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.

Evaluation of chromane derivatives: Promising privileged scaffolds for lead discovery within Alzheimer's disease.

The chromane ring system is widely distributed in nature and has proven to be a highly potent pharmacophore in medicinal chemistry, which includes the area of Alzheimer's and Parkinson's diseases. We report on the development of a gem-dimethylchroman-4-ol family that was shown to give good inhibition of equine serum butyrylcholinesterase (eqBuChE) (in the range 2.9 - 7.3 µM) and in the same range of currently used drugs. We also synthesized a small library of gem-dimethylchroman-4-amine compounds, via a simple reductive amination of the corresponding chromanone precursor, that were also selective for eqBuChE presenting inhibitions in the range 7.6 - 67 µM. Kinetic studies revealed that they were mixed inhibitors. Insights into their mechanism of action were obtained through molecular docking and STD-NMR experiments, and the most active examples showed excellent drug-likeness and pharmacological properties predicted using Swiss-ADME. We also prepared a set of propargyl gem-dimethylchromanamines, for monoamine oxidase (MAO) inhibition but they were only moderately active (the best being 28% inhibition at 1 µM on MAO-B). Overall, our compounds were found to be best suited as inhibitors for BuChE.

Design and synthesis of chromone-based monoamine oxidase B inhibitors with improved drug-like properties.

The absence of disease modifying drugs in Parkinson's disease therapy urges for new chemical entities acting on relevant PD-associated biological targets. As a result, developing selective and reversible inhibitors targeting MAO-B is still a desirable line of therapeutic research. Within this framework, a small library of chromone derivatives was synthesized and screened towards human monoamine oxidases. Structural modifications on the chromone 3-phenylcarboxamide resulted in potent MAO-B inhibitors with an improved drug-like profile, and for the first time we obtained potent and selective chromone 2-phenylcarboxamides acting in the low nanomolar range. Compounds 5-hydroxy-4-oxo-N-phenyl-4H-chromene-3-carboxamide (38) (IC50 = 13.0 nM) and N-(4-chlorophenyl)-5-hydroxy-4-oxo-4H-chromene-3-carboxamide (41) (IC50 = 8.3 nM) stood out as reversible, potent, selective and non-cytotoxic MAO-B inhibitors bearing a favourable drug-like profile. Both compounds displayed cytoprotective effects towards iron(III) oxidative stressor.

New deferiprone derivatives as multi-functional cholinesterase inhibitors: design, synthesis and in vitro evaluation.

In order to obtain multi-functional molecules for Alzheimer's disease, a series of deferiprone derivatives has been synthesized and evaluated in vitro with the hypothesis that they can restore the cholinergic tone and attenuate the dyshomeostasis of the metals mainly involved in the pathology. These compounds were designed as dual binding site AChE inhibitors: they possess an arylalkylamine moiety connected via an alkyl chain to a 3-hydroxy-4-pyridone fragment, to allow the simultaneous interaction with catalytic active site (CAS) and peripheral anionic site (PAS) of the enzyme. Deferiprone moiety and 2-aminopyridine, 2-aminopyrimidine or 2,4-diaminopyrimidine groups have been incorporated into these compounds, in order to obtain molecules potentially able to chelate bio-metals colocalized in Aß plaques and involved in the generation of radical species. Synthesized compounds were tested by enzymatic inhibition studies towards EeAChE and eqBChE using Ellman's method. The most potent EeAChE inhibitor is compound 5a, with a Ki of 788 ± 51 nM, while the most potent eqBChE inhibitors are compounds 12 and 19, with Ki values of 182 ± 18 nM and 258 ± 25 nM respectively. Selected compounds, among the most potent cholinesterases inhibitors, were able to form complex with iron and in some cases with copper and zinc. Moreover, these compounds were characterized by low toxicity on U-87 MG Cell Line from human brain (glioblastoma astrocytoma).

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.

Mediterranean products as promising source of multi-target agents in the treatment of metabolic syndrome.

Alteration of nutritional habits play an essential role on the risk of developing Metabolic Syndrome (MetS). Several epidemiological studies have shown that assuming diets rich of foods included in the Mediterranean diet (MetDiet) pattern like, such as olive oil, nuts, fruit, fiber, vegetables, wine and grain cereals has protective effects on the different risk factors characterizing the MetS. The beneficial effects of the MetDiet in the MetS are mainly due to the antioxidant and anti-inflammatory properties of the most abundant phytochemical components of such foods as polyphenols like resveratrol and oleuropein, allyl sulfides, ellagic acid, mono- and poly-unsaturated fatty acids (MUFA and PUFA), tocopherols and flavonoids like quercetin, which have shown positive results in the prevention of cardiovascular diseases (CVDs), with related risk factors, like hypertension, hypercholesterolemia and obesity. In this review, we highlighted the multi-target activities of the bioactive components contained in some foods typical of the Mediterranean area like olive oil, onion, liquorice, rosemary, oregano, hazelnut, pistachio, "Melannurca" apple, red wine, hot pepper, Citrus sp. fruits, saffron and garlic, with particular focus on their impact on health outcomes in relation to MetS main key factors, such as insulin resistance (IR) and type 2 diabetes mellitus (T2DM), endothelial dysfunctions, inflammatory response, oxidative stress and dyslipidaemic and hypercholesterolemic effects.

The Mediterranean Diet as source of bioactive compounds with multi-targeting anti-cancer profile.

Many bioactive agents have been extracted from plants or belong to functional foods and have been considered in the treatment of serious and multifactorial diseases, such as cancer. In particular, this review is focused on the anti-cancer properties owned by several natural products typically from the Mediterranean area. In some regions of the South of Italy, a lower cancer incidence has been observed. There is increasing evidence that adherence to a Mediterranean dietary pattern correlates with reduced risk of several cancer types. This could be mainly attributed to the typical lifestyle aspects of the Mediterranean diet, such as high consumption of fruit and vegetables. In this review, the main natural products of the Mediterranean area are discussed, with particular attention on their anti-cancer properties endowed with multi-target profiles.

A computer-assisted discovery of novel potential anti-obesity compounds as selective carbonic anhydrase VA inhibitors.

The human Carbonic anhydrases (hCA) VA and VB play a key role in ureagenesis, gluconeogenesis, lipogenesis and in the metabolism regulation, thus representing highly popular drug targets. Albeit several hCA inhibitors have been designed and are currently in clinical use, serious drug interactions have been reported due to their poor selectivity. In this perspective, the drug repurposing approach could be a useful tool in order to investigate the drug promiscuity/polypharmacology profile. In this study, virtual screening techniques and in vitro assays were combined to identify novel selective hCA VA inhibitors from among around 94000 compounds. The docking analysis highlighted 12 promising best hits, biologically characterized in terms of their hCA VA inhibitory activity. Interestingly, among them, the anticancer agents fludarabine and lenvatinib and the antiepileptic rufinamide were able to selectively inhibit the enzyme activity in the micromolar range, while a pyrido-indole derivative, the homovanillic acid sulfate and the desacetyl metabolite of the antibacterial cephapirin in the nanomolar range.

Benzo[b]tiophen-3-ol derivatives as effective inhibitors of human monoamine oxidase: design, synthesis, and biological activity.

A series of benzo[b]thiophen-3-ols were synthesised and investigated as potential human monoamine oxidase (hMAO) inhibitors in vitro as well as ex vivo in rat cortex synaptosomes by means of evaluation of 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio and lactate dehydrogenase (LDH) activity. Most of these compounds possessed high selectivity for the MAO-B isoform and a discrete antioxidant and chelating potential. Molecular docking studies of all the compounds underscored potential binding site interactions suitable for MAO inhibition activity, and suggested structural requirements to further improve the activity of this scaffold by chemical modification of the aryl substituents. Starting from this heterocyclic nucleus, novel lead compounds for the treatment of neurodegenerative disease could be developed.

Benzoic acid-derived nitrones: A new class of potential acetylcholinesterase inhibitors and neuroprotective agents.

The discovery of new chemical entities endowed with potent and selective acetylcholinesterase (AChE) and/or butyrylcholinesterase (BChE) inhibitory activity is still a relevant subject for Alzheimer's disease therapy. Therefore, a small library of benzoic based amide nitrones (compounds 24 to 42) was synthesized and screened toward cholinesterase enzymes. SAR studies showed that the tert-butyl moiety is the most favourable nitrone pattern. In general, tert-butyl derivatives effectively inhibited AChE, being compound 33 the most potent (IC50 = 8.3 ±â€¯0.3 µM; Ki 5.2 µM). The data pointed to a non-competitive inhibition mechanism of action, which was also observed for the standard donepezil. None of compounds showed BChE inhibitory activity. Molecular modelling studies provided insights into the enzyme-inhibitor interactions and rationalised the experimental data, confirming that the binding mode of nitrones 33 and 38 towards AChE has the most favourable binding free energy. The tert-butylnitrones 33 and 38 were not cytotoxic on different cell lines (SH-SY5Y and HepG2). Moreover, compound 33 was able to prevent t-BHP-induced oxidative stress in SH-SY5Y differentiated cells. Due to its AChE selectivity and promising cytoprotective properties, as well as its appropriate drug-like profile pointing toward blood-brain barrier permeability, compound 33 is proposed as a valid lead for a further optimization step.

4-(3-Nitrophenyl)thiazol-2-ylhydrazone derivatives as antioxidants and selective hMAO-B inhibitors: synthesis, biological activity and computational analysis.

A new series of 4-(3-nitrophenyl)thiazol-2-ylhydrazone derivatives were designed, synthesised, and evaluated to assess their inhibitory effect on the human monoamine oxidase (hMAO) A and B isoforms. Different (un)substituted (hetero)aromatic substituents were linked to N1 of the hydrazone in order to establish robust structure-activity relationships. The results of the biological testing demonstrated that the presence of the hydrazothiazole nucleus bearing at C4 a phenyl ring functionalised at the meta position with a nitro group represents an important pharmacophoric feature to obtain selective and reversible human MAO-B inhibition for the treatment of neurodegenerative disorders. In addition, the most potent and selective MAO-B inhibitors were evaluated in silico as potential cholinesterase (AChE/BuChE) inhibitors and in vitro for antioxidant activities. The results obtained from molecular modelling studies provided insight into the multiple interactions and structural requirements for the reported MAO inhibitory properties.

Multi-target-directed ligands for Alzheimer's disease: Discovery of chromone-based monoamine oxidase/cholinesterase inhibitors.

There has been a substantial research effort to design multi-target ligands for the treatment of Alzheimer's disease (AD), an approach that is moved by the knowledge that AD is a complex and multifactorial disease affecting many linked to pathological pathways. Accordingly, we have devoted efforts to develop multi-target ligands based on the chromone scaffold. As a result, a small library of chromone derivatives was synthesized and screened towards human cholinesterases and monoamine oxidases. Compounds 2-(dimethylamino)ethyl (E)-3-(4-oxo-2-(p-methylphenlcarbamoyl)-4H-chromen-6-yl)acrylate (9a) and 2-(dimethylamino)ethyl (E)-3-(4-oxo-3-(phenylcarbamoyl)-4H-chromen-6-yl)acrylate (23a) were identified as the most promising multi-target inhibitors of the series. Compound 9a acted as a potent, selective and bifunctional AChEI (IC50 = 0.21 µM, Ki = 0.19 µM) and displayed dual hMAO inhibitory activity (hMAO-A IC50 = 0.94 µM, Ki = 0.057 µM and hMAO-B IC50 = 3.81 µM, Ki = 0.48 µM). Compound 23a acted as a selective IMAO-B (IC50 = 0.63 µM, Ki = 0.34 µM) while still displaying hChE inhibitory and bifunctional activity in the low micromolar range. Overall, these two compounds stand out as reversible multi-target inhibitors with favourable permeability, toxicological and drug-like profiles, thus being valid candidates for subsequent optimization and pre-clinical studies.

The Mu.Ta.Lig. Chemotheca: A Community-Populated Molecular Database for Multi-Target Ligands Identification and Compound-Repurposing.

For every lead compound developed in medicinal chemistry research, numerous other inactive or less active candidates are synthetized/isolated and tested. The majority of these compounds will not be selected for further development due to a sub-optimal pharmacological profile. However, some poorly active or even inactive compounds could live a second life if tested against other targets. Thus, new therapeutic opportunities could emerge and synergistic activities could be identified and exploited for existing compounds by sharing information between researchers who are working on different targets. The Mu.Ta.Lig (Multi-Target Ligand) Chemotheca database aims to offer such opportunities by facilitating information exchange among researchers worldwide. After a preliminary registration, users can (a) virtually upload structures and activity data for their compounds with corresponding, and eventually known activity data, and (b) search for other available compounds uploaded by the users community. Each piece of information about given compounds is owned by the user who initially uploaded it and multiple ownership is possible (this occurs if different users uploaded the same compounds or information pertaining to the same compounds). A web-based graphical user interface has been developed to assist compound uploading, compounds searching and data retrieval. Physico-chemical and ADME properties as well as substructure-based PAINS evaluations are computed on the fly for each uploaded compound. Samples of compounds that match a set of search criteria and additional data on these compounds could be requested directly from their owners with no mediation by the Mu.Ta.Lig Chemotheca team. Guest access provides a simplified search interface to retrieve only basic information such as compound IDs and related 2D or 3D chemical structures. Moreover, some compounds can be hidden to Guest users according to an owner's decision. In contrast, registered users have full access to all of the Chemotheca data including the permission to upload new compounds and/or update experimental/theoretical data (e.g., activities against new targets tested) related to already stored compounds. In order to facilitate scientific collaborations, all available data are connected to the corresponding owner's email address (available for registered users only). The Chemotheca web site is accessible at http://chemotheca.unicz.it.

Design, synthesis and biochemical evaluation of novel multi-target inhibitors as potential anti-Parkinson agents.

New 4-(3-nitrophenyl)thiazol-2-ylhydrazone derivatives are proposed as dual-target-directed monoamine oxidase B (MAO-B) and acetylcholinesterase (AChE) inhibitors, as well as antioxidant agents, for the treatment of neurodegenerative disorders such as Parkinson's disease. Rational molecular design, target recognition and predicted pharmacokinetic properties have been evaluated by means of molecular modelling. Based on these properties, compounds were synthesized and evaluated in vitro as MAO-B and AChE inhibitors, and compared to the activities at their corresponding isozymes, monoamine oxidase A (MAO-A) and butyrylcholinesterase (BuChE), respectively. Anti-oxidant properties, potentially useful in the treatment of neurodegenerative disorders, have been also investigated in vitro. Among the evaluated compounds, three inhibitors may be considered as promising dual inhibitors of MAO-B and AChE, in vitro. MAO-B inhibition was also shown to be competitive and reversible for compound 19.

Coumarin versus Chromone Monoamine Oxidase B Inhibitors: Quo Vadis?

Because of the lack of significant disease-modifying drugs for neurodegenerative disorders, a pressing need for new chemical entities endowed with IMAO-B still exists. Within this framework, and for the first time, a study was performed to compare coumarin- and chomone-3-phenylcarboxamide scaffolds. Compounds 10a and 10b were the most potent, selective, and reversible noncompetitive IMAO-B. The benzopyrone sp2 oxygen atom was found to be position independent and a productive contributor for the ligand-enzyme complex stability.