Bifunctional phenolic-choline conjugates as anti-oxidants and acetylcholinesterase inhibitors

Antiplatelet and Anticoagulant Effects of Two New Phenylpropanoid Sucrose Esters and Other Secondary Metabolites from the Aerial Part of Canna edulis

This study isolated pure compounds from Canna edulis aerial parts and assessed their antiplatelet and anticoagulant potential. Structural elucidation resulted in the identification of two new compounds: caneduloside A (1) and caneduloside B (2), and eleven known compounds: 6'-acetyl-3,6,2'-tri-p-coumaroyl sucrose (3), 6'-acetyl-3,6,2'-triferuloyl sucrose (4), tiliroside (5), afzelin (6), quercitrin (7), 2-hydroxycinnamaldehyde (8), cinnamic acid (9), 3,4-dimethoxycinnamic acid (10), dehydrovomifoliol (11), 4-hydroxy-3,5-dimethoxybenzaldehyde (12), and (S)-(-)-rosmarinic acid (13). Compounds 3, 4, 6-9, 13 were previously reported for antithrombotic properties. Hence, antithrombotic tests were conducted for 1, 2, 5, 10-12. All tested compounds demonstrated a dose-dependent antiaggregatory effect, and 10 and 12 were the most potent for both ADP and collagen activators. Additionally, 10 and 12 showed anticoagulant effects, with prolonged prothrombin time and activated partial thromboplastin time. The new compound 1 displayed antiplatelet and anticoagulant activity, while 2 mildly inhibited platelet aggregation. C. edulis is a potential source for developing antithrombotic agents.

Conjugation, Prodrug, and Co-Administration Strategies in Support of Nanotechnologies to Improve the Therapeutic Efficacy of Phytochemicals in the Central Nervous System

Phytochemicals, produced as secondary plant metabolites, have shown interesting potential therapeutic activities against neurodegenerative diseases and cancer. Unfortunately, poor bioavailability and rapid metabolic processes compromise their therapeutic use, and several strategies are currently proposed for overcoming these issues. The present review summarises strategies for enhancing the central nervous system's phytochemical efficacy. Particular attention has been paid to the use of phytochemicals in combination with other drugs (co-administrations) or administration of phytochemicals as prodrugs or conjugates, particularly when these approaches are supported by nanotechnologies exploiting conjugation strategies with appropriate targeting molecules. These aspects are described for polyphenols and essential oil components, which can improve their loading as prodrugs in nanocarriers, or be part of nanocarriers designed for targeted co-delivery to achieve synergistic anti-glioma or anti-neurodegenerative effects. The use of in vitro models, able to simulate the blood-brain barrier, neurodegeneration or glioma, and useful for optimizing innovative formulations before their in vivo administration via intravenous, oral, or nasal routes, is also summarised. Among the described compounds, quercetin, curcumin, resveratrol, ferulic acid, geraniol, and cinnamaldehyde can be efficaciously formulated to attain brain-targeting characteristics, and may therefore be therapeutically useful against glioma or neurodegenerative diseases.

Antioxidant Compounds in the Treatment of Alzheimer's Disease: Natural, Hybrid, and Synthetic Products

Alzheimer's disease (AD) which is associated with cognitive dysfunction and memory lapse has become a health concern. Various targets and pathways have been involved in AD's progress, such as deficit of acetylcholine (ACh), oxidative stress, inflammation, β-amyloid (Aβ) deposits, and biometal dyshomeostasis. Multiple pieces of evidence indicate that stress oxidative participation in an early stage of AD and the generated ROS could enable neurodegenerative disease leading to neuronal cell death. Hence, antioxidant therapies are applied in treating AD as a beneficial strategy. This review refers to the development and use of antioxidant compounds based on natural products, hybrid designs, and synthetic compounds. The results of using these antioxidant compounds were discussed with the given examples, and future directions for the development of antioxidants were evaluated.

Rosmarinic acid potentiates and detoxifies tacrine in combination for Alzheimer's disease

BACKGROUND

There is no doubt that Alzheimer's disease (AD) is one of the greatest threats facing mankind today. Within the next few decades, Acetylcholinesterase inhibitors (AChEIs) will be the most widely used treatment for Alzheimer's disease. The withdrawal of the first generation AChEIs drug Tacrine (TAC)/ Cognex from the market as a result of hepatotoxicity has always been an interesting case study. Rosmarinic acid (RA) is a natural compound of phenolic acids that has pharmacological activity for inhibiting Alzheimer's disease, as well as liver protection.

PURPOSE AND STUDY DESIGN

In this study, we determined that RA can reduce the hepatotoxicity of TAC, and both of them act synergistically to inhibit the progression of AD in mice.

METHODS

In addition to the wild type mice (WT) group, the 6-month-old APP/PS1 (APPswe/PSEN1dE9) double-transgenic (Tg) mice were randomly divided into 6 groups: Tg group, TAC group, RA group, TAC+Silymarin (SIL) group, TAC+RA-L (Rosmarinic Acid Low Dose) goup and TAC+RA-H (Rosmarinic Acid High Dose) group. A series of experiments were carried out, including open field test, Morris water maze test, Hematoxylin - Eosin (HE) staining, Nissl staining, biochemical analysis, immunofluorescence analysis, western blotting analysis and so on.

RESULTS

RA combined with TAC could enter the brain tissue of AD mice, and the combination of drugs could better improve the cognitive behavior and brain pathological damage of AD mice, reduce the expression of A β oligomer, inhibit the deposition of A β, inhibit the activity of AChE and enhance the level of Ach in hippocampus. Both in vivo and in vitro experiments showed that RA could alleviate the hepatotoxicity or liver injury induced by TAC. The Western blot analysis of the liver of AD mice showed that RA combined with TAC might inhibit the apoptosis of Bcl-2/Bax, reduce the programmed apoptosis mediated by caspase-3 and reduce the burden of liver induced by TAC, could inhibit the development of liver apoptosis by alleviating the hepatotoxicity of TAC and inhibiting the phosphorylation of JNK.

CONCLUSION

The potential drug combination that combines rosmarinic acid with tacrine could reduce tacrine's hepatotoxicity as well as enhance its therapeutic effect on Alzheimer's disease.

Multifunctional Small Molecules as Potential Anti-Alzheimer's Disease Agents

Alzheimer's disease (AD) is a severe multifactorial neurodegenerative disorder characterized by a progressive loss of neurons in the brain. Despite research efforts, the pathogenesis and mechanism of AD progression are not yet completely understood. There are only a few symptomatic drugs approved for the treatment of AD. The multifactorial character of AD suggests that it is important to develop molecules able to target the numerous pathological mechanisms associated with the disease. Thus, in the context of the worldwide recognized interest of multifunctional ligand therapy, we report herein the synthesis, characterization, physicochemical and biological evaluation of a set of five (1a-e) new ferulic acid-based hybrid compounds, namely feroyl-benzyloxyamidic derivatives enclosing different substituent groups, as potential anti-Alzheimer's disease agents. These hybrids can keep both the radical scavenging activity and metal chelation capacity of the naturally occurring ferulic acid scaffold, presenting also good/mild capacity for inhibition of self-Aβ aggregation and fairly good inhibition of Cu-induced Aβ aggregation. The predicted pharmacokinetic properties point towards good absorption, comparable to known oral drugs.

Novel Donepezil-Arylsulfonamide Hybrids as Multitarget-Directed Ligands for Potential Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) is one of the most devastating neurodegenerative disorders, characterized by multiple pathological features. Therefore, multi-target drug discovery has been one of the most active fields searching for new effective anti-AD therapies. Herein, a series of hybrid compounds are reported which were designed and developed by combining an aryl-sulfonamide function with a benzyl-piperidine moiety, the pharmacophore of donepezil (a current anti-AD acetylcholinesterase AChE inhibitor drug) or its benzyl-piperazine analogue. The in vitro results indicate that some of these hybrids achieve optimized activity towards two main AD targets, by displaying excellent AChE inhibitory potencies, as well as the capability to prevent amyloid-β (Aβ) aggregation. Some of these hybrids also prevented Aβ-induced cell toxicity. Significantly, drug-like properties were predicted, including for blood-brain permeability. Compound 9 emerged as a promising multi-target lead compound (AChE inhibition (IC₅₀ 1.6 μM); Aβ aggregation inhibition 60.7%). Overall, this family of hybrids is worthy of further exploration, due to the wide biological activity of sulfonamides.

A review on ferulic acid and analogs based scaffolds for the management of Alzheimer's disease

Alzheimer's disease (AD) is an age-related multifactorial neurodegenerative disorder characterized by severe central cholinergic neuronal loss, gradually contributing to cognitive dysfunction and impaired motor activity, resulting in the brain's cell death at the later stages of AD. Although the etiology of AD is not well understood, however, several factors such as oxidative stress, deposition of amyloid-β (Aβ) peptides to form Aβ plaques, intraneuronal accumulation of hyperphosphorylated tau protein, and low level of acetylcholine are thought to play a major role in the pathogenesis of AD. There is practically no drug for AD treatment that can address the basic factors responsible for the neurodegeneration and slow down the disease progression. The currently available therapies for AD in the market focus on providing only symptomatic relief without addressing the aforesaid basic factors responsible for the neurodegeneration. Ferulic acid (FA) is a phenol derivative from natural sources and serves as a potential pharmacophore that exerts multiple pharmacological properties such as antioxidant, neuroprotection, Aβ aggregation modulation, and anti-inflammatory. Several FA based hybrid analogs are under investigation as a multi-target directed ligand (MTDLs) to develop novel hybrid compounds for the treatment of AD. In the present review article, we are focused on the critical pathogenic factors responsible for the onset of AD followed by the developments of FA pharmacophore-based hybrids compounds as a novel multifunctional therapeutic agent to address the limitations associated with available treatment for AD. The rationale behind the development of these compounds and their pharmacological activities in particular to their ChE inhibition (ChEI), neuroprotection, antioxidant property, Aβ aggregation modulation, and metal chelation ability, are discussed in detail. We have also discussed the discovery of caffeic and cinnamic acids based MTDLs for AD. This review paper provides an in-depth insight into the research progress and current status of these novel therapeutics in AD and prospects for developing a druggable molecule with desired pharmacological affinity and reduced toxicity for the management of AD.

Multi-Targeting Tacrine Conjugates with Cholinesterase and Amyloid-Beta Inhibitory Activities: New Anti-Alzheimer's Agents

Alzheimer's disease (AD) is a severe age dependent and chronic problem with no cure so far. The available treatments are temporary, acting over short period of time. The main pathological hallmark of the disease includes cholinergic dysfunction, oxidative stress, accumulation of Aβ fibrils and tau tangles. In context with the multi-factorial nature of this disease, two different series of molecules were developed to hit the multifactorial disease targets. Mainly, the molecules were designed to inhibit the AChE and aggregation of Aβ, and also oxidative damage. Two novel series of TAC-fenbufen/menbutone conjugated molecules were designed, synthesized and bio-assayed. All compounds showed inhibition capacity towards AChE, Aβ aggregation and moderate to good radical scavenging capacity. Particularly, five TAC-menbutone molecules showed improved AChE and Aβ aggregation inhibition capacity compared to TAC-fenbufen conjugated molecules. Overall, these novel series of molecules may be potential drug lead molecules in the treatment of AD.

Sustainable Straightforward Synthesis and Evaluation of the Antioxidant and Antimicrobial Activity of Sinapine and Analogues

Naturally occurring sinapine was successfully synthesized through a proline-mediated Knoevenagel-Doebner condensation in ethanol. This synthetic process involving biobased syringaldehyde, Meldrum's acid, and choline chloride offers a sustainable alternative to the existing low-yield pathways. This two-step strategy gives access to sinapine in a 52% overall yield and has been implemented in the synthesis of sinapine analogues, using 4-hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, and vanillin as precursors, giving target molecules with 34-61% overall isolated yields. The purity of synthetic sinapine and its analogues (ca. 95%) was assessed by NMR and high-performance liquid chromatography-mass spectrometry analyses. Furthermore, the antioxidant and antimicrobial activities were assessed, and the potential of this series of molecules was confirmed.

Design, Synthesis, and In Vitro Evaluation of Hydroxybenzimidazole-Donepezil Analogues as Multitarget-Directed Ligands for the Treatment of Alzheimer's Disease

A series of multi-target-directed ligands (MTDLs), obtained by attachment of a hydroxyphenylbenzimidazole (BIM) unit to donepezil (DNP) active mimetic moiety (benzyl-piperidine/-piperazine) was designed, synthesized, and evaluated as potential anti-Alzheimer's disease (AD) drugs in terms of biological activity (inhibition of acetylcholinesterase (AChE) and β-amyloid (Aβ) aggregation), metal chelation, and neuroprotection capacity. Among the DNP-BIM hybrids studied herein, the structural isomerization did not significantly improve the biological properties, while some substitutions, namely fluorine atom in each moiety or the methoxy group in the benzyl ring, evidenced higher cholinergic AChE activity. All the compounds are able to chelate Cu and Zn metal ions through their bidentate BIM moieties, but compound 5, containing a three-dentate chelating unit, is the strongest Cu(II) chelator. Concerning the viability on neuroblastoma cells, compounds 9 and 10 displayed the highest reduction of Aβ-induced cell toxicity. In silico calculations of some pharmacokinetic descriptors indicate that all the compounds but the nitro derivatives have good potential oral-bioavailability. Overall, it can be concluded that most of the studied DNP-BIM conjugates showed quite good anti-AD properties, therefore deserving to be considered in further studies with the aim of understanding and treating AD.

Donepezil-based hybrids as multifunctional anti-Alzheimer's disease chelating agents: Effect of positional isomerization

The intricate and multifactorial nature of Alzheimer's disease (AD) requires the development of compounds able to hit different pathophysiological targets, such as cholinergic dysfunction, deposits of amyloid beta (Aβ) peptide and metal dyshomeostasis. In order to continue the search for new anti-AD drugs, a design strategy was once more followed based on repositioning donepezil (DNP) drug, by ortho-attaching a benzylpiperidine mimetic of DNP moiety to a hydroxyphenyl-benzimidazole (BIM) chelating unit (compound 1). Herein, compound 1 and a positional isomer 2 are compared in terms of their potential multiple properties: both present good acetylcholinesterase (AChE) inhibition (low μmolar range) and are moderate/good inhibitors of Aβ self- and Cu-mediated aggregation, the inhibition process being mainly due to ligand intercalation between the β-sheets of the fibrils; compound 1 has a higher chelating capacity towards Cu²⁺ and Zn²⁺ (pCu = 14.3, pZn = 6.4, pH 7.4, C_L/C_M = 10, C_M = 10^-6 M) than 2 (pCu = 10.7, pZn = 6.3), attributed to its ability to establish a tridentate (N,O,O) coordination to the metal ion. Both compounds are eligible as drug candidates for oral administration but compound 1 shows improved neuroprotective role by completely preventing Aβ-induced cell toxicity.

Current Scenario of Pb Toxicity in Plants: Unraveling Plethora of Physiological Responses

Lead (Pb) is an extremely toxic metal for all living forms including plants. It enters plants through roots from soil or soil solution. It is considered as one of the most eminent examples of anthropogenic environmental pollutant added in environment through mining and smelting of lead ores, coal burning, waste from battery industries, leaded paints, metal plating, and automobile exhaust. Uptake of Pb in plants is a nonselective process and is driven by H⁺/ATPases. Translocation of Pb metal ions occurs by apoplastic movement resulting in deposition of metal ions in the endodermis and is further transported by symplastic movement. Plants exposed to high concentration of Pb show toxic symptoms due to the overproduction of reactive oxygen species (ROS) through Fenton-Haber-Weiss reaction. ROS include superoxide anion, hydroxyl radical, and hydrogen peroxide, which reach to macro- and micro-cellular levels in the plant cells and cause oxidative damage. Plant growth and plethora of biochemical and physiological attributes including plant growth, water status, photosynthetic efficiency, antioxidative defense system, phenolic compounds, metal chelators, osmolytes, and redox status are adversely influenced by Pb toxicity. Plants respond to toxic levels of Pb in varied ways such as restricted uptake of metal, chelation of metal ions to the root endodermis, enhancement in activity of antioxidative defense, alteration in metal transporters expression, and involvement of plant growth regulators.

Novel tacrine-benzofuran hybrids as potential multi-target drug candidates for the treatment of Alzheimer's Disease

Pursuing the widespread interest on multi-target drugs to combat Alzheimer´s disease (AD), a new series of hybrids was designed and developed based on the repositioning of the well-known acetylcholinesterase (AChE) inhibitor, tacrine (TAC), by its coupling to benzofuran (BF) derivatives. The BF framework aims to endow the conjugate molecules with ability for inhibition of AChE (bimodal way) and of amyloid-beta peptide aggregation, besides providing metal (Fe, Cu) chelating ability and concomitant extra anti-oxidant activity, for the hybrids with hydroxyl substitution. The new TAC-BF conjugates showed very good activity for AChE inhibition (sub-micromolar range) and good capacity for the inhibition of self- and Cu-mediated Aβ aggregation, with dependence on the linker size and substituent groups of each main moiety. Neuroprotective effects were also found for the compounds through viability assays of neuroblastoma cells, after Aβ_1-42 induced toxicity. Structure-activity relationship analysis provides insights on the best structural parameters, to take in consideration for future studies in view of potential applications in AD therapy.

New Multitarget Hybrids Bearing Tacrine and Phenylbenzothiazole Motifs as Potential Drug Candidates for Alzheimer's Disease

Research on neurodegenerative brain disorders, namely the age-dependent Alzheimer's disease (AD), has been intensified in the last decade due to the absence of a cure and the recognized increasing of life expectancy for populations. To address the multifactorial nature and complexity of AD, a multi-target-directed ligand approach was herein employed, by designing a set of six selected hybrids (14⁻19) that combine in the same entity two pharmacophores: tacrine (TAC) and 2-phenylbenzothiazole (PhBTA). The compounds contain a methoxy substituent at the PhBTA moiety and have a variable length linker between that and the TAC moiety. The docking studies showed that all the compounds assure a dual-binding mode of acetylcholinesterase (AChE) inhibition, establishing π-stacking and H-bond interactions with aminoacid residues at both active binding sites of the enzyme (CAS and PAS). The bioassays revealed that the designed compounds display excellent AChE inhibitory activity in the sub-micromolar range (0.06⁻0.27 μM) and moderate inhibition values for amyloid-β (Aβ) self-aggregation (27⁻44.6%), compounds 14 and 15 being the lead compounds. Regarding neuroprotective effects in neuroblastoma cells, compounds 15, 16 and 19 revealed the capacity to prevent Aβ-induced toxicity, but compound 16 showed the highest neuroprotective effect. Overall these hybrid compounds, in particular 15 and 16, with promising multitarget anti-AD ability, encourage further pursuing studies on this type of TAC-PhBTA derivatives for potential AD therapy.

Donepezil structure-based hybrids as potential multifunctional anti-Alzheimer's drug candidates

A new series of multifunctional hybrids, based on the structure of the donepezil (DNP) drug, have been developed and evaluated as potential anti Alzheimer's disease (AD) agents. The rationale of this study was the conjugation of a benzylpiperidine/benzylpiperazine moiety with derivatives of bioactive heterocyclics (benzimidazole or benzofuran), to mimic the main structure of DNP and to endow the hybrids with additional relevant properties such as inhibition of amyloid beta (Aβ) peptide aggregation, antioxidant activity and metal chelation. Overall, they showed good activity for AChE inhibition (IC50=4.0-30.0 μΜ) and moderate ability for inhibition of Aβ1-42 self-mediated aggregation. The hybrids containing chelating groups showed improvement in the inhibition of Cu-induced Aβ42 aggregation and the antioxidant capacity. Moreover, neuroprotective effects of these compounds were evidenced in neuroblastoma cells after Aβ1-42 induced toxicity. Structure-activity relationship allowed the identification of some promising compounds and the main determinant structural features for the targeted properties.

Development of coumarin-benzofuran hybrids as versatile multitargeted compounds for the treatment of Alzheimer's Disease

Alzheimer's disease (AD), the most common cause of dementia, is a neurodegenerative disorder characterized by progressive deterioration of memory and cognition. The evidenced multifactorial nature of AD has been considered the main reason for the absence of cure so far. Therefore, the development of novel hybrids to treat the disease is very much essential. Focusing on this, a novel series of coumarin-benzofuran hybrids have been designed and screened as anti-Alzheimer's disease agents. The strategy is to obtain an effective mimetic of donepezil, which is acetylcholinesterase inhibitor. Herein, the two main scaffolds namely coumarin and benzofuran are known pharmacophore moieties and we have performed their molecular design, pharmacokinetic descriptor studies for drug-likeliness. Further, in vitro studies such as antioxidant capacity, acetylcholinesterase (AChE) inhibition and amyloid-β (Aβ) self-aggregation inhibition have also been performed. Most importantly, these studies revealed that the newly synthesized hybrids can be versatile and promising drug-like moieties as efficient anti-AD agents.

Novel Tacrine-Hydroxyphenylbenzimidazole hybrids as potential multitarget drug candidates for Alzheimer's disease

Alzheimer's disease (AD) is a severe age-dependent neurodegenerative disorder affecting millions of people, with no cure so far. The current treatments only achieve some temporary amelioration of the cognition symptoms. The main characteristics of the patient brains include the accumulation of amyloid plaques and neurofibrillary tangles (outside and inside the neurons) but also cholinergic deficit, increased oxidative stress and dyshomeostasis of transition metal ions. Considering the multi-factorial nature of AD, we report herein the development of a novel series of potential multi-target directed drugs which, besides the capacity to recover the cholinergic neurons, can also target other AD hallmarks. The novel series of tacrine-hydroxyphenylbenzimidazole (TAC-BIM) hybrid molecules has been designed, synthesized and studied for their multiple biological activities. These agents showed improved AChE inhibitory activity (IC₅₀ in nanomolar range), as compared with the single drug tacrine (TAC), and also a high inhibition of self-induced- and Cu-induced-Aβ aggregation (up to 75%). They also present moderate radical scavenging activity and metal chelating ability. In addition, neuroprotective studies revealed that all these tested compounds are able to inhibit the neurotoxicity induced by Aβ and Fe/AscH(-) in neuronal cells. Hence, for this set of hybrids, structure-activity relationships are discussed and finally it is highlighted their real promising interest as potential anti-AD drugs.

Synthesis, structure, antioxidant activity, and water solubility of trolox ion conjugates

The interaction of trolox with ammonia, alkylamines of different classes, and amino derivatives of heterocyclic compounds, including nitroxyl radicals and alkaloids, led to the production of ammonium salts called ion conjugates (ICs). Five ICs were characterised by X-ray diffraction. This is the first time a wide range of ICs were made from trolox with amines, and ESI-MS data demonstrated they have the potential to generate pseudomolecular [(A⁻B⁺) + H]⁺ ions. For all obtained trolox ICs, a significant increase (1–3 orders of magnitude) in water solubility was achieved while retaining high antioxidant activity. ICs synthesised from two biologically active fragments may be used to create polyfunctional agents with varying solubility and bioavailability.

Hydroxypyridinone-benzofuran hybrids with potential protective roles for Alzheimer´s disease therapy

A series of (3-hydroxy-4-pyridinone)-benzofuran hybrids have been developed and studied as potential multitargeting drugs for Alzheimer's disease (AD). Their design envisaged mainly to mimic the donepezil drug, a marketed inhibitor of acetylcholinesterase (AChE), and to endow the conjugate molecules with extra-properties such as metal chelation, radical scavenging and inhibition of amyloid peptide (Aβ) aggregation. Thus, a set of eleven new hybrid compounds was developed and evaluated for chemical and biological properties, in solution and in neuronal cell environment. The results are discussed in terms of the type of substituents on both main moieties and the linker size. The closest similarity with donepezil, in terms of AChE inhibitory activity, was obtained for the O-benzyl-hydroxypyridinone hybrids containing a 2-methylene linker, although still less active than the drug. However, the free-hydroxypyridinone hybrids present higher activity for the Aβ aggregation inhibition, metal chelating capacity and radical scavenging activity. Overall, some compounds demonstrated capacity to exert a multiple action by hitting three- (7d) or four- (8d, 8f) pathophysiological targets of AD. Furthermore, the compounds showed neuroprotective effects in neuronal cells subjected to model stressors of AD, but not significant dependence on the substituent groups. Importantly, the compounds evidenced drug-likeness properties, including good membrane permeability.

Acetamide Derivatives of Chromen-2-ones as Potent Cholinesterase Inhibitors

Alzheimer's disease (AD), a neurodegenerative disorder, is a serious medical issue worldwide with drastic social consequences. Inhibition of cholinesterase is one of the rational and effective approaches to retard the symptoms of AD and, hence, consistent efforts are being made to develop efficient anti-cholinesterase agents. In pursuit of this, a series of 19 acetamide derivatives of chromen-2-ones were synthesized and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potential. All the synthesized compounds exhibited significant anti-AChE and anti-BChE activity, with IC₅₀ values in the range of 0.24-10.19 μM and 0.64-30.08 μM, respectively, using donepezil hydrochloride as the standard. Out of 19 compounds screened, 3 compounds, viz. 22, 40, and 43, caused 50% inhibition of AChE at 0.24, 0.25, and 0.25 μM, respectively. A kinetic study revealed them to be mixed-type inhibitors, binding with both the CAS and PAS sites of AChE. The above-selected compounds were found to be effective inhibitors of AChE-induced and self-mediated Aβ_1-42 aggregation. ADMET predictions demonstrated that these compounds may possess suitable blood-brain barrier (BBB) permeability. Hemolytic assay results revealed that these compounds did not lyse human RBCs up to a thousand times of their IC₅₀ value. MTT assays performed for the shortlisted compounds showed them to be negligibly toxic after 24 h of treatment with the SH-SY5Y neuroblastoma cells. These results provide insights for further optimization of the scaffolds for designing the next generation of compounds as lead cholinesterase inhibitors.

The Contribution of Buckwheat Genetic Resources to Health and Dietary Diversity

Despite several reports on the beneficial effects of buckwheat in prevention of human diseases, little attention has been devoted to the variability of biochemical and physiological traits in different buckwheat genetic resources. This review describes the biochemical evaluation of buckwheat genetic resources and the identification of elite genotypes for plant breeding and exploitation. The various types of bioactive compounds present in different varieties provide basic background information needed for the efficient production of buckwheat foods with added value. In this review, we will provide an integrated view of the biochemistry of bioactive compounds of buckwheat plants of different origin, especially of fagopyrin, proteins and amino acids, as well as of other phenolic compounds including rutin and chlorogenic acid. In addition to the genetic background, the effect of different growth conditions is discussed. The health effects of fagopyrin, phenolic acids, specific proteins and rutin are also presented.

Tacrine-allyl/propargylcysteine–benzothiazole trihybrids as potential anti-Alzheimer's drug candidates

Eight novel trihybrids as potential anti-Alzheimer's drugs showed high AChEI and anti-Aβ aggregation capacity, moderate anti-ROS activity and low MAO inhibition.

New Tacrine Hybrids with Natural-Based Cysteine Derivatives as Multitargeted Drugs for Potential Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a devastating age-dependent neurodegenerative disorder. The main hallmarks are impairment of cholinergic system and accumulation in brain of beta-amyloid (Aβ) aggregates, which have been associated with oxidative damage and dyshomeostasis of redox-active biometals. The absence of an efficient treatment that could delay or cure AD has been attributed to the complexity and multifactorial nature of this disease. With this in mind and the recent interest on natural-based drugs, we have explored a set of natural-based hybrid compounds by conjugation of a tacrine moiety with an S-allylcysteine (garlic constituent) or S-propargylcysteine moiety aimed at improving the cholinergic system and neuroprotective capacity. The docking modeling studies allowed the selection of linkers to optimize the bimodal drug interaction with acetylcholinesterase enzyme (AChE) active site. The compounds were evaluated for some representative biological properties, including AChE activity and Aβ aggregation inhibition, as well as for their neuroprotective activity to Aβ- and ROS-induced cellular toxicity. The most promising results were achieved by compounds 9d for the AChE inhibition and 9l for the remarkable prevention of superoxide production and Aβ-induced cellular toxicity.

Copper(II) complexation of tacrine hybrids with potential anti-neurodegenerative roles

The complexity and multifactorial nature of neurodegenerative diseases turn quite difficult the development of adequate drugs for their treatment. Multi-target analogues, in conjugation with natural moieties, have been developed in order to combine acetylcholinesterase (AChE) inhibition with antioxidant properties, metal-binding capacity and inhibition of amyloid-β (Aβ) aggregation. Due to the recent interest on natural-based drugs and also the importance of studying the role of transition metal ions in the disease process, we herein evaluate the copper chelating capacity and inhibitory ability for self- and Cu-induced Aβ1-42 aggregation of two nature-base hybrid model compounds obtained from conjugation of a tacrine moiety with a S-allylcystein (1) or S-propargylcystein (2) moiety. Both compounds show a moderate chelating power towards Cu(II) (pCu 7.13-7.51, CL/CCu=10, CCu=10(-6)M, pH7.4), with predominant formation of 1:1 complex species (CuL, CuH-1L) for which the coordination sphere involves the N-amide and the NH2 amine of the cysteine derivative as well as the NH of tacrine. The compounds are able to improve the inhibition of Aβ aggregation in the presence of Cu(II) and this is slightly more relevant for the allyl derivative (1), a stronger copper chelator, than for the propargyl (2). Moreover, the presence of a chloro atom in the tacrine moiety and the size of the chain length between the two NH groups appeared also to improve the inhibition capacity for Aβ aggregation.

Effect of chlorocholine chlorid on phenolic acids accumulation and polyphenols formation of buckwheat plants

BACKGROUND

Effect of chlorocholine chloride (CCC) on phenolic acids composition and polyphenols accumulation in various anatomical parts (stems, leaves and inflorescences) of common buckwheat (Fagopyrum esculentum Moench) in the early stages of vegetation period were surveyed.

RESULTS

Treatment of buckwheat seeds with 2% of CCC has been increased content of total phenolics in the stems, leaves and inflorescences. On analyzing the different parts of buckwheat plants, 9 different phenolic acids - vanilic acid, ferulic acid, trans-ferulic acid, chlorogenic acid, salycilic acid, cinamic acid, p-coumaric acid, p-anisic acid, methoxycinamic acid and catechins were identified. The levels of identified phenolic acids varied not only significantly among the plant organs but also between early stages of vegetation period. Same changes as in contents of chlorogenic acid, ferulic acid, trans-ferulic acid were found for content of salycilic acid. The content of these phenolic acids has been significant increased under effect of 2% CCC treatment at the phase I (formation of buds) in the stems and at the phase II (beginning of flowering) in the leaves and then inflorescences respectively. The content of catechins as potential buckwheat antioxidants has been increased at the early stages of vegetation period after treatment with 2% CCC.

CONCLUSIONS

The obtained results suggest that influence of CCC on the phenolics composition can be a result of various mechanisms of CCC uptake, transforming and/or its translocation in the buckwheat seedlings.

Interaction between Plectranthus barbatus herbal tea components and acetylcholinesterase: binding and activity studies

Plectranthus barbatus water extracts, have been used as herbal teas, for the treatment of various diseases. In a previous study it was demonstrated that antioxidant and anti-acetylcholinesterase active extract constituents and their metabolites were found in the plasma of rats after P. barbatus tea intraperitoneal administration. Consequently, a decrease in brain acetylcholinesterase activity occurred. The aim of the present research is to elucidate how P. barbatus extract components interact with acetylcholinesterase. The estimated thermodynamic parameters suggest that the main intermolecular interaction is hydrophobic association, although hydrogen bonds between flavonoids and the active gorge of the acetylcholinesterase molecule seem to occur and have a great impact on acetylcholinesterase inhibition. The hydroxyl positions in flavonoids seem to be of utmost importance for enzyme inhibition, as they interact with specific amino acid residues in the active gorge. FTIR analysis showed that the plant extract components do not interfere with the secondary structure of the enzyme, but decreases the rate of hydrogen-deuterium exchange, possibly by decreasing solvent accessibility in the acetylcholinesterase active gorge. The spectroscopic data complements docking studies of acetylcholinesterase inhibition by plant phenolic compounds, clarifying the dominant interactions between enzyme and inhibitor and the most important structural features of the inhibitor molecules.

Multifunctional iron-chelators with protective roles against neurodegenerative diseases

The multifactorial nature of Alzheimer's disease (AD), and the absence of a disease modifying drug, makes the development of new multifunctional drugs an attractive therapeutic strategy. Taking into account the hallmarks of AD patient brains, such as low levels of acetylcholine, misfolding of proteins and associated beta-amyloid (Aβ) aggregation, oxidative stress and metal dyshomeostasis, we have developed a series of compounds that merge three different approaches: metal attenuation, anti-Aβ aggregation and anti-acetylcholinesterase activity. Therefore, 3-hydroxy-4-pyridinone (3,4-HP) and benzothiazole molecular moieties were selected as starting frameworks due to their well known affinity for iron and Aβ peptides, respectively. The linkers between these two main functional groups were selected on the basis of virtual screening, so that the final molecule could further inhibit the acetylcholinesterase, responsible for the cholinergic losses. We describe herein the design and synthesis of the new hybrid compounds, followed by the assessment of solution properties, namely iron chelation and anti-oxidant capacity. The compounds were bioassayed for their capacity to inhibit AChE, as well as self- and Zn mediated-Aβ(1-42) aggregation. Finally, we assessed their effects on the viability of neuronal cells stressed with Aβ(42).