A comprehensive review of multi-target directed ligands in the treatment of Alzheimer's disease

Topoisomerase II-targeting anticancer clinical candidates and drugs: A critical analysis, unravelling molecular medicinal insights and promising research roadmap

In recent years, the USFDA-approved drug molecules are being frequently analyzed to provide perspectives and strategies for novel therapeutic discovery and development. Some of the remarkable analyses include physicochemical properties of drugs relevant to oral bioavailability, frequent presence of drug relevant-structural motifs, natural products as sources of new drugs, and synthetic approaches to new drugs. In this review article, for the first time, we present a structure-function analysis of human topoisomerase II (hTopo II) inhibitors those are currently clinically used or under clinical trials for anticancer treatment. The case studies and a critical molecular medicinal insight for their therapeutic development have been presented. The review illustrates various key aspects: the hTopo II inhibitors' molecular modulations, common pharmacophores, interactions at molecular level crucial for inhibition of enzyme at its various stages of catalytic function, and network polypharmacology of Topo II with different targets. Numerous toxicophore motifs have been identified, which provide important alerts while designing and discovering novel therapeutic agents. A range of innovative approaches including property-focused strategies, ADCs, and Click Activated Protodrugs Against Cancer (CAPAC) that have addressed challenges faced in the hTopo II-based therapeutic development have been discussed. The analysis with perspectives represents a valuable educational and research resource that will encourage hTopo II-inhibition and its network polypharmacology based drug discovery studies.

Carvacrol/thymol derivatives as highly selective BuChE inhibitors with anti-inflammatory activities: Discovery and bio-evaluation

In this study, nine novel carvacrol/thymol derivatives incorporating carbamate groups were designed, synthesized, and evaluated as multifunctional anti-AD agents. These derivatives displayed superior BuChE inhibitory and anti-inflammatory characteristics compared to the parent compounds. While the derivatives exhibited AChE IC50 values exceeding the detectable limit (>100 μM), they demonstrated high potency as BuChE inhibitors, with IC50 values ranging from 0.05 to 9.62 μM. In an inflammation model of BV2 microglial cells induced by lipopolysaccharide (LPS), the derivatives effectively reduced the levels of the pro-inflammatory cytokine interleukin-1β (IL1β), with inhibition rates of IL1β exceeding 50 % at 10 μM. Notably, compound SXF3 ‌attained the highest BuChE inhibition efficacy (eqBuChE IC50 = 0.05 ± 0.003 μM, hBuChE IC50 = 0.04 ± 0.001 μM), the highest selectivity for BuChE (with a selectivity index, SI, exceeding 2000, calculated as the ratio of eeAChE IC50 to eqBuChE IC50) and high anti-inflammatory activity (inhibition of IL1β, IC50 = 8.33 ± 0.08 μM). In a scopolamine-induced AD mouse model, SXF3 (15 mg/kg) significantly reduced the latency to the platform and attenuated memory deficits. Biochemical analysis confirmed that SXF3 significantly increased acetylcholine (ACh) levels in the mice hippocampus, primarily due to the inhibition of BuChE rather than AChE, and that SXF3 significantly reduced IL1β levels to normal, further confirming its anti-inflammatory activities. Hence, the selective BuChE inhibitory properties and anti-inflammatory attributes of SXF3 render it a promising candidate for further investigation in the treatment of AD.

In silico screening of naturally derived dietary compounds as potential butyrylcholinesterase inhibitors for Alzheimer's disease treatment

Alzheimer's disease (AD) is a progressive neurodegenerative condition that causes a substantial decline in cognitive functions and affects memory, thinking abilities, and daily behavior. The most prominent hallmark of AD pathogenesis is the formation of amyloid-β plaques, among other associated pathways such as neurofibrillary tangles, mitochondrial dysfunction, neuroinflammation, and oxidative stress. Butyrylcholinesterase (BuChE), an acetylcholine-degrading enzyme, plays a critical role in the progression of Alzheimer's disease, particularly through its involvement in amyloid-β plaque formation. Thus, the inhibition of BuChE is considered a valuable therapeutic strategy for the management of AD. The present study aimed to identify potential bioactive chemicals from naturally occurring dietary compounds that could improve neurocognitive function and appear as a viable treatment for AD by inhibiting the function of BuChE. A small library of 44 natural dietary chemicals from a variety of dietary plants was subjected to comprehensive in silico studies, including molecular docking, molecular mechanics generalized born surface area (MM-GBSA) calculations, pharmacokinetics assessments, toxicity profiles, molecular dynamics (MD) simulation, and density functional theory (DFT) analysis. These studies revealed that CID 129886986 and CID 115269 showed stronger binding affinities with drug-likeness and no toxicity than the FDA-approved standard drug, Donepezil. Additionally, they exhibited strong structural stability with fewer fluctuations throughout the simulation, making them promising candidates for Alzheimer's disease treatment.

Discovery of new dual butyrylcholinesterase (BuChE) inhibitors and 5-HT7 receptor antagonists as compounds used to treat Alzheimer's disease symptoms

Alzheimer's disease is a neurodegenerative condition with no effective cure, and current therapies, like donepezil, only alleviate symptoms. Research has explored cholinesterase inhibitors and strategies targeting tau protein, often combining inhibitors with 5-HT receptor antagonists, particularly 5-HT6. However, dual-action BuChE inhibitors and 5-HT7 antagonists have not been studied until now. This study evaluated such compounds in an animal model, focusing on two candidates: compound 18 (BuChE IC50 = 4.75 μM; 5-HT7Ki = 7 nM) and compound 50 (BuChE IC50 = 2.53 μM; 5-HT7Ki = 1 nM). Compound 50 showed robust cognitive improvements, enhancing memory consolidation and acquisition, particularly in reversing scopolamine-induced deficits. In contrast, compound 18 exhibited limited or dose-dependent efficacy, potentially limiting its applicability. These findings highlight the strong potential of compound 50 for cognitive enhancement therapies and suggest it warrants further investigation.

Therapeutic Potential of Tricyclic Pyridazinone-Based Molecules: An Overview

Pyridazin-3(2H)one-based molecules have always attracted the attention of medicinal chemists due to their different pharmacological properties. The incorporation of such nuclei in therapeutically active molecules either as monocyclic units or as fused bi- or tricyclic scaffolds results in a wide range of pharmacological effects such as anti-inflammatory, analgesic, anticancer, antimicrobial, antiviral, cardiovascular-protective, antiulcer, and many other useful pharmacological activities. In accordance with our consolidated experience gained over the years in the chemistry and biology of tricyclic pyridazin-3(2H)ones, this review summarizes SAR studies of such pyridazinone-based polycyclic compounds endowed with various biological and therapeutic properties.

TCnet: A Novel Strategy to Predict Target Combination of Alzheimer's Disease via Network-Based Methods

Alzheimer's disease (AD) is a complex neurodegenerative disorder with an unclear pathogenesis; the traditional ″single gene-single target-single drug″ strategy is insufficient for effective treatment. This study explores a novel strategy for the multitarget therapy of AD by integrating multiomics data and employing network analysis. Different from conventional single-target methods, TCnet adopts a mechanism-driven strategy, utilizing multiomics data to decompose disease mechanisms, construct potential target combinations, and prioritize the optimal combinations using a scoring function. TCnet not only advances our understanding of disease mechanisms but also facilitates large-scale drug screening. This approach was further employed to screen active compounds from Huang-Lian-Jie-Du-Tang (HLJDT), identifying quercetin as a candidate targeting GSK3β and ADAM17. Subsequent in vitro experiments confirmed the neuroprotective and anti-inflammatory effects of quercetin. Overall, TCnet offers a promising approach for predicting target combinations and provides new insights and directions for drug discovery in AD.

Analysis of skeletal diversity of multi-target directed ligands (MTDLs) targeting Alzheimer's disease

Alzheimer's disease (AD) remains a significant healthcare challenge, necessitating innovative therapeutic approaches to address its complex and multifactorial nature. Traditional drug discovery strategies targeting single molecular targets are not sufficient for the effective treatment of AD. In recent years, MTDLs have emerged as promising candidates for AD therapy, aiming to simultaneously modulate multiple pathological targets. Among the various strategies employed in MTDL design, pharmacophore hybridization offers a versatile approach to integrate diverse pharmacophoric features within a single molecular scaffold. This strategy provides access to a wide array of chemical space for the design and development of novel therapeutic agents. This review, therefore, provides a comprehensive overview of skeletal diversity exhibited by MTDLs designed recently for AD therapy based on pharmacophore hybridization approach. A diverse range of pharmacophoric elements and core scaffolds hybridized to construct MTDLs that has the potential to target multiple pathological features of AD including amyloid-beta aggregation, tau protein hyperphosphorylation, cholinergic dysfunction, oxidative stress, and neuroinflammation are discussed. Through the comprehensive analysis and integration of structural insights of key biomolecular targets, this review aims to enhance optimization efforts in MTDL design, ultimately striving towards a comprehensive cure for the multifaceted pathophysiology of the disease.

Alkaloids from Caliphruria subedentata (Amaryllidaceae) as Regulators of AChE, BuChE, NMDA and GSK3 Activity: An In Vitro and In Silico Approach for Mimicking Alzheimer´s Disease

Patients with Alzheimer's disease (AD) have two types of abnormal protein buildups: amyloid plaques and neurofibrillary tangles, in addition to the early synaptic dysfunction associated with the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Impairment of the glutamatergic system is also crucial for neuronal survival, as it can cause synaptic dysfunction that overstimulates glutamate receptors, especially N-methyl-d-aspartate receptors (NMDARs). Another protein affecting neuronal health is glycogen synthase kinase-3 (GSK3), a widely preserved serine/threonine protein kinase linked to neuronal disorders, including AD. In recent years, alkaloids from the Amaryllidaceae have received great attention for their known anticholinergic activity, as well as their antioxidant, antigenotoxic, and neuroprotective properties. In this context, the identification of compounds capable of interacting with different targets involved in AD provides a possible new therapeutic strategy. In this study, we conducted a combination of in vitro and in silico approaches to identify the potential of C. subedentata in regulating key proteins involved in AD. Viability and neuroprotection assays were performed to evaluate the neuroprotection exerted by C. subedentata extract against neurotoxicity induced by Aβ (1-42) peptide and Okadaic acid in SH-SY5Y cells. Computational methods such as docking and molecular dynamic and viability therapeutic analysis were conducted to explore the interaction of alkaloids from C. subedentata with target proteins (AChE, BuChE, NMDA, and GSK-3) involved in AD. Our findings show that C. subedentata extract exerts neuroprotective effects against neurotoxic stimuli induced by Aβ (1-42) peptide and Okadaic acid. In addition, in silico approaches provide insight into how C. subedentata extract alkaloids interact with key proteins involved in AD. These findings provide insights into the potential therapeutic effects and action mechanisms of these alkaloids. We hope these rapid findings can contribute as a bridge to the identification of new molecules with the potential to counteract the effects of AD.

Development of novel melatonin-isatin hybrids as multifunctional agents for Alzheimer's disease

The development of multifunctional agents has been a heated area of research for AD treatment in recent years. In this work, a series of melatonin-isatin hybrids were designed, synthesized, and evaluated as multifunctional agents for treating AD. In vitro studies indicated that most of the synthesized compounds displayed moderate to good MAO-B inhibition activities and good antioxidant activities. In particular, compounds IM-5 and IM-10 exhibited the best inhibitory activities with IC50 value of 12.4 μM and 15.6 μM against MAO-B, and potent antioxidant activities with their ORAC-FL values of 4.6 and 5.2 at 5 μM, respectively. ThT assay revealed compounds IM-5 and IM-10 exhibited the optimal Aβ1-42 self-induced aggregation inhibitory activities with the inhibition ratio of 72.8% and 69.7% at 20 μM. In addition, compounds IM-5 and IM-10 exhibited low cytotoxicities and significant neuroprotective effects on Aβ1-42-induced and H2O2-induced SH-SY5Y cell injury. More importantly, compounds IM-5 and IM-10 could significantly ameliorate the memory impairment and cognition injury in scopolamine-induced mice. The SwissADME program was used to predict drug-like properties of compounds IM-5 and IM-10 which exhibited they had good pharmacokinetics and drug-likeness properties. Molecular docking study further manifested that compounds IM-5 and IM-10 showed high hMAO-B inhibitory potency. In summary, all above results revealed compounds IM-5 and IM-10 might be promising multifunctional agents for AD treatment.

Lipidomics-driven drug discovery and delivery strategies in glioblastoma

With few viable treatment options, glioblastoma (GBM) is still one of the most aggressive and deadly types of brain cancer. Recent developments in lipidomics have demonstrated the potential of lipid metabolism as a therapeutic target in GBM. The thorough examination of lipids in biological systems, or lipidomics, is essential to comprehending the changed lipid profiles found in GBM, which are linked to the tumor's ability to grow, survive, and resist treatment. The use of lipidomics in drug delivery and discovery is examined in this study, focusing on how it may be used to find new biomarkers, create multi-target directed ligands, and improve drug delivery systems. We also cover the use of FDA-approved medications, clinical trials that use lipid-targeted medicines, and the integration of lipidomics with other omics technologies. This study emphasizes lipidomics as a possible tool in developing more effective treatment methods for GBM by exploring various lipid-centric techniques.

Recent advancements in the therapeutic approaches for Alzheimer's disease treatment: current and future perspective

Alzheimer's disease (AD) is a complex, incurable neurological condition characterized by cognitive decline, cholinergic neuron reduction, and neuronal loss. Its exact pathology remains uncertain, but multiple treatment hypotheses have emerged. The current treatments, single or combined, alleviate only symptoms and struggle to manage AD due to its multifaceted pathology. The developmental drugs target pivotal disease factors involved in the envisaged hypotheses and include targets such as amyloid aggregation, hyperphosphorylated tau proteins, and receptors like cholinergic, adrenergic, etc. Present-day research focuses on multi-target directed ligands (MTDLs), which inhibit multiple factors simultaneously, helping slow the disease's progression. This review attempts to collate the recent information related to proposed hypotheses for AD etiology. It systematically organizes the advances in various therapeutic options for AD, with a particular emphasis on clinical candidates. Also, it is expected to help medicinal chemists design novel AD treatments based on available information, which could be helpful to AD patients.

Cross-disease drug discovery based on bioinformatics and virtual screening: Study of key genes in Alzheimer's disease and ovarian cancer

BACKGROUND

Alzheimer's disease (AD) and cancer, both age-related diseases, are characterized by abnormal cellular behavior. Epidemiological data indicate an inverse relationship between AD and various cancers. Accordingly, this study seeks to analyze the negatively correlated genes between AD and ovarian cancer and identify closely related compounds through virtual screening technology to explore potential therapeutic drugs.

METHODS

Microarray data were downloaded from the Gene Expression Omnibus database, and negatively correlated genes between AD and ovarian cancer were identified using bioinformatics analysis. Clinical prognostic and survival analyses were performed to identify genes most negatively associated with these diseases. The top ten compounds with the strongest binding to the target genes were screened from the ChemDiv database using virtual screening technology, considering the blood-brain barrier. Molecular dynamics simulations were used to identify potential sites for the binding of these compounds to the target protein MX1. Additionally, point mutation analysis of the target protein was performed. Finally, the binding site was verified in vitro.

RESULTS

The MX1 gene was most significantly negatively associated with AD and ovarian cancer. Molecular dynamics simulations revealed intersection sites at Glu-227 and Gly-188, where MX1 binds tightly to the head compound.

CONCLUSION

This study successfully identified MX1 as being negatively associated with AD and ovarian cancer and assessed the potential drug compounds that bind most closely to it. Our findings provide important rationale and candidate targets for the development of novel therapeutic strategies for AD and ovarian cancer.

Exploring Quinazoline as a Scaffold for Developing Novel Therapeutics in Alzheimer's Disease

Quinazoline, a privileged scaffold in medicinal chemistry, offers promising potential in the synthesis of anti-Alzheimer's disease (AD) drugs. This heterocyclic compound, characterized by its fused benzene and pyrimidine rings, enables the design of multifunctional agents targeting AD pathology. The drug-like aspects and pharmaceutical features of quinazoline derivatives have the potential to give rise to various therapeutic drugs. AD is a progressive neurodegenerative condition marked by memory decline, cognitive deterioration, and language disorders. Given its complexity and multifaceted nature, there is a pressing need to discover multi-target drugs to effectively address this debilitating disorder. A comprehensive literature review has demonstrated that quinazoline derivatives exhibit a wide range of therapeutic potential for AD. These compounds function as inhibitors of cholinesterases, β-amyloid aggregation, oxidative stress, and tau protein, among other protective effects. Here, we highlight the most significant and recent research on quinazoline-based anti-AD agents, aiming to support the development and discovery of novel treatments for AD.

1,3,5-Triazine: A Promising Molecular Scaffold for Novel Agents for the Treatment of Alzheimer's Disease

Currently, Alzheimer's disease (AD) is one of the most frequent forms of dementia. From a molecular perspective, the molecular characteristics that better define this disease consist of abnormal protein deposits between neuronal cells, namely senile plaques (SPs) and neurofibrillary tangles (NFTs), consisting of protein aggregates of amyloid-β and hyperphosphorylated tau protein, respectively. In addition to these protein aggregates, a third molecular hallmark of AD consists of depleted neurotransmitter acetylcholine levels. To date, the treatments developed for this disease are mostly focused on the use of AChE inhibitors, presenting only a symptomatic approach against the disease instead of a cure. Triazines are nitrogen-containing heterocyclic compounds that, throughout the years, have attracted a lot of curiosity from medicinal chemists for presenting numerous biological properties and being widely present in nature. In particular, this class of compounds has been associated with inhibiting several biological targets, emerging as a promising class for developing new pharmacological agents. However, there is still a scarcity of knowledge regarding the potential of this type of compound against any of the hallmarks of AD. For this reason, this paper intends to fulfill this absence by highlighting the potential of a subclass of triazines, 1,3,5-triazines (sym-triazines), as promising molecules for developing novel AD treatments. Thus, an in-depth analysis of 1,3,5-triazine derivatives is performed regarding its inhibitory activity against AChE (cholinergic hypothesis) and its capability to inhibit amyloid-β formation and aggregation (amyloid hypothesis). Through this analysis, it is possible to indicate some structural features optimal for each described activity, a compilation that we believe to be essential for the scientific community in this never-ending pursuit.

New Brusatol Derivatives as Anti-Settlement Agents Against Barnacles, Targeting HSP90: Design, Synthesis, Biological Evaluation, and Molecular Docking Investigations

The increasing challenge of marine biofouling, mainly due to barnacle settlement, necessitates the development of effective antifoulants with minimal environmental toxicity. In this study, fifteen derivatives of brusatol were synthesized and characterized using 13C-NMR, 1H-NMR, and mass spectrometry. All the semi-synthesized compounds obtained using the Multi-Target-Directed Ligand (MTDL) strategy, when evaluated as anti-settlement agents against barnacles, showed promising activity. Compound 3 exhibited the highest anti-settlement capacity, with an EC50 value of 0.1475 μg/mL, an LC50/EC50 ratio of 42.2922 (>15 indicating low toxicity), and a resuscitation rate of 71.11%, while it showed no significant phenotypic differences in the zebrafish embryos after treatment for 48 h. The toxicity screening of zebrafish also demonstrated the low ecotoxicity of the selected compounds. Furthermore, homology modeling of the HSP90 structure was performed based on related protein sequences in barnacles. Subsequently, molecular docking studies were conducted on HSP90 using these newly synthesized derivatives. Molecular docking analyses showed that most activated derivatives displayed low binding energies with HSP90, aligning well with the biological results. They were found to interact with key residues in the binding site, specifically ARG243, TYR101, and LEU73. These computational findings are anticipated to aid in predicting the enzyme targets of the tested inhibitors and their potential interactions, thus facilitating the design of novel antifoulants in future research endeavors.

Deoxyvasicinone hybrids in the management of Alzheimer's disease: Recent advances on manmade derivatives, pharmacological activities, and structure-activity relationship

Alzheimer's disease (AD) is a prevalent neurological illness that affects over 80% of aged adults globally in cases of dementia. Although the exact pathophysiological causes of AD remain unclear, its pathogenesis is primarily driven by several distinct biochemical alterations: (i) the accumulation of toxic Aβ plaques, (ii) the hyperphosphorylation of tau proteins, (iii) oxidative stress resulting in cell death, and (iv) an imbalance between the two main neurotransmitters, glutamate and acetylcholine (ACh). Currently, there are very few medications available and no treatment. Presently marketed medications include memantine, an N-methyl-d-aspartate receptor (NMDA) antagonist, and acetylcholinesterase (AChE) inhibitors: rivastigmine, donepezil, and galantamine. Unfortunately, these medications are only useful in the initial stages of AD. The mentioned medications only provide symptomatic relief and do not slow down the disease progression in the advanced stages. Therefore, there is an urgent need to develop potential candidates to treat AD, symptomatically and therapeutically. Many research groups focus on natural products due to their diverse therapeutic profiles and easy availability. One such natural product is deoxyvasicinone, isolated from Adhatoda vasica. Given its broad pharmacological profile, various researchers have developed semisynthetic hybrids of deoxyvasicinone to address multifaceted diseases like AD. In this review article, we tried to summarize the semisynthetic hybrids of deoxyvasicinone developed over the past decade (2014-2024) for managing AD. We focus on their design, pharmacological activity, and structure-activity relationship (SAR) analysis. We hope this review enhances the reader's understanding of future exploratory options for deoxyvasicinone hybrids in AD management.

Conjugates of amiridine and salicylic derivatives as promising multifunctional CNS agents for potential treatment of Alzheimer's disease

New conjugates of amiridine and salicylic derivatives (salicylamide, salicylimine, and salicylamine) with different lengths of alkylene spacers were designed, synthesized, and evaluated as potential multifunctional central nervous system therapeutic agents for Alzheimer's disease (AD). Conjugates demonstrated high acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition (IC50: AChE, 0.265-4.24 μM; BChE, 0.01-0.64 μM) but poor activity against off-target carboxylesterase (CES). Specifically, conjugates with a (CH2)8 spacer showed the highest AChE and BChE inhibition: 3-16 times more effective than amiridine. Salicylamides 7b and 7c had the maximum BChE/AChE selectivity ratios: 193 and 138, respectively. Conjugates were mixed-type reversible inhibitors of both cholinesterases and displaced propidium from the AChE peripheral anionic site (PAS) at the level of donepezil. All conjugates inhibited Aβ42 self-aggregation in the thioflavin test; inhibition increased with spacer elongation, being greatest for (CH2)8. The results agreed with molecular docking to AChE, BChE, and Aβ42. Conjugates exhibited high 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)•+-scavenging activity comparable to the standard antioxidant Trolox, and they showed the ability to bind Cu2+, Fe2+, and Zn2+. Conjugates had favorable predicted intestinal absorption and blood-brain barrier permeability. Altogether, the results indicate that the new conjugates possess potential for further development as multifunctional anti-AD drug candidates.

Novel Natural Candidates for Replacing Synthetic Additives in Nutraceutical and Pharmaceutical Areas: Two Senna Species (S. alata (L.) Roxb. and S. occidentalis (L.) Link)

Senna alata (L.) Roxb. and Senna occidentalis (L.) Link (family Fabaceae) are commonly used in different systems of traditional medicine to treat ailments. The present study was designed to determine the phytoconstituents, antioxidant, enzyme inhibition, and antimicrobial activities of the methanolic extract from the leaves of these two Senna species. A total of 75 phenolic compounds belonging to dihydroxybenzoic acids, dihydroxycinnamic acids, flavonoid C-glycosides, flavonoid O-glycosides, flavonoid aglycones, anthraquinone glycosides, and anthraquinone aglycones were identified. Flavonoid C-glycosides were only found in S. occidentalis while sennosides A, B, and C were only detected in S. alata. In line with its higher total phenolic and flavonoids contents, S. alata exerted significantly (p < 0.05) higher antiradical (2,2-diphenyl-1-picrylhydrazy (DPPH) = 58.36 mg trolox equivalent (TE)/g; 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) = 118.86 mg TE/g), ions reducing (cupric reducing antioxidant capacity (CUPRAC) = 93.85 mg TE/g; ferric reducing antioxidant power (FRAP) = 50.42 mg TE/g), and total antioxidant (1.39 mmol TE/g) activities than S. occidentalis. S. alata revealed significantly (p < 0.05) higher inhibitory effect against butyrylcholinesterase (1.67 mg galantamine equivalent (GALAE)/g), tyrosinase (45.07 mg KAE/g) 45.07 mg kojic acid equivalent (KAE)/g), α-glucosidase (0.73 mmol acarbose equivalent (ACAE)/g), and α-amylase (2.95 mmol ACAE/g) enzymes. Both species showed high antibacterial and antifungal activities with remarkable antifungal activity exerted by S. alata against Trichoderma viride (minimum inhibition concentration (MIC) 1 mg/mL), similar to that of Ketoconazole. The study utilized molecular docking, molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) free energy calculations, and molecular dynamics simulations to evaluate the binding interactions between anthraquinone glycosides and various bacterial enzymes, including targets from Escherichia coli and Staphylococcus aureus. The findings suggest that compounds like sennoside A, sennoside B, and chrysophanol exhibit strong binding affinities, stable interactions, and potential as antimicrobial inhibitors, especially against vital bacterial proteins such as MurE and 30S ribosome S3. In conclusion, our findings underscore the biopharmaceutical potential of these two Senna species, suggesting their significance as sources of bioactive agents for health-related applications.

Cinnamic Acid Derivatives: Recent Discoveries and Development Strategies for Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder that leads to cognitive decline and memory impairment. It is characterized by the accumulation of Amyloid-beta (Aβ) plaques, the abnormal phosphorylation of tau protein forming neurofibrillary tangles, and is often accompanied by neuroinflammation and oxidative stress, which contribute to neuronal loss and brain atrophy. At present, clinical anti-AD drugs are mostly single-target, improving the cognitive ability of AD patients, but failing to effectively slow down the progression of AD. Therefore, research on effective multi-target drugs for AD has become an urgent problem to address. The main derivatives of hydroxycinnamic acid, caffeic acid, and ferulic acid, are widely present in nature and have many pharmacological activities, such as antimicrobial, antioxidant, anti-inflammatory, neuroprotective, anti-Aβ deposition, and so on. The occurrence and development of AD are often accompanied by pathologies, such as oxidative stress, neuroinflammation, and Aβ deposition, suggesting that caffeic acid and ferulic acid can be used in the research on anti-AD drugs. Therefore, in this article, we have summarized the multi-target anti-AD derivatives based on caffeic acid and ferulic acid in recent years, and discussed the new design direction of cinnamic acid derivatives as backbone compounds. It is hoped that this review will provide some useful strategies for anti-AD drugs based on cinnamic acid derivatives.

Design, synthesis, and biological evaluation of tetrahydropyrimidine analogue as GSK-3β/Aβ aggregation inhibitor and anti-Alzheimer's agent

The complex nature of Alzheimer's disease (AD) etiopathology is among the principal hurdles to developing effective anti-Alzheimer agents. Tau pathology and Amyloid-β (Aβ) accumulation are hallmarks and validated therapeutic strategies of AD. GSK-3β is a serine/threonine kinase involved in tau phosphorylation. Its excessive activity also contributes to the production of Aβ plaques, making GSK-3β an attractive AD target. Taking this into account, In this article, we outline the design, synthesis, and biological validation of a focused library of 1,2,3,4-tetrahydropyrimidine based derivatives as inhibitors of GSK-3β, tau phosphorylation, and Aβ accumulation. The inhibitory activity of forty nine synthetic compounds was tested against GSK-3β and other AD-relevant kinases. The kinetic experiments revealed the mode of GSK-3β inhibition by the most potent compound 44. The in- vitro drug metabolism and pharmacokinetic studies were thereafter performed. The anti-aggregation activity of the most potent GSK-3β inhibitor was tested using AD transgenic Caenorhabditis elegans (C. elegans) strain CL2006 for quantification of Aβ plaques and BR5706 C. elegans strain for tau pathology evaluation. We then evaluated the blood-brain barrier permeability and got promising results. Therefore, we present compound 44 as a potential ATP-competitive GSK-3β inhibitor with good metabolism and pharmacokinetic profile, anti-aggregation properties for amyloid beta protein, and reduction in tau-phosphorylation levels. We recommend more investigation into compound 44-based small molecules as possible targets for AD disease-modifying treatments.

Acetylcholinesterase inhibitory phloroglucinols from tropic Rhodomyrtus tomentosa

Four previously undescribed phloroglucinols, including three pairs of enantiomers, (±)-rhodotomentodimer F, (±)-rhodotomentodimer G, and (±)-rhodotomentomonomer E, and one phloroglucinol-sesquiterpene meroterpenoid, rhodotomentodione E, together with one previously reported congener, (±)-rhodomyrtosone A, were obtained from the leaves of Rhodomyrtus tomentosa. The structures including absolute configurations of previously undescribed isolates were elucidated by extensive spectroscopic analysis (HRESIMS and NMR), ECD calculations, and single-crystal X-ray diffraction. (±)-Rhodotomentodimer F is a rare phloroglucinol derivative conjugated by a β-triketone moiety and an unprecedented resorcinol unit via the formation of a rare bis-furan ring system, whereas (±)-rhodotomentomonomer E shares a rearranged pentacyclic scaffold. Pharmacologically, (±)-rhodotomentomonomer E showed the strongest human acetylcholinesterase (hAChE) inhibitory effect with an IC50 value of 1.04 ± 0.05 μM. Molecular formula studies revealed that hydrogen bonds formed between hAChE residues Glu202, Ser203, Ala204, Gly121, Gly122, Tyr337, and His447 and (±)-rhodotomentomonomer E played crucial roles in its observed activity. These findings indicated that the leaves of Rhodomyrtus tomentosa can supply a rich source of hAChE inhibitors. These inhibitors might potentially be utilized in the therapeutic strategy for Alzheimer's disease, offering promising candidates for further research and development.

Recent advances in the natural product analogues for the treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) represent a hallmark of numerous incapacitating and untreatable conditions, the incidence of which is escalating swiftly, exemplified by Alzheimer's disease and Parkinson's disease. There is an urgent necessity to create pharmaceuticals that exhibit high efficacy and minimal toxicity in order to address these debilitating diseases. The structural complexity and diversity of natural products confer upon them a broad spectrum of biological activities, thereby significantly contributing to the history of drug discovery. Nevertheless, natural products present challenges in drug discovery, including time-consuming separation processes, low content, low bioavailability, and other related issues. To address these challenges, numerous analogs of natural products have been synthesized. This methodology enables the rapid synthesis of analogs of natural products with the potential to serve as lead compounds for drug development, thereby paving the way for the discovery of novel pharmaceuticals. This paper provides a summary of 127 synthetic analogues featuring various natural product structures, including flavonoids, alkaloids, coumarins, phenylpropanoids, terpenoids, polyphenols, and amides. The compounds are categorized based on their efficacy in treating various diseases. Furthermore, this article delves into the structure-activity relationship (SAR) of certain analogues, offering a thorough point of reference for the systematic development of pharmaceuticals aimed at addressing neurodegenerative conditions.

Essential Oil Composition and Anti-Cholinesterase Properties of Cryptomeria japonica Foliage Harvested in São Miguel Island (Azores) in Two Different Seasons

The Azorean Cryptomeria japonica forest operations and wood industry generate considerable foliage biomass residues that are used for local essential oil (EO) production. However, research on seasonal variation of C. japonica EO remains scarce. In this study, the EOs from fresh Azorean C. japonica foliage (Az-CJF) collected in autumn (Aut) and spring (Spr) were obtained via hydrodistillation and investigated for their physical properties, yield, chemical composition, and bioactivities. Both EOs presented a strong odor, a yellowish color, a density around 0.9 g·mL-1, and similar yields (approximately 1% v/w, dry matter). Nevertheless, the GC-MS analyses showed a decrease in monoterpene hydrocarbons (MH) and an increase in oxygenated sesquiterpenes (OS) contents in Spr-EO compared with Aut-EO (16% vs. 35% for MH and 45% vs. 31% for OS, respectively). In addition, the predominant components were kaur-16-ene (23%) for Spr-EO and phyllocladene (19%) for Aut-EO, revealing that both EOs were rich in diterpene hydrocarbons (29% vs. 26%). Concerning its toxicity against brine shrimp, a low mortality (0-38%) was observed at a concentration range of 100-180 μg·mL-1. Regarding the anti-cholinesterase properties, both EOs were inactive against acetylcholinesterase but showed anti-butyrylcholinesterase activity superior to (-)-α-pinene, a major compound of Az-CJF EO (IC50 values: 84, 148, and 648 μg·mL-1 for Spr-EO, Aut-EO, and α-pinene, respectively). Overall, the results indicate the potential benefit of both seasonal EOs in Alzheimer's disease treatment. In conclusion, this study demonstrated that season strongly influences the Az-CJF EO quantitative composition and thus its bioactivity, aiding in the selection of the most high-quality raw materials for use in Azorean C. japonica EO aromatherapy industry.

Design, synthesis and evaluation of benzothiazole-derived phenyl thioacetamides as dual inhibitors of monoamine oxidases and cholinesterases

A series of rationally designed benzothiazole-derived thioacetamides was synthesized and investigated for monoamine oxidases (MAO-A and MAO-B) and cholinesterases (AChE and BChE) inhibition properties. The tested compounds 18-31 inhibited MAO-A and MAO-B in the micromolar to nanomolar range and AChE in the submicromolar range. Compound 28 was identified as the most potent MAO-A inhibitor with an IC50 = 0.030 ± 0.008 µM, whereas compound 30 showed the highest potency towards MAO-B and AChE with IC50 values of 0.015 ± 0.007 µM and 0.114 ± 0.003 µM, respectively. Further, compound 30 inhibited BChE at an IC50 value of 4.125 ± 0.143 µM. Among all screened molecules, compound 30 emerged as the lead dual MAO-B and AChE inhibitor that blocked these enzymes in a competitive-reversible and mixed-reversible mode, respectively. Selected compounds have displayed iron-chelation and antioxidant properties. Further, computational assessment of ligand binding affinity and pharmacokinetic parameters of all new compounds and molecular dynamic simulation of compound 30 with MAO-B and AChE were carried out to understand ligand efficiency, pharmacokinetic, and virtual molecular interaction profile, respectively. The in silico ADMET prediction studies revealed a few undesired pharmacokinetic attributes of our compounds. The attempted virtual lead-based library synthesis and subsequent biological investigation produced a new benzothiazole-bearing dual MAO-B and AChE inhibitor as a prospective MTDL candidate for treating neurological disorders.

Advances in understanding biomarkers and treating neurological diseases - Role of the cerebellar dysfunction and emerging therapies

Cerebellar dysfunction is increasingly recognized as a critical factor in various neurological diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Research has revealed distinct cerebellar atrophy patterns in conditions such as AD and multiple system atrophy, and studies in mice have highlighted its impact on motor control and cognitive functions. Emerging research into autism spectrum disorder (ASD) has identified key targets, such as elevated levels of chemokine receptors and ZIC family genes. Biomarkers, including cerebrospinal fluid (CSF), genetic markers, and advances in AI and bioinformatics, are enhancing early diagnosis and personalized treatment across neurodegenerative disorders. Notable advancements include improved diagnostic tools, gene therapy, and novel clinical trials. Despite progress, challenges such as the bloodbrain barrier and neuroinflammation persist. Current therapies for AD, PD, HD, and ALS, including antisense oligonucleotides and stem cell treatments, show promise but require further investigation. A comprehensive approach that integrates diagnostic methods and innovative therapies is essential for effective management and improved patient outcomes.

Edaravone N-benzyl pyridinium derivatives: BACE-1 inhibition, kinetics and in silico binding pose determination

BACE-1 plays a pivotal role in the production of β-amyloid (Aβ) peptides, implicated in Alzheimer's Disease (AD) pathology. We previously described edaravone N-benzyl pyridinium derivatives (EBPDs) that exhibited multifunctional activity against multiple AD targets. In this study we explored the EBPDs BACE-1 inhibitory activity to potentially enhance the compounds therapeutic profile. The EBPDs exhibited moderate BACE-1 inhibitory activity (IC50 = 44.10 µM - 123.70 µM) and obtained IC50 values between 2.0 and 5.8-fold greater than resveratrol, a known BACE-1 inhibitor (IC50 = 253.20 µM), in this assay. Compound 3 was the most potent inhibitor with an IC50 of 44.10 µM and a Ki of 19.96 µM and a mixed-type mode of inhibition that favored binding in a competitive manner. Molecular docking identified crucial interactions with BACE-1 active site residues, supported by 100 ns MD simulations. The study highlighted the EBPDs therapeutic potential as BACE-1 inhibitors and multifunctional anti-AD therapeutic agents.

Multitarget-Directed Ligands Hitting Serotonin Receptors: A Medicinal Chemistry Survey

Serotonin (5-hydroxytryptamine, 5-HT) is a ubiquitous neurotransmitter in the human body. In the central nervous system, 5-HT affects sleep, pain, mood, appetite, and attention, while in the peripheral nervous system, 5-HT modulates peristalsis, mucus production, and blood vessel dilation. Fourteen membrane receptors mediate 5-HT activity. In agreement with the crucial roles played by 5-HT, many drugs target 5-HT receptors (5-HTRs). Therefore, it is unsurprising that many efforts have been devoted to discovering multitarget-directed ligands (MTDLs) capable of engaging one or more 5-HTRs plus another target phenotypically linked to a particular disease. In this review, we will describe medicinal chemistry efforts in designing MTDLs encompassing activity for one or more 5-HTRs, starting with atypical antipsychotics and moving to dual 5-HT1AR/serotonin transporter ligands, 5-HT6R antagonists/acetyl cholinesterases inhibitors, and 5-HT4R agonists/acetyl cholinesterases inhibitors. We will also provide an outlook on the most recent efforts made in the field.

Advances in Cholinesterase Inhibitor Research-An Overview of Preclinical Studies of Selected Organoruthenium(II) Complexes

Cholinesterase (ChE) inhibitors are crucial therapeutic agents for the symptomatic treatment of certain chronic neurodegenerative diseases linked to functional disorders of the cholinergic system. Significant research efforts have been made to develop novel derivatives of classical ChE inhibitors and ChE inhibitors with novel scaffolds. Over the past decade, ruthenium complexes have emerged as promising novel therapeutic alternatives for the treatment of neurodegenerative diseases. Our research group has investigated a number of newly synthesized organoruthenium(II) complexes for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Three complexes (C1a, C1-C, and C1) inhibit ChE in a pharmacologically relevant range. C1a reversibly inhibits AChE and BChE without undesirable peripheral effects, making it a promising candidate for the treatment of Alzheimer's disease. C1-Cl complex reversibly and competitively inhibits ChEs, particularly AChE. It inhibits nerve-evoked skeletal muscle twitch and tetanic contraction in a concentration-dependent manner with no effect on directly elicited twitch and tetanic contraction and is promising for further preclinical studies as a competitive neuromuscular blocking agent. C1 is a selective, competitive, and reversible inhibitor of BChE that inhibits horse serum BChE (hsBChE) without significant effect on the peripheral neuromuscular system and is a highly species-specific inhibitor of hsBChE that could serve as a species-specific drug target. This research contributes to the expanding knowledge of ChE inhibitors based on ruthenium complexes and highlights their potential as promising therapeutic candidates for chronic neurodegenerative diseases.

Design of Promising Thiazoloindazole-Based Acetylcholinesterase Inhibitors Guided by Molecular Docking and Experimental Insights

Alzheimer's disease is characterized by a progressive deterioration of cognitive function and memory loss, and it is closely associated with the dysregulation of cholinergic neurotransmission. Since acetylcholinesterase (AChE) is a critical enzyme in the nervous system, responsible for breaking down the neurotransmitter acetylcholine, its inhibition holds a significant interest in the treatment of various neurological disorders. Therefore, it is crucial to develop efficient AChE inhibitors capable of increasing acetylcholine levels, ultimately leading to improved cholinergic neurotransmission. The results reported here represent a step forward in the development of novel thiazoloindazole-based compounds that have the potential to serve as effective AChE inhibitors. Molecular docking studies revealed that certain of the evaluated nitroindazole-based compounds outperformed donepezil, a well-known AChE inhibitor used in Alzheimer's disease treatment. Sustained by these findings, two series of compounds were synthesized. One series included a triazole moiety (Tl45a-c), while the other incorporated a carbazole moiety (Tl58a-c). These compounds were isolated in yields ranging from 66 to 87% through nucleophilic substitution and Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reactions. Among the synthesized compounds, the thiazoloindazole-based 6b core derivatives emerged as selective AChE inhibitors, exhibiting remarkable IC50 values of less than 1.0 μM. Notably, derivative Tl45b displays superior performance as an AChE inhibitor, boasting the lowest IC50 (0.071 ± 0.014 μM). Structure-activity relationship (SAR) analysis indicated that derivatives containing the bis(trifluoromethyl)phenyl-triazolyl group demonstrated the most promising activity against AChE, when compared to more rigid substituents such as carbazolyl moiety. The combination of molecular docking and experimental synthesis provides a suitable and promising strategy for the development of new efficient thiazoloindazole-based AChE inhibitors.

One flask cascade approach to a complex pyrano[2,3-c]pyrazole-pyrazolone hybrid heterocyclic system and its initiatory neurobiological profiling

A one-pot multicomponent approach towards a hybrid heterocyclic pyrano[2,3-c]pyrazole-pyrazolone framework involving tandem Knoevenagel condensation, sequential intermolecular 1,6-Michael addition, and 6-endo dig cyclization between diynones and pyrazolones, mediated by DBU, has been discovered. This process embodies several green and sustainable chemistry features. Preliminary bioactivity profiling of the new chemical entities indicates neuroprotective and AChE inhibitory activities.

Stepwise Structural Simplification of the Dihydroxyanthraquinone Moiety of a Multitarget Rhein-Based Anti-Alzheimer Lead to Improve Drug Metabolism and Pharmacokinetic Properties

Multitarget compounds have emerged as promising drug candidates to cope with complex multifactorial diseases, like Alzheimer's disease (AD). Most multitarget compounds are designed by linking two pharmacophores through a tether chain (linked hybrids), which results in rather large molecules that are particularly useful to hit targets with large binding cavities, but at the expense of suffering from suboptimal physicochemical/pharmacokinetic properties. Molecular size reduction by removal of superfluous structural elements while retaining the key pharmacophoric motifs may represent a compromise solution to achieve both multitargeting and favorable physicochemical/PK properties. Here, we report the stepwise structural simplification of the dihydroxyanthraquinone moiety of a rhein-huprine hybrid lead by hydroxy group removal-ring contraction-ring opening-ring removal, which has led to new analogs that retain or surpass the potency of the lead on its multiple AD targets while exhibiting more favorable drug metabolism and pharmacokinetic (DMPK) properties and safety profile. In particular, the most simplified acetophenone analog displays dual nanomolar inhibition of human acetylcholinesterase and butyrylcholinesterase (IC50 = 6 nM and 13 nM, respectively), moderately potent inhibition of human BACE-1 (48% inhibition at 15 µM) and Aβ42 and tau aggregation (73% and 68% inhibition, respectively, at 10 µM), favorable in vitro brain permeation, higher aqueous solubility (18 µM) and plasma stability (100/96/86% remaining in human/mouse/rat plasma after 6 h incubation), and lower acute toxicity in a model organism (zebrafish embryos; LC50 >> 100 µM) than the initial lead, thereby confirming the successful lead optimization by structural simplification.

Harnessing the Therapeutic Potential of Peptides for Synergistic Treatment of Alzheimer's Disease by Targeting Aβ Aggregation, Metal-Mediated Aβ Aggregation, Cholinesterase, Tau Degradation, and Oxidative Stress

Alzheimer's disease (AD) is a progressive multifaceted neurodegenerative disease and remains a formidable global health challenge. The current medication for AD gives symptomatic relief and, thus, urges us to look for alternative disease-modifying therapies based on a multitarget directed approach. Looking at the remarkable progress made in peptide drug development in the last decade and the benefits associated with peptides, they offer valuable chemotypes [multitarget directed ligands (MTDLs)] as AD therapeutics. This review recapitulates the current developments made in harnessing peptides as MTDLs in combating AD by targeting multiple key pathways involved in the disease's progression. The peptides hold immense potential and represent a convincing avenue in the pursuit of novel AD therapeutics. While hurdles remain, ongoing research offers hope that peptides may eventually provide a multifaceted approach to combat AD.

Drug Development for Alzheimer's and Parkinson's Disease: Where Do We Go Now?

Neurodegenerative diseases (NDs) are a set of progressive, chronic, and incurable diseases characterized by the gradual loss of neurons, culminating in the decline of cognitive and/or motor functions. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common NDs and represent an enormous burden both in terms of human suffering and economic cost. The available therapies for AD and PD only provide symptomatic and palliative relief for a limited period and are unable to modify the diseases' progression. Over the last decades, research efforts have been focused on developing new pharmacological treatments for these NDs. However, to date, no breakthrough treatment has been discovered. Hence, the development of disease-modifying drugs able to halt or reverse the progression of NDs remains an unmet clinical need. This review summarizes the major hallmarks of AD and PD and the drugs available for pharmacological treatment. It also sheds light on potential directions that can be pursued to develop new, disease-modifying drugs to treat AD and PD, describing as representative examples some advances in the development of drug candidates targeting oxidative stress and adenosine A2A receptors.

Rational design of a near-infrared fluorescent probe for monitoring butyrylcholinesterase activity and its application in development of inhibitors

Butyrylcholinesterase (BChE) is widely expressed in multiple tissues and has a vital role in several key human disorders, such as Alzheimer's disease and tumorigenesis. However, the role of BChE in human disorders has not been investigated. Thus, to quantitatively detect and visualize dynamical variations in BChE activity is essential for exploring the biological roles of BChE in the progression of a number of human disorders. Herein, based on the substrate characteristics of BChE, we customized and synthesized three near-infrared (NIR) fluorescent probe substrates with cyanine-skeleton, and finally selected a NIR fluorescence probe substrate named CYBA. The CYBA demonstrated a significant increase in fluorescence when interacting with BChE, but mainly avoided AChE. Upon the addition of BChE, CYBA could be specifically hydrolyzed to TBO, resulting in a significant NIR fluorescence signal enhancement at 710 nm. Systematic evaluation revealed that CYBA exhibited exceptional chemical stability in complex biosamples and possessed remarkable selectivity and sensitivity towards BChE. Moreover, CYBA was successfully applied for real-time imaging of endogenous BChE activity in two types of nerve-related living cells. Additionally, CYBA demonstrated exceptional stability in the detection of complex biological samples in plasma recovery studies (97.51%-104.01%). Furthermore, CYBA was used to construct a high-throughput screening (HTS) method for BChE inhibitors using human plasma as the enzyme source. We evaluated inhibitory effects of a series of natural products and four flavonoids were identified as potent inhibitors of BChE. Collectively, CYBA can serve as a practical tool to track the changes of BChE activity in complicated biological environments due to its excellent capabilities.