACE1) and acetylcholinesterase (AChE) as well as to avoid amyloid beta (Aβ_1–42) oligomerization. The backbone of designed molecules consisted of a trisubstituted aromatic ring, one of the substituents was a heterocyclic amine (piperidine, morpholine, pyrrolidine or N-methyl pyrrolidine) separated from the aromatic system by three carbon atoms. The set of compounds was screened in silico employing molecular docking calculations and chemoinformatic analyses. Based on Gibbs free energy of binding, binding mode and in silico predicted toxicity results, three of the best candidates were selected, synthesized, and evaluated in vitro; F3S4-m, F2S4-m, and F2S4-p. All three compounds prevented Aβ_1–42 aggregation (F3S4-m in 30.5%, F2S4-p in 42.1%, and F2S4-m in 60.9%). Additionally, inhibitory activity against AChE (ki 0.40 μM and 0.19 μM) and BACE1 (IC₅₀ 15.97 μM and 8.38 μM) was also observed for compounds F2S4-m and F3S4-m, respectively. Despite the BACE IC₅₀ results demonstrated that all compounds are very less potent respect to peptidomimetic inhibitor (PI-IV IC₅₀ 3.20 nM), we can still say that F3S4-m is capable to inhibit AChE and BACE1.

Identification of Potential Poly (ADP-Ribose) Polymerase-1 Inhibitors Derived from Rauwolfia serpentina: Possible Implication in Cancer Therapy

Poly (ADP-ribose) polymerase-1 (PARP-1) has been recognized as a prospective target for the development of novel cancer therapeutics. Several PARP-1 inhibitors are currently being considered for anticancer drug development and clinical investigation. Lately, natural compounds seem to be excellent alternative drug candidates for cancer treatment. Rauwolfia serpentina is a medicinal plant traditionally used in Indian subcontinents to treat various diseases. This study has been designed to identify the bioactive compounds derived from R. serpentina for possible binding and inhibition of PARP-1 using the molecular docking approach. Thirteen compounds were found to interact with the target with a binding affinity greater than the value of -9.0 kcal/mol. After screening the physicochemical properties, only 5 ligands (ajmalicine, yohimbine, isorauhimbine, rauwolscine, and 1,2-dihydrovomilenine) were found to obey all the parameters of Lipinski's rule of five, showed maximum drug-likeness, and possess no significant toxicity. These ligands displayed strong interactions with target PARP-1 via several hydrogen bonds and hydrophobic interactions. Therefore, these identified compounds derived from R. serpentina can be considered for drug development against cancer-targeting PARP-1.

Elucidating Antiangiogenic Potential of Rauwolfia serpentina: VEGFR-2 Targeting-Based Molecular Docking Study

Angiogenesis plays a critical role in tumorigenesis as it provides the necessary blood supply to the newly grown solid tumor. It helps maintain the tumor microenvironment, promotes tumor development, progression, and metastasis. The vascular epithelial growth factor (VEGF), interacting with the tyrosine kinase receptor VEGFR-2 on endothelial cells, exerts its proangiogenic activity. Hence, targeting the VEGFR-2 signaling is considered a promising strategy to inhibit angiogenesis and thus cancer treatment. This study aims to identify the bioactive compounds derived from the medicinal herb Rauwolfia serpentina that effectively binds with VEGFR-2. The bioactive compounds of R. serpentina were first screened for their physicochemical properties using the DataWarrior program (version 5.5.0). Finally, 17 compounds that obeyed Lipinski's rule of five and showed good drug-likeness were selected for molecular docking studies. Molecular docking results showed that the ligands ajmalicidine, 1, 2-dihydrovomilenine, rauwolscine, yohimbine, ajmaline, and papaverine interact strongly with the target VEGFR-2 receptor. Hydrogen bonds and hydrophobic interactions stabilized the interactions of these compounds with VEGFR-2. These compounds showed favourable drug-like properties and possess no significant toxicity. Therefore, the findings of this study indicate that the compounds derived from R. serpentina can be considered for the development of antiangiogenic drug candidates by targeting VEGFR-2.

Concatenation of molecular docking and molecular simulation of BACE-1, γ-secretase targeted ligands: in pursuit of Alzheimer's treatment

INTRODUCTION

Alzheimer's disease (AD), the most predominant cause of dementia, has evolved tremendously with an escalating frequency, mainly affecting the elderly population. An effective means of delaying, preventing, or treating AD is yet to be achieved. The failure rate of dementia drug trials has been relatively higher than in other disease-related clinical trials. Hence, multi-targeted therapeutic approaches are gaining attention in pharmacological developments.

AIMS

As an extension of our earlier reports, we have performed docking and molecular dynamic (MD) simulation studies for the same 13 potential ligands against beta-site APP cleaving enzyme 1 (BACE-1) and γ-secretase as a therapeutic target for AD. The In-silico screening of these ligands as potential inhibitors of BACE-1 and γ-secretase was performed using AutoDock enabled PyRx v-0.8. The protein-ligand interactions were analyzed in Discovery Studio 2020 (BIOVIA). The stability of the most promising ligand against BACE-1 and γ-secretase was evaluated by MD simulation using Desmond-2018 (Schrodinger, LLC, NY, USA).

RESULTS

The computational screening revealed that the docking energy values for each of the ligands against both the target enzymes were in the range of -7.0 to -10.1 kcal/mol. Among the 13 ligands, 8 (55E, 6Z2, 6Z5, BRW, F1B, GVP, IQ6, and X37) showed binding energies of ≤-8 kcal/mol against BACE-1 and γ-secretase. For the selected enzyme targets, BACE-1 and γ-secretase, 6Z5 displayed the lowest binding energy of -10.1 and -9.8 kcal/mol, respectively. The MD simulation study confirmed the stability of BACE-6Z5 and γ-secretase-6Z5 complexes and highlighted the formation of a stable complex between 6Z5 and target enzymes.

CONCLUSION

The virtual screening, molecular docking, and molecular dynamics simulation studies revealed the potential of these multi-enzyme targeted ligands. Among the studied ligands, 6Z5 seems to have the best binding potential and forms a stable complex with BACE-1 and γ-secretase. We recommend the synthesis of 6Z5 for future in-vitro and in-vivo studies.