Novel multifunctional tacrine-donepezil hybrids against Alzheimer's disease: Design synthesis and bioactivity studies.

A series of tacrine-donepezil hybrids were synthesized as potential multifunctional anti-Alzheimer's disease (AD) compounds. For this purpose, tacrine and the benzylpiperidine moiety of donepezil were fused with a hydrazone group to achieve a small library of tacrine-donepezil hybrids. In agreement with the design, all compounds showed inhibitory activity toward both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC50 values in the low micromolar range. Kinetic studies on the most potent cholinesterase (ChE) inhibitors within the series showed a mixed-type inhibition mechanism on both enzymes. Also, the docking studies indicated that the compounds inhibit ChEs by dual binding site (DBS) interactions. Notably, tacrine-donepezil hybrids also exhibited significant neuroprotection against H2O2-induced cell death in a differentiated human neuroblastoma (SH-SY5Y) cell line at concentrations close to their IC50 values on ChEs and showed high to medium blood-brain barrier (BBB) permeability on human cerebral microvascular endothelial cells (HBEC-5i). Besides, the compounds do not cause remarkable toxicity in a human hepatocellular carcinoma cell line (HepG2) and SH-SY5Y cells. Additionally, the compounds were predicted to also have good bioavailability. Among the tested compounds, H4, H16, H17, and H24 stand out with their biological profile. Taken together, the proposed novel tacrine-donepezil scaffold represents a promising starting point for the development of novel anti-ChE multifunctional agents against AD.

Association between Albumin Alterations and Renal Function in Patients with Type 2 Diabetes Mellitus.

Diabetic kidney disease (DKD) is a major cause of morbidity and mortality in individuals with type 2 diabetes mellitus (T2DM). The aim of this study was to investigate whether albumin structural alterations correlate with DKD severity and evaluate whether native and reduced albumin concentrations could complement the diagnosis of DKD. To this end, one hundred and seventeen T2DM patients without (n = 42) and with (n = 75) DKD (DKD I-III upon KDIGO classification) were evaluated; the total albumin concentration (tHA) was quantified by a bromocresol green assay, while structural alterations were profiled via liquid chromatography-high-resolution mass spectrometry (LC-HRMS). The concentrations of native albumin (eHA, effective albumin) and reduced albumin (rHA) were subsequently assessed. The HRMS analyses revealed a reduced relative amount of native albumin in DKD patients along with an increased abundance of altered forms, especially those bearing oxidative modifications. Accordingly, both eHA and rHA values varied during the stages of progressive renal failure, and these alterations were dose-dependently correlated with renal dysfunction. A ROC curve analysis revealed a significantly greater sensitivity and specificity of eHA and rHA than of tHA for diagnosing DKD. Importantly, according to the multivariate logistic regression analysis, the eHA was identified as an independent predictor of DKD.

Exopolysaccharides from vaginal lactobacilli modulate microbial biofilms.

BACKGROUND: Exopolysaccharides (EPS) secreted by beneficial lactobacilli exert a plethora of positive activities, but little is known about their effects on biofilms of opportunistic vaginal pathogens and especially on biofilms of lactobacilli themselves. Here, the EPS produced by six vaginal lactobacilli, belonging to Lactobacillus crispatus (BC1, BC4, BC5) and Lactobacillus gasseri (BC9, BC12, BC14) species were isolated from cultural supernatants and lyophilized. RESULTS: Lactobacillus EPS were chemically characterized in terms of monosaccharide composition by liquid chromatography (LC) analysis coupled to UV and mass spectrometry (MS) detection. Moreover, the ability of EPS (0.1, 0.5, 1 mg/mL) to stimulate the biofilm formation of lactobacilli and to inhibit the formation of pathogens' biofilms was evaluated by crystal violet (CV) staining and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Isolated EPS (yields 133-426 mg/L) were heteropolysaccharides mainly composed of D-mannose (40-52%) and D-glucose (11-30%). For the first time we demonstrated that Lactobacillus EPS were able to stimulate in a dose-dependent manner (p < 0.05) the formation of biofilms of ten strains belonging to L. crispatus, L. gasseri and Limosilactobacillus vaginalis species, in terms of cell viability (84-282% increase at 1 mg/mL) and especially biofilm biomass (40-195% increase at 1 mg/mL), quantified with MTT assay and CV staining, respectively. EPS released from L. crispatus and L. gasseri were found to better stimulate the biofilms of the same producer species rather than that of other species, including producing strains themselves and other strains. Conversely, the biofilm formation of bacterial (Escherichia coli, Staphylococcus spp., Enterococcus spp. and Streptococcus agalactiae) and fungal (Candida spp.) pathogens was inhibited. The anti-biofilm activity was dose-dependent and was more marked for L. gasseri-derived EPS (inhibition up to 86%, 70%, and 58% at 1 mg/mL, 0.5 mg/mL, and 0.1 mg/mL, respectively), whilst L. crispatus-derived EPS resulted overall less efficient (inhibition up to 58% at 1 mg/mL and 40% at 0.5 mg/mL) (p < 0.05). CONCLUSIONS: Lactobacilli-derived EPS favour the biofilm formation of lactobacilli preventing, at the same time, that of opportunistic pathogens. These results support the possible employment of EPS as postbiotics in medicine as a therapeutic/preventive strategy to counteract vaginal infections.

Quinolinetrione-tacrine hybrids as multi-target-directed ligands against Alzheimer's disease.

Multi-target drug discovery is one of the most active fields in the search for new drugs against Alzheimer's disease (AD). This is because the complexity of AD pathological network might be adequately tackled by multi-target-directed ligands (MTDLs) aimed at modulating simultaneously multiple targets of such a network. In a continuation of our efforts to develop MTDLs for AD, we have been focusing on the molecular hybridization of the acetylcholinesterase inhibitor tacrine with the aim of expanding its anti-AD profile. Herein, we manipulated the structure of a previously developed tacrine-quinone hybrid (1). We designed and synthesized a novel set of MTDLs (2-6) by replacing the naphthoquinone scaffold of 1 with that of 2,5,8-quinolinetrione. The most interesting hybrid 3 inhibited cholinesterase enzymes at nanomolar concentrations. In addition, 3 exerted antioxidant effects in menadione-induced oxidative stress of SH-SY5Y cells. Importantly, 3 also showed low hepatotoxicity and good anti-amyloid aggregation properties. Remarkably, we uncovered the potential of the quinolinetrione scaffold, as a novel anti-amyloid aggregation and antioxidant motif to be used in further anti-AD MTDL drug discovery endeavors.

Determination of Effective Albumin in Patients With Decompensated Cirrhosis: Clinical and Prognostic Implications.

BACKGROUND AND AIMS: Circulating albumin in cirrhosis can be dysfunctional because of accumulating structural damages, leading to the concept of effective albumin concentration (eAlb), referring to the albumin portion presenting structural and functional integrity. We aimed to estimate eAlb in patients with decompensated cirrhosis and analyze its relationships with albumin function and clinical outcomes as compared to total albumin concentration (tAlb). APPROACH AND RESULTS: We evaluated 319 patients with cirrhosis hospitalized for acute decompensation (AD) with and without acute-on-chronic liver failure (ACLF) and 18 age- and sex-comparable outpatients with compensated cirrhosis. tAlb was quantified by standard assay, whereas eAlb was estimated combining liquid chromatography/electrospray ionization/mass spectrometry and standard methods. Albumin binding and detoxification efficiency were evaluated by electron paramagnetic resonance analysis. Circulating albumin in patients with decompensated cirrhosis displayed multiple structural abnormalities, with reversible oxidation and glycation being the most frequent. As a result, eAlb progressively declined with the worsening of cirrhosis and was superior to tAlb in stratifying patients between compensated cirrhosis, AD, and ACLF, as well as patients with and without complications. Moreover, eAlb, but not tAlb, was closely associated with binding capacities in ACLF. Finally, eAlb at admission predicted the occurrence of ACLF within 30 days and mortality at 90 days better than tAlb. CONCLUSIONS: This large, observational study provides the evidence in patients with decompensated cirrhosis that eAlb can be quantified and differentiated from tAlb routinely measured in clinical practice. As compared to tAlb, eAlb is more closely associated with disease severity and albumin dysfunction and carries a greater prognostic power. These results prompt future research assessing eAlb as a biomarker for predicting prognosis and treatment response.

Targeting neuronal calcium channels and GSK3ß for Alzheimer's disease with naturally-inspired Diels-Alder adducts.

The complexity of neurodegenerative diseases, among which Alzheimer's disease plays a pivotal role, poses one of the tough therapeutic challenges of present time. In this perspective, a multitarget approach appears as a promising strategy to simultaneously interfere with different defective pathways. In this paper, a structural simplification plan was performed on our previously reported multipotent polycyclic compounds, in order to obtain a simpler pharmacophoric central core with improved pharmacokinetic properties, while maintaining the modulating activity on neuronal calcium channels and glycogen synthase kinase 3-beta (GSK-3ß), as validated targets to combat Alzheimer's disease. The molecular pruning approach applied here led to tetrahydroisoindole-dione (1), tetrahydromethanoisoindole-dione (2) and tetrahydroepoxyisoindole-dione (3) structures, easily affordable by Diels-Alder cycloaddition. Preliminary data indicated structure 3 as the most appropriate, thus a SAR study was performed by introducing different substituents, selected on the basis of the commercial availability of the furan derivatives required for the synthetic procedure. The results indicated compound 10 as a promising, structurally atypical, safe and BBB-penetrating Cav modulator, inhibiting both L- and N-calcium channels, likely responsible for the Ca2+ overload observed in Alzheimer's disease. In a multitarget perspective, compound 11 appeared as an effective prototype, endowed with improved Cav inhibitory activity, with respect to the reference drug nifedipine, and encouraging modulating activity on GSK-3ß.

Discovery of an Allosteric Ligand Binding Site in SMYD3 Lysine Methyltransferase.

SMYD3 is a multifunctional epigenetic enzyme with lysine methyltransferase activity and various interaction partners. It is implicated in the pathophysiology of cancers but with an unclear mechanism. To discover tool compounds for clarifying its biochemistry and potential as a therapeutic target, a set of drug-like compounds was screened in a biosensor-based competition assay. Diperodon was identified as an allosteric ligand; its R and S enantiomers were isolated, and their affinities to SMYD3 were determined (KD =42 and 84 µM, respectively). Co-crystallization revealed that both enantiomers bind to a previously unidentified allosteric site in the C-terminal protein binding domain, consistent with its weak inhibitory effect. No competition between diperodon and HSP90 (a known SMYD3 interaction partner) was observed although SMYD3-HSP90 binding was confirmed (KD =13 µM). Diperodon clearly represents a novel starting point for the design of tool compounds interacting with a druggable allosteric site, suitable for the exploration of noncatalytic SMYD3 functions and therapeutics with new mechanisms of action.

Bio-Guided Fractionation of Stem Bark Extracts from Phyllanthus muellarianus: Identification of Phytocomponents with Anti-Cholinesterase Activity.

A combination of flash chromatography, solid phase extraction, high-performance liquid chromatography, and in vitro bioassays was used to isolate phytocomponents endowed with anticholinesterase activity in extract from Phyllanthus muellarianus. Phytocomponents responsible for the anti-cholinesterase activity of subfractions PMF1 and PMF4 were identified and re-assayed to confirm their activity. Magnoflorine was identified as an active phytocomponent from PMF1 while nitidine was isolated from PMF4. Magnoflorine was shown to be a selective inhibitor of human butyrylcholinesterase-hBChE (IC50 = 131 ± 9 µM and IC50 = 1120 ± 83 µM, for hBuChE and human acetylcholinesterase-hAChE, respectively), while nitidine showed comparable inhibitory potencies against both enzymes (IC50 = 6.68 ± 0.13 µM and IC50 = 5.31 ± 0.50 µM, for hBChE and hAChE, respectively). When compared with the commercial anti-Alzheimer drug galanthamine, nitidine was as potent as galanthamine against hAChE and one order of magnitude more potent against hBuChE. Furthermore, nitidine also showed significant, although weak, antiaggregating activity towards amyloid-ß self-aggregation.

From Combinations to Single-Molecule Polypharmacology-Cromolyn-Ibuprofen Conjugates for Alzheimer's Disease.

Despite Alzheimer's disease (AD) incidence being projected to increase worldwide, the drugs currently on the market can only mitigate symptoms. Considering the failures of the classical paradigm "one target-one drug-one disease" in delivering effective medications for AD, polypharmacology appears to be a most viable therapeutic strategy. Polypharmacology can involve combinations of multiple drugs and/or single chemical entities modulating multiple targets. Taking inspiration from an ongoing clinical trial, this work aims to convert a promising cromolyn-ibuprofen drug combination into single-molecule "codrugs." Such codrugs should be able to similarly modulate neuroinflammatory and amyloid pathways, while showing peculiar pros and cons. By exploiting a linking strategy, we designed and synthesized a small set of cromolyn-ibuprofen conjugates (4-6). Preliminary plasma stability and neurotoxicity assays allowed us to select diamide 5 and ethanolamide 6 as promising compounds for further studies. We investigated their immunomodulatory profile in immortalized microglia cells, in vitro anti-aggregating activity towards Aß42-amyloid self-aggregation, and their cellular neuroprotective effect against Aß42-induced neurotoxicity. The fact that 6 effectively reduced Aß-induced neuronal death, prompted its investigation into an in vivo model. Notably, 6 was demonstrated to significantly increase the longevity of Aß42-expressing Drosophila and to improve fly locomotor performance.

New Coumarin Derivatives as Cholinergic and Cannabinoid System Modulators.

In the last years, the connection between the endocannabinoid system (eCS) and neuroprotection has been discovered, and evidence indicates that eCS signaling is involved in the regulation of cognitive processes and in the pathophysiology of Alzheimer's disease (AD). Accordingly, pharmacotherapy targeting eCS could represent a valuable contribution in fighting a multifaceted disease such as AD, opening a new perspective for the development of active agents with multitarget potential. In this paper, a series of coumarin-based carbamic and amide derivatives were designed and synthesized as multipotent compounds acting on cholinergic system and eCS-related targets. Indeed, they were tested with appropriate enzymatic assays on acetyl and butyryl-cholinesterases and on fatty acid amide hydrolase (FAAH), and also evaluated as cannabinoid receptor (CB1 and CB2) ligands. Moreover, their ability to reduce the self-aggregation of beta amyloid protein (Aß42) was assessed. Compounds 2 and 3, bearing a carbamate function, emerged as promising inhibitors of hAChE, hBuChE, FAAH and Aß42 self-aggregation, albeit with moderate potencies, while the amide 6 also appears a promising CB1/CB2 receptors ligand. These data prove for the new compounds an encouraging multitarget profile, deserving further evaluation.

Solid Lipid Microparticles for Oral Delivery of Catalase: Focus on the Protein Structural Integrity and Gastric Protection.

Protein inactivation either during the production process or along the gastrointestinal tract is the major problem associated with the development of oral delivery systems for biological drugs. This work presents an evaluation of the structural integrity and the biological activity of a model protein, catalase, after its encapsulation in glyceryl trimyristate-based solid lipid microparticles (SLMs) obtained by the spray congealing technology. Circular dichroism and fluorescence spectroscopies were used to assess the integrity of catalase released from SLMs. The results confirmed that no conformational change occurred during the production process and both the secondary and tertiary structures were retained. Catalase is highly sensitive to temperature and undergoes denaturation above 60 °C; nevertheless, spray congealing allowed the retention of most biological activity due to the loading of the drug at the solid state, markedly reducing the risk of denaturation. Catalase activity after exposure to simulated gastric conditions (considering both acidic pH and the presence of gastric digestive hydrolases) ranged from 35 to 95% depending on the carrier: increasing of both the fatty acid chain length and the degree of substitution of the glyceride enhanced residual enzyme activity. SLMs allowed the protein release in a simulated intestinal environment and were not cytotoxic against HT29 cells. In conclusion, the encapsulation of proteins into SLMs by spray congealing might be a promising strategy for the formulation of nontoxic and inexpensive oral biotherapeutic products.

Unveiling the molecular mechanisms underpinning biorecognition of early-glycated human serum albumin and receptor for advanced glycation end products.

Serum levels of early-glycated albumin are significantly increased in patients with diabetes mellitus and may play a role in worsening inflammatory status and sustaining diabetes-related complications. To investigate possible pathological recognition involving early-glycated albumin and the receptor for advanced glycation end products (RAGE), an early-glycated human serum albumin (HSAgly), with a glycation pattern representative of the glycated HSA form abundant in diabetic patients, and the recombinant human RAGE ectodomain (VC1) were used. Biorecognition between the two interactants was investigated by combining surface plasmon resonance (SPR) analysis and affinity chromatography coupled with mass spectrometry (affinity-MS) for peptide extraction and identification. SPR analysis proved early-glycated albumin could interact with the RAGE ectodomain with a steady-state affinity constant of 6.05 ± 0.96 × 10-7 M. Such interaction was shown to be specific, as confirmed by a displacement assay with chondroitin sulfate, a known RAGE binder. Affinity-MS studies were performed to map the surface area involved in the recognition. These studies highlighted that a region surrounding Lys525 and part of subdomain IA were involved in VC1 recognition. Finally, an in silico analysis highlighted (i) a key role for glycation at Lys525 (the most commonly glycated residue in HSA in diabetic patients) through a triggering mechanism similar to that previously observed for AGEs or advanced lipoxidation end products and (ii) a stabilizing role for subdomain IA. Albeit a moderate affinity for complex formation, the high plasma levels of early-glycated albumin and high percentage of glycation at Lys525 in diabetic patients make this interaction of possible pathological relevance. Graphical abstract.

N-1,2,3-triazole-isatin derivatives for cholinesterase and ß-amyloid aggregation inhibition: A comprehensive bioassay study.

Our goal was the evaluation of a series of N-1,2,3-triazole-isatin derivatives for multi-target activity which included cholinesterase (ChE) inhibition and ß-amyloid (Aß) peptide anti-aggregation. The compounds have shown considerable promise as butyrylcholinesterase (BuChE) inhibitors. Although the inhibition of eel acetylcholinesterase (eeAChE) was weak, the inhibitions against equine BuChE (eqBuChE) and human BuChE (hBuChE) were more significant with a best inhibition against eqBuChE of 0.46 µM. In some cases, these molecules gave better inhibitions for hBuChE than eqBuChE. For greater insights into their mode of action, molecular docking studies were carried out, followed by STD-NMR validation. In addition, some of these compounds showed weak Aß anti-aggregation activity. Hepatotoxicity studies showed that they were non-hepatoxic and neurotoxicity studies using neurite outgrowth experiments led to the conclusion that these compounds are only weakly neurotoxic.

Unveiling the Biochemistry of the Epigenetic Regulator SMYD3.

SET and MYND domain-containing protein 3 (SMYD3) is a lysine methyltransferase that plays a central role in a variety of cancer diseases, exerting its pro-oncogenic activity by methylation of key proteins, of both nuclear and cytoplasmic nature. However, the role of SMYD3 in the initiation and progression of cancer is not yet fully understood and further biochemical characterization is required to support the discovery of therapeutics targeting this enzyme. We have therefore developed robust protocols for production, handling, and crystallization of SMYD3 and biophysical and biochemical assays for clarification of SMYD3 biochemistry and identification of useful lead compounds. Specifically, a time-resolved biosensor assay was developed for kinetic characterization of SMYD3 interactions. Functional differences in SMYD3 interactions with its natural small molecule ligands SAM and SAH were revealed, with SAM forming a very stable complex. A variety of peptides mimicking putative substrates of SMYD3 were explored in order to expose structural features important for recognition. The interaction between SMYD3 and some peptides was influenced by SAM. A nonradioactive SMYD3 activity assay using liquid chromatography-mass spectrometry (LC-MS) analysis explored substrate features of importance also for methylation. Methylation was notable only toward MAP kinase kinase kinase 2 (MAP3K2_K260)-mimicking peptides, although binary and tertiary complexes were detected also with other peptides. The analysis supported a random bi-bi mechanistic model for SMYD3 methyltransferase catalysis. Our work unveiled complexities in SMYD3 biochemistry and resulted in procedures suitable for further studies and identification of novel starting points for design of effective and specific leads for this potential oncology target.

Tacrines as Therapeutic Agents for Alzheimer's Disease. IV. The Tacripyrines and Related Annulated Tacrines.

Notwithstanding the clinical use of tacrine was hampered by severe hepatotoxicity, tacrine still remains a reference scaffold in the search for new efficient drugs for Alzheimer's disease therapy. In this account we summarize the efforts toward the development and characterization of non-hepatotoxic tacripyrines and related tacrine analogues resulting from the substitution of the benzene ring by a 1,4-dihydropyridine, a 1,2,3,4-tetrahydropyrimidine or a pyridone nucleus. These efforts have successfully led to the identification of a number of promising hits endowed with interesting multifunctional profiles. These include the 4'-metoxytacripyrine (S)-ITH122, able to target cholinesterases (ChEs), beta-amyloid (Aß) and Ca2+ channels, the racemic 3'-methoxytacripyrimidine EB65F2, the first fully balanced micromolar inhibitor of ChEs and Ca2+ channels, and tacripyrine (-)-SCR1693 a GSK-3ß (enzyme involved in tau phosphorylation) inhibitor able to also lower Aß production in N2a cells.

QuinoxalineTacrine QT78, a Cholinesterase Inhibitor as a Potential Ligand for Alzheimer's Disease Therapy.

We report the synthesis and relevant pharmacological properties of the quinoxalinetacrine (QT) hybrid QT78 in a project targeted to identify new non-hepatotoxic tacrine derivatives for Alzheimer's disease therapy. We have found that QT78 is less toxic than tacrine at high concentrations (from 100 µM to 1 mM), less potent than tacrine as a ChE inhibitor, but shows selective BuChE inhibition (IC50 (hAChE) = 22.0 ± 1.3 µM; IC50 (hBuChE) = 6.79 ± 0.33 µM). Moreover, QT78 showed effective and strong neuroprotection against diverse toxic stimuli, such as rotenone plus oligomycin-A or okadaic acid, of biological significance for Alzheimer's disease.

Exploiting the Chalcone Scaffold to Develop Multifunctional Agents for Alzheimer's Disease.

Alzheimer's disease still represents an untreated multifaceted pathology, and drugs able to stop or reverse its progression are urgently needed. In this paper, a series of naturally inspired chalcone-based derivatives were designed as structural simplification of our previously reported benzofuran lead compound, aiming at targeting both acetyl (AChE)- and butyryl (BuChE) cholinesterases that, despite having been studied for years, still deserve considerable attention. In addition, the new compounds could also modulate different pathways involved in disease progression, due to the peculiar trans-α,ß-unsaturated ketone in the chalcone framework. All molecules presented in this study were evaluated for cholinesterase inhibition on the human enzymes and for antioxidant and neuroprotective activities on a SH-SY5Y cell line. The results proved that almost all the new compounds were low micromolar inhibitors, showing different selectivity depending on the appended substituent; some of them were also effective antioxidant and neuroprotective agents. In particular, compound 4, endowed with dual AChE/BuChE inhibitory activity, was able to decrease ROS formation and increase GSH levels, resulting in enhanced antioxidant endogenous defense. Moreover, this compound also proved to counteract the neurotoxicity elicited by Aß1⁻42 oligomers, showing a promising neuroprotective potential.

Increasing Polarity in Tacrine and Huprine Derivatives: Potent Anticholinesterase Agents for the Treatment of Myasthenia Gravis.

Symptomatic treatment of myasthenia gravis is based on the use of peripherally-acting acetylcholinesterase (AChE) inhibitors that, in some cases, must be discontinued due to the occurrence of a number of side-effects. Thus, new AChE inhibitors are being developed and investigated for their potential use against this disease. Here, we have explored two alternative approaches to get access to peripherally-acting AChE inhibitors as new agents against myasthenia gravis, by structural modification of the brain permeable anti-Alzheimer AChE inhibitors tacrine, 6-chlorotacrine, and huprine Y. Both quaternization upon methylation of the quinoline nitrogen atom, and tethering of a triazole ring, with, in some cases, the additional incorporation of a polyphenol-like moiety, result in more polar compounds with higher inhibitory activity against human AChE (up to 190-fold) and butyrylcholinesterase (up to 40-fold) than pyridostigmine, the standard drug for symptomatic treatment of myasthenia gravis. The novel compounds are furthermore devoid of brain permeability, thereby emerging as interesting leads against myasthenia gravis.

Imidazopyranotacrines as Non-Hepatotoxic, Selective Acetylcholinesterase Inhibitors, and Antioxidant Agents for Alzheimer's Disease Therapy.

Herein we describe the synthesis and in vitro biological evaluation of thirteen new, racemic, diversely functionalized imidazo pyranotacrines as non-hepatotoxic, multipotent tacrine analogues. Among these compounds, 1-(5-amino-2-methyl-4-(1-methyl-1H-imidazol-2-yl)-6,7,8,9-tetrahydro-4H-pyrano[2,3-b]quinolin-3-yl)ethan-1-one (4) is non-hepatotoxic (cell viability assay on HepG2 cells), a selective but moderately potent EeAChE inhibitor (IC50 = 38.7 ± 1.7 µM), and a very potent antioxidant agent on the basis of the ORAC test (2.31 ± 0.29 µmol·Trolox/µmol compound).

From AChE to BACE1 inhibitors: The role of the amine on the indanone scaffold.

In recent years, a progressive increase in age-related disorders could be observed in most western countries, among which Alzheimer's disease (AD) is one of the most challenging. BACE1 could be seen as an attractive target to develop disease-modifying compounds, and in this context, a new series of hybrid molecules was designed and synthesized, based on a previously identified multitarget lead compound. In particular, the amino side chain was appropriately modified to fit BACE1 as additional target. In vitro testing results pointed out compound 8 (IC50=2.49±0.08 µM), bearing the bulky bis(4-fluorophenyl)methyl)piperazine substituent, as the most potent BACE1 inhibitor of the series.